Fix: code refactoring of viewer streams in relayd
[lttng-tools.git] / src / bin / lttng-relayd / live.c
index 69e2eb3b286c2f54cad19fefbdbe1e5f2bb93492..d558b71487813aadf6206427c5a2f658589bbcb7 100644 (file)
@@ -45,6 +45,7 @@
 #include <common/compat/socket.h>
 #include <common/defaults.h>
 #include <common/futex.h>
+#include <common/index/index.h>
 #include <common/sessiond-comm/sessiond-comm.h>
 #include <common/sessiond-comm/inet.h>
 #include <common/sessiond-comm/relayd.h>
 #include "cmd.h"
 #include "live.h"
 #include "lttng-relayd.h"
-#include "lttng-viewer.h"
 #include "utils.h"
 #include "health-relayd.h"
 #include "testpoint.h"
+#include "viewer-stream.h"
 
 static struct lttng_uri *live_uri;
 
@@ -95,6 +96,215 @@ void cleanup(void)
        free(live_uri);
 }
 
+/*
+ * Receive a request buffer using a given socket, destination allocated buffer
+ * of length size.
+ *
+ * Return the size of the received message or else a negative value on error
+ * with errno being set by recvmsg() syscall.
+ */
+static
+ssize_t recv_request(struct lttcomm_sock *sock, void *buf, size_t size)
+{
+       ssize_t ret;
+
+       assert(sock);
+       assert(buf);
+
+       ret = sock->ops->recvmsg(sock, buf, size, 0);
+       if (ret < 0 || ret != size) {
+               if (ret == 0) {
+                       /* Orderly shutdown. Not necessary to print an error. */
+                       DBG("Socket %d did an orderly shutdown", sock->fd);
+               } else {
+                       ERR("Relay failed to receive request.");
+               }
+               ret = -1;
+       }
+
+       return ret;
+}
+
+/*
+ * Send a response buffer using a given socket, source allocated buffer of
+ * length size.
+ *
+ * Return the size of the sent message or else a negative value on error with
+ * errno being set by sendmsg() syscall.
+ */
+static
+ssize_t send_response(struct lttcomm_sock *sock, void *buf, size_t size)
+{
+       ssize_t ret;
+
+       assert(sock);
+       assert(buf);
+
+       ret = sock->ops->sendmsg(sock, buf, size, 0);
+       if (ret < 0) {
+               ERR("Relayd failed to send response.");
+       }
+
+       return ret;
+}
+
+/*
+ * Atomically check if new streams got added in the session since the last
+ * check and reset the flag to 0.
+ *
+ * Returns 1 if new streams got added, 0 if nothing changed, a negative value
+ * on error.
+ */
+static
+int check_new_streams(uint64_t session_id, struct lttng_ht *sessions_ht)
+{
+       int ret;
+       unsigned long current_val;
+       struct relay_session *session;
+
+       assert(sessions_ht);
+
+       session = session_find_by_id(sessions_ht, session_id);
+       if (!session) {
+               DBG("Relay session %" PRIu64 " not found", session_id);
+               ret = -1;
+               goto error;
+       }
+
+       current_val = uatomic_cmpxchg(&session->new_streams, 1, 0);
+       ret = current_val;
+
+error:
+       return ret;
+}
+
+/*
+ * Send viewer streams to the given socket. The ignore_sent_flag indicates if
+ * this function should ignore the sent flag or not.
+ *
+ * Return 0 on success or else a negative value.
+ */
+static
+ssize_t send_viewer_streams(struct lttcomm_sock *sock,
+               struct relay_session *session, unsigned int ignore_sent_flag)
+{
+       ssize_t ret;
+       struct lttng_viewer_stream send_stream;
+       struct lttng_ht_iter iter;
+       struct relay_viewer_stream *vstream;
+
+       assert(session);
+
+       rcu_read_lock();
+
+       cds_lfht_for_each_entry(viewer_streams_ht->ht, &iter.iter, vstream,
+                       stream_n.node) {
+               health_code_update();
+
+               /* Ignore if not the same session. */
+               if (vstream->session_id != session->id ||
+                               (!ignore_sent_flag && vstream->sent_flag)) {
+                       continue;
+               }
+
+               send_stream.id = htobe64(vstream->stream_handle);
+               send_stream.ctf_trace_id = htobe64(vstream->ctf_trace->id);
+               send_stream.metadata_flag = htobe32(vstream->metadata_flag);
+               strncpy(send_stream.path_name, vstream->path_name,
+                               sizeof(send_stream.path_name));
+               strncpy(send_stream.channel_name, vstream->channel_name,
+                               sizeof(send_stream.channel_name));
+
+               DBG("Sending stream %" PRIu64 " to viewer", vstream->stream_handle);
+               ret = send_response(sock, &send_stream, sizeof(send_stream));
+               if (ret < 0) {
+                       goto end_unlock;
+               }
+               vstream->sent_flag = 1;
+       }
+
+       ret = 0;
+
+end_unlock:
+       rcu_read_unlock();
+       return ret;
+}
+
+/*
+ * Create every viewer stream possible for the given session with the seek
+ * type. Three counters *can* be return which are in order the total amount of
+ * viewer stream of the session, the number of unsent stream and the number of
+ * stream created. Those counters can be NULL and thus will be ignored.
+ *
+ * Return 0 on success or else a negative value.
+ */
+static
+int make_viewer_streams(struct relay_session *session,
+               enum lttng_viewer_seek seek_t, uint32_t *nb_total, uint32_t *nb_unsent,
+               uint32_t *nb_created)
+{
+       int ret;
+       struct relay_stream *stream;
+       struct lttng_ht_iter iter;
+
+       assert(session);
+
+       /*
+        * This is to make sure we create viewer streams for a full received
+        * channel. For instance, if we have 8 streams for a channel that are
+        * concurrently being flagged ready, we can end up creating just a subset
+        * of the 8 streams (the ones that are flagged). This lock avoids this
+        * limbo state.
+        */
+       pthread_mutex_lock(&session->viewer_ready_lock);
+
+       /*
+        * Create viewer streams for relay streams that are ready to be used for a
+        * the given session id only.
+        */
+       cds_lfht_for_each_entry(relay_streams_ht->ht, &iter.iter, stream,
+                       stream_n.node) {
+               struct relay_viewer_stream *vstream;
+
+               health_code_update();
+
+               if (stream->session->id != session->id ||
+                               !stream->ctf_trace || !stream->viewer_ready) {
+                       /*
+                        * Ignore stream from a different session. Don't create streams
+                        * with no ctf_trace or not ready for the viewer.
+                        */
+                       continue;
+               }
+
+               vstream = viewer_stream_find_by_id(stream->stream_handle);
+               if (!vstream) {
+                       vstream = viewer_stream_create(stream, seek_t);
+                       if (!vstream) {
+                               ret = -1;
+                               goto error_unlock;
+                       }
+                       if (nb_created) {
+                               /* Update number of created stream counter. */
+                               (*nb_created)++;
+                       }
+               } else if (!vstream->sent_flag && nb_unsent) {
+                       /* Update number of unsent stream counter. */
+                       (*nb_unsent)++;
+               }
+               /* Update number of total stream counter. */
+               if (nb_total) {
+                       (*nb_total)++;
+               }
+       }
+
+       ret = 0;
+
+error_unlock:
+       pthread_mutex_unlock(&session->viewer_ready_lock);
+       return ret;
+}
+
 /*
  * Write to writable pipe used to notify a thread.
  */
@@ -461,16 +671,10 @@ int viewer_connect(struct relay_command *cmd)
 
