sessiond: notification: synchronize notification client (and list)
[lttng-tools.git] / src / bin / lttng-sessiond / notification-thread-events.c
index df801be59d77f1b50561cae48705177277f133cb..285bcf951aafe3a5bb2801777e7a13eb06dc5ec7 100644 (file)
@@ -1,18 +1,8 @@
 /*
- * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
  *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License, version 2 only, as
- * published by the Free Software Foundation.
+ * SPDX-License-Identifier: GPL-2.0-only
  *
- * This program is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
- * more details.
- *
- * You should have received a copy of the GNU General Public License along with
- * this program; if not, write to the Free Software Foundation, Inc., 51
- * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
 #define _LGPL_SOURCE
 #include <common/sessiond-comm/sessiond-comm.h>
 #include <common/macros.h>
 #include <lttng/condition/condition.h>
-#include <lttng/action/action.h>
+#include <lttng/action/action-internal.h>
 #include <lttng/notification/notification-internal.h>
 #include <lttng/condition/condition-internal.h>
 #include <lttng/condition/buffer-usage-internal.h>
+#include <lttng/condition/session-consumed-size-internal.h>
+#include <lttng/condition/session-rotation-internal.h>
 #include <lttng/notification/channel-internal.h>
 
 #include <time.h>
 #define CLIENT_POLL_MASK_IN (LPOLLIN | LPOLLERR | LPOLLHUP | LPOLLRDHUP)
 #define CLIENT_POLL_MASK_IN_OUT (CLIENT_POLL_MASK_IN | LPOLLOUT)
 
+enum lttng_object_type {
+       LTTNG_OBJECT_TYPE_UNKNOWN,
+       LTTNG_OBJECT_TYPE_NONE,
+       LTTNG_OBJECT_TYPE_CHANNEL,
+       LTTNG_OBJECT_TYPE_SESSION,
+};
+
 struct lttng_trigger_list_element {
-       struct lttng_trigger *trigger;
+       /* No ownership of the trigger object is assumed. */
+       const struct lttng_trigger *trigger;
        struct cds_list_head node;
 };
 
 struct lttng_channel_trigger_list {
        struct channel_key channel_key;
+       /* List of struct lttng_trigger_list_element. */
        struct cds_list_head list;
+       /* Node in the channel_triggers_ht */
        struct cds_lfht_node channel_triggers_ht_node;
+       /* call_rcu delayed reclaim. */
+       struct rcu_head rcu_node;
+};
+
+/*
+ * List of triggers applying to a given session.
+ *
+ * See:
+ *   - lttng_session_trigger_list_create()
+ *   - lttng_session_trigger_list_build()
+ *   - lttng_session_trigger_list_destroy()
+ *   - lttng_session_trigger_list_add()
+ */
+struct lttng_session_trigger_list {
+       /*
+        * Not owned by this; points to the session_info structure's
+        * session name.
+        */
+       const char *session_name;
+       /* List of struct lttng_trigger_list_element. */
+       struct cds_list_head list;
+       /* Node in the session_triggers_ht */
+       struct cds_lfht_node session_triggers_ht_node;
+       /*
+        * Weak reference to the notification system's session triggers
+        * hashtable.
+        *
+        * The session trigger list structure structure is owned by
+        * the session's session_info.
+        *
+        * The session_info is kept alive the the channel_infos holding a
+        * reference to it (reference counting). When those channels are
+        * destroyed (at runtime or on teardown), the reference they hold
+        * to the session_info are released. On destruction of session_info,
+        * session_info_destroy() will remove the list of triggers applying
+        * to this session from the notification system's state.
+        *
+        * This implies that the session_triggers_ht must be destroyed
+        * after the channels.
+        */
+       struct cds_lfht *session_triggers_ht;
+       /* Used for delayed RCU reclaim. */
+       struct rcu_head rcu_node;
 };
 
 struct lttng_trigger_ht_element {
        struct lttng_trigger *trigger;
        struct cds_lfht_node node;
+       /* call_rcu delayed reclaim. */
+       struct rcu_head rcu_node;
 };
 
 struct lttng_condition_list_element {
@@ -75,13 +122,41 @@ struct notification_client_list_element {
        struct cds_list_head node;
 };
 
+/*
+ * Thread safety of notification_client and notification_client_list.
+ *
+ * The notification thread (main thread) and the action executor
+ * interact through client lists. Hence, when the action executor
+ * thread looks-up the list of clients subscribed to a given
+ * condition, it will acquire a reference to the list and lock it
+ * while attempting to communicate with the various clients.
+ *
+ * It is not necessary to reference-count clients as they are guaranteed
+ * to be 'alive' if they are present in a list and that list is locked. Indeed,
+ * removing references to the client from those subscription lists is part of
+ * the work performed on destruction of a client.
+ *
+ * No provision for other access scenarios are taken into account;
+ * this is the bare minimum to make these accesses safe and the
+ * notification thread's state is _not_ "thread-safe" in any general
+ * sense.
+ */
 struct notification_client_list {
-       struct lttng_trigger *trigger;
+       pthread_mutex_t lock;
+       struct urcu_ref ref;
+       const struct lttng_trigger *trigger;
        struct cds_list_head list;
-       struct cds_lfht_node notification_trigger_ht_node;
+       /* Weak reference to container. */
+       struct cds_lfht *notification_trigger_clients_ht;
+       struct cds_lfht_node notification_trigger_clients_ht_node;
+       /* call_rcu delayed reclaim. */
+       struct rcu_head rcu_node;
 };
 
 struct notification_client {
+       /* Nests within the notification_client_list lock. */
+       pthread_mutex_t lock;
+       notification_client_id id;
        int socket;
        /* Client protocol version. */
        uint8_t major, minor;
@@ -99,7 +174,16 @@ struct notification_client {
         */
        struct cds_list_head condition_list;
        struct cds_lfht_node client_socket_ht_node;
+       struct cds_lfht_node client_id_ht_node;
        struct {
+               /*
+                * If a client's communication is inactive, it means that a
+                * fatal error has occurred (could be either a protocol error or
+                * the socket API returned a fatal error). No further
+                * communication should be attempted; the client is queued for
+                * clean-up.
+                */
+               bool active;
                struct {
                        /*
                         * During the reception of a message, the reception
@@ -145,6 +229,8 @@ struct notification_client {
                        struct lttng_dynamic_buffer buffer;
                } outbound;
        } communication;
+       /* call_rcu delayed reclaim. */
+       struct rcu_head rcu_node;
 };
 
 struct channel_state_sample {
@@ -152,23 +238,29 @@ struct channel_state_sample {
        struct cds_lfht_node channel_state_ht_node;
        uint64_t highest_usage;
        uint64_t lowest_usage;
+       uint64_t channel_total_consumed;
+       /* call_rcu delayed reclaim. */
+       struct rcu_head rcu_node;
 };
 
 static unsigned long hash_channel_key(struct channel_key *key);
-static int evaluate_condition(struct lttng_condition *condition,
+static int evaluate_buffer_condition(const struct lttng_condition *condition,
                struct lttng_evaluation **evaluation,
-               struct notification_thread_state *state,
-               struct channel_state_sample *previous_sample,
-               struct channel_state_sample *latest_sample,
-               uint64_t buffer_capacity);
+               const struct notification_thread_state *state,
+               const struct channel_state_sample *previous_sample,
+               const struct channel_state_sample *latest_sample,
+               uint64_t previous_session_consumed_total,
+               uint64_t latest_session_consumed_total,
+               struct channel_info *channel_info);
 static
-int send_evaluation_to_clients(struct lttng_trigger *trigger,
-               struct lttng_evaluation *evaluation,
+int send_evaluation_to_clients(const struct lttng_trigger *trigger,
+               const struct lttng_evaluation *evaluation,
                struct notification_client_list *client_list,
                struct notification_thread_state *state,
                uid_t channel_uid, gid_t channel_gid);
 
 
+/* session_info API */
 static
 void session_info_destroy(void *_data);
 static
@@ -177,7 +269,9 @@ static
 void session_info_put(struct session_info *session_info);
 static
 struct session_info *session_info_create(const char *name,
-               uid_t uid, gid_t gid);
+               uid_t uid, gid_t gid,
+               struct lttng_session_trigger_list *trigger_list,
+               struct cds_lfht *sessions_ht);
 static
 void session_info_add_channel(struct session_info *session_info,
                struct channel_info *channel_info);
@@ -185,17 +279,43 @@ static
 void session_info_remove_channel(struct session_info *session_info,
                struct channel_info *channel_info);
 
+/* lttng_session_trigger_list API */
+static
+struct lttng_session_trigger_list *lttng_session_trigger_list_create(
+               const char *session_name,
+               struct cds_lfht *session_triggers_ht);
+static
+struct lttng_session_trigger_list *lttng_session_trigger_list_build(
+               const struct notification_thread_state *state,
+               const char *session_name);
+static
+void lttng_session_trigger_list_destroy(
+               struct lttng_session_trigger_list *list);
+static
+int lttng_session_trigger_list_add(struct lttng_session_trigger_list *list,
+               const struct lttng_trigger *trigger);
+
+
 static
-int match_client(struct cds_lfht_node *node, const void *key)
+int match_client_socket(struct cds_lfht_node *node, const void *key)
 {
        /* This double-cast is intended to supress pointer-to-cast warning. */
-       int socket = (int) (intptr_t) key;
-       struct notification_client *client;
+       const int socket = (int) (intptr_t) key;
+       const struct notification_client *client = caa_container_of(node,
+                       struct notification_client, client_socket_ht_node);
 
-       client = caa_container_of(node, struct notification_client,
-                       client_socket_ht_node);
+       return client->socket == socket;
+}
+
+static
+int match_client_id(struct cds_lfht_node *node, const void *key)
+{
+       /* This double-cast is intended to supress pointer-to-cast warning. */
+       const notification_client_id id = *((notification_client_id *) key);
+       const struct notification_client *client = caa_container_of(
+                       node, struct notification_client, client_id_ht_node);
 
-       return !!(client->socket == socket);
+       return client->id == id;
 }
 
 static
@@ -211,6 +331,18 @@ int match_channel_trigger_list(struct cds_lfht_node *node, const void *key)
                        (channel_key->domain == trigger_list->channel_key.domain));
 }
 
+static
+int match_session_trigger_list(struct cds_lfht_node *node, const void *key)
+{
+       const char *session_name = (const char *) key;
+       struct lttng_session_trigger_list *trigger_list;
+
+       trigger_list = caa_container_of(node, struct lttng_session_trigger_list,
+                       session_triggers_ht_node);
+
+       return !!(strcmp(trigger_list->session_name, session_name) == 0);
+}
+
 static
 int match_channel_state_sample(struct cds_lfht_node *node, const void *key)
 {
@@ -253,49 +385,44 @@ int match_condition(struct cds_lfht_node *node, const void *key)
 }
 
 static
-int match_client_list(struct cds_lfht_node *node, const void *key)
+int match_client_list_condition(struct cds_lfht_node *node, const void *key)
 {
-       struct lttng_trigger *trigger_key = (struct lttng_trigger *) key;
+       struct lttng_condition *condition_key = (struct lttng_condition *) key;
        struct notification_client_list *client_list;
-       struct lttng_condition *condition;
-       struct lttng_condition *condition_key = lttng_trigger_get_condition(
-                       trigger_key);
+       const struct lttng_condition *condition;
 
        assert(condition_key);
 
        client_list = caa_container_of(node, struct notification_client_list,
-                       notification_trigger_ht_node);
-       condition = lttng_trigger_get_condition(client_list->trigger);
+                       notification_trigger_clients_ht_node);
+       condition = lttng_trigger_get_const_condition(client_list->trigger);
 
        return !!lttng_condition_is_equal(condition_key, condition);
 }
 
 static
-int match_client_list_condition(struct cds_lfht_node *node, const void *key)
+int match_session(struct cds_lfht_node *node, const void *key)
 {
-       struct lttng_condition *condition_key = (struct lttng_condition *) key;
-       struct notification_client_list *client_list;
-       struct lttng_condition *condition;
-
-       assert(condition_key);
-
-       client_list = caa_container_of(node, struct notification_client_list,
-                       notification_trigger_ht_node);
-       condition = lttng_trigger_get_condition(client_list->trigger);
+       const char *name = key;
+       struct session_info *session_info = caa_container_of(
+               node, struct session_info, sessions_ht_node);
 
-       return !!lttng_condition_is_equal(condition_key, condition);
+       return !strcmp(session_info->name, name);
 }
 
 static
 unsigned long lttng_condition_buffer_usage_hash(
-       struct lttng_condition *_condition)
+       const struct lttng_condition *_condition)
 {
-       unsigned long hash = 0;
+       unsigned long hash;
+       unsigned long condition_type;
        struct lttng_condition_buffer_usage *condition;
 
        condition = container_of(_condition,
                        struct lttng_condition_buffer_usage, parent);
 
+       condition_type = (unsigned long) condition->parent.type;
+       hash = hash_key_ulong((void *) condition_type, lttng_ht_seed);
        if (condition->session_name) {
                hash ^= hash_key_str(condition->session_name, lttng_ht_seed);
        }
@@ -321,18 +448,61 @@ unsigned long lttng_condition_buffer_usage_hash(
        return hash;
 }
 
+static
+unsigned long lttng_condition_session_consumed_size_hash(
+       const struct lttng_condition *_condition)
+{
+       unsigned long hash;
+       unsigned long condition_type =
+                       (unsigned long) LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE;
+       struct lttng_condition_session_consumed_size *condition;
+       uint64_t val;
+
+       condition = container_of(_condition,
+                       struct lttng_condition_session_consumed_size, parent);
+
+       hash = hash_key_ulong((void *) condition_type, lttng_ht_seed);
+       if (condition->session_name) {
+               hash ^= hash_key_str(condition->session_name, lttng_ht_seed);
+       }
+       val = condition->consumed_threshold_bytes.value;
+       hash ^= hash_key_u64(&val, lttng_ht_seed);
+       return hash;
+}
+
+static
+unsigned long lttng_condition_session_rotation_hash(
+       const struct lttng_condition *_condition)
+{
+       unsigned long hash, condition_type;
+       struct lttng_condition_session_rotation *condition;
+
+       condition = container_of(_condition,
+                       struct lttng_condition_session_rotation, parent);
+       condition_type = (unsigned long) condition->parent.type;
+       hash = hash_key_ulong((void *) condition_type, lttng_ht_seed);
+       assert(condition->session_name);
+       hash ^= hash_key_str(condition->session_name, lttng_ht_seed);
+       return hash;
+}
+
 /*
  * The lttng_condition hashing code is kept in this file (rather than
  * condition.c) since it makes use of GPLv2 code (hashtable utils), which we
  * don't want to link in liblttng-ctl.
  */
 static
-unsigned long lttng_condition_hash(struct lttng_condition *condition)
+unsigned long lttng_condition_hash(const struct lttng_condition *condition)
 {
        switch (condition->type) {
        case LTTNG_CONDITION_TYPE_BUFFER_USAGE_LOW:
        case LTTNG_CONDITION_TYPE_BUFFER_USAGE_HIGH:
                return lttng_condition_buffer_usage_hash(condition);
+       case LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE:
+               return lttng_condition_session_consumed_size_hash(condition);
+       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_ONGOING:
+       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_COMPLETED:
+               return lttng_condition_session_rotation_hash(condition);
        default:
                ERR("[notification-thread] Unexpected condition type caught");
                abort();
@@ -349,6 +519,49 @@ unsigned long hash_channel_key(struct channel_key *key)
        return key_hash ^ domain_hash;
 }
 
