+ discarded_events = 0;
+ cds_lfht_for_each_entry_duplicate(ht->ht,
+ ht->hash_fct(&id, lttng_ht_seed),
+ ht->match_fct, &id,
+ &iter.iter, stream, node_session_id.node) {
+ if (stream->chan->key == key) {
+ discarded_events = stream->chan->discarded_events;
+ break;
+ }
+ }
+ pthread_mutex_unlock(&consumer_data.lock);
+ rcu_read_unlock();
+
+ DBG("UST consumer discarded events command for session id %"
+ PRIu64 ", channel key %" PRIu64, id, key);
+
+ health_code_update();
+
+ /* Send back returned value to session daemon */
+ ret = lttcomm_send_unix_sock(sock, &discarded_events, sizeof(discarded_events));
+ if (ret < 0) {
+ PERROR("send discarded events");
+ goto error_fatal;
+ }
+
+ break;
+ }
+ case LTTNG_CONSUMER_LOST_PACKETS:
+ {
+ int ret;
+ uint64_t lost_packets;
+ struct lttng_ht_iter iter;
+ struct lttng_ht *ht;
+ struct lttng_consumer_stream *stream;
+ uint64_t id = msg.u.lost_packets.session_id;
+ uint64_t key = msg.u.lost_packets.channel_key;
+
+ DBG("UST consumer lost packets command for session id %"
+ PRIu64, id);
+ rcu_read_lock();
+ pthread_mutex_lock(&consumer_data.lock);
+
+ ht = consumer_data.stream_list_ht;
+
+ /*
+ * We only need a reference to the channel, but they are not
+ * directly indexed, so we just use the first matching stream
+ * to extract the information we need, we default to 0 if not
+ * found (no packets lost if the channel is not yet in use).
+ */
+ lost_packets = 0;
+ cds_lfht_for_each_entry_duplicate(ht->ht,
+ ht->hash_fct(&id, lttng_ht_seed),
+ ht->match_fct, &id,
+ &iter.iter, stream, node_session_id.node) {
+ if (stream->chan->key == key) {
+ lost_packets = stream->chan->lost_packets;
+ break;
+ }
+ }
+ pthread_mutex_unlock(&consumer_data.lock);
+ rcu_read_unlock();
+
+ DBG("UST consumer lost packets command for session id %"
+ PRIu64 ", channel key %" PRIu64, id, key);
+
+ health_code_update();
+
+ /* Send back returned value to session daemon */
+ ret = lttcomm_send_unix_sock(sock, &lost_packets,
+ sizeof(lost_packets));
+ if (ret < 0) {
+ PERROR("send lost packets");
+ goto error_fatal;
+ }
+
+ break;
+ }
+ case LTTNG_CONSUMER_SET_CHANNEL_MONITOR_PIPE:
+ {
+ int channel_monitor_pipe;
+
+ ret_code = LTTCOMM_CONSUMERD_SUCCESS;
+ /* Successfully received the command's type. */
+ ret = consumer_send_status_msg(sock, ret_code);
+ if (ret < 0) {
+ goto error_fatal;
+ }
+
+ ret = lttcomm_recv_fds_unix_sock(sock, &channel_monitor_pipe,
+ 1);
+ if (ret != sizeof(channel_monitor_pipe)) {
+ ERR("Failed to receive channel monitor pipe");
+ goto error_fatal;
+ }
+
+ DBG("Received channel monitor pipe (%d)", channel_monitor_pipe);
+ ret = consumer_timer_thread_set_channel_monitor_pipe(
+ channel_monitor_pipe);
+ if (!ret) {
+ int flags;
+
+ ret_code = LTTCOMM_CONSUMERD_SUCCESS;
+ /* Set the pipe as non-blocking. */
+ ret = fcntl(channel_monitor_pipe, F_GETFL, 0);
+ if (ret == -1) {
+ PERROR("fcntl get flags of the channel monitoring pipe");
+ goto error_fatal;
+ }
+ flags = ret;
+
+ ret = fcntl(channel_monitor_pipe, F_SETFL,
+ flags | O_NONBLOCK);
+ if (ret == -1) {
+ PERROR("fcntl set O_NONBLOCK flag of the channel monitoring pipe");
+ goto error_fatal;
+ }
+ DBG("Channel monitor pipe set as non-blocking");
+ } else {
+ ret_code = LTTCOMM_CONSUMERD_ALREADY_SET;
+ }
+ goto end_msg_sessiond;
+ }
+ case LTTNG_CONSUMER_ROTATE_CHANNEL:
+ {
+ struct lttng_consumer_channel *channel;
+ uint64_t key = msg.u.rotate_channel.key;
+
+ channel = consumer_find_channel(key);
+ if (!channel) {
+ DBG("Channel %" PRIu64 " not found", key);
+ ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
+ } else {
+ /*
+ * Sample the rotate position of all the streams in
+ * this channel.