        health_code_update();
 
-       /* Get version from the other side. */
-       ret = cmd->sock->ops->recvmsg(cmd->sock, &msg, sizeof(msg), 0);
-       if (ret < 0 || ret != sizeof(msg)) {
-               if (ret == 0) {
-                       /* Orderly shutdown. Not necessary to print an error. */
-                       DBG("Socket %d did an orderly shutdown", cmd->sock->fd);
-               } else {
-                       ERR("Relay failed to receive the version values.");
-               }
-               ret = -1;
+       DBG("Viewer is establishing a connection to the relayd.");
+
+       ret = recv_request(cmd->sock, &msg, sizeof(msg));
+       if (ret < 0) {
                goto end;
        }
 
@@ -481,8 +685,8 @@ int viewer_connect(struct relay_command *cmd)
 
        /* Major versions must be the same */
        if (reply.major != be32toh(msg.major)) {
-               DBG("Incompatible major versions (%u vs %u)", reply.major,
-                               be32toh(msg.major));
+               DBG("Incompatible major versions ([relayd] %u vs [client] %u)",
+                               reply.major, be32toh(msg.major));
                ret = -1;
                goto end;
        }
@@ -513,10 +717,10 @@ int viewer_connect(struct relay_command *cmd)
 
        health_code_update();
 
-       ret = cmd->sock->ops->sendmsg(cmd->sock, &reply,
-                       sizeof(struct lttng_viewer_connect), 0);
+
+       ret = send_response(cmd->sock, &reply, sizeof(reply));
        if (ret < 0) {
-               ERR("Relay sending version");
+               goto end;
        }
 
        health_code_update();
@@ -541,43 +745,29 @@ int viewer_list_sessions(struct relay_command *cmd,
        struct lttng_viewer_list_sessions session_list;
        unsigned long count;
        long approx_before, approx_after;
-       struct lttng_ht_node_ulong *node;
        struct lttng_ht_iter iter;
        struct lttng_viewer_session send_session;
        struct relay_session *session;
 
        DBG("List sessions received");
 
-       if (cmd->version_check_done == 0) {
-               ERR("Trying to list sessions before version check");
-               ret = -1;
-               goto end_no_session;
-       }
-
        rcu_read_lock();
        cds_lfht_count_nodes(sessions_ht->ht, &approx_before, &count, &approx_after);
        session_list.sessions_count = htobe32(count);
 
        health_code_update();
 
-       ret = cmd->sock->ops->sendmsg(cmd->sock, &session_list,
-                       sizeof(session_list), 0);
+       ret = send_response(cmd->sock, &session_list, sizeof(session_list));
        if (ret < 0) {
-               ERR("Relay sending sessions list");
                goto end_unlock;
        }
 
        health_code_update();
 
-       cds_lfht_for_each_entry(sessions_ht->ht, &iter.iter, node, node) {
+       cds_lfht_for_each_entry(sessions_ht->ht, &iter.iter, session,
+                       session_n.node) {
                health_code_update();
 
-               node = lttng_ht_iter_get_node_ulong(&iter);
-               if (!node) {
-                       goto end_unlock;
-               }
-               session = caa_container_of(node, struct relay_session, session_n);
-
                strncpy(send_session.session_name, session->session_name,
                                sizeof(send_session.session_name));
                strncpy(send_session.hostname, session->hostname,
@@ -589,10 +779,8 @@ int viewer_list_sessions(struct relay_command *cmd,
 
                health_code_update();
 
-               ret = cmd->sock->ops->sendmsg(cmd->sock, &send_session,
-                               sizeof(send_session), 0);
+               ret = send_response(cmd->sock, &send_session, sizeof(send_session));
                if (ret < 0) {
-                       ERR("Relay sending session info");
                        goto end_unlock;
                }
        }
@@ -606,249 +794,6 @@ end_unlock:
        rcu_read_unlock();
 