+static
+unsigned long hash_client_socket(int socket)
+{
+       return hash_key_ulong((void *) (unsigned long) socket, lttng_ht_seed);
+}
+
+static
+unsigned long hash_client_id(notification_client_id id)
+{
+       return hash_key_u64(&id, lttng_ht_seed);
+}
+
+/*
+ * Get the type of object to which a given condition applies. Bindings let
+ * the notification system evaluate a trigger's condition when a given
+ * object's state is updated.
+ *
+ * For instance, a condition bound to a channel will be evaluated everytime
+ * the channel's state is changed by a channel monitoring sample.
+ */
+static
+enum lttng_object_type get_condition_binding_object(
+               const struct lttng_condition *condition)
+{
+       switch (lttng_condition_get_type(condition)) {
+       case LTTNG_CONDITION_TYPE_BUFFER_USAGE_LOW:
+       case LTTNG_CONDITION_TYPE_BUFFER_USAGE_HIGH:
+       case LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE:
+               return LTTNG_OBJECT_TYPE_CHANNEL;
+       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_ONGOING:
+       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_COMPLETED:
+               return LTTNG_OBJECT_TYPE_SESSION;
+       default:
+               return LTTNG_OBJECT_TYPE_UNKNOWN;
+       }
+}
+
+static
+void free_channel_info_rcu(struct rcu_head *node)
+{
+       free(caa_container_of(node, struct channel_info, rcu_node));
+}
+
 static
 void channel_info_destroy(struct channel_info *channel_info)
 {
@@ -364,7 +577,13 @@ void channel_info_destroy(struct channel_info *channel_info)
        if (channel_info->name) {
                free(channel_info->name);
        }
-       free(channel_info);
+       call_rcu(&channel_info->rcu_node, free_channel_info_rcu);
+}
+
+static
+void free_session_info_rcu(struct rcu_head *node)
+{
+       free(caa_container_of(node, struct session_info, rcu_node));
 }
 
 /* Don't call directly, use the ref-counting mechanism. */
@@ -372,13 +591,23 @@ static
 void session_info_destroy(void *_data)
 {
        struct session_info *session_info = _data;
+       int ret;
 
        assert(session_info);
        if (session_info->channel_infos_ht) {
-               cds_lfht_destroy(session_info->channel_infos_ht, NULL);
+               ret = cds_lfht_destroy(session_info->channel_infos_ht, NULL);
+               if (ret) {
+                       ERR("[notification-thread] Failed to destroy channel information hash table");
+               }
        }
+       lttng_session_trigger_list_destroy(session_info->trigger_list);
+
+       rcu_read_lock();
+       cds_lfht_del(session_info->sessions_ht,
+                       &session_info->sessions_ht_node);
+       rcu_read_unlock();
        free(session_info->name);
-       free(session_info);
+       call_rcu(&session_info->rcu_node, free_session_info_rcu);
 }
 
 static
@@ -400,7 +629,9 @@ void session_info_put(struct session_info *session_info)
 }
 
 static
-struct session_info *session_info_create(const char *name, uid_t uid, gid_t gid)
+struct session_info *session_info_create(const char *name, uid_t uid, gid_t gid,
+               struct lttng_session_trigger_list *trigger_list,
+               struct cds_lfht *sessions_ht)
 {
        struct session_info *session_info;
 
@@ -425,6 +656,8 @@ struct session_info *session_info_create(const char *name, uid_t uid, gid_t gid)
        }
        session_info->uid = uid;
        session_info->gid = gid;
+       session_info->trigger_list = trigger_list;
+       session_info->sessions_ht = sessions_ht;
 end:
        return session_info;
 error:
@@ -489,12 +722,122 @@ error:
        return NULL;
 }
 
-/* This function must be called with the RCU read lock held. */
 static
-int evaluate_condition_for_client(struct lttng_trigger *trigger,
-               struct lttng_condition *condition,
-               struct notification_client *client,
-               struct notification_thread_state *state)
+bool notification_client_list_get(struct notification_client_list *list)
+{
+       return urcu_ref_get_unless_zero(&list->ref);
+}
+
+static
+void free_notification_client_list_rcu(struct rcu_head *node)
+{
+       free(caa_container_of(node, struct notification_client_list,
+                       rcu_node));
+}
+
+static
+void notification_client_list_release(struct urcu_ref *list_ref)
+{
+       struct notification_client_list *list =
+                       container_of(list_ref, typeof(*list), ref);
+       struct notification_client_list_element *client_list_element, *tmp;
+
+       if (list->notification_trigger_clients_ht) {
+               rcu_read_lock();
+               cds_lfht_del(list->notification_trigger_clients_ht,
+                               &list->notification_trigger_clients_ht_node);
+               rcu_read_unlock();
+               list->notification_trigger_clients_ht = NULL;
+       }
+       cds_list_for_each_entry_safe(client_list_element, tmp,
+                                    &list->list, node) {
+               free(client_list_element);
+       }
+       pthread_mutex_destroy(&list->lock);
+       call_rcu(&list->rcu_node, free_notification_client_list_rcu);
+}
+
+static
+struct notification_client_list *notification_client_list_create(
+               const struct lttng_trigger *trigger)
+{
+       struct notification_client_list *client_list =
+                       zmalloc(sizeof(*client_list));
+
+       if (!client_list) {
+               goto error;
+       }
+       pthread_mutex_init(&client_list->lock, NULL);
+       urcu_ref_init(&client_list->ref);
+       cds_lfht_node_init(&client_list->notification_trigger_clients_ht_node);
+       CDS_INIT_LIST_HEAD(&client_list->list);
+       client_list->trigger = trigger;
+error:
+       return client_list;
+}
+
+static
+void publish_notification_client_list(
+               struct notification_thread_state *state,
+               struct notification_client_list *list)
+{
+       const struct lttng_condition *condition =
+                       lttng_trigger_get_const_condition(list->trigger);
+
+       assert(!list->notification_trigger_clients_ht);
+
+       list->notification_trigger_clients_ht =
+                       state->notification_trigger_clients_ht;
+
+       rcu_read_lock();
+       cds_lfht_add(state->notification_trigger_clients_ht,
+                       lttng_condition_hash(condition),
+                       &list->notification_trigger_clients_ht_node);
+       rcu_read_unlock();
+}
+
+static
+void notification_client_list_put(struct notification_client_list *list)
+{
+       if (!list) {
+               return;
+       }
+       return urcu_ref_put(&list->ref, notification_client_list_release);
+}
+
+/* Provides a reference to the returned list. */
+static
+struct notification_client_list *get_client_list_from_condition(
+       struct notification_thread_state *state,
+       const struct lttng_condition *condition)
+{
+       struct cds_lfht_node *node;
+       struct cds_lfht_iter iter;
+       struct notification_client_list *list = NULL;
+
+       rcu_read_lock();
+       cds_lfht_lookup(state->notification_trigger_clients_ht,
+                       lttng_condition_hash(condition),
+                       match_client_list_condition,
+                       condition,
+                       &iter);
+       node = cds_lfht_iter_get_node(&iter);
+       if (node) {
+               list = container_of(node, struct notification_client_list,
+                               notification_trigger_clients_ht_node);
+               list = notification_client_list_get(list) ? list : NULL;
+       }
+
+       rcu_read_unlock();
+       return list;
+}
+
+static
+int evaluate_channel_condition_for_client(
+               const struct lttng_condition *condition,
+               struct notification_thread_state *state,
+               struct lttng_evaluation **evaluation,
+               uid_t *session_uid, gid_t *session_gid)
 {
        int ret;
        struct cds_lfht_iter iter;
@@ -503,23 +846,17 @@ int evaluate_condition_for_client(struct lttng_trigger *trigger,
        struct channel_key *channel_key = NULL;
        struct channel_state_sample *last_sample = NULL;
        struct lttng_channel_trigger_list *channel_trigger_list = NULL;
-       struct lttng_evaluation *evaluation = NULL;
-       struct notification_client_list client_list = { 0 };
-       struct notification_client_list_element client_list_element = { 0 };
 
-       assert(trigger);
-       assert(condition);
-       assert(client);
-       assert(state);
+       rcu_read_lock();
 
-       /* Find the channel associated with the trigger. */
+       /* Find the channel associated with the condition. */
        cds_lfht_for_each_entry(state->channel_triggers_ht, &iter,
-                       channel_trigger_list , channel_triggers_ht_node) {
+                       channel_trigger_list, channel_triggers_ht_node) {
                struct lttng_trigger_list_element *element;
 
                cds_list_for_each_entry(element, &channel_trigger_list->list, node) {
-                       struct lttng_condition *current_condition =
-                               lttng_trigger_get_condition(
+                       const struct lttng_condition *current_condition =
+                                       lttng_trigger_get_const_condition(
                                                element->trigger);
 
                        assert(current_condition);
@@ -540,7 +877,7 @@ int evaluate_condition_for_client(struct lttng_trigger *trigger,
 
        if (!channel_key){
                /* No channel found; normal exit. */
-               DBG("[notification-thread] No channel associated with newly subscribed-to condition");
+               DBG("[notification-thread] No known channel associated with newly subscribed-to condition");
                ret = 0;
                goto end;
        }
@@ -574,66 +911,216 @@ int evaluate_condition_for_client(struct lttng_trigger *trigger,
                goto end;
        }
 
-       ret = evaluate_condition(condition, &evaluation, state, NULL,
-                       last_sample, channel_info->capacity);
+       ret = evaluate_buffer_condition(condition, evaluation, state,
+                       NULL, last_sample,
+                       0, channel_info->session_info->consumed_data_size,
+                       channel_info);
        if (ret) {
                WARN("[notification-thread] Fatal error occurred while evaluating a newly subscribed-to condition");
                goto end;
        }
 
-       if (!evaluation) {
-               /* Evaluation yielded nothing. Normal exit. */
-               DBG("[notification-thread] Newly subscribed-to condition evaluated to false, nothing to report to client");
-               ret = 0;
-               goto end;
-       }
-
-       /*
-        * Create a temporary client list with the client currently
-        * subscribing.
-        */
-       cds_lfht_node_init(&client_list.notification_trigger_ht_node);
-       CDS_INIT_LIST_HEAD(&client_list.list);
-       client_list.trigger = trigger;
-
-       CDS_INIT_LIST_HEAD(&client_list_element.node);
-       client_list_element.client = client;
-       cds_list_add(&client_list_element.node, &client_list.list);
+       *session_uid = channel_info->session_info->uid;
+       *session_gid = channel_info->session_info->gid;
+end:
+       rcu_read_unlock();
+       return ret;
+}
 
-       /* Send evaluation result to the newly-subscribed client. */
-       DBG("[notification-thread] Newly subscribed-to condition evaluated to true, notifying client");
-       ret = send_evaluation_to_clients(trigger, evaluation, &client_list,
-                       state, channel_info->session_info->uid,
-                       channel_info->session_info->gid);
+static
+const char *get_condition_session_name(const struct lttng_condition *condition)
+{
+       const char *session_name = NULL;
+       enum lttng_condition_status status;
 
+       switch (lttng_condition_get_type(condition)) {
+       case LTTNG_CONDITION_TYPE_BUFFER_USAGE_LOW:
+       case LTTNG_CONDITION_TYPE_BUFFER_USAGE_HIGH:
+               status = lttng_condition_buffer_usage_get_session_name(
+                               condition, &session_name);
+               break;
+       case LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE:
+               status = lttng_condition_session_consumed_size_get_session_name(
+                               condition, &session_name);
+               break;
+       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_ONGOING:
+       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_COMPLETED:
+               status = lttng_condition_session_rotation_get_session_name(
+                               condition, &session_name);
+               break;
+       default:
+               abort();
+       }
+       if (status != LTTNG_CONDITION_STATUS_OK) {
+               ERR("[notification-thread] Failed to retrieve session rotation condition's session name");
+               goto end;
+       }
 end:
-       return ret;
+       return session_name;
 }
 
 static
-int notification_thread_client_subscribe(struct notification_client *client,
-               struct lttng_condition *condition,
+int evaluate_session_condition_for_client(
+               const struct lttng_condition *condition,
                struct notification_thread_state *state,
-               enum lttng_notification_channel_status *_status)
+               struct lttng_evaluation **evaluation,
+               uid_t *session_uid, gid_t *session_gid)
 {
-       int ret = 0;
+       int ret;
        struct cds_lfht_iter iter;
        struct cds_lfht_node *node;
-       struct notification_client_list *client_list;
-       struct lttng_condition_list_element *condition_list_element = NULL;
-       struct notification_client_list_element *client_list_element = NULL;
-       enum lttng_notification_channel_status status =
-                       LTTNG_NOTIFICATION_CHANNEL_STATUS_OK;
+       const char *session_name;
+       struct session_info *session_info = NULL;
 