+ */
+ ret = lttng_consumer_rotate_channel(channel, key,
+ msg.u.rotate_channel.relayd_id,
+ msg.u.rotate_channel.metadata,
+ ctx);
+ if (ret < 0) {
+ ERR("Rotate channel failed");
+ ret_code = LTTCOMM_CONSUMERD_ROTATION_FAIL;
+ }
+
+ health_code_update();
+ }
+ ret = consumer_send_status_msg(sock, ret_code);
+ if (ret < 0) {
+ /* Somehow, the session daemon is not responding anymore. */
+ goto end_rotate_channel_nosignal;
+ }
+
+ /*
+ * Rotate the streams that are ready right now.
+ * FIXME: this is a second consecutive iteration over the
+ * streams in a channel, there is probably a better way to
+ * handle this, but it needs to be after the
+ * consumer_send_status_msg() call.
+ */
+ if (channel) {
+ ret = lttng_consumer_rotate_ready_streams(
+ channel, key, ctx);
+ if (ret < 0) {
+ ERR("Rotate channel failed");
+ }
+ }
+ break;
+end_rotate_channel_nosignal:
+ goto end_nosignal;
+ }
+ case LTTNG_CONSUMER_CLEAR_CHANNEL:
+ {
+ struct lttng_consumer_channel *channel;
+ uint64_t key = msg.u.clear_channel.key;
+
+ channel = consumer_find_channel(key);
+ if (!channel) {
+ DBG("Channel %" PRIu64 " not found", key);
+ ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
+ } else {
+ ret = lttng_consumer_clear_channel(channel);
+ if (ret) {
+ ERR("Clear channel failed key %" PRIu64, key);
+ ret_code = ret;
+ }
+
+ health_code_update();
+ }
+ ret = consumer_send_status_msg(sock, ret_code);
+ if (ret < 0) {
+ /* Somehow, the session daemon is not responding anymore. */
+ goto end_nosignal;
+ }
+ break;
+ }
+ case LTTNG_CONSUMER_INIT:
+ {
+ ret_code = lttng_consumer_init_command(ctx,
+ msg.u.init.sessiond_uuid);
+ health_code_update();
+ ret = consumer_send_status_msg(sock, ret_code);
+ if (ret < 0) {
+ /* Somehow, the session daemon is not responding anymore. */
+ goto end_nosignal;
+ }
+ break;
+ }
+ case LTTNG_CONSUMER_CREATE_TRACE_CHUNK:
+ {
+ const struct lttng_credentials credentials = {
+ .uid = msg.u.create_trace_chunk.credentials.value.uid,
+ .gid = msg.u.create_trace_chunk.credentials.value.gid,
+ };
+ const bool is_local_trace =
+ !msg.u.create_trace_chunk.relayd_id.is_set;
+ const uint64_t relayd_id =
+ msg.u.create_trace_chunk.relayd_id.value;
+ const char *chunk_override_name =
+ *msg.u.create_trace_chunk.override_name ?
+ msg.u.create_trace_chunk.override_name :
+ NULL;
+ struct lttng_directory_handle *chunk_directory_handle = NULL;
+
+ /*
+ * The session daemon will only provide a chunk directory file
+ * descriptor for local traces.
+ */
+ if (is_local_trace) {
+ int chunk_dirfd;
+
+ /* Acnowledge the reception of the command. */
+ ret = consumer_send_status_msg(sock,
+ LTTCOMM_CONSUMERD_SUCCESS);
+ if (ret < 0) {
+ /* Somehow, the session daemon is not responding anymore. */
+ goto end_nosignal;
+ }
+
+ /*
+ * Receive trace chunk domain dirfd.