 end:
-end_no_session:
-       return ret;
-}
-
-/*
- * Open index file using a given viewer stream.
- *
- * Return 0 on success or else a negative value.
- */
-static int open_index(struct relay_viewer_stream *stream)
-{
-       int ret;
-       char fullpath[PATH_MAX];
-       struct ctf_packet_index_file_hdr hdr;
-
-       if (stream->tracefile_count > 0) {
-               ret = snprintf(fullpath, sizeof(fullpath), "%s/" DEFAULT_INDEX_DIR "/%s_%"
-                               PRIu64 DEFAULT_INDEX_FILE_SUFFIX, stream->path_name,
-                               stream->channel_name, stream->tracefile_count_current);
-       } else {
-               ret = snprintf(fullpath, sizeof(fullpath), "%s/" DEFAULT_INDEX_DIR "/%s"
-                               DEFAULT_INDEX_FILE_SUFFIX, stream->path_name,
-                               stream->channel_name);
-       }
-       if (ret < 0) {
-               PERROR("snprintf index path");
-               goto error;
-       }
-
-       DBG("Opening index file %s in read only", fullpath);
-       ret = open(fullpath, O_RDONLY);
-       if (ret < 0) {
-               if (errno == ENOENT) {
-                       ret = -ENOENT;
-                       goto error;
-               } else {
-                       PERROR("opening index in read-only");
-               }
-               goto error;
-       }
-       stream->index_read_fd = ret;
-       DBG("Opening index file %s in read only, (fd: %d)", fullpath, ret);
-
-       ret = lttng_read(stream->index_read_fd, &hdr, sizeof(hdr));
-       if (ret < sizeof(hdr)) {
-               PERROR("Reading index header");
-               goto error;
-       }
-       if (be32toh(hdr.magic) != CTF_INDEX_MAGIC) {
-               ERR("Invalid header magic");
-               ret = -1;
-               goto error;
-       }
-       if (be32toh(hdr.index_major) != CTF_INDEX_MAJOR ||
-                       be32toh(hdr.index_minor) != CTF_INDEX_MINOR) {
-               ERR("Invalid header version");
-               ret = -1;
-               goto error;
-       }
-       ret = 0;
-
-error:
-       return ret;
-}
-
-/*
- * Allocate and init a new viewer_stream.
- *
- * Copies the values from the stream passed in parameter and insert the new
- * stream in the viewer_streams_ht.
- *
- * MUST be called with rcu_read_lock held.
- *
- * Returns 0 on success or a negative value on error.
- */
-static
-int init_viewer_stream(struct relay_stream *stream, int seek_last)
-{
-       int ret;
-       struct relay_viewer_stream *viewer_stream;
-
-       assert(stream);
-
-       viewer_stream = zmalloc(sizeof(*viewer_stream));
-       if (!viewer_stream) {
-               PERROR("relay viewer stream zmalloc");
-               ret = -1;
-               goto error;
-       }
-       viewer_stream->session_id = stream->session->id;
-       viewer_stream->stream_handle = stream->stream_handle;
-       viewer_stream->path_name = strndup(stream->path_name,
-                       LTTNG_VIEWER_PATH_MAX);
-       viewer_stream->channel_name = strndup(stream->channel_name,
-                       LTTNG_VIEWER_NAME_MAX);
-       viewer_stream->tracefile_count = stream->tracefile_count;
-       viewer_stream->metadata_flag = stream->metadata_flag;
-       viewer_stream->tracefile_count_last = -1ULL;
-       if (seek_last) {
-               viewer_stream->tracefile_count_current =
-                       stream->tracefile_count_current;
-       } else {
-               viewer_stream->tracefile_count_current =
-                       stream->oldest_tracefile_id;
-       }
-
-       viewer_stream->ctf_trace = stream->ctf_trace;
-       if (viewer_stream->metadata_flag) {
-               viewer_stream->ctf_trace->viewer_metadata_stream =
-                       viewer_stream;
-       }
-       uatomic_inc(&viewer_stream->ctf_trace->refcount);
-
-       lttng_ht_node_init_u64(&viewer_stream->stream_n, stream->stream_handle);
-       lttng_ht_add_unique_u64(viewer_streams_ht, &viewer_stream->stream_n);
-
-       viewer_stream->index_read_fd = -1;
-       viewer_stream->read_fd = -1;
-
-       /*
-        * This is to avoid a race between the initialization of this object and
-        * the close of the given stream. If the stream is unable to find this
-        * viewer stream when closing, this copy will at least take the latest
-        * value.
-        * We also need that for the seek_last.
-        */
-       viewer_stream->total_index_received = stream->total_index_received;
-
-       /*
-        * If we never received an index for the current stream, delay
-        * the opening of the index, otherwise open it right now.
-        */
-       if (viewer_stream->tracefile_count_current ==
-                       stream->tracefile_count_current &&
-                       viewer_stream->total_index_received == 0) {
-               viewer_stream->index_read_fd = -1;
-       } else {
-               ret = open_index(viewer_stream);
-               if (ret < 0) {
-                       goto error;
-               }
-       }
-
-       if (seek_last && viewer_stream->index_read_fd > 0) {
-               ret = lseek(viewer_stream->index_read_fd,
-                               viewer_stream->total_index_received *
-                                       sizeof(struct ctf_packet_index),
-                               SEEK_CUR);
-               if (ret < 0) {
-                       goto error;
-               }
-               viewer_stream->last_sent_index =
-                       viewer_stream->total_index_received;
-       }
-
-       ret = 0;
-
-error:
-       return ret;
-}
-
-/*
- * Rotate a stream to the next tracefile.
- *
- * Returns 0 on success, 1 on EOF, a negative value on error.
- */
-static
-int rotate_viewer_stream(struct relay_viewer_stream *viewer_stream,
-               struct relay_stream *stream)
-{
-       int ret;
-       uint64_t tracefile_id;
-
-       assert(viewer_stream);
-
-       tracefile_id = (viewer_stream->tracefile_count_current + 1) %
-               viewer_stream->tracefile_count;
-       /*
-        * Detect the last tracefile to open.
-        */
-       if (viewer_stream->tracefile_count_last != -1ULL &&
-                       viewer_stream->tracefile_count_last ==
-                       viewer_stream->tracefile_count_current) {
-               ret = 1;
-               goto end;
-       }
-
-       if (stream) {
-               pthread_mutex_lock(&stream->viewer_stream_rotation_lock);
-       }
-       /*
-        * The writer and the reader are not working in the same
-        * tracefile, we can read up to EOF, we don't care about the
-        * total_index_received.
-        */
-       if (!stream || (stream->tracefile_count_current != tracefile_id)) {
-               viewer_stream->close_write_flag = 1;
-       } else {
-               /*
-                * We are opening a file that is still open in write, make
-                * sure we limit our reading to the number of indexes
-                * received.
-                */
-               viewer_stream->close_write_flag = 0;
-               if (stream) {
-                       viewer_stream->total_index_received =
-                               stream->total_index_received;
-               }
-       }
-       viewer_stream->tracefile_count_current = tracefile_id;
-
-       ret = close(viewer_stream->index_read_fd);
-       if (ret < 0) {
-               PERROR("close index file %d",
-                               viewer_stream->index_read_fd);
-       }
-       viewer_stream->index_read_fd = -1;
-       ret = close(viewer_stream->read_fd);
-       if (ret < 0) {
-               PERROR("close tracefile %d",
-                               viewer_stream->read_fd);
-       }
-       viewer_stream->read_fd = -1;
-
-       pthread_mutex_lock(&viewer_stream->overwrite_lock);
-       viewer_stream->abort_flag = 0;
-       pthread_mutex_unlock(&viewer_stream->overwrite_lock);
-
-       viewer_stream->index_read_fd = -1;
-       viewer_stream->read_fd = -1;
-
-       if (stream) {
-               pthread_mutex_unlock(&stream->viewer_stream_rotation_lock);
-       }
-       ret = open_index(viewer_stream);
-       if (ret < 0) {
-               goto error;
-       }
-
-       ret = 0;
-
-end:
-error:
        return ret;
 }
 