-       /*
-        * Ensure that the client has not already subscribed to this condition
-        * before.
-        */
-       cds_list_for_each_entry(condition_list_element, &client->condition_list, node) {
-               if (lttng_condition_is_equal(condition_list_element->condition,
-                               condition)) {
-                       status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ALREADY_SUBSCRIBED;
-                       goto end;
+       rcu_read_lock();
+       session_name = get_condition_session_name(condition);
+
+       /* Find the session associated with the trigger. */
+       cds_lfht_lookup(state->sessions_ht,
+                       hash_key_str(session_name, lttng_ht_seed),
+                       match_session,
+                       session_name,
+                       &iter);
+       node = cds_lfht_iter_get_node(&iter);
+       if (!node) {
+               DBG("[notification-thread] No known session matching name \"%s\"",
+                               session_name);
+               ret = 0;
+               goto end;
+       }
+
+       session_info = caa_container_of(node, struct session_info,
+                       sessions_ht_node);
+       session_info_get(session_info);
+
+       /*
+        * Evaluation is performed in-line here since only one type of
+        * session-bound condition is handled for the moment.
+        */
+       switch (lttng_condition_get_type(condition)) {
+       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_ONGOING:
+               if (!session_info->rotation.ongoing) {
+                       ret = 0;
+                       goto end_session_put;
+               }
+
+               *evaluation = lttng_evaluation_session_rotation_ongoing_create(
+                               session_info->rotation.id);
+               if (!*evaluation) {
+                       /* Fatal error. */
+                       ERR("[notification-thread] Failed to create session rotation ongoing evaluation for session \"%s\"",
+                                       session_info->name);
+                       ret = -1;
+                       goto end_session_put;
+               }
+               ret = 0;
+               break;
+       default:
+               ret = 0;
+               goto end_session_put;
+       }
+
+       *session_uid = session_info->uid;
+       *session_gid = session_info->gid;
+
+end_session_put:
+       session_info_put(session_info);
+end:
+       rcu_read_unlock();
+       return ret;
+}
+
+static
+int evaluate_condition_for_client(const struct lttng_trigger *trigger,
+               const struct lttng_condition *condition,
+               struct notification_client *client,
+               struct notification_thread_state *state)
+{
+       int ret;
+       struct lttng_evaluation *evaluation = NULL;
+       struct notification_client_list client_list = {
+               .lock = PTHREAD_MUTEX_INITIALIZER,
+       };
+       struct notification_client_list_element client_list_element = { 0 };
+       uid_t object_uid = 0;
+       gid_t object_gid = 0;
+
+       assert(trigger);
+       assert(condition);
+       assert(client);
+       assert(state);
+
+       switch (get_condition_binding_object(condition)) {
+       case LTTNG_OBJECT_TYPE_SESSION:
+               ret = evaluate_session_condition_for_client(condition, state,
+                               &evaluation, &object_uid, &object_gid);
+               break;
+       case LTTNG_OBJECT_TYPE_CHANNEL:
+               ret = evaluate_channel_condition_for_client(condition, state,
+                               &evaluation, &object_uid, &object_gid);
+               break;
+       case LTTNG_OBJECT_TYPE_NONE:
+               ret = 0;
+               goto end;
+       case LTTNG_OBJECT_TYPE_UNKNOWN:
+       default:
+               ret = -1;
+               goto end;
+       }
+       if (ret) {
+               /* Fatal error. */
+               goto end;
+       }
+       if (!evaluation) {
+               /* Evaluation yielded nothing. Normal exit. */
+               DBG("[notification-thread] Newly subscribed-to condition evaluated to false, nothing to report to client");
+               ret = 0;
+               goto end;
+       }
+
+       /*
+        * Create a temporary client list with the client currently
+        * subscribing.
+        */
+       cds_lfht_node_init(&client_list.notification_trigger_clients_ht_node);
+       CDS_INIT_LIST_HEAD(&client_list.list);
+       client_list.trigger = trigger;
+
+       CDS_INIT_LIST_HEAD(&client_list_element.node);
+       client_list_element.client = client;
+       cds_list_add(&client_list_element.node, &client_list.list);
+
+       /* Send evaluation result to the newly-subscribed client. */
+       DBG("[notification-thread] Newly subscribed-to condition evaluated to true, notifying client");
+       ret = send_evaluation_to_clients(trigger, evaluation, &client_list,
+                       state, object_uid, object_gid);
+
+end:
+       return ret;
+}
+
+static
+int notification_thread_client_subscribe(struct notification_client *client,
+               struct lttng_condition *condition,
+               struct notification_thread_state *state,
+               enum lttng_notification_channel_status *_status)
+{
+       int ret = 0;
+       struct notification_client_list *client_list = NULL;
+       struct lttng_condition_list_element *condition_list_element = NULL;
+       struct notification_client_list_element *client_list_element = NULL;
+       enum lttng_notification_channel_status status =
+                       LTTNG_NOTIFICATION_CHANNEL_STATUS_OK;
+
+       /*
+        * Ensure that the client has not already subscribed to this condition
+        * before.
+        */
+       cds_list_for_each_entry(condition_list_element, &client->condition_list, node) {
+               if (lttng_condition_is_equal(condition_list_element->condition,
+                               condition)) {
+                       status = LTTNG_NOTIFICATION_CHANNEL_STATUS_ALREADY_SUBSCRIBED;
+                       goto end;
                }
        }
 
@@ -648,8 +1135,6 @@ int notification_thread_client_subscribe(struct notification_client *client,
                goto error;
        }
 
-       rcu_read_lock();
-
        /*
         * Add the newly-subscribed condition to the client's subscription list.
         */
@@ -657,34 +1142,32 @@ int notification_thread_client_subscribe(struct notification_client *client,
        condition_list_element->condition = condition;
        cds_list_add(&condition_list_element->node, &client->condition_list);
 
-       cds_lfht_lookup(state->notification_trigger_clients_ht,
-                       lttng_condition_hash(condition),
-                       match_client_list_condition,
-                       condition,
-                       &iter);
-       node = cds_lfht_iter_get_node(&iter);
-       if (!node) {
+       client_list = get_client_list_from_condition(state, condition);
+       if (!client_list) {
                /*
                 * No notification-emiting trigger registered with this
                 * condition. We don't evaluate the condition right away
                 * since this trigger is not registered yet.
                 */
                free(client_list_element);
-               goto end_unlock;
+               goto end;
        }
 
-       client_list = caa_container_of(node, struct notification_client_list,
-                       notification_trigger_ht_node);
        /*
         * The condition to which the client just subscribed is evaluated
         * at this point so that conditions that are already TRUE result
         * in a notification being sent out.
+        *
+        * The client_list's trigger is used without locking the list itself.
+        * This is correct since the list doesn't own the trigger and the
+        * object is immutable.
         */
        if (evaluate_condition_for_client(client_list->trigger, condition,
                        client, state)) {
                WARN("[notification-thread] Evaluation of a condition on client subscription failed, aborting.");
                ret = -1;
-               goto end_unlock;
+               free(client_list_element);
+               goto end;
        }
 
        /*
@@ -694,13 +1177,17 @@ int notification_thread_client_subscribe(struct notification_client *client,
         */
        client_list_element->client = client;
        CDS_INIT_LIST_HEAD(&client_list_element->node);
+
+       pthread_mutex_lock(&client_list->lock);
        cds_list_add(&client_list_element->node, &client_list->list);
-end_unlock:
-       rcu_read_unlock();
+       pthread_mutex_unlock(&client_list->lock);
 end:
        if (_status) {
                *_status = status;
        }
+       if (client_list) {
+               notification_client_list_put(client_list);
+       }
        return ret;
 error:
        free(condition_list_element);
@@ -715,8 +1202,6 @@ int notification_thread_client_unsubscribe(
                struct notification_thread_state *state,
                enum lttng_notification_channel_status *_status)
 {
-       struct cds_lfht_iter iter;
-       struct cds_lfht_node *node;
        struct notification_client_list *client_list;
        struct lttng_condition_list_element *condition_list_element,
                        *condition_tmp;
@@ -758,30 +1243,24 @@ int notification_thread_client_unsubscribe(
         * Remove the client from the list of clients interested the trigger
         * matching the condition.
         */
-       rcu_read_lock();
-       cds_lfht_lookup(state->notification_trigger_clients_ht,
-                       lttng_condition_hash(condition),
-                       match_client_list_condition,
-                       condition,
-                       &iter);
-       node = cds_lfht_iter_get_node(&iter);
-       if (!node) {
-               goto end_unlock;
+       client_list = get_client_list_from_condition(state, condition);
+       if (!client_list) {
+               goto end;
        }
 
-       client_list = caa_container_of(node, struct notification_client_list,
-                       notification_trigger_ht_node);
+       pthread_mutex_lock(&client_list->lock);
        cds_list_for_each_entry_safe(client_list_element, client_tmp,
                        &client_list->list, node) {
-               if (client_list_element->client->socket != client->socket) {
+               if (client_list_element->client->id != client->id) {
                        continue;
                }
                cds_list_del(&client_list_element->node);
                free(client_list_element);
                break;
        }
-end_unlock:
-       rcu_read_unlock();
+       pthread_mutex_unlock(&client_list->lock);
+       notification_client_list_put(client_list);
+       client_list = NULL;
 end:
        lttng_condition_destroy(condition);
        if (_status) {
@@ -790,29 +1269,33 @@ end:
        return 0;
 }
 
+static
+void free_notification_client_rcu(struct rcu_head *node)
+{
+       free(caa_container_of(node, struct notification_client, rcu_node));
+}
+
 static
 void notification_client_destroy(struct notification_client *client,
                struct notification_thread_state *state)
 {
-       struct lttng_condition_list_element *condition_list_element, *tmp;
-
        if (!client) {
                return;
        }
 
-       /* Release all conditions to which the client was subscribed. */
-       cds_list_for_each_entry_safe(condition_list_element, tmp,
-                       &client->condition_list, node) {
-               (void) notification_thread_client_unsubscribe(client,
-                               condition_list_element->condition, state, NULL);
-       }
-
+       /*
+        * The client object is not reachable by other threads, no need to lock
+        * the client here.
+        */
        if (client->socket >= 0) {
                (void) lttcomm_close_unix_sock(client->socket);
+               client->socket = -1;
        }
+       client->communication.active = false;
        lttng_dynamic_buffer_reset(&client->communication.inbound.buffer);
        lttng_dynamic_buffer_reset(&client->communication.outbound.buffer);
-       free(client);
+       pthread_mutex_destroy(&client->lock);
+       call_rcu(&client->rcu_node, free_notification_client_rcu);
 }
 
 /*
@@ -828,8 +1311,8 @@ struct notification_client *get_client_from_socket(int socket,
        struct notification_client *client = NULL;
 
        cds_lfht_lookup(state->client_socket_ht,
-                       hash_key_ulong((void *) (unsigned long) socket, lttng_ht_seed),
-                       match_client,
+                       hash_client_socket(socket),
+                       match_client_socket,
                        (void *) (unsigned long) socket,
                        &iter);
        node = cds_lfht_iter_get_node(&iter);
@@ -844,51 +1327,90 @@ end:
 }
 
 static
-bool trigger_applies_to_channel(struct lttng_trigger *trigger,
-               struct channel_info *channel_info)
+bool buffer_usage_condition_applies_to_channel(
+               const struct lttng_condition *condition,
+               const struct channel_info *channel_info)
 {
        enum lttng_condition_status status;
-       struct lttng_condition *condition;
-       const char *trigger_session_name = NULL;
-       const char *trigger_channel_name = NULL;
-       enum lttng_domain_type trigger_domain;
+       enum lttng_domain_type condition_domain;
+       const char *condition_session_name = NULL;
+       const char *condition_channel_name = NULL;
 
-       condition = lttng_trigger_get_condition(trigger);
-       if (!condition) {
+       status = lttng_condition_buffer_usage_get_domain_type(condition,
+                       &condition_domain);
+       assert(status == LTTNG_CONDITION_STATUS_OK);
+       if (channel_info->key.domain != condition_domain) {
                goto fail;
        }
 
-       switch (lttng_condition_get_type(condition)) {
-       case LTTNG_CONDITION_TYPE_BUFFER_USAGE_LOW:
-       case LTTNG_CONDITION_TYPE_BUFFER_USAGE_HIGH:
-               break;
-       default:
+       status = lttng_condition_buffer_usage_get_session_name(
+                       condition, &condition_session_name);
+       assert((status == LTTNG_CONDITION_STATUS_OK) && condition_session_name);
+
+       status = lttng_condition_buffer_usage_get_channel_name(
+                       condition, &condition_channel_name);
+       assert((status == LTTNG_CONDITION_STATUS_OK) && condition_channel_name);
+
+       if (strcmp(channel_info->session_info->name, condition_session_name)) {
+               goto fail;
+       }
+       if (strcmp(channel_info->name, condition_channel_name)) {
                goto fail;
        }
 
-       status = lttng_condition_buffer_usage_get_domain_type(condition,
-                       &trigger_domain);
-       assert(status == LTTNG_CONDITION_STATUS_OK);
-       if (channel_info->key.domain != trigger_domain) {
+       return true;
+fail:
+       return false;
+}
+
+static
+bool session_consumed_size_condition_applies_to_channel(
+               const struct lttng_condition *condition,
+               const struct channel_info *channel_info)
+{
+       enum lttng_condition_status status;
+       const char *condition_session_name = NULL;
+
+       status = lttng_condition_session_consumed_size_get_session_name(
+                       condition, &condition_session_name);
+       assert((status == LTTNG_CONDITION_STATUS_OK) && condition_session_name);
+
+       if (strcmp(channel_info->session_info->name, condition_session_name)) {
                goto fail;
        }
 
-       status = lttng_condition_buffer_usage_get_session_name(
-                       condition, &trigger_session_name);
-       assert((status == LTTNG_CONDITION_STATUS_OK) && trigger_session_name);
+       return true;
+fail:
+       return false;
+}
 
-       status = lttng_condition_buffer_usage_get_channel_name(
-                       condition, &trigger_channel_name);
-       assert((status == LTTNG_CONDITION_STATUS_OK) && trigger_channel_name);
+static
+bool trigger_applies_to_channel(const struct lttng_trigger *trigger,
+               const struct channel_info *channel_info)
+{
+       const struct lttng_condition *condition;
+       bool trigger_applies;
 
-       if (strcmp(channel_info->session_info->name, trigger_session_name)) {
+       condition = lttng_trigger_get_const_condition(trigger);
+       if (!condition) {
                goto fail;
        }
-       if (strcmp(channel_info->name, trigger_channel_name)) {
+
+       switch (lttng_condition_get_type(condition)) {
+       case LTTNG_CONDITION_TYPE_BUFFER_USAGE_LOW:
+       case LTTNG_CONDITION_TYPE_BUFFER_USAGE_HIGH:
+               trigger_applies = buffer_usage_condition_applies_to_channel(
+                               condition, channel_info);
+               break;
+       case LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE:
+               trigger_applies = session_consumed_size_condition_applies_to_channel(
+                               condition, channel_info);
+               break;
+       default:
                goto fail;
        }
 
-       return true;
+       return trigger_applies;
 fail:
        return false;
 }
@@ -912,14 +1434,197 @@ bool trigger_applies_to_client(struct lttng_trigger *trigger,
        return applies;
 }
 