+ */
+ ret = lttcomm_recv_fds_unix_sock(sock, &chunk_dirfd, 1);
+ if (ret != sizeof(chunk_dirfd)) {
+ ERR("Failed to receive trace chunk domain directory file descriptor");
+ goto error_fatal;
+ }
+
+ DBG("Received trace chunk domain directory fd (%d)",
+ chunk_dirfd);
+ chunk_directory_handle = lttng_directory_handle_create_from_dirfd(
+ chunk_dirfd);
+ if (!chunk_directory_handle) {
+ ERR("Failed to initialize chunk domain directory handle from directory file descriptor");
+ if (close(chunk_dirfd)) {
+ PERROR("Failed to close chunk directory file descriptor");
+ }
+ goto error_fatal;
+ }
+ }
+
+ ret_code = lttng_consumer_create_trace_chunk(
+ !is_local_trace ? &relayd_id : NULL,
+ msg.u.create_trace_chunk.session_id,
+ msg.u.create_trace_chunk.chunk_id,
+ (time_t) msg.u.create_trace_chunk
+ .creation_timestamp,
+ chunk_override_name,
+ msg.u.create_trace_chunk.credentials.is_set ?
+ &credentials :
+ NULL,
+ chunk_directory_handle);
+ lttng_directory_handle_put(chunk_directory_handle);
+ goto end_msg_sessiond;
+ }
+ case LTTNG_CONSUMER_CLOSE_TRACE_CHUNK:
+ {
+ enum lttng_trace_chunk_command_type close_command =
+ msg.u.close_trace_chunk.close_command.value;
+ const uint64_t relayd_id =
+ msg.u.close_trace_chunk.relayd_id.value;
+ struct lttcomm_consumer_close_trace_chunk_reply reply;
+ char closed_trace_chunk_path[LTTNG_PATH_MAX];
+ int ret;
+
+ ret_code = lttng_consumer_close_trace_chunk(
+ msg.u.close_trace_chunk.relayd_id.is_set ?
+ &relayd_id :
+ NULL,
+ msg.u.close_trace_chunk.session_id,
+ msg.u.close_trace_chunk.chunk_id,
+ (time_t) msg.u.close_trace_chunk.close_timestamp,
+ msg.u.close_trace_chunk.close_command.is_set ?
+ &close_command :
+ NULL, closed_trace_chunk_path);
+ reply.ret_code = ret_code;
+ reply.path_length = strlen(closed_trace_chunk_path) + 1;
+ ret = lttcomm_send_unix_sock(sock, &reply, sizeof(reply));
+ if (ret != sizeof(reply)) {
+ goto error_fatal;
+ }
+ ret = lttcomm_send_unix_sock(sock, closed_trace_chunk_path,
+ reply.path_length);
+ if (ret != reply.path_length) {
+ goto error_fatal;
+ }
+ goto end_nosignal;
+ }
+ case LTTNG_CONSUMER_TRACE_CHUNK_EXISTS:
+ {
+ const uint64_t relayd_id =
+ msg.u.trace_chunk_exists.relayd_id.value;
+
+ ret_code = lttng_consumer_trace_chunk_exists(
+ msg.u.trace_chunk_exists.relayd_id.is_set ?
+ &relayd_id : NULL,
+ msg.u.trace_chunk_exists.session_id,
+ msg.u.trace_chunk_exists.chunk_id);
+ goto end_msg_sessiond;
+ }
+ default:
+ break;
+ }
+
+end_nosignal:
+ /*
+ * Return 1 to indicate success since the 0 value can be a socket
+ * shutdown during the recv() or send() call.
+ */
+ ret = 1;
+ goto end;
+
+end_msg_sessiond:
+ /*
+ * The returned value here is not useful since either way we'll return 1 to
+ * the caller because the session daemon socket management is done
+ * elsewhere. Returning a negative code or 0 will shutdown the consumer.
+ */
+ ret = consumer_send_status_msg(sock, ret_code);
+ if (ret < 0) {
+ goto error_fatal;
+ }
+ ret = 1;
+ goto end;
+
+end_channel_error:
+ if (channel) {
+ /*
+ * Free channel here since no one has a reference to it. We don't
+ * free after that because a stream can store this pointer.