@@ -860,14 +805,9 @@ int viewer_get_new_streams(struct relay_command *cmd,
                struct lttng_ht *sessions_ht)
 {
        int ret, send_streams = 0;
-       uint32_t nb_streams = 0;
+       uint32_t nb_created = 0, nb_unsent = 0, nb_streams = 0;
        struct lttng_viewer_new_streams_request request;
        struct lttng_viewer_new_streams_response response;
-       struct lttng_viewer_stream send_stream;
-       struct relay_stream *stream;
-       struct relay_viewer_stream *viewer_stream;
-       struct lttng_ht_node_ulong *node;
-       struct lttng_ht_iter iter;
        struct relay_session *session;
 
        assert(cmd);
@@ -875,40 +815,25 @@ int viewer_get_new_streams(struct relay_command *cmd,
 
        DBG("Get new streams received");
 
-       if (cmd->version_check_done == 0) {
-               ERR("Trying to get streams before version check");
-               ret = -1;
-               goto end_no_session;
-       }
-
        health_code_update();
 
-       ret = cmd->sock->ops->recvmsg(cmd->sock, &request, sizeof(request), 0);
-       if (ret < 0 || ret != sizeof(request)) {
-               if (ret == 0) {
-                       /* Orderly shutdown. Not necessary to print an error. */
-                       DBG("Socket %d did an orderly shutdown", cmd->sock->fd);
-               } else {
-                       ERR("Relay failed to receive the command parameters.");
-               }
-               ret = -1;
+       /* Receive the request from the connected client. */
+       ret = recv_request(cmd->sock, &request, sizeof(request));
+       if (ret < 0) {
                goto error;
        }
 
        health_code_update();
 
        rcu_read_lock();
-       lttng_ht_lookup(sessions_ht,
-                       (void *)((unsigned long) be64toh(request.session_id)), &iter);
-       node = lttng_ht_iter_get_node_ulong(&iter);
-       if (node == NULL) {
+       session = session_find_by_id(sessions_ht, be64toh(request.session_id));
+       if (!session) {
                DBG("Relay session %" PRIu64 " not found",
                                be64toh(request.session_id));
                response.status = htobe32(VIEWER_NEW_STREAMS_ERR);
                goto send_reply;
        }
 
-       session = caa_container_of(node, struct relay_session, session_n);
        if (cmd->session_id == session->id) {
                /* We confirmed the viewer is asking for the same session. */
                send_streams = 1;
@@ -919,48 +844,23 @@ int viewer_get_new_streams(struct relay_command *cmd,
                goto send_reply;
        }
 
-       /*
-        * Fill the viewer_streams_ht to count the number of streams ready to be
-        * sent and avoid concurrency issues on the relay_streams_ht and don't rely
-        * on a total session stream count.
-        */
-       pthread_mutex_lock(&session->viewer_ready_lock);
-       cds_lfht_for_each_entry(relay_streams_ht->ht, &iter.iter, stream,
-                       stream_n.node) {
-               struct relay_viewer_stream *vstream;
-
-               health_code_update();
-
-               /*
-                * Don't send stream if no ctf_trace, wrong session or if the stream is
-                * not ready for the viewer.
-                */
-               if (stream->session != cmd->session ||
-                               !stream->ctf_trace || !stream->viewer_ready) {
-                       continue;
-               }
-
-               vstream = live_find_viewer_stream_by_id(stream->stream_handle);
-               if (!vstream) {
-                       ret = init_viewer_stream(stream, 0);
-                       if (ret < 0) {
-                               pthread_mutex_unlock(&session->viewer_ready_lock);
-                               goto end_unlock;
-                       }
-                       nb_streams++;
-               } else if (!vstream->sent_flag) {
-                       nb_streams++;
-               }
+       if (!send_streams) {
+               goto send_reply;
        }
-       pthread_mutex_unlock(&session->viewer_ready_lock);
 
+       ret = make_viewer_streams(session, VIEWER_SEEK_LAST, NULL, &nb_unsent,
+                       &nb_created);
+       if (ret < 0) {
+               goto end_unlock;
+       }
+       /* Only send back the newly created streams with the unsent ones. */
+       nb_streams = nb_created + nb_unsent;
        response.streams_count = htobe32(nb_streams);
 
 send_reply:
        health_code_update();
-       ret = cmd->sock->ops->sendmsg(cmd->sock, &response, sizeof(response), 0);
+       ret = send_response(cmd->sock, &response, sizeof(response));
        if (ret < 0) {
-               ERR("Relay sending viewer attach response");
                goto end_unlock;
        }
        health_code_update();
@@ -974,40 +874,17 @@ send_reply:
                goto end_unlock;
        }
 
