src/bin/lttng-sessiond/session.h

   1 /*
   2  * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
   3  *
   4  * SPDX-License-Identifier: GPL-2.0-only
   5  *
   6  */
   7
   8 #ifndef _LTT_SESSION_H
   9 #define _LTT_SESSION_H
  10
  11 #include <limits.h>
  12 #include <stdbool.h>
  13 #include <urcu/list.h>
  14
  15 #include <common/hashtable/hashtable.h>
  16 #include <common/dynamic-array.h>
  17 #include <lttng/rotation.h>
  18 #include <lttng/location.h>
  19 #include <lttng/lttng-error.h>
  20
  21 #include "snapshot.h"
  22 #include "trace-kernel.h"
  23 #include "consumer.h"
  24
  25 struct ltt_ust_session;
  26
  27 typedef void (*ltt_session_destroy_notifier)(const struct ltt_session *session,
  28                 void *user_data);
  29 typedef void (*ltt_session_clear_notifier)(const struct ltt_session *session,
  30                 void *user_data);
  31
  32 /*
  33  * Tracing session list
  34  *
  35  * Statically declared in session.c and can be accessed by using
  36  * session_get_list() function that returns the pointer to the list.
  37  */
  38 struct ltt_session_list {
  39         /*
  40          * This lock protects any read/write access to the list and
  41          * next_uuid. All public functions in session.c acquire this
  42          * lock and release it before returning. If none of those
  43          * functions are used, the lock MUST be acquired in order to
  44          * iterate or/and do any actions on that list.
  45          */
  46         pthread_mutex_t lock;
  47         /*
  48          * This condition variable is signaled on every removal from
  49          * the session list.
  50          */
  51         pthread_cond_t removal_cond;
  52
  53         /*
  54          * Session unique ID generator. The session list lock MUST be
  55          * upon update and read of this counter.
  56          */
  57         uint64_t next_uuid;
  58
  59         /* Linked list head */
  60         struct cds_list_head head;
  61 };
  62
  63 /*
  64  * This data structure contains information needed to identify a tracing
  65  * session for both LTTng and UST.
  66  */
  67 struct ltt_session {
  68         char name[NAME_MAX];
  69         bool has_auto_generated_name;
  70         bool name_contains_creation_time;
  71         char hostname[HOST_NAME_MAX]; /* Local hostname. */
  72         /* Path of the last closed chunk. */
  73         char last_chunk_path[LTTNG_PATH_MAX];
  74         time_t creation_time;
  75         struct ltt_kernel_session *kernel_session;
  76         struct ltt_ust_session *ust_session;
  77         struct urcu_ref ref;
  78         /*
  79          * Protect any read/write on this session data structure. This lock must be
  80          * acquired *before* using any public functions declared below. Use
  81          * session_lock() and session_unlock() for that.
  82          */
  83         pthread_mutex_t lock;
  84         struct cds_list_head list;
  85         uint64_t id;            /* session unique identifier */
  86         /* Indicates if the session has been added to the session list and ht.*/
  87         bool published;
  88         /* Indicates if a destroy command has been applied to this session. */
  89         bool destroyed;
  90         /* UID/GID of the user owning the session */
  91         uid_t uid;
  92         gid_t gid;
  93         /*
  94          * Network session handle. A value of 0 means that there is no remote
  95          * session established.
  96          */
  97         uint64_t net_handle;
  98         /*
  99          * This consumer is only set when the create_session_uri call is made.
 100          * This contains the temporary information for a consumer output. Upon
 101          * creation of the UST or kernel session, this consumer, if available, is
 102          * copied into those sessions.
 103          */
 104         struct consumer_output *consumer;
 105         /*
 106          * Indicates whether or not the user has specified an output directory
 107          * or if it was configured using the default configuration.
 108          */
 109         bool has_user_specified_directory;
 110         /* Did at least ONE start command has been triggered?. */
 111         unsigned int has_been_started:1;
 112         /*
 113          * Is the session active? Start trace command sets this to 1 and the stop
 114          * command reset it to 0.
 115          */
 116         unsigned int active:1;
 117
 118         /* Snapshot representation in a session. */
 119         struct snapshot snapshot;
 120         /* Indicate if the session has to output the traces or not. */
 121         unsigned int output_traces;
 122         /*
 123          * This session is in snapshot mode. This means that channels enabled
 124          * will be set in overwrite mode by default and must be in mmap
 125          * output mode. Note that snapshots can be taken on a session that
 126          * is not in "snapshot_mode". This parameter only affects channel
 127          * creation defaults.
 128          */
 129         unsigned int snapshot_mode;
 130         /*
 131          * A session that has channels that don't use 'mmap' output can't be
 132          * used to capture snapshots. This is set to true whenever a
 133          * 'splice' kernel channel is enabled.
 134          */
 135         bool has_non_mmap_channel;
 136         /*
 137          * Timer set when the session is created for live reading.
 138          */
 139         unsigned int live_timer;
 140         /*
 141          * Path where to keep the shared memory files.
 142          */
 143         char shm_path[PATH_MAX];
 144         /*
 145          * Node in ltt_sessions_ht_by_id.
 146          */
 147         struct lttng_ht_node_u64 node;
 148         /*
 149          * Timer to check periodically if a relay and/or consumer has completed
 150          * the last rotation.