+/* Must be called with RCU read lock held. */
 static
-int match_session(struct cds_lfht_node *node, const void *key)
+struct lttng_session_trigger_list *get_session_trigger_list(
+               struct notification_thread_state *state,
+               const char *session_name)
 {
-       const char *name = key;
-       struct session_info *session_info = caa_container_of(
-               node, struct session_info, sessions_ht_node);
+       struct lttng_session_trigger_list *list = NULL;
+       struct cds_lfht_node *node;
+       struct cds_lfht_iter iter;
 
-       return !strcmp(session_info->name, name);
+       cds_lfht_lookup(state->session_triggers_ht,
+                       hash_key_str(session_name, lttng_ht_seed),
+                       match_session_trigger_list,
+                       session_name,
+                       &iter);
+       node = cds_lfht_iter_get_node(&iter);
+       if (!node) {
+               /*
+                * Not an error, the list of triggers applying to that session
+                * will be initialized when the session is created.
+                */
+               DBG("[notification-thread] No trigger list found for session \"%s\" as it is not yet known to the notification system",
+                               session_name);
+               goto end;
+       }
+
+       list = caa_container_of(node,
+                       struct lttng_session_trigger_list,
+                       session_triggers_ht_node);
+end:
+       return list;
+}
+
+/*
+ * Allocate an empty lttng_session_trigger_list for the session named
+ * 'session_name'.
+ *
+ * No ownership of 'session_name' is assumed by the session trigger list.
+ * It is the caller's responsability to ensure the session name is alive
+ * for as long as this list is.
+ */
+static
+struct lttng_session_trigger_list *lttng_session_trigger_list_create(
+               const char *session_name,
+               struct cds_lfht *session_triggers_ht)
+{
+       struct lttng_session_trigger_list *list;
+
+       list = zmalloc(sizeof(*list));
+       if (!list) {
+               goto end;
+       }
+       list->session_name = session_name;
+       CDS_INIT_LIST_HEAD(&list->list);
+       cds_lfht_node_init(&list->session_triggers_ht_node);
+       list->session_triggers_ht = session_triggers_ht;
+
+       rcu_read_lock();
+       /* Publish the list through the session_triggers_ht. */
+       cds_lfht_add(session_triggers_ht,
+                       hash_key_str(session_name, lttng_ht_seed),
+                       &list->session_triggers_ht_node);
+       rcu_read_unlock();
+end:
+       return list;
+}
+
+static
+void free_session_trigger_list_rcu(struct rcu_head *node)
+{
+       free(caa_container_of(node, struct lttng_session_trigger_list,
+                       rcu_node));
+}
+
+static
+void lttng_session_trigger_list_destroy(struct lttng_session_trigger_list *list)
+{
+       struct lttng_trigger_list_element *trigger_list_element, *tmp;
+
+       /* Empty the list element by element, and then free the list itself. */
+       cds_list_for_each_entry_safe(trigger_list_element, tmp,
+                       &list->list, node) {
+               cds_list_del(&trigger_list_element->node);
+               free(trigger_list_element);
+       }
+       rcu_read_lock();
+       /* Unpublish the list from the session_triggers_ht. */
+       cds_lfht_del(list->session_triggers_ht,
+                       &list->session_triggers_ht_node);
+       rcu_read_unlock();
+       call_rcu(&list->rcu_node, free_session_trigger_list_rcu);
+}
+
+static
+int lttng_session_trigger_list_add(struct lttng_session_trigger_list *list,
+               const struct lttng_trigger *trigger)
+{
+       int ret = 0;
+       struct lttng_trigger_list_element *new_element =
+                       zmalloc(sizeof(*new_element));
+
+       if (!new_element) {
+               ret = -1;
+               goto end;
+       }
+       CDS_INIT_LIST_HEAD(&new_element->node);
+       new_element->trigger = trigger;
+       cds_list_add(&new_element->node, &list->list);
+end:
+       return ret;
+}
+
+static
+bool trigger_applies_to_session(const struct lttng_trigger *trigger,
+               const char *session_name)
+{
+       bool applies = false;
+       const struct lttng_condition *condition;
+
+       condition = lttng_trigger_get_const_condition(trigger);
+       switch (lttng_condition_get_type(condition)) {
+       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_ONGOING:
+       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_COMPLETED:
+       {
+               enum lttng_condition_status condition_status;
+               const char *condition_session_name;
+
+               condition_status = lttng_condition_session_rotation_get_session_name(
+                       condition, &condition_session_name);
+               if (condition_status != LTTNG_CONDITION_STATUS_OK) {
+                       ERR("[notification-thread] Failed to retrieve session rotation condition's session name");
+                       goto end;
+               }
+
+               assert(condition_session_name);
+               applies = !strcmp(condition_session_name, session_name);
+               break;
+       }
+       default:
+               goto end;
+       }
+end:
+       return applies;
+}
+
+/*
+ * Allocate and initialize an lttng_session_trigger_list which contains
+ * all triggers that apply to the session named 'session_name'.
+ *
+ * No ownership of 'session_name' is assumed by the session trigger list.
+ * It is the caller's responsability to ensure the session name is alive
+ * for as long as this list is.
+ */
+static
+struct lttng_session_trigger_list *lttng_session_trigger_list_build(
+               const struct notification_thread_state *state,
+               const char *session_name)
+{
+       int trigger_count = 0;
+       struct lttng_session_trigger_list *session_trigger_list = NULL;
+       struct lttng_trigger_ht_element *trigger_ht_element = NULL;
+       struct cds_lfht_iter iter;
+
+       session_trigger_list = lttng_session_trigger_list_create(session_name,
+                       state->session_triggers_ht);
+
+       /* Add all triggers applying to the session named 'session_name'. */
+       cds_lfht_for_each_entry(state->triggers_ht, &iter, trigger_ht_element,
+                       node) {
+               int ret;
+
+               if (!trigger_applies_to_session(trigger_ht_element->trigger,
+                               session_name)) {
+                       continue;
+               }
+
+               ret = lttng_session_trigger_list_add(session_trigger_list,
+                               trigger_ht_element->trigger);
+               if (ret) {
+                       goto error;
+               }
+
+               trigger_count++;
+       }
+
+       DBG("[notification-thread] Found %i triggers that apply to newly created session",
+                       trigger_count);
+       return session_trigger_list;
+error:
+       lttng_session_trigger_list_destroy(session_trigger_list);
+       return NULL;
 }
 
 static
@@ -930,6 +1635,7 @@ struct session_info *find_or_create_session_info(
        struct session_info *session = NULL;
        struct cds_lfht_node *node;
        struct cds_lfht_iter iter;
+       struct lttng_session_trigger_list *trigger_list;
 
        rcu_read_lock();
        cds_lfht_lookup(state->sessions_ht,
@@ -945,18 +1651,34 @@ struct session_info *find_or_create_session_info(
                                sessions_ht_node);
                assert(session->uid == uid);
                assert(session->gid == gid);
+               session_info_get(session);
                goto end;
        }
 
-       session = session_info_create(name, uid, gid);
+       trigger_list = lttng_session_trigger_list_build(state, name);
+       if (!trigger_list) {
+               goto error;
+       }
+
+       session = session_info_create(name, uid, gid, trigger_list,
+                       state->sessions_ht);
        if (!session) {
                ERR("[notification-thread] Failed to allocation session info for session \"%s\" (uid = %i, gid = %i)",
                                name, uid, gid);
-               goto end;
+               lttng_session_trigger_list_destroy(trigger_list);
+               goto error;
        }
+       trigger_list = NULL;
+
+       cds_lfht_add(state->sessions_ht, hash_key_str(name, lttng_ht_seed),
+                       &session->sessions_ht_node);
 end:
        rcu_read_unlock();
        return session;
+error:
+       rcu_read_unlock();
+       session_info_put(session);
+       return NULL;
 }
 
 static
@@ -988,7 +1710,7 @@ int handle_notification_thread_command_add_channel(
        session_info = find_or_create_session_info(state, session_name,
                        session_uid, session_gid);
        if (!session_info) {
-               /* Allocation error or an internal error occured. */
+               /* Allocation error or an internal error occurred. */
                goto error;
        }
 
@@ -998,6 +1720,7 @@ int handle_notification_thread_command_add_channel(
                goto error;
        }
 
+       rcu_read_lock();
        /* Build a list of all triggers applying to the new channel. */
        cds_lfht_for_each_entry(state->triggers_ht, &iter, trigger_ht_element,
                        node) {
@@ -1010,6 +1733,7 @@ int handle_notification_thread_command_add_channel(
 
                new_element = zmalloc(sizeof(*new_element));
                if (!new_element) {
+                       rcu_read_unlock();
                        goto error;
                }
                CDS_INIT_LIST_HEAD(&new_element->node);
@@ -1017,6 +1741,7 @@ int handle_notification_thread_command_add_channel(
                cds_list_add(&new_element->node, &trigger_list);
                trigger_count++;
        }
+       rcu_read_unlock();
 
        DBG("[notification-thread] Found %i triggers that apply to newly added channel",
                        trigger_count);
@@ -1042,6 +1767,7 @@ int handle_notification_thread_command_add_channel(
                        hash_channel_key(&new_channel_info->key),
                        &channel_trigger_list->channel_triggers_ht_node);
        rcu_read_unlock();
+       session_info_put(session_info);
        *cmd_result = LTTNG_OK;
        return 0;
 error:
@@ -1050,6 +1776,20 @@ error:
        return 1;
 }
 
+static
+void free_channel_trigger_list_rcu(struct rcu_head *node)
+{
+       free(caa_container_of(node, struct lttng_channel_trigger_list,
+                       rcu_node));
+}
+
+static
+void free_channel_state_sample_rcu(struct rcu_head *node)
+{
+       free(caa_container_of(node, struct channel_state_sample,
+                       rcu_node));
+}
+
 static
 int handle_notification_thread_command_remove_channel(
        struct notification_thread_state *state,
@@ -1092,7 +1832,7 @@ int handle_notification_thread_command_remove_channel(
                free(trigger_list_element);
        }
        cds_lfht_del(state->channel_triggers_ht, node);
-       free(trigger_list);
+       call_rcu(&trigger_list->rcu_node, free_channel_trigger_list_rcu);
 
        /* Free sampled channel state. */
        cds_lfht_lookup(state->channel_state_ht,
@@ -1111,7 +1851,7 @@ int handle_notification_thread_command_remove_channel(
                                channel_state_ht_node);
 
                cds_lfht_del(state->channel_state_ht, node);
-               free(sample);
+               call_rcu(&sample->rcu_node, free_channel_state_sample_rcu);
        }
 
        /* Remove the channel from the channels_ht and free it. */
@@ -1128,8 +1868,121 @@ int handle_notification_thread_command_remove_channel(
        channel_info_destroy(channel_info);
 end:
        rcu_read_unlock();
-       *cmd_result = LTTNG_OK;
-       return 0;
+       *cmd_result = LTTNG_OK;
+       return 0;
+}
+
+static
+int handle_notification_thread_command_session_rotation(
+       struct notification_thread_state *state,
+       enum notification_thread_command_type cmd_type,
+       const char *session_name, uid_t session_uid, gid_t session_gid,
+       uint64_t trace_archive_chunk_id,
+       struct lttng_trace_archive_location *location,
+       enum lttng_error_code *_cmd_result)
+{
+       int ret = 0;
+       enum lttng_error_code cmd_result = LTTNG_OK;
+       struct lttng_session_trigger_list *trigger_list;
+       struct lttng_trigger_list_element *trigger_list_element;
+       struct session_info *session_info;
+
+       rcu_read_lock();
+
+       session_info = find_or_create_session_info(state, session_name,
+                       session_uid, session_gid);
+       if (!session_info) {
+               /* Allocation error or an internal error occurred. */
+               ret = -1;
+               cmd_result = LTTNG_ERR_NOMEM;
+               goto end;
+       }
+
+       session_info->rotation.ongoing =
+                       cmd_type == NOTIFICATION_COMMAND_TYPE_SESSION_ROTATION_ONGOING;
+       session_info->rotation.id = trace_archive_chunk_id;
+       trigger_list = get_session_trigger_list(state, session_name);
+       if (!trigger_list) {
+               DBG("[notification-thread] No triggers applying to session \"%s\" found",
+                               session_name);
+               goto end;
+       }
+
+       cds_list_for_each_entry(trigger_list_element, &trigger_list->list,
+                       node) {
+               const struct lttng_condition *condition;
+               const struct lttng_action *action;
+               const struct lttng_trigger *trigger;
+               struct notification_client_list *client_list;
+               struct lttng_evaluation *evaluation = NULL;
+               enum lttng_condition_type condition_type;
+               bool client_list_is_empty;
+
+               trigger = trigger_list_element->trigger;
+               condition = lttng_trigger_get_const_condition(trigger);
+               assert(condition);
+               condition_type = lttng_condition_get_type(condition);
+
+               if (condition_type == LTTNG_CONDITION_TYPE_SESSION_ROTATION_ONGOING &&
+                               cmd_type != NOTIFICATION_COMMAND_TYPE_SESSION_ROTATION_ONGOING) {
+                       continue;
+               } else if (condition_type == LTTNG_CONDITION_TYPE_SESSION_ROTATION_COMPLETED &&
+                               cmd_type != NOTIFICATION_COMMAND_TYPE_SESSION_ROTATION_COMPLETED) {
+                       continue;
+               }
+
+               action = lttng_trigger_get_const_action(trigger);
+
+               /* Notify actions are the only type currently supported. */
+               assert(lttng_action_get_type_const(action) ==
+                               LTTNG_ACTION_TYPE_NOTIFY);
+
+               client_list = get_client_list_from_condition(state, condition);
+               assert(client_list);
+
+               pthread_mutex_lock(&client_list->lock);
+               client_list_is_empty = cds_list_empty(&client_list->list);
+               pthread_mutex_unlock(&client_list->lock);
+               if (client_list_is_empty) {
+                       /*
+                        * No clients interested in the evaluation's result,
+                        * skip it.
+                        */
+                       continue;
+               }
+
+               if (cmd_type == NOTIFICATION_COMMAND_TYPE_SESSION_ROTATION_ONGOING) {
+                       evaluation = lttng_evaluation_session_rotation_ongoing_create(
+                                       trace_archive_chunk_id);
+               } else {
+                       evaluation = lttng_evaluation_session_rotation_completed_create(
+                                       trace_archive_chunk_id, location);
+               }
+
+               if (!evaluation) {
+                       /* Internal error */
+                       ret = -1;
+                       cmd_result = LTTNG_ERR_UNK;
+                       goto put_list;
+               }
+
+               /* Dispatch evaluation result to all clients. */
+               ret = send_evaluation_to_clients(trigger_list_element->trigger,
+                               evaluation, client_list, state,
+                               session_info->uid,
+                               session_info->gid);
+               lttng_evaluation_destroy(evaluation);
+put_list:
+               notification_client_list_put(client_list);
+               if (caa_unlikely(ret)) {
+                       break;
+               }
+       }
+end:
+       session_info_put(session_info);
+       *_cmd_result = cmd_result;
+       rcu_read_unlock();
+       return ret;
 }
 
 static
@@ -1160,8 +2013,7 @@ int condition_is_supported(struct lttng_condition *condition)
                 * buffers. Therefore, we reject triggers that require that
                 * mechanism to be available to be evaluated.
                 */
-               ret = kernel_supports_ring_buffer_snapshot_sample_positions(
-                               kernel_tracer_fd);
+               ret = kernel_supports_ring_buffer_snapshot_sample_positions();
                break;
        }
        default:
@@ -1171,13 +2023,105 @@ end:
        return ret;
 }
 