-       /* We should only be there if we have a session to attach to. */
-       cds_lfht_for_each_entry(viewer_streams_ht->ht, &iter.iter, viewer_stream,
-                       stream_n.node) {
-               health_code_update();
-
-               /* Don't send back if session does not match or already sent. */
-               if (viewer_stream->session_id != cmd->session->id ||
-                               viewer_stream->sent_flag) {
-                       continue;
-               }
-
-               send_stream.id = htobe64(viewer_stream->stream_handle);
-               send_stream.ctf_trace_id = htobe64(viewer_stream->ctf_trace->id);
-               send_stream.metadata_flag = htobe32(viewer_stream->metadata_flag);
-               strncpy(send_stream.path_name, viewer_stream->path_name,
-                               sizeof(send_stream.path_name));
-               strncpy(send_stream.channel_name, viewer_stream->channel_name,
-                               sizeof(send_stream.channel_name));
-
-               ret = cmd->sock->ops->sendmsg(cmd->sock, &send_stream,
-                               sizeof(send_stream), 0);
-               if (ret < 0) {
-                       ERR("Relay sending stream %" PRIu64, viewer_stream->stream_handle);
-                       goto end_unlock;
-               }
-               DBG("Sent stream %" PRIu64 " to viewer", viewer_stream->stream_handle);
-               viewer_stream->sent_flag = 1;
+       /*
+        * Send stream and *DON'T* ignore the sent flag so every viewer streams
+        * that were not sent from that point will be sent to the viewer.
+        */
+       ret = send_viewer_streams(cmd->sock, session, 0);
+       if (ret < 0) {
+               goto end_unlock;
        }
 
-       ret = 0;
-
 end_unlock:
        rcu_read_unlock();
-end_no_session:
 error:
        return ret;
 }
@@ -1019,58 +896,38 @@ static
 int viewer_attach_session(struct relay_command *cmd,
                struct lttng_ht *sessions_ht)
 {
-       int ret, send_streams = 0;
+       int send_streams = 0;
+       ssize_t ret;
        uint32_t nb_streams = 0;
+       enum lttng_viewer_seek seek_type;
        struct lttng_viewer_attach_session_request request;
        struct lttng_viewer_attach_session_response response;
-       struct lttng_viewer_stream send_stream;
-       struct relay_stream *stream;
-       struct relay_viewer_stream *viewer_stream;
-       struct lttng_ht_node_ulong *node;
-       struct lttng_ht_node_u64 *node64;
-       struct lttng_ht_iter iter;
        struct relay_session *session;
-       int seek_last = 0;
 
        assert(cmd);
        assert(sessions_ht);
 
        DBG("Attach session received");
 
-       if (cmd->version_check_done == 0) {
-               ERR("Trying to attach session before version check");
-               ret = -1;
-               goto end_no_session;
-       }
-
        health_code_update();
 
-       ret = cmd->sock->ops->recvmsg(cmd->sock, &request, sizeof(request), 0);
-       if (ret < 0 || ret != sizeof(request)) {
-               if (ret == 0) {
-                       /* Orderly shutdown. Not necessary to print an error. */
-                       DBG("Socket %d did an orderly shutdown", cmd->sock->fd);
-               } else {
-                       ERR("Relay failed to receive the attach parameters.");
-               }
-               ret = -1;
+       /* Receive the request from the connected client. */
+       ret = recv_request(cmd->sock, &request, sizeof(request));
+       if (ret < 0) {
                goto error;
        }
 
        health_code_update();
 
        rcu_read_lock();
-       lttng_ht_lookup(sessions_ht,
-                       (void *)((unsigned long) be64toh(request.session_id)), &iter);
-       node = lttng_ht_iter_get_node_ulong(&iter);
-       if (node == NULL) {
+       session = session_find_by_id(sessions_ht, be64toh(request.session_id));
+       if (!session) {
                DBG("Relay session %" PRIu64 " not found",
                                be64toh(request.session_id));
                response.status = htobe32(VIEWER_ATTACH_UNK);
                goto send_reply;
        }
 
-       session = caa_container_of(node, struct relay_session, session_n);
        if (cmd->session_id == session->id) {
                /* Same viewer already attached, just send the stream list. */
                send_streams = 1;
@@ -1093,10 +950,8 @@ int viewer_attach_session(struct relay_command *cmd,
 
        switch (be32toh(request.seek)) {
        case VIEWER_SEEK_BEGINNING:
-               /* Default behaviour. */
-               break;
        case VIEWER_SEEK_LAST:
-               seek_last = 1;
+               seek_type = be32toh(request.seek);
                break;
        default:
                ERR("Wrong seek parameter");
@@ -1105,58 +960,20 @@ int viewer_attach_session(struct relay_command *cmd,
                goto send_reply;
        }
 
-       if (send_streams) {
-               /* We should only be there if we have a session to attach to. */
-               assert(session);
-
-               /*
-                * Fill the viewer_streams_ht to count the number of streams
-                * ready to be sent and avoid concurrency issues on the
-                * relay_streams_ht and don't rely on a total session stream count.
-                */
-               pthread_mutex_lock(&session->viewer_ready_lock);
-               cds_lfht_for_each_entry(relay_streams_ht->ht, &iter.iter, node, node) {
-                       struct relay_viewer_stream *vstream;
-
-                       health_code_update();
-
-                       node = lttng_ht_iter_get_node_ulong(&iter);
-                       if (!node) {
-                               continue;
-                       }
-                       stream = caa_container_of(node, struct relay_stream, stream_n);
-                       if (stream->session != cmd->session) {
-                               continue;
-                       }
-
-                       /*
-                        * Don't send streams with no ctf_trace, they are not
-                        * ready to be read.
-                        */
-                       if (!stream->ctf_trace || !stream->viewer_ready) {
-                               continue;
-                       }
-
-                       vstream = live_find_viewer_stream_by_id(stream->stream_handle);
-                       if (!vstream) {
-                               ret = init_viewer_stream(stream, seek_last);
-                               if (ret < 0) {
-                                       pthread_mutex_unlock(&session->viewer_ready_lock);
-                                       goto end_unlock;
-                               }
-                       }
-                       nb_streams++;
-               }
-               pthread_mutex_unlock(&session->viewer_ready_lock);
+       if (!send_streams) {
+               goto send_reply;
+       }
 