 151          */
 152         bool rotation_pending_check_timer_enabled;
 153         timer_t rotation_pending_check_timer;
 154         /* Timer to periodically rotate a session. */
 155         bool rotation_schedule_timer_enabled;
 156         timer_t rotation_schedule_timer;
 157         /* Value for periodic rotations, 0 if disabled. */
 158         uint64_t rotate_timer_period;
 159         /* Value for size-based rotations, 0 if disabled. */
 160         uint64_t rotate_size;
 161         /*
 162          * Keep a state if this session was rotated after the last stop command.
 163          * We only allow one rotation after a stop. At destroy, we also need to
 164          * know if a rotation occurred since the last stop to rename the current
 165          * chunk. After a stop followed by rotate, all subsequent clear
 166          * (without prior start) will succeed, but will be effect-less.
 167          */
 168         bool rotated_after_last_stop;
 169         /*
 170          * Track whether the session was cleared after last stop. All subsequent
 171          * clear (without prior start) will succeed, but will be effect-less. A
 172          * subsequent rotate (without prior start) will return an error.
 173          */
 174         bool cleared_after_last_stop;
 175         /*
 176          * True if the session has had an explicit non-quiet rotation.
 177          */
 178         bool rotated;
 179         /*
 180          * Condition and trigger for size-based rotations.
 181          */
 182         struct lttng_condition *rotate_condition;
 183         struct lttng_trigger *rotate_trigger;
 184         LTTNG_OPTIONAL(uint64_t) most_recent_chunk_id;
 185         struct lttng_trace_chunk *current_trace_chunk;
 186         struct lttng_trace_chunk *chunk_being_archived;
 187         /* Current state of a rotation. */
 188         enum lttng_rotation_state rotation_state;
 189         bool quiet_rotation;
 190         char *last_archived_chunk_name;
 191         LTTNG_OPTIONAL(uint64_t) last_archived_chunk_id;
 192         struct lttng_dynamic_array destroy_notifiers;
 193         struct lttng_dynamic_array clear_notifiers;
 194         /* Session base path override. Set non-null. */
 195         char *base_path;
 196 };
 197
 198 enum lttng_error_code session_create(const char *name, uid_t uid, gid_t gid,
 199                 struct ltt_session **out_session);
 200 void session_lock(struct ltt_session *session);
 201 void session_unlock(struct ltt_session *session);
 202
 203 /*
 204  * The session list lock covers more ground than its name implies. While
 205  * it does protect against concurent mutations of the session list, it is
 206  * also used as a multi-session lock when synchronizing newly-registered
 207  * 'user space tracer' and 'agent' applications.
 208  *
 209  * In other words, it prevents session configurations from changing while they
 210  * are being transmitted to the various applications.
 211  */
 212 void session_lock_list(void);
 213 int session_trylock_list(void);
 214 void session_unlock_list(void);
 215
 216 void session_destroy(struct ltt_session *session);
 217 int session_add_destroy_notifier(struct ltt_session *session,
 218                 ltt_session_destroy_notifier notifier, void *user_data);
 219
 220 int session_add_clear_notifier(struct ltt_session *session,
 221                 ltt_session_clear_notifier notifier, void *user_data);
 222 void session_notify_clear(struct ltt_session *session);
 223
 224 bool session_get(struct ltt_session *session);
 225 void session_put(struct ltt_session *session);
 226
 227 enum consumer_dst_type session_get_consumer_destination_type(
 228                 const struct ltt_session *session);
 229 const char *session_get_net_consumer_hostname(
 230                 const struct ltt_session *session);
 231 void session_get_net_consumer_ports(
 232                 const struct ltt_session *session,
 233                 uint16_t *control_port, uint16_t *data_port);
 234 struct lttng_trace_archive_location *session_get_trace_archive_location(
 235                 const struct ltt_session *session);
 236
 237 struct ltt_session *session_find_by_name(const char *name);
 238 struct ltt_session *session_find_by_id(uint64_t id);
 239
 240 struct ltt_session_list *session_get_list(void);
 241 void session_list_wait_empty(void);
 242
 243 bool session_access_ok(struct ltt_session *session, uid_t uid);
 244
 245 int session_reset_rotation_state(struct ltt_session *session,
 246                 enum lttng_rotation_state result);
 247
 248 /* Create a new trace chunk object from the session's configuration. */
 249 struct lttng_trace_chunk *session_create_new_trace_chunk(
 250                 const struct ltt_session *session,
 251                 const struct consumer_output *consumer_output_override,
 252                 const char *session_base_path_override,
 253                 const char *chunk_name_override);
 254
 255 /*
 256  * Set `new_trace_chunk` as the session's current trace chunk. A reference
 257  * to `new_trace_chunk` is acquired by the session. The chunk is created
 258  * on remote peers (consumer and relay daemons).
 259  *
 260  * A reference to the session's current trace chunk is returned through
 261  * `current_session_trace_chunk` on success.
 262  */
 263 int session_set_trace_chunk(struct ltt_session *session,
 264                 struct lttng_trace_chunk *new_trace_chunk,
 265                 struct lttng_trace_chunk **current_session_trace_chunk);
 266
 267 /*
 268  * Close a chunk on the remote peers of a session. Has no effect on the
 269  * ltt_session itself.
 270  */
 271 int session_close_trace_chunk(struct ltt_session *session,
 272                 struct lttng_trace_chunk *trace_chunk,
 273                 enum lttng_trace_chunk_command_type close_command,
 274                 char *path);
 275
 276 /* Open a packet in all channels of a given session. */
 277 enum lttng_error_code session_open_packets(struct ltt_session *session);
 278
 279 bool session_output_supports_trace_chunks(const struct ltt_session *session);
 280
 281 #endif /* _LTT_SESSION_H */