+/* Must be called with RCU read lock held. */
+static
+int bind_trigger_to_matching_session(const struct lttng_trigger *trigger,
+               struct notification_thread_state *state)
+{
+       int ret = 0;
+       const struct lttng_condition *condition;
+       const char *session_name;
+       struct lttng_session_trigger_list *trigger_list;
+
+       condition = lttng_trigger_get_const_condition(trigger);
+       switch (lttng_condition_get_type(condition)) {
+       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_ONGOING:
+       case LTTNG_CONDITION_TYPE_SESSION_ROTATION_COMPLETED:
+       {
+               enum lttng_condition_status status;
+
+               status = lttng_condition_session_rotation_get_session_name(
+                               condition, &session_name);
+               if (status != LTTNG_CONDITION_STATUS_OK) {
+                       ERR("[notification-thread] Failed to bind trigger to session: unable to get 'session_rotation' condition's session name");
+                       ret = -1;
+                       goto end;
+               }
+               break;
+       }
+       default:
+               ret = -1;
+               goto end;
+       }
+
+       trigger_list = get_session_trigger_list(state, session_name);
+       if (!trigger_list) {
+               DBG("[notification-thread] Unable to bind trigger applying to session \"%s\" as it is not yet known to the notification system",
+                               session_name);
+               goto end;
+
+       }
+
+       DBG("[notification-thread] Newly registered trigger bound to session \"%s\"",
+                       session_name);
+       ret = lttng_session_trigger_list_add(trigger_list, trigger);
+end:
+       return ret;
+}
+
+/* Must be called with RCU read lock held. */
+static
+int bind_trigger_to_matching_channels(const struct lttng_trigger *trigger,
+               struct notification_thread_state *state)
+{
+       int ret = 0;
+       struct cds_lfht_node *node;
+       struct cds_lfht_iter iter;
+       struct channel_info *channel;
+
+       cds_lfht_for_each_entry(state->channels_ht, &iter, channel,
+                       channels_ht_node) {
+               struct lttng_trigger_list_element *trigger_list_element;
+               struct lttng_channel_trigger_list *trigger_list;
+               struct cds_lfht_iter lookup_iter;
+
+               if (!trigger_applies_to_channel(trigger, channel)) {
+                       continue;
+               }
+
+               cds_lfht_lookup(state->channel_triggers_ht,
+                               hash_channel_key(&channel->key),
+                               match_channel_trigger_list,
+                               &channel->key,
+                               &lookup_iter);
+               node = cds_lfht_iter_get_node(&lookup_iter);
+               assert(node);
+               trigger_list = caa_container_of(node,
+                               struct lttng_channel_trigger_list,
+                               channel_triggers_ht_node);
+
+               trigger_list_element = zmalloc(sizeof(*trigger_list_element));
+               if (!trigger_list_element) {
+                       ret = -1;
+                       goto end;
+               }
+               CDS_INIT_LIST_HEAD(&trigger_list_element->node);
+               trigger_list_element->trigger = trigger;
+               cds_list_add(&trigger_list_element->node, &trigger_list->list);
+               DBG("[notification-thread] Newly registered trigger bound to channel \"%s\"",
+                               channel->name);
+       }
+end:
+       return ret;
+}
+
 /*
  * FIXME A client's credentials are not checked when registering a trigger, nor
  *       are they stored alongside with the trigger.
  *
  * The effects of this are benign since:
  *     - The client will succeed in registering the trigger, as it is valid,
- *     - The trigger will, internally, be bound to the channel,
+ *     - The trigger will, internally, be bound to the channel/session,
  *     - The notifications will not be sent since the client's credentials
  *       are checked against the channel at that moment.
  *
@@ -1201,7 +2145,6 @@ int handle_notification_thread_command_register_trigger(
        struct notification_client_list_element *client_list_element, *tmp;
        struct cds_lfht_node *node;
        struct cds_lfht_iter iter;
-       struct channel_info *channel;
        bool free_trigger = true;
 
        rcu_read_lock();
@@ -1253,14 +2196,11 @@ int handle_notification_thread_command_register_trigger(
         * It is not skipped as this is the only action type currently
         * supported.
         */
-       client_list = zmalloc(sizeof(*client_list));
+       client_list = notification_client_list_create(trigger);
        if (!client_list) {
                ret = -1;
                goto error_free_ht_element;
        }
-       cds_lfht_node_init(&client_list->notification_trigger_ht_node);
-       CDS_INIT_LIST_HEAD(&client_list->list);
-       client_list->trigger = trigger;
 
        /* Build a list of clients to which this new trigger applies. */
        cds_lfht_for_each_entry(state->client_socket_ht, &iter, client,
@@ -1272,52 +2212,37 @@ int handle_notification_thread_command_register_trigger(
                client_list_element = zmalloc(sizeof(*client_list_element));
                if (!client_list_element) {
                        ret = -1;
-                       goto error_free_client_list;
+                       goto error_put_client_list;
                }
                CDS_INIT_LIST_HEAD(&client_list_element->node);
                client_list_element->client = client;
                cds_list_add(&client_list_element->node, &client_list->list);
        }
 
-       cds_lfht_add(state->notification_trigger_clients_ht,
-                       lttng_condition_hash(condition),
-                       &client_list->notification_trigger_ht_node);
-
-       /*
-        * Add the trigger to list of triggers bound to the channels currently
-        * known.
-        */
-       cds_lfht_for_each_entry(state->channels_ht, &iter, channel,
-                       channels_ht_node) {
-               struct lttng_trigger_list_element *trigger_list_element;
-               struct lttng_channel_trigger_list *trigger_list;
-
-               if (!trigger_applies_to_channel(trigger, channel)) {
-                       continue;
+       switch (get_condition_binding_object(condition)) {
+       case LTTNG_OBJECT_TYPE_SESSION:
+               /* Add the trigger to the list if it matches a known session. */
+               ret = bind_trigger_to_matching_session(trigger, state);
+               if (ret) {
+                       goto error_put_client_list;
                }
-
-               cds_lfht_lookup(state->channel_triggers_ht,
-                               hash_channel_key(&channel->key),
-                               match_channel_trigger_list,
-                               &channel->key,
-                               &iter);
-               node = cds_lfht_iter_get_node(&iter);
-               assert(node);
-               trigger_list = caa_container_of(node,
-                               struct lttng_channel_trigger_list,
-                               channel_triggers_ht_node);
-
-               trigger_list_element = zmalloc(sizeof(*trigger_list_element));
-               if (!trigger_list_element) {
-                       ret = -1;
-                       goto error_free_client_list;
+               break;
+       case LTTNG_OBJECT_TYPE_CHANNEL:
+               /*
+                * Add the trigger to list of triggers bound to the channels
+                * currently known.
+                */
+               ret = bind_trigger_to_matching_channels(trigger, state);
+               if (ret) {
+                       goto error_put_client_list;
                }
-               CDS_INIT_LIST_HEAD(&trigger_list_element->node);
-               trigger_list_element->trigger = trigger;
-               cds_list_add(&trigger_list_element->node, &trigger_list->list);
-
-               /* A trigger can only apply to one channel. */
                break;
+       case LTTNG_OBJECT_TYPE_NONE:
+               break;
+       default:
+               ERR("[notification-thread] Unknown object type on which to bind a newly registered trigger was encountered");
+               ret = -1;
+               goto error_put_client_list;
        }
 
        /*
@@ -1345,13 +2270,15 @@ int handle_notification_thread_command_register_trigger(
         * current state. Otherwise, the next evaluation cycle may only see
         * that the evaluations remain the same (true for samples n-1 and n) and
         * the client will never know that the condition has been met.
+        *
+        * No need to lock the list here as it has not been published yet.
         */
        cds_list_for_each_entry_safe(client_list_element, tmp,
                        &client_list->list, node) {
                ret = evaluate_condition_for_client(trigger, condition,
                                client_list_element->client, state);
                if (ret) {
-                       goto error_free_client_list;
+                       goto error_put_client_list;
                }
        }
 
@@ -1359,31 +2286,31 @@ int handle_notification_thread_command_register_trigger(
         * Client list ownership transferred to the
         * notification_trigger_clients_ht.
         */
+       publish_notification_client_list(state, client_list);
        client_list = NULL;
 
        *cmd_result = LTTNG_OK;
-error_free_client_list:
-       if (client_list) {
-               cds_list_for_each_entry_safe(client_list_element, tmp,
-                               &client_list->list, node) {
-                       free(client_list_element);
-               }
-               free(client_list);
-       }
+
+error_put_client_list:
+       notification_client_list_put(client_list);
+
 error_free_ht_element:
        free(trigger_ht_element);
 error:
        if (free_trigger) {
-               struct lttng_action *action = lttng_trigger_get_action(trigger);
-
-               lttng_condition_destroy(condition);
-               lttng_action_destroy(action);
                lttng_trigger_destroy(trigger);
        }
        rcu_read_unlock();
        return ret;
 }
 
+static
+void free_lttng_trigger_ht_element_rcu(struct rcu_head *node)
+{
+       free(caa_container_of(node, struct lttng_trigger_ht_element,
+                       rcu_node));
+}
+
 static
 int handle_notification_thread_command_unregister_trigger(
                struct notification_thread_state *state,
@@ -1391,14 +2318,12 @@ int handle_notification_thread_command_unregister_trigger(
                enum lttng_error_code *_cmd_reply)
 {
        struct cds_lfht_iter iter;
-       struct cds_lfht_node *node, *triggers_ht_node;
+       struct cds_lfht_node *triggers_ht_node;
        struct lttng_channel_trigger_list *trigger_list;
        struct notification_client_list *client_list;
-       struct notification_client_list_element *client_list_element, *tmp;
        struct lttng_trigger_ht_element *trigger_ht_element = NULL;
        struct lttng_condition *condition = lttng_trigger_get_condition(
                        trigger);
-       struct lttng_action *action;
        enum lttng_error_code cmd_reply;
 
        rcu_read_lock();
@@ -1423,8 +2348,8 @@ int handle_notification_thread_command_unregister_trigger(
 
                cds_list_for_each_entry_safe(trigger_element, tmp,
                                &trigger_list->list, node) {
-                       struct lttng_condition *current_condition =
-                                       lttng_trigger_get_condition(
+                       const struct lttng_condition *current_condition =
+                                       lttng_trigger_get_const_condition(
                                                trigger_element->trigger);
 
                        assert(current_condition);
@@ -1444,33 +2369,22 @@ int handle_notification_thread_command_unregister_trigger(
         * Remove and release the client list from
         * notification_trigger_clients_ht.
         */
-       cds_lfht_lookup(state->notification_trigger_clients_ht,
-                       lttng_condition_hash(condition),
-                       match_client_list,
-                       trigger,
-                       &iter);
-       node = cds_lfht_iter_get_node(&iter);
-       assert(node);
-       client_list = caa_container_of(node, struct notification_client_list,
-                       notification_trigger_ht_node);
-       cds_list_for_each_entry_safe(client_list_element, tmp,
-                       &client_list->list, node) {
-               free(client_list_element);
-       }
-       cds_lfht_del(state->notification_trigger_clients_ht, node);
-       free(client_list);
+       client_list = get_client_list_from_condition(state, condition);
+       assert(client_list);
+
+       /* Put new reference and the hashtable's reference. */
+       notification_client_list_put(client_list);
+       notification_client_list_put(client_list);
+       client_list = NULL;
 
        /* Remove trigger from triggers_ht. */
        trigger_ht_element = caa_container_of(triggers_ht_node,
                        struct lttng_trigger_ht_element, node);
        cds_lfht_del(state->triggers_ht, triggers_ht_node);
 
-       condition = lttng_trigger_get_condition(trigger_ht_element->trigger);
-       lttng_condition_destroy(condition);
-       action = lttng_trigger_get_action(trigger_ht_element->trigger);
-       lttng_action_destroy(action);
+       /* Release the ownership of the trigger. */
        lttng_trigger_destroy(trigger_ht_element->trigger);
-       free(trigger_ht_element);
+       call_rcu(&trigger_ht_element->rcu_node, free_lttng_trigger_ht_element_rcu);
 end:
        rcu_read_unlock();
        if (_cmd_reply) {
@@ -1489,9 +2403,9 @@ int handle_notification_thread_command(
        struct notification_thread_command *cmd;
 
        /* Read the event pipe to put it back into a quiescent state. */
-       ret = read(lttng_pipe_get_readfd(handle->cmd_queue.event_pipe), &counter,
+       ret = lttng_read(lttng_pipe_get_readfd(handle->cmd_queue.event_pipe), &counter,
                        sizeof(counter));
-       if (ret == -1) {
+       if (ret != sizeof(counter)) {
                goto error;
        }
 
@@ -1531,6 +2445,21 @@ int handle_notification_thread_command(
                                cmd->parameters.remove_channel.domain,
                                &cmd->reply_code);
                break;
+       case NOTIFICATION_COMMAND_TYPE_SESSION_ROTATION_ONGOING:
+       case NOTIFICATION_COMMAND_TYPE_SESSION_ROTATION_COMPLETED:
+               DBG("[notification-thread] Received session rotation %s command",
+                               cmd->type == NOTIFICATION_COMMAND_TYPE_SESSION_ROTATION_ONGOING ?
+                               "ongoing" : "completed");
+               ret = handle_notification_thread_command_session_rotation(
+                               state,
+                               cmd->type,
+                               cmd->parameters.session_rotation.session_name,
+                               cmd->parameters.session_rotation.uid,
+                               cmd->parameters.session_rotation.gid,
+                               cmd->parameters.session_rotation.trace_archive_chunk_id,
+                               cmd->parameters.session_rotation.location,
+                               &cmd->reply_code);
+               break;
        case NOTIFICATION_COMMAND_TYPE_QUIT:
                DBG("[notification-thread] Received quit command");
                cmd->reply_code = LTTNG_OK;
@@ -1559,12 +2488,6 @@ error:
        return -1;
 }
 