-               response.streams_count = htobe32(nb_streams);
+       ret = make_viewer_streams(session, seek_type, &nb_streams, NULL, NULL);
+       if (ret < 0) {
+               goto end_unlock;
        }
+       response.streams_count = htobe32(nb_streams);
 
 send_reply:
        health_code_update();
-       ret = cmd->sock->ops->sendmsg(cmd->sock, &response, sizeof(response), 0);
+       ret = send_response(cmd->sock, &response, sizeof(response));
        if (ret < 0) {
-               ERR("Relay sending viewer attach response");
                goto end_unlock;
        }
        health_code_update();
@@ -1170,167 +987,14 @@ send_reply:
                goto end_unlock;
        }
 
-       /* We should only be there if we have a session to attach to. */
-       assert(session);
-       cds_lfht_for_each_entry(viewer_streams_ht->ht, &iter.iter, node, node) {
-               health_code_update();
-
-               node64 = lttng_ht_iter_get_node_u64(&iter);
-               if (!node64) {
-                       continue;
-               }
-               viewer_stream = caa_container_of(node64, struct relay_viewer_stream,
-                               stream_n);
-               if (viewer_stream->session_id != cmd->session->id) {
-                       continue;
-               }
-
-               send_stream.id = htobe64(viewer_stream->stream_handle);
-               send_stream.ctf_trace_id = htobe64(viewer_stream->ctf_trace->id);
-               send_stream.metadata_flag = htobe32(viewer_stream->metadata_flag);
-               strncpy(send_stream.path_name, viewer_stream->path_name,
-                               sizeof(send_stream.path_name));
-               strncpy(send_stream.channel_name, viewer_stream->channel_name,
-                               sizeof(send_stream.channel_name));
-
-               ret = cmd->sock->ops->sendmsg(cmd->sock, &send_stream,
-                               sizeof(send_stream), 0);
-               if (ret < 0) {
-                       ERR("Relay sending stream %" PRIu64, viewer_stream->stream_handle);
-                       goto end_unlock;
-               }
-               DBG("Sent stream %" PRIu64 " to viewer", viewer_stream->stream_handle);
-               viewer_stream->sent_flag = 1;
+       /* Send stream and ignore the sent flag. */
+       ret = send_viewer_streams(cmd->sock, session, 1);
+       if (ret < 0) {
+               goto end_unlock;
        }
-       ret = 0;
 
 end_unlock:
        rcu_read_unlock();
-end_no_session:
-error:
-       return ret;
-}
-
-/*
- * Get viewer stream from stream id.
- *
- * RCU read side lock MUST be acquired.
- */
-struct relay_viewer_stream *live_find_viewer_stream_by_id(uint64_t stream_id)
-{
-       struct lttng_ht_node_u64 *node;
-       struct lttng_ht_iter iter;
-       struct relay_viewer_stream *stream = NULL;
-
-       lttng_ht_lookup(viewer_streams_ht, &stream_id, &iter);
-       node = lttng_ht_iter_get_node_u64(&iter);
-       if (node == NULL) {
-               DBG("Relay viewer stream %" PRIu64 " not found", stream_id);
-               goto end;
-       }
-       stream = caa_container_of(node, struct relay_viewer_stream, stream_n);
-
-end:
-       return stream;
-}
-
-static
-void deferred_free_viewer_stream(struct rcu_head *head)
-{
-       struct relay_viewer_stream *stream =
-               caa_container_of(head, struct relay_viewer_stream, rcu_node);
-
-       free(stream->path_name);
-       free(stream->channel_name);
-       free(stream);
-}
-
-static
-void delete_viewer_stream(struct relay_viewer_stream *vstream)
-{
-       int delret;
-       struct lttng_ht_iter iter;
-
-       iter.iter.node = &vstream->stream_n.node;
-       delret = lttng_ht_del(viewer_streams_ht, &iter);
-       assert(!delret);
-}
-
-static
-void destroy_viewer_stream(struct relay_viewer_stream *vstream)
-{
-       unsigned long ret_ref;
-       int ret;
-
-       assert(vstream);
-       ret_ref = uatomic_add_return(&vstream->ctf_trace->refcount, -1);
-       assert(ret_ref >= 0);
-
-       if (vstream->read_fd >= 0) {
-               ret = close(vstream->read_fd);
-               if (ret < 0) {
-                       PERROR("close read_fd");
-               }
-       }
-       if (vstream->index_read_fd >= 0) {
-               ret = close(vstream->index_read_fd);
-               if (ret < 0) {
-                       PERROR("close index_read_fd");
-               }
-       }
-
-       /*
-        * If the only stream left in the HT is the metadata stream,
-        * we need to remove it because we won't detect a EOF for this
-        * stream.
-        */
-       if (ret_ref == 1 && vstream->ctf_trace->viewer_metadata_stream) {
-               delete_viewer_stream(vstream->ctf_trace->viewer_metadata_stream);
-               destroy_viewer_stream(vstream->ctf_trace->viewer_metadata_stream);
-               vstream->ctf_trace->metadata_stream = NULL;
-               DBG("Freeing ctf_trace %" PRIu64, vstream->ctf_trace->id);
-               /*
-                * The streaming-side is already closed and we can't receive a new
-                * stream concurrently at this point (since the session is being
-                * destroyed), so when we detect the refcount equals 0, we are the
-                * only owners of the ctf_trace and we can free it ourself.
-                */
-               free(vstream->ctf_trace);
-       }
-
-       call_rcu(&vstream->rcu_node, deferred_free_viewer_stream);
-}
-
-/*
- * Atomically check if new streams got added in the session since the last
- * check and reset the flag to 0.
- *
- * Returns 1 if new streams got added, 0 if nothing changed, a negative value
- * on error.
- */
-static
-int check_new_streams(uint64_t session_id, struct lttng_ht *sessions_ht)
-{
-       struct lttng_ht_node_ulong *node;
-       struct lttng_ht_iter iter;
-       struct relay_session *session;
-       unsigned long current_val;
-       int ret;
-
-       lttng_ht_lookup(sessions_ht,
-                       (void *)((unsigned long) session_id), &iter);
-       node = lttng_ht_iter_get_node_ulong(&iter);
-       if (node == NULL) {
-               DBG("Relay session %" PRIu64 " not found", session_id);
-               ret = -1;
-               goto error;
-       }
-
-       session = caa_container_of(node, struct relay_session, session_n);
-
-       current_val = uatomic_cmpxchg(&session->new_streams, 1, 0);
-       ret = current_val;
-
 error:
        return ret;
 }
@@ -1356,24 +1020,16 @@ int viewer_get_next_index(struct relay_command *cmd,
 
        DBG("Viewer get next index");
 
-       if (cmd->version_check_done == 0) {
-               ERR("Trying to request index before version check");
-               ret = -1;
-               goto end_no_session;
-       }
-
        health_code_update();
-       ret = cmd->sock->ops->recvmsg(cmd->sock, &request_index,
-                       sizeof(request_index), 0);
-       if (ret < 0 || ret != sizeof(request_index)) {
-               ret = -1;
-               ERR("Relay didn't receive the whole packet");
+
+       ret = recv_request(cmd->sock, &request_index, sizeof(request_index));
+       if (ret < 0) {
                goto end;
        }
        health_code_update();
 
        rcu_read_lock();
-       vstream = live_find_viewer_stream_by_id(be64toh(request_index.stream_id));
+       vstream = viewer_stream_find_by_id(be64toh(request_index.stream_id));
        if (!vstream) {
                ret = -1;
                goto end_unlock;
@@ -1391,7 +1047,8 @@ int viewer_get_next_index(struct relay_command *cmd,
 
        /* First time, we open the index file */
        if (vstream->index_read_fd < 0) {
-               ret = open_index(vstream);
+               ret = index_open(vstream->path_name, vstream->channel_name,
+                               vstream->tracefile_count, vstream->tracefile_count_current);
                if (ret == -ENOENT) {
                        /*
                         * The index is created only when the first data packet arrives, it
@@ -1403,6 +1060,7 @@ int viewer_get_next_index(struct relay_command *cmd,
                        viewer_index.status = htobe32(VIEWER_INDEX_ERR);
                        goto send_reply;
                }
+               vstream->index_read_fd = ret;
        }
 
        rstream = relay_stream_find_by_id(vstream->stream_handle);
@@ -1410,13 +1068,13 @@ int viewer_get_next_index(struct relay_command *cmd,
                if (vstream->abort_flag) {
                        /* Rotate on abort (overwrite). */
                        DBG("Viewer rotate because of overwrite");
-                       ret = rotate_viewer_stream(vstream, rstream);
+                       ret = viewer_stream_rotate(vstream, rstream);
                        if (ret < 0) {
                                goto end_unlock;
                        } else if (ret == 1) {
                                viewer_index.status = htobe32(VIEWER_INDEX_HUP);
-                               delete_viewer_stream(vstream);
-                               destroy_viewer_stream(vstream);
+                               viewer_stream_delete(vstream);
+                               viewer_stream_destroy(vstream);
                                goto send_reply;
                        }
                }
@@ -1446,8 +1104,8 @@ int viewer_get_next_index(struct relay_command *cmd,
                        vstream->total_index_received == vstream->last_sent_index) {
                /* Last index sent and current tracefile closed in write */
                viewer_index.status = htobe32(VIEWER_INDEX_HUP);
-               delete_viewer_stream(vstream);
-               destroy_viewer_stream(vstream);
+               viewer_stream_delete(vstream);
+               viewer_stream_destroy(vstream);
                goto send_reply;
        } else {
                vstream->close_write_flag = 1;
@@ -1474,17 +1132,18 @@ int viewer_get_next_index(struct relay_command *cmd,
                 */
                viewer_index.status = htobe32(VIEWER_INDEX_RETRY);
                pthread_mutex_unlock(&vstream->overwrite_lock);
-               ret = rotate_viewer_stream(vstream, rstream);
+               ret = viewer_stream_rotate(vstream, rstream);
                if (ret < 0) {
                        goto end_unlock;
                } else if (ret == 1) {
                        viewer_index.status = htobe32(VIEWER_INDEX_HUP);
-                       delete_viewer_stream(vstream);
-                       destroy_viewer_stream(vstream);
+                       viewer_stream_delete(vstream);
+                       viewer_stream_destroy(vstream);
                        goto send_reply;
                }
                goto send_reply;
        }
+
        ret = lttng_read(vstream->index_read_fd, &packet_index,
                        sizeof(packet_index));
        pthread_mutex_unlock(&vstream->overwrite_lock);
@@ -1495,18 +1154,17 @@ int viewer_get_next_index(struct relay_command *cmd,
                if (vstream->close_write_flag == 1) {
                        viewer_index.status = htobe32(VIEWER_INDEX_RETRY);
                        /* Rotate on normal EOF */
-                       ret = rotate_viewer_stream(vstream, rstream);
+                       ret = viewer_stream_rotate(vstream, rstream);
                        if (ret < 0) {
                                goto end_unlock;
                        } else if (ret == 1) {
                                viewer_index.status = htobe32(VIEWER_INDEX_HUP);
-                               delete_viewer_stream(vstream);
-                               destroy_viewer_stream(vstream);
+                               viewer_stream_delete(vstream);
+                               viewer_stream_destroy(vstream);
                                goto send_reply;
                        }
                } else {
-                       PERROR("Relay reading index file %d",
-                                       vstream->index_read_fd);
+                       PERROR("Relay reading index file %d", vstream->index_read_fd);
                        viewer_index.status = htobe32(VIEWER_INDEX_ERR);
                }
                goto send_reply;
@@ -1529,21 +1187,19 @@ int viewer_get_next_index(struct relay_command *cmd,
 send_reply:
        viewer_index.flags = htobe32(viewer_index.flags);
        health_code_update();
-       ret = cmd->sock->ops->sendmsg(cmd->sock, &viewer_index,
-                       sizeof(viewer_index), 0);
+
+       ret = send_response(cmd->sock, &viewer_index, sizeof(viewer_index));
        if (ret < 0) {
-               ERR("Relay index to viewer");
                goto end_unlock;
        }
        health_code_update();
 