-static
-unsigned long hash_client_socket(int socket)
-{
-       return hash_key_ulong((void *) (unsigned long) socket, lttng_ht_seed);
-}
-
 static
 int socket_set_non_blocking(int socket)
 {
@@ -1588,11 +2511,14 @@ end:
        return ret;
 }
 
+/* Client lock must be acquired by caller. */
 static
 int client_reset_inbound_state(struct notification_client *client)
 {
        int ret;
 
+       ASSERT_LOCKED(client->lock);
+
        ret = lttng_dynamic_buffer_set_size(
                        &client->communication.inbound.buffer, 0);
        assert(!ret);
@@ -1623,14 +2549,19 @@ int handle_notification_thread_client_connect(
                ret = -1;
                goto error;
        }
+       pthread_mutex_init(&client->lock, NULL);
+       client->id = state->next_notification_client_id++;
        CDS_INIT_LIST_HEAD(&client->condition_list);
        lttng_dynamic_buffer_init(&client->communication.inbound.buffer);
        lttng_dynamic_buffer_init(&client->communication.outbound.buffer);
        client->communication.inbound.expect_creds = true;
+
+       pthread_mutex_lock(&client->lock);
        ret = client_reset_inbound_state(client);
+       pthread_mutex_unlock(&client->lock);
        if (ret) {
                ERR("[notification-thread] Failed to reset client communication's inbound state");
-               ret = 0;
+               ret = 0;
                goto error;
        }
 
@@ -1671,6 +2602,9 @@ int handle_notification_thread_client_connect(
        cds_lfht_add(state->client_socket_ht,
                        hash_client_socket(client->socket),
                        &client->client_socket_ht_node);
+       cds_lfht_add(state->client_id_ht,
+                       hash_client_id(client->id),
+                       &client->client_id_ht_node);
        rcu_read_unlock();
 
        return ret;
@@ -1679,9 +2613,44 @@ error:
        return ret;
 }
 
-int handle_notification_thread_client_disconnect(
-               int client_socket,
+/* RCU read-lock must be held by the caller. */
+/* Client lock must be held by the caller */
+static
+int notification_thread_client_disconnect(
+               struct notification_client *client,
                struct notification_thread_state *state)
+{
+       int ret;
+       struct lttng_condition_list_element *condition_list_element, *tmp;
+
+       /* Acquire the client lock to disable its communication atomically. */
+       client->communication.active = false;
+       ret = lttng_poll_del(&state->events, client->socket);
+       if (ret) {
+               ERR("[notification-thread] Failed to remove client socket %d from poll set",
+                               client->socket);
+       }
+
+       cds_lfht_del(state->client_socket_ht, &client->client_socket_ht_node);
+       cds_lfht_del(state->client_id_ht, &client->client_id_ht_node);
+
+       /* Release all conditions to which the client was subscribed. */
+       cds_list_for_each_entry_safe(condition_list_element, tmp,
+                       &client->condition_list, node) {
+               (void) notification_thread_client_unsubscribe(client,
+                               condition_list_element->condition, state, NULL);
+       }
+
+       /*
+        * Client no longer accessible to other threads (through the
+        * client lists).
+        */
+       notification_client_destroy(client, state);
+       return ret;
+}
+
+int handle_notification_thread_client_disconnect(
+               int client_socket, struct notification_thread_state *state)
 {
        int ret = 0;
        struct notification_client *client;
@@ -1698,13 +2667,9 @@ int handle_notification_thread_client_disconnect(
                goto end;
        }
 
-       ret = lttng_poll_del(&state->events, client_socket);
-       if (ret) {
-               ERR("[notification-thread] Failed to remove client socket from poll set");
-       }
-        cds_lfht_del(state->client_socket_ht,
-                       &client->client_socket_ht_node);
-       notification_client_destroy(client, state);
+       pthread_mutex_lock(&client->lock);
+       ret = notification_thread_client_disconnect(client, state);
+       pthread_mutex_unlock(&client->lock);
 end:
        rcu_read_unlock();
        return ret;
@@ -1720,11 +2685,13 @@ int handle_notification_thread_client_disconnect_all(
        rcu_read_lock();
        DBG("[notification-thread] Closing all client connections");
        cds_lfht_for_each_entry(state->client_socket_ht, &iter, client,
-               client_socket_ht_node) {
+                       client_socket_ht_node) {
                int ret;
 
-               ret = handle_notification_thread_client_disconnect(
-                               client->socket, state);
+               pthread_mutex_lock(&client->lock);
+               ret = notification_thread_client_disconnect(
+                               client, state);
+               pthread_mutex_unlock(&client->lock);
                if (ret) {
                        error_encoutered = true;
                }
@@ -1740,6 +2707,7 @@ int handle_notification_thread_trigger_unregister_all(
        struct cds_lfht_iter iter;
        struct lttng_trigger_ht_element *trigger_ht_element;
 
+       rcu_read_lock();
        cds_lfht_for_each_entry(state->triggers_ht, &iter, trigger_ht_element,
                        node) {
                int ret = handle_notification_thread_command_unregister_trigger(
@@ -1748,9 +2716,11 @@ int handle_notification_thread_trigger_unregister_all(
                        error_occurred = true;
                }
        }
+       rcu_read_unlock();
        return error_occurred ? -1 : 0;
 }
 
+/* Client lock must be acquired by caller. */
 static
 int client_flush_outgoing_queue(struct notification_client *client,
                struct notification_thread_state *state)
@@ -1758,6 +2728,8 @@ int client_flush_outgoing_queue(struct notification_client *client,
        ssize_t ret;
        size_t to_send_count;
 
+       ASSERT_LOCKED(client->lock);
+
        assert(client->communication.outbound.buffer.size != 0);
        to_send_count = client->communication.outbound.buffer.size;
        DBG("[notification-thread] Flushing client (socket fd = %i) outgoing queue",
@@ -1766,8 +2738,7 @@ int client_flush_outgoing_queue(struct notification_client *client,
        ret = lttcomm_send_unix_sock_non_block(client->socket,
                        client->communication.outbound.buffer.data,
                        to_send_count);
-       if ((ret < 0 && (errno == EAGAIN || errno == EWOULDBLOCK)) ||
-                       (ret > 0 && ret < to_send_count)) {
+       if ((ret >= 0 && ret < to_send_count)) {
                DBG("[notification-thread] Client (socket fd = %i) outgoing queue could not be completely flushed",
                                client->socket);
                to_send_count -= max(ret, 0);
@@ -1796,8 +2767,7 @@ int client_flush_outgoing_queue(struct notification_client *client,
                /* Generic error, disconnect the client. */
                ERR("[notification-thread] Failed to send flush outgoing queue, disconnecting client (socket fd = %i)",
                                client->socket);
-               ret = handle_notification_thread_client_disconnect(
-                               client->socket, state);
+               ret = notification_thread_client_disconnect(client, state);
                if (ret) {
                        goto error;
                }
@@ -1823,51 +2793,242 @@ error:
        return -1;
 }
 
+/* Client lock must be acquired by caller. */
+static
+int client_send_command_reply(struct notification_client *client,
+               struct notification_thread_state *state,
+               enum lttng_notification_channel_status status)
+{
+       int ret;
+       struct lttng_notification_channel_command_reply reply = {
+               .status = (int8_t) status,
+       };
+       struct lttng_notification_channel_message msg = {
+               .type = (int8_t) LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_COMMAND_REPLY,
+               .size = sizeof(reply),
+       };
+       char buffer[sizeof(msg) + sizeof(reply)];
+
+       ASSERT_LOCKED(client->lock);
+
+       if (client->communication.outbound.queued_command_reply) {
+               /* Protocol error. */
+               goto error;
+       }
+
+       memcpy(buffer, &msg, sizeof(msg));
+       memcpy(buffer + sizeof(msg), &reply, sizeof(reply));
+       DBG("[notification-thread] Send command reply (%i)", (int) status);
+
+       /* Enqueue buffer to outgoing queue and flush it. */
+       ret = lttng_dynamic_buffer_append(
+                       &client->communication.outbound.buffer,
+                       buffer, sizeof(buffer));
+       if (ret) {
+               goto error;
+       }
+
+       ret = client_flush_outgoing_queue(client, state);
+       if (ret) {
+               goto error;
+       }
+
+       if (client->communication.outbound.buffer.size != 0) {
+               /* Queue could not be emptied. */
+               client->communication.outbound.queued_command_reply = true;
+       }
+
+       return 0;
+error:
+       return -1;
+}
+
+static
+int client_handle_message_unknown(struct notification_client *client,
+               struct notification_thread_state *state)
+{
+       int ret;
+
+       pthread_mutex_lock(&client->lock);
+
+       /*
+        * Receiving message header. The function will be called again
+        * once the rest of the message as been received and can be
+        * interpreted.
+        */
+       const struct lttng_notification_channel_message *msg;
+
+       assert(sizeof(*msg) == client->communication.inbound.buffer.size);
+       msg = (const struct lttng_notification_channel_message *)
+                             client->communication.inbound.buffer.data;
+
+       if (msg->size == 0 ||
+                       msg->size > DEFAULT_MAX_NOTIFICATION_CLIENT_MESSAGE_PAYLOAD_SIZE) {
+               ERR("[notification-thread] Invalid notification channel message: length = %u",
+                               msg->size);
+               ret = -1;
+               goto end;
+       }
+
+       switch (msg->type) {
+       case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_SUBSCRIBE:
+       case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_UNSUBSCRIBE:
+       case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_HANDSHAKE:
+               break;
+       default:
+               ret = -1;
+               ERR("[notification-thread] Invalid notification channel message: unexpected message type");
+               goto end;
+       }
+
+       client->communication.inbound.bytes_to_receive = msg->size;
+       client->communication.inbound.msg_type =
+                       (enum lttng_notification_channel_message_type) msg->type;
+       ret = lttng_dynamic_buffer_set_size(
+                       &client->communication.inbound.buffer, msg->size);
+end:
+       pthread_mutex_unlock(&client->lock);
+       return ret;
+}
+
 static
-int client_send_command_reply(struct notification_client *client,
-               struct notification_thread_state *state,
-               enum lttng_notification_channel_status status)
+int client_handle_message_handshake(struct notification_client *client,
+               struct notification_thread_state *state)
 {
        int ret;
-       struct lttng_notification_channel_command_reply reply = {
-               .status = (int8_t) status,
+       struct lttng_notification_channel_command_handshake *handshake_client;
+       const struct lttng_notification_channel_command_handshake handshake_reply = {
+                       .major = LTTNG_NOTIFICATION_CHANNEL_VERSION_MAJOR,
+                       .minor = LTTNG_NOTIFICATION_CHANNEL_VERSION_MINOR,
        };
-       struct lttng_notification_channel_message msg = {
-               .type = (int8_t) LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_COMMAND_REPLY,
-               .size = sizeof(reply),
+       const struct lttng_notification_channel_message msg_header = {
+                       .type = LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_HANDSHAKE,
+                       .size = sizeof(handshake_reply),
        };
-       char buffer[sizeof(msg) + sizeof(reply)];
-
-       if (client->communication.outbound.queued_command_reply) {
-               /* Protocol error. */
-               goto error;
+       enum lttng_notification_channel_status status =
+                       LTTNG_NOTIFICATION_CHANNEL_STATUS_OK;
+       char send_buffer[sizeof(msg_header) + sizeof(handshake_reply)];
+
+       pthread_mutex_lock(&client->lock);
+
+       memcpy(send_buffer, &msg_header, sizeof(msg_header));
+       memcpy(send_buffer + sizeof(msg_header), &handshake_reply,
+                       sizeof(handshake_reply));
+
+       handshake_client =
+                       (struct lttng_notification_channel_command_handshake *)
+                                       client->communication.inbound.buffer
+                                                       .data;
+       client->major = handshake_client->major;
+       client->minor = handshake_client->minor;
+       if (!client->communication.inbound.creds_received) {
+               ERR("[notification-thread] No credentials received from client");
+               ret = -1;
+               goto end;
        }
 
-       memcpy(buffer, &msg, sizeof(msg));
-       memcpy(buffer + sizeof(msg), &reply, sizeof(reply));
-       DBG("[notification-thread] Send command reply (%i)", (int) status);
+       client->uid = LTTNG_SOCK_GET_UID_CRED(
+                       &client->communication.inbound.creds);
+       client->gid = LTTNG_SOCK_GET_GID_CRED(
+                       &client->communication.inbound.creds);
+       DBG("[notification-thread] Received handshake from client (uid = %u, gid = %u) with version %i.%i",
+                       client->uid, client->gid, (int) client->major,
+                       (int) client->minor);
+
+       if (handshake_client->major !=
+                       LTTNG_NOTIFICATION_CHANNEL_VERSION_MAJOR) {
+               status = LTTNG_NOTIFICATION_CHANNEL_STATUS_UNSUPPORTED_VERSION;
+       }
 
-       /* Enqueue buffer to outgoing queue and flush it. */
        ret = lttng_dynamic_buffer_append(
-                       &client->communication.outbound.buffer,
-                       buffer, sizeof(buffer));
+                       &client->communication.outbound.buffer, send_buffer,
+                       sizeof(send_buffer));
        if (ret) {
-               goto error;
+               ERR("[notification-thread] Failed to send protocol version to notification channel client");
+               goto end;
        }
 
+       client->validated = true;
+       client->communication.active = true;
+
        ret = client_flush_outgoing_queue(client, state);
        if (ret) {
-               goto error;
+               goto end;
        }
 
-       if (client->communication.outbound.buffer.size != 0) {
-               /* Queue could not be emptied. */
-               client->communication.outbound.queued_command_reply = true;
+       ret = client_send_command_reply(client, state, status);
+       if (ret) {
+               ERR("[notification-thread] Failed to send reply to notification channel client");
+               goto end;
        }
 
-       return 0;
-error:
-       return -1;
+       /* Set reception state to receive the next message header. */
+       ret = client_reset_inbound_state(client);
+       if (ret) {
+               ERR("[notification-thread] Failed to reset client communication's inbound state");
+               goto end;
+       }
+
+end:
+       pthread_mutex_unlock(&client->lock);
+       return ret;
+}
+
+static
+int client_handle_message_subscription(
+               struct notification_client *client,
+               enum lttng_notification_channel_message_type msg_type,
+               struct notification_thread_state *state)
+{
+       int ret;
+       struct lttng_condition *condition;
+       enum lttng_notification_channel_status status =
+                       LTTNG_NOTIFICATION_CHANNEL_STATUS_OK;
+       struct lttng_payload_view condition_view =
+                       lttng_payload_view_from_dynamic_buffer(
+                                       &client->communication.inbound.buffer,
+                                       0, -1);
+       size_t expected_condition_size;
+
+       pthread_mutex_lock(&client->lock);
+       expected_condition_size = client->communication.inbound.buffer.size;
+       pthread_mutex_unlock(&client->lock);
+
+       ret = lttng_condition_create_from_payload(&condition_view, &condition);
+       if (ret != expected_condition_size) {
+               ERR("[notification-thread] Malformed condition received from client");
+               goto end;
+       }
+
+       if (msg_type == LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_SUBSCRIBE) {
+               ret = notification_thread_client_subscribe(
+                               client, condition, state, &status);
+       } else {
+               ret = notification_thread_client_unsubscribe(
+                               client, condition, state, &status);
+       }
+       if (ret) {
+               goto end;
+       }
+
+       pthread_mutex_lock(&client->lock);
+       ret = client_send_command_reply(client, state, status);
+       if (ret) {
+               ERR("[notification-thread] Failed to send reply to notification channel client");
+               goto end_unlock;
+       }
+
+       /* Set reception state to receive the next message header. */
+       ret = client_reset_inbound_state(client);
+       if (ret) {
+               ERR("[notification-thread] Failed to reset client communication's inbound state");
+               goto end_unlock;
+       }
+
+end_unlock:
+       pthread_mutex_unlock(&client->lock);
+end:
+       return ret;
 }
 
 static
@@ -1889,158 +3050,19 @@ int client_dispatch_message(struct notification_client *client,
        switch (client->communication.inbound.msg_type) {
        case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_UNKNOWN:
        {
-               /*
-                * Receiving message header. The function will be called again
-                * once the rest of the message as been received and can be
-                * interpreted.
-                */
-               const struct lttng_notification_channel_message *msg;
-
-               assert(sizeof(*msg) ==
-                               client->communication.inbound.buffer.size);
-               msg = (const struct lttng_notification_channel_message *)
-                               client->communication.inbound.buffer.data;
-
-               if (msg->size == 0 || msg->size > DEFAULT_MAX_NOTIFICATION_CLIENT_MESSAGE_PAYLOAD_SIZE) {
-                       ERR("[notification-thread] Invalid notification channel message: length = %u", msg->size);
-                       ret = -1;
-                       goto end;
-               }
-
-               switch (msg->type) {
-               case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_SUBSCRIBE:
-               case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_UNSUBSCRIBE:
-               case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_HANDSHAKE:
-                       break;
-               default:
-                       ret = -1;
-                       ERR("[notification-thread] Invalid notification channel message: unexpected message type");
-                       goto end;
-               }
-
-               client->communication.inbound.bytes_to_receive = msg->size;
-               client->communication.inbound.msg_type =
-                               (enum lttng_notification_channel_message_type) msg->type;
-               ret = lttng_dynamic_buffer_set_size(
-                               &client->communication.inbound.buffer, msg->size);
-               if (ret) {
-                       goto end;
-               }
+               ret = client_handle_message_unknown(client, state);
                break;
        }
        case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_HANDSHAKE:
        {
-               struct lttng_notification_channel_command_handshake *handshake_client;
-               struct lttng_notification_channel_command_handshake handshake_reply = {
-                       .major = LTTNG_NOTIFICATION_CHANNEL_VERSION_MAJOR,
-                       .minor = LTTNG_NOTIFICATION_CHANNEL_VERSION_MINOR,
-               };
-               struct lttng_notification_channel_message msg_header = {
-                       .type = LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_HANDSHAKE,
-                       .size = sizeof(handshake_reply),
-               };
-               enum lttng_notification_channel_status status =
-                               LTTNG_NOTIFICATION_CHANNEL_STATUS_OK;
-               char send_buffer[sizeof(msg_header) + sizeof(handshake_reply)];
-
-               memcpy(send_buffer, &msg_header, sizeof(msg_header));
-               memcpy(send_buffer + sizeof(msg_header), &handshake_reply,
-                               sizeof(handshake_reply));
-
-               handshake_client =
-                               (struct lttng_notification_channel_command_handshake *)
-                                       client->communication.inbound.buffer.data;
-               client->major = handshake_client->major;
-               client->minor = handshake_client->minor;
-               if (!client->communication.inbound.creds_received) {
-                       ERR("[notification-thread] No credentials received from client");
-                       ret = -1;
-                       goto end;
-               }
-
-               client->uid = LTTNG_SOCK_GET_UID_CRED(
-                               &client->communication.inbound.creds);
-               client->gid = LTTNG_SOCK_GET_GID_CRED(
-                               &client->communication.inbound.creds);
-               DBG("[notification-thread] Received handshake from client (uid = %u, gid = %u) with version %i.%i",
-                               client->uid, client->gid, (int) client->major,
-                               (int) client->minor);
-
-               if (handshake_client->major != LTTNG_NOTIFICATION_CHANNEL_VERSION_MAJOR) {
-                       status = LTTNG_NOTIFICATION_CHANNEL_STATUS_UNSUPPORTED_VERSION;
-               }
-
-               ret = lttng_dynamic_buffer_append(&client->communication.outbound.buffer,
-                               send_buffer, sizeof(send_buffer));
-               if (ret) {
-                       ERR("[notification-thread] Failed to send protocol version to notification channel client");
-                       goto end;
-               }
-
-               ret = client_flush_outgoing_queue(client, state);
-               if (ret) {
-                       goto end;
-               }
-
-               ret = client_send_command_reply(client, state, status);
-               if (ret) {
-                       ERR("[notification-thread] Failed to send reply to notification channel client");
-                       goto end;
-               }
-
-               /* Set reception state to receive the next message header. */
-               ret = client_reset_inbound_state(client);
-               if (ret) {
-                       ERR("[notification-thread] Failed to reset client communication's inbound state");
-                       goto end;
-               }
-               client->validated = true;
+               ret = client_handle_message_handshake(client, state);
                break;
        }
        case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_SUBSCRIBE:
        case LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_UNSUBSCRIBE:
        {
-               struct lttng_condition *condition;
-               enum lttng_notification_channel_status status =
-                               LTTNG_NOTIFICATION_CHANNEL_STATUS_OK;
-               const struct lttng_buffer_view condition_view =
-                               lttng_buffer_view_from_dynamic_buffer(
-                                       &client->communication.inbound.buffer,
-                                       0, -1);
-               size_t expected_condition_size =
-                               client->communication.inbound.buffer.size;
-
-               ret = lttng_condition_create_from_buffer(&condition_view,
-                               &condition);
-               if (ret != expected_condition_size) {
-                       ERR("[notification-thread] Malformed condition received from client");
-                       goto end;
-               }
-
-               if (client->communication.inbound.msg_type ==
-                               LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_SUBSCRIBE) {
-                       ret = notification_thread_client_subscribe(client,
-                                       condition, state, &status);
-               } else {
-                       ret = notification_thread_client_unsubscribe(client,
-                                       condition, state, &status);
-               }
-               if (ret) {
-                       goto end;
-               }
-
-               ret = client_send_command_reply(client, state, status);
-               if (ret) {
-                       ERR("[notification-thread] Failed to send reply to notification channel client");
-                       goto end;
-               }
-
-               /* Set reception state to receive the next message header. */
-               ret = client_reset_inbound_state(client);
-               if (ret) {
-                       ERR("[notification-thread] Failed to reset client communication's inbound state");
-                       goto end;
-               }
+               ret = client_handle_message_subscription(client,
+                               client->communication.inbound.msg_type, state);
                break;
        }
        default:
@@ -2058,6 +3080,7 @@ int handle_notification_thread_client_in(
        struct notification_client *client;
        ssize_t recv_ret;
        size_t offset;
+       bool message_is_complete = false;
 
        client = get_client_from_socket(socket, state);
        if (!client) {
@@ -2066,6 +3089,7 @@ int handle_notification_thread_client_in(
                goto end;
        }
 
+       pthread_mutex_lock(&client->lock);
        offset = client->communication.inbound.buffer.size -
                        client->communication.inbound.bytes_to_receive;
        if (client->communication.inbound.expect_creds) {
@@ -2082,12 +3106,17 @@ int handle_notification_thread_client_in(
                                client->communication.inbound.buffer.data + offset,
                                client->communication.inbound.bytes_to_receive);
        }
+       if (recv_ret >= 0) {
+               client->communication.inbound.bytes_to_receive -= recv_ret;
+               message_is_complete = client->communication.inbound
+                                                     .bytes_to_receive == 0;
+       }
+       pthread_mutex_unlock(&client->lock);
        if (recv_ret < 0) {
                goto error_disconnect_client;
        }
 
-       client->communication.inbound.bytes_to_receive -= recv_ret;
-       if (client->communication.inbound.bytes_to_receive == 0) {
+       if (message_is_complete) {
                ret = client_dispatch_message(client, state);
                if (ret) {
                        /*
@@ -2096,13 +3125,13 @@ int handle_notification_thread_client_in(
                         */
                        goto error_disconnect_client;
                }
-       } else {
-               goto end;
        }
 end:
        return ret;
 error_disconnect_client:
-       ret = handle_notification_thread_client_disconnect(socket, state);
+       pthread_mutex_lock(&client->lock);
+       ret = notification_thread_client_disconnect(client, state);
+       pthread_mutex_unlock(&client->lock);
        return ret;
 }
 
@@ -2120,7 +3149,9 @@ int handle_notification_thread_client_out(
                goto end;
        }
 
+       pthread_mutex_lock(&client->lock);
        ret = client_flush_outgoing_queue(client, state);
+       pthread_mutex_unlock(&client->lock);
        if (ret) {
                goto end;
        }
@@ -2129,20 +3160,17 @@ end:
 }
 
 static
-bool evaluate_buffer_usage_condition(struct lttng_condition *condition,
-               struct channel_state_sample *sample, uint64_t buffer_capacity)
+bool evaluate_buffer_usage_condition(const struct lttng_condition *condition,
+               const struct channel_state_sample *sample,
+               uint64_t buffer_capacity)
 {
        bool result = false;
        uint64_t threshold;
        enum lttng_condition_type condition_type;
-       struct lttng_condition_buffer_usage *use_condition = container_of(
+       const struct lttng_condition_buffer_usage *use_condition = container_of(
                        condition, struct lttng_condition_buffer_usage,
                        parent);
 
-       if (!sample) {
-               goto end;
-       }
-
        if (use_condition->threshold_bytes.set) {
                threshold = use_condition->threshold_bytes.value;
        } else {
@@ -2154,7 +3182,7 @@ bool evaluate_buffer_usage_condition(struct lttng_condition *condition,
                 * forego this double-multiplication or it could be performed
                 * as fixed-point math.
                 *
-                * Note that caching should accomodate the case where the
+                * Note that caching should accommodates the case where the
                 * condition applies to multiple channels (i.e. don't assume
                 * that all channels matching my_chann* have the same size...)
                 */
@@ -2186,32 +3214,73 @@ bool evaluate_buffer_usage_condition(struct lttng_condition *condition,
                        result = true;
                }
        }
-end:
+
        return result;
 }
 
 static
-int evaluate_condition(struct lttng_condition *condition,
+bool evaluate_session_consumed_size_condition(
+               const struct lttng_condition *condition,
+               uint64_t session_consumed_size)
+{
+       uint64_t threshold;
+       const struct lttng_condition_session_consumed_size *size_condition =
+                       container_of(condition,
+                               struct lttng_condition_session_consumed_size,
+                               parent);
+
+       threshold = size_condition->consumed_threshold_bytes.value;
+       DBG("[notification-thread] Session consumed size condition being evaluated: threshold = %" PRIu64 ", current size = %" PRIu64,
+                       threshold, session_consumed_size);
+       return session_consumed_size >= threshold;
+}
+
+static
+int evaluate_buffer_condition(const struct lttng_condition *condition,
                struct lttng_evaluation **evaluation,
-               struct notification_thread_state *state,
-               struct channel_state_sample *previous_sample,
-               struct channel_state_sample *latest_sample,
-               uint64_t buffer_capacity)
+               const struct notification_thread_state *state,
+               const struct channel_state_sample *previous_sample,
+               const struct channel_state_sample *latest_sample,
+               uint64_t previous_session_consumed_total,
+               uint64_t latest_session_consumed_total,
+               struct channel_info *channel_info)
 {
        int ret = 0;
        enum lttng_condition_type condition_type;
-       bool previous_sample_result;
+       const bool previous_sample_available = !!previous_sample;
+       bool previous_sample_result = false;
        bool latest_sample_result;
 
        condition_type = lttng_condition_get_type(condition);
-       /* No other condition type supported for the moment. */
-       assert(condition_type == LTTNG_CONDITION_TYPE_BUFFER_USAGE_LOW ||
-                       condition_type == LTTNG_CONDITION_TYPE_BUFFER_USAGE_HIGH);
 
-       previous_sample_result = evaluate_buffer_usage_condition(condition,
-                       previous_sample, buffer_capacity);
-       latest_sample_result = evaluate_buffer_usage_condition(condition,
-                       latest_sample, buffer_capacity);
+       switch (condition_type) {
+       case LTTNG_CONDITION_TYPE_BUFFER_USAGE_LOW:
+       case LTTNG_CONDITION_TYPE_BUFFER_USAGE_HIGH:
+               if (caa_likely(previous_sample_available)) {
+                       previous_sample_result =
+                               evaluate_buffer_usage_condition(condition,
+                                       previous_sample, channel_info->capacity);
+               }
+               latest_sample_result = evaluate_buffer_usage_condition(
+                               condition, latest_sample,
+                               channel_info->capacity);
+               break;
+       case LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE:
+               if (caa_likely(previous_sample_available)) {
+                       previous_sample_result =
+                               evaluate_session_consumed_size_condition(
+                                       condition,
+                                       previous_session_consumed_total);
+               }
+               latest_sample_result =
+                               evaluate_session_consumed_size_condition(
+                                       condition,
+                                       latest_session_consumed_total);
+               break;
+       default:
+               /* Unknown condition type; internal error. */
+               abort();
+       }
 
        if (!latest_sample_result ||
                        (previous_sample_result == latest_sample_result)) {
@@ -2224,23 +3293,36 @@ int evaluate_condition(struct lttng_condition *condition,
                goto end;
        }
 