-       DBG("Index %" PRIu64 "for stream %" PRIu64 "sent",
+       DBG("Index %" PRIu64 " for stream %" PRIu64 " sent",
                        vstream->last_sent_index, vstream->stream_handle);
 
 end_unlock:
        rcu_read_unlock();
 
-end_no_session:
 end:
        return ret;
 }
@@ -1569,18 +1225,10 @@ int viewer_get_packet(struct relay_command *cmd,
 
        DBG2("Relay get data packet");
 
-       if (cmd->version_check_done == 0) {
-               ERR("Trying to get packet before version check");
-               ret = -1;
-               goto end;
-       }
-
        health_code_update();
-       ret = cmd->sock->ops->recvmsg(cmd->sock, &get_packet_info,
-                       sizeof(get_packet_info), 0);
-       if (ret < 0 || ret != sizeof(get_packet_info)) {
-               ret = -1;
-               ERR("Relay didn't receive the whole packet");
+
+       ret = recv_request(cmd->sock, &get_packet_info, sizeof(get_packet_info));
+       if (ret < 0) {
                goto end;
        }
        health_code_update();
@@ -1589,7 +1237,7 @@ int viewer_get_packet(struct relay_command *cmd,
        memset(&reply, 0, sizeof(reply));
 
        rcu_read_lock();
-       stream = live_find_viewer_stream_by_id(be64toh(get_packet_info.stream_id));
+       stream = viewer_stream_find_by_id(be64toh(get_packet_info.stream_id));
        if (!stream) {
                goto error;
        }
@@ -1687,18 +1335,17 @@ send_reply:
        reply.flags = htobe32(reply.flags);
 
        health_code_update();
-       ret = cmd->sock->ops->sendmsg(cmd->sock, &reply, sizeof(reply), 0);
+
+       ret = send_response(cmd->sock, &reply, sizeof(reply));
        if (ret < 0) {
-               ERR("Relay data header to viewer");
                goto end_unlock;
        }
        health_code_update();
 
        if (send_data) {
                health_code_update();
-               ret = cmd->sock->ops->sendmsg(cmd->sock, data, len, 0);
+               ret = send_response(cmd->sock, data, len);
                if (ret < 0) {
-                       ERR("Relay send data to viewer");
                        goto end_unlock;
                }
                health_code_update();
@@ -1735,24 +1382,16 @@ int viewer_get_metadata(struct relay_command *cmd)
 
        DBG("Relay get metadata");
 
-       if (cmd->version_check_done == 0) {
-               ERR("Trying to get metadata before version check");
-               ret = -1;
-               goto end;
-       }
-
        health_code_update();
-       ret = cmd->sock->ops->recvmsg(cmd->sock, &request,
-                       sizeof(request), 0);
-       if (ret < 0 || ret != sizeof(request)) {
-               ret = -1;
-               ERR("Relay didn't receive the whole packet");
+
+       ret = recv_request(cmd->sock, &request, sizeof(request));
+       if (ret < 0) {
                goto end;
        }
        health_code_update();
 
        rcu_read_lock();
-       stream = live_find_viewer_stream_by_id(be64toh(request.stream_id));
+       stream = viewer_stream_find_by_id(be64toh(request.stream_id));
        if (!stream || !stream->metadata_flag) {
                ERR("Invalid metadata stream");
                goto error;
@@ -1806,17 +1445,15 @@ error:
 
 send_reply:
        health_code_update();
-       ret = cmd->sock->ops->sendmsg(cmd->sock, &reply, sizeof(reply), 0);
+       ret = send_response(cmd->sock, &reply, sizeof(reply));
        if (ret < 0) {
-               ERR("Relay data header to viewer");
                goto end_unlock;
        }
        health_code_update();
 
        if (len > 0) {
-               ret = cmd->sock->ops->sendmsg(cmd->sock, data, len, 0);
+               ret = send_response(cmd->sock, data, len);
                if (ret < 0) {
-                       ERR("Relay send data to viewer");
                        goto end_unlock;
                }
        }
@@ -1840,14 +1477,9 @@ static
 void live_relay_unknown_command(struct relay_command *cmd)
 {
        struct lttcomm_relayd_generic_reply reply;
-       int ret;
 
        reply.ret_code = htobe32(LTTNG_ERR_UNK);
-       ret = cmd->sock->ops->sendmsg(cmd->sock, &reply,
-                       sizeof(struct lttcomm_relayd_generic_reply), 0);
-       if (ret < 0) {
-               ERR("Relay sending unknown command");
-       }
+       (void) send_response(cmd->sock, &reply, sizeof(reply));
 }
 
 /*
@@ -1858,8 +1490,25 @@ int process_control(struct lttng_viewer_cmd *recv_hdr,
                struct relay_command *cmd, struct lttng_ht *sessions_ht)
 {
        int ret = 0;
+       uint32_t msg_value;
+
+       assert(recv_hdr);
+       assert(cmd);
+       assert(sessions_ht);
+
+       msg_value = be32toh(recv_hdr->cmd);
+
+       /*
+        * Make sure we've done the version check before any command other then a
+        * new client connection.
+        */
+       if (msg_value != VIEWER_CONNECT && !cmd->version_check_done) {
+               ERR("Viewer cmd value %" PRIu32 " before version check", msg_value);
+               ret = -1;
+               goto end;
+       }
 
-       switch (be32toh(recv_hdr->cmd)) {
+       switch (msg_value) {
        case VIEWER_CONNECT:
                ret = viewer_connect(cmd);
                break;
@@ -1982,7 +1631,7 @@ void viewer_del_streams(uint64_t session_id)
                        continue;
                }
 
-               delete_viewer_stream(stream);
+               viewer_stream_delete(stream);
                assert(stream->ctf_trace);
 
                if (stream->metadata_flag) {
@@ -1994,7 +1643,7 @@ void viewer_del_streams(uint64_t session_id)
                        stream->ctf_trace->metadata_sent = 0;
                        stream->ctf_trace->viewer_metadata_stream = NULL;
                } else {
-                       destroy_viewer_stream(stream);
+                       viewer_stream_destroy(stream);
                }
        }
        rcu_read_unlock();
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