-       if (evaluation && latest_sample_result) {
+       if (!evaluation || !latest_sample_result) {
+               goto end;
+       }
+
+       switch (condition_type) {
+       case LTTNG_CONDITION_TYPE_BUFFER_USAGE_LOW:
+       case LTTNG_CONDITION_TYPE_BUFFER_USAGE_HIGH:
                *evaluation = lttng_evaluation_buffer_usage_create(
                                condition_type,
                                latest_sample->highest_usage,
-                               buffer_capacity);
-               if (!*evaluation) {
-                       ret = -1;
-                       goto end;
-               }
+                               channel_info->capacity);
+               break;
+       case LTTNG_CONDITION_TYPE_SESSION_CONSUMED_SIZE:
+               *evaluation = lttng_evaluation_session_consumed_size_create(
+                               latest_session_consumed_total);
+               break;
+       default:
+               abort();
+       }
+
+       if (!*evaluation) {
+               ret = -1;
+               goto end;
        }
 end:
        return ret;
 }
 
 static
-int client_enqueue_dropped_notification(struct notification_client *client,
-               struct notification_thread_state *state)
+int client_enqueue_dropped_notification(struct notification_client *client)
 {
        int ret;
        struct lttng_notification_channel_message msg = {
@@ -2248,81 +3330,108 @@ int client_enqueue_dropped_notification(struct notification_client *client,
                .size = 0,
        };
 
+       ASSERT_LOCKED(client->lock);
+
        ret = lttng_dynamic_buffer_append(
                        &client->communication.outbound.buffer, &msg,
                        sizeof(msg));
        return ret;
 }
 
+/*
+ * Permission checks relative to notification channel clients are performed
+ * here. Notice how object, client, and trigger credentials are involved in
+ * this check.
+ *
+ * The `object` credentials are the credentials associated with the "subject"
+ * of a condition. For instance, a `rotation completed` condition applies
+ * to a session. When that condition is met, it will produce an evaluation
+ * against a session. Hence, in this case, the `object` credentials are the
+ * credentials of the "subject" session.
+ *
+ * The `trigger` credentials are the credentials of the user that registered the
+ * trigger.
+ *
+ * The `client` credentials are the credentials of the user that created a given
+ * notification channel.
+ *
+ * In terms of visibility, it is expected that non-privilieged users can only
+ * register triggers against "their" objects (their own sessions and
+ * applications they are allowed to interact with). They can then open a
+ * notification channel and subscribe to notifications associated with those
+ * triggers.
+ *
+ * As for privilieged users, they can register triggers against the objects of
+ * other users. They can then subscribe to the notifications associated to their
+ * triggers. Privilieged users _can't_ subscribe to the notifications of
+ * triggers owned by other users; they must create their own triggers.
+ *
+ * This is more a concern of usability than security. It would be difficult for
+ * a root user reliably subscribe to a specific set of conditions without
+ * interference from external users (those could, for instance, unregister
+ * their triggers).
+ */
 static
-int send_evaluation_to_clients(struct lttng_trigger *trigger,
-               struct lttng_evaluation *evaluation,
+int send_evaluation_to_clients(const struct lttng_trigger *trigger,
+               const struct lttng_evaluation *evaluation,
                struct notification_client_list* client_list,
                struct notification_thread_state *state,
-               uid_t channel_uid, gid_t channel_gid)
+               uid_t object_uid, gid_t object_gid)
 {
        int ret = 0;
-       struct lttng_dynamic_buffer msg_buffer;
+       struct lttng_payload msg_payload;
        struct notification_client_list_element *client_list_element, *tmp;
-       struct lttng_notification *notification;
-       struct lttng_condition *condition;
-       ssize_t expected_notification_size, notification_size;
-       struct lttng_notification_channel_message msg;
-
-       lttng_dynamic_buffer_init(&msg_buffer);
-
-       condition = lttng_trigger_get_condition(trigger);
-       assert(condition);
-
-       notification = lttng_notification_create(condition, evaluation);
-       if (!notification) {
-               ret = -1;
-               goto end;
-       }
+       const struct lttng_notification notification = {
+               .condition = (struct lttng_condition *) lttng_trigger_get_const_condition(trigger),
+               .evaluation = (struct lttng_evaluation *) evaluation,
+       };
+       struct lttng_notification_channel_message msg_header = {
+               .type = (int8_t) LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION,
+       };
+       const struct lttng_credentials *trigger_creds = lttng_trigger_get_credentials(trigger);
 
-       expected_notification_size = lttng_notification_serialize(notification,
-                       NULL);
-       if (expected_notification_size < 0) {
-               ERR("[notification-thread] Failed to get size of serialized notification");
-               ret = -1;
-               goto end;
-       }
+       lttng_payload_init(&msg_payload);
 
-       msg.type = (int8_t) LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION;
-       msg.size = (uint32_t) expected_notification_size;
-       ret = lttng_dynamic_buffer_append(&msg_buffer, &msg, sizeof(msg));
+       ret = lttng_dynamic_buffer_append(&msg_payload.buffer, &msg_header,
+                       sizeof(msg_header));
        if (ret) {
                goto end;
        }
 
-       ret = lttng_dynamic_buffer_set_size(&msg_buffer,
-                       msg_buffer.size + expected_notification_size);
+       ret = lttng_notification_serialize(&notification, &msg_payload);
        if (ret) {
-               goto end;
-       }
-
-       notification_size = lttng_notification_serialize(notification,
-                       msg_buffer.data + sizeof(msg));
-       if (notification_size != expected_notification_size) {
                ERR("[notification-thread] Failed to serialize notification");
                ret = -1;
                goto end;
        }
 
+       /* Update payload size. */
+       ((struct lttng_notification_channel_message *) msg_payload.buffer.data)
+                       ->size = (uint32_t)(
+                       msg_payload.buffer.size - sizeof(msg_header));
+
+       pthread_mutex_lock(&client_list->lock);
        cds_list_for_each_entry_safe(client_list_element, tmp,
                        &client_list->list, node) {
                struct notification_client *client =
                                client_list_element->client;
 
-               if (client->uid != channel_uid && client->gid != channel_gid &&
+               ret = 0;
+               pthread_mutex_lock(&client->lock);
+               if (client->uid != object_uid && client->gid != object_gid &&
                                client->uid != 0) {
                        /* Client is not allowed to monitor this channel. */
-                       DBG("[notification-thread] Skipping client at it does not have the permission to receive notification for this channel");
-                       continue;
+                       DBG("[notification-thread] Skipping client at it does not have the object permission to receive notification for this trigger");
+                       goto unlock_client;
+               }
+
+               if (client->uid != trigger_creds->uid && client->gid != trigger_creds->gid) {
+                       DBG("[notification-thread] Skipping client at it does not have the permission to receive notification for this trigger");
+                       goto unlock_client;
                }
 
                DBG("[notification-thread] Sending notification to client (fd = %i, %zu bytes)",
-                               client->socket, msg_buffer.size);
+                               client->socket, msg_payload.buffer.size);
                if (client->communication.outbound.buffer.size) {
                        /*
                         * Outgoing data is already buffered for this client;
@@ -2336,30 +3445,37 @@ int send_evaluation_to_clients(struct lttng_trigger *trigger,
                        if (!client->communication.outbound.dropped_notification) {
                                client->communication.outbound.dropped_notification = true;
                                ret = client_enqueue_dropped_notification(
-                                               client, state);
+                                               client);
                                if (ret) {
-                                       goto end;
+                                       goto unlock_client;
                                }
                        }
-                       continue;
+                       goto unlock_client;
                }
 
                ret = lttng_dynamic_buffer_append_buffer(
                                &client->communication.outbound.buffer,
-                               &msg_buffer);
+                               &msg_payload.buffer);
                if (ret) {
-                       goto end;
+                       goto unlock_client;
                }
 
                ret = client_flush_outgoing_queue(client, state);
                if (ret) {
-                       goto end;
+                       goto unlock_client;
+               }
+unlock_client:
+               pthread_mutex_unlock(&client->lock);
+               if (ret) {
+                       goto end_unlock_list;
                }
        }
        ret = 0;
+
+end_unlock_list:
+       pthread_mutex_unlock(&client_list->lock);
 end:
-       lttng_notification_destroy(notification);
-       lttng_dynamic_buffer_reset(&msg_buffer);
+       lttng_payload_reset(&msg_payload);
        return ret;
 }
 
@@ -2369,13 +3485,14 @@ int handle_notification_thread_channel_sample(
 {
        int ret = 0;
        struct lttcomm_consumer_channel_monitor_msg sample_msg;
-       struct channel_state_sample previous_sample, latest_sample;
        struct channel_info *channel_info;
        struct cds_lfht_node *node;
        struct cds_lfht_iter iter;
        struct lttng_channel_trigger_list *trigger_list;
        struct lttng_trigger_list_element *trigger_list_element;
        bool previous_sample_available = false;
+       struct channel_state_sample previous_sample, latest_sample;
+       uint64_t previous_session_consumed_total, latest_session_consumed_total;
 
        /*
         * The monitoring pipe only holds messages smaller than PIPE_BUF,
@@ -2394,6 +3511,7 @@ int handle_notification_thread_channel_sample(
        latest_sample.key.domain = domain;
        latest_sample.highest_usage = sample_msg.highest;
        latest_sample.lowest_usage = sample_msg.lowest;
+       latest_sample.channel_total_consumed = sample_msg.total_consumed;
 
        rcu_read_lock();
 
@@ -2419,12 +3537,16 @@ int handle_notification_thread_channel_sample(
        }
        channel_info = caa_container_of(node, struct channel_info,
                        channels_ht_node);
-       DBG("[notification-thread] Handling channel sample for channel %s (key = %" PRIu64 ") in session %s (highest usage = %" PRIu64 ", lowest usage = %" PRIu64")",
+       DBG("[notification-thread] Handling channel sample for channel %s (key = %" PRIu64 ") in session %s (highest usage = %" PRIu64 ", lowest usage = %" PRIu64", total consumed = %" PRIu64")",
                        channel_info->name,
                        latest_sample.key.key,
                        channel_info->session_info->name,
                        latest_sample.highest_usage,
-                       latest_sample.lowest_usage);
+                       latest_sample.lowest_usage,
+                       latest_sample.channel_total_consumed);
+
+       previous_session_consumed_total =
+                       channel_info->session_info->consumed_data_size;
 
        /* Retrieve the channel's last sample, if it exists, and update it. */
        cds_lfht_lookup(state->channel_state_ht,
@@ -2440,12 +3562,17 @@ int handle_notification_thread_channel_sample(
                stored_sample = caa_container_of(node,
                                struct channel_state_sample,
                                channel_state_ht_node);
+
                memcpy(&previous_sample, stored_sample,
                                sizeof(previous_sample));
                stored_sample->highest_usage = latest_sample.highest_usage;
                stored_sample->lowest_usage = latest_sample.lowest_usage;
                stored_sample->channel_total_consumed = latest_sample.channel_total_consumed;
                previous_sample_available = true;
+
+               latest_session_consumed_total =
+                               previous_session_consumed_total +
+                               (latest_sample.channel_total_consumed - previous_sample.channel_total_consumed);
        } else {
                /*
                 * This is the channel's first sample, allocate space for and
@@ -2464,8 +3591,15 @@ int handle_notification_thread_channel_sample(
                cds_lfht_add(state->channel_state_ht,
                                hash_channel_key(&stored_sample->key),
                                &stored_sample->channel_state_ht_node);
+
+               latest_session_consumed_total =
+                               previous_session_consumed_total +
+                               latest_sample.channel_total_consumed;
        }
 
+       channel_info->session_info->consumed_data_size =
+                       latest_session_consumed_total;
+
        /* Find triggers associated with this channel. */
        cds_lfht_lookup(state->channel_triggers_ht,
                        hash_channel_key(&latest_sample.key),
@@ -2480,54 +3614,51 @@ int handle_notification_thread_channel_sample(
        trigger_list = caa_container_of(node, struct lttng_channel_trigger_list,
                        channel_triggers_ht_node);
        cds_list_for_each_entry(trigger_list_element, &trigger_list->list,
-                       node) {
-               struct lttng_condition *condition;
-               struct lttng_action *action;
-               struct lttng_trigger *trigger;
-               struct notification_client_list *client_list;
+                       node) {
+               const struct lttng_condition *condition;
+               const struct lttng_action *action;
+               const struct lttng_trigger *trigger;
+               struct notification_client_list *client_list = NULL;
                struct lttng_evaluation *evaluation = NULL;
+               bool client_list_is_empty;
 
+               ret = 0;
                trigger = trigger_list_element->trigger;
-               condition = lttng_trigger_get_condition(trigger);
+               condition = lttng_trigger_get_const_condition(trigger);
                assert(condition);
-               action = lttng_trigger_get_action(trigger);
+               action = lttng_trigger_get_const_action(trigger);
 
                /* Notify actions are the only type currently supported. */
-               assert(lttng_action_get_type(action) ==
+               assert(lttng_action_get_type_const(action) ==
                                LTTNG_ACTION_TYPE_NOTIFY);
 
                /*
                 * Check if any client is subscribed to the result of this
                 * evaluation.
                 */
-               cds_lfht_lookup(state->notification_trigger_clients_ht,
-                               lttng_condition_hash(condition),
-                               match_client_list,
-                               trigger,
-                               &iter);
-               node = cds_lfht_iter_get_node(&iter);
-               assert(node);
-
-               client_list = caa_container_of(node,
-                               struct notification_client_list,
-                               notification_trigger_ht_node);
-               if (cds_list_empty(&client_list->list)) {
+               client_list = get_client_list_from_condition(state, condition);
+               assert(client_list);
+               client_list_is_empty = cds_list_empty(&client_list->list);
+               if (client_list_is_empty) {
                        /*
                         * No clients interested in the evaluation's result,
                         * skip it.
                         */
-                       continue;
+                       goto put_list;
                }
 
-               ret = evaluate_condition(condition, &evaluation, state,
+               ret = evaluate_buffer_condition(condition, &evaluation, state,
                                previous_sample_available ? &previous_sample : NULL,
-                               &latest_sample, channel_info->capacity);
-               if (ret) {
-                       goto end_unlock;
+                               &latest_sample,
+                               previous_session_consumed_total,
+                               latest_session_consumed_total,
+                               channel_info);
+               if (caa_unlikely(ret)) {
+                       goto put_list;
                }
 
-               if (!evaluation) {
-                       continue;
+               if (caa_likely(!evaluation)) {
+                       goto put_list;
                }
 
                /* Dispatch evaluation result to all clients. */
@@ -2536,8 +3667,10 @@ int handle_notification_thread_channel_sample(
                                channel_info->session_info->uid,
                                channel_info->session_info->gid);
                lttng_evaluation_destroy(evaluation);
+put_list:
+               notification_client_list_put(client_list);
                if (caa_unlikely(ret)) {
-                       goto end_unlock;
+                       break;
                }
        }
 end_unlock:
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