+ */
+ destroy_channel(channel);
+ }
+ /* We have to send a status channel message indicating an error. */
+ ret = consumer_send_status_channel(sock, NULL);
+ if (ret < 0) {
+ /* Stop everything if session daemon can not be notified. */
+ goto error_fatal;
+ }
+ ret = 1;
+ goto end;
+
+error_fatal:
+ /* This will issue a consumer stop. */
+ ret = -1;
+ goto end;
+
+end:
+ rcu_read_unlock();
+ health_code_update();
+ return ret;
+}
+
+void lttng_ustctl_flush_buffer(struct lttng_consumer_stream *stream,
+ int producer_active)
+{
+ assert(stream);
+ assert(stream->ustream);
+
+ ustctl_flush_buffer(stream->ustream, producer_active);
+}
+
+/*
+ * Take a snapshot for a specific stream.
+ *
+ * Returns 0 on success, < 0 on error
+ */
+int lttng_ustconsumer_take_snapshot(struct lttng_consumer_stream *stream)
+{
+ assert(stream);
+ assert(stream->ustream);
+
+ return ustctl_snapshot(stream->ustream);
+}
+
+/*
+ * Sample consumed and produced positions for a specific stream.
+ *
+ * Returns 0 on success, < 0 on error.
+ */
+int lttng_ustconsumer_sample_snapshot_positions(
+ struct lttng_consumer_stream *stream)
+{
+ assert(stream);
+ assert(stream->ustream);
+
+ return ustctl_snapshot_sample_positions(stream->ustream);
+}
+
+/*
+ * Get the produced position
+ *
+ * Returns 0 on success, < 0 on error
+ */
+int lttng_ustconsumer_get_produced_snapshot(
+ struct lttng_consumer_stream *stream, unsigned long *pos)
+{
+ assert(stream);
+ assert(stream->ustream);
+ assert(pos);
+
+ return ustctl_snapshot_get_produced(stream->ustream, pos);
+}
+
+/*
+ * Get the consumed position
+ *
+ * Returns 0 on success, < 0 on error
+ */
+int lttng_ustconsumer_get_consumed_snapshot(
+ struct lttng_consumer_stream *stream, unsigned long *pos)
+{
+ assert(stream);
+ assert(stream->ustream);
+ assert(pos);
+
+ return ustctl_snapshot_get_consumed(stream->ustream, pos);
+}
+
+void lttng_ustconsumer_flush_buffer(struct lttng_consumer_stream *stream,
+ int producer)
+{
+ assert(stream);
+ assert(stream->ustream);
+
+ ustctl_flush_buffer(stream->ustream, producer);
+}
+
+void lttng_ustconsumer_clear_buffer(struct lttng_consumer_stream *stream)
+{
+ assert(stream);
+ assert(stream->ustream);
+
+ ustctl_clear_buffer(stream->ustream);
+}
+
+int lttng_ustconsumer_get_current_timestamp(
+ struct lttng_consumer_stream *stream, uint64_t *ts)
+{
+ assert(stream);
+ assert(stream->ustream);
+ assert(ts);
+
+ return ustctl_get_current_timestamp(stream->ustream, ts);
+}
+
+int lttng_ustconsumer_get_sequence_number(
+ struct lttng_consumer_stream *stream, uint64_t *seq)
+{
+ assert(stream);
+ assert(stream->ustream);
+ assert(seq);
+
+ return ustctl_get_sequence_number(stream->ustream, seq);
+}
+
+/*
+ * Called when the stream signals the consumer that it has hung up.
+ */
+void lttng_ustconsumer_on_stream_hangup(struct lttng_consumer_stream *stream)
+{
+ assert(stream);
+ assert(stream->ustream);
+
+ pthread_mutex_lock(&stream->lock);
+ if (!stream->quiescent) {
+ ustctl_flush_buffer(stream->ustream, 0);
+ stream->quiescent = true;
+ }
+ pthread_mutex_unlock(&stream->lock);
+ stream->hangup_flush_done = 1;
+}
+
+void lttng_ustconsumer_del_channel(struct lttng_consumer_channel *chan)
+{
+ int i;
+
+ assert(chan);
+ assert(chan->uchan);
+ assert(chan->buffer_credentials.is_set);
+
+ if (chan->switch_timer_enabled == 1) {
+ consumer_timer_switch_stop(chan);
+ }
+ for (i = 0; i < chan->nr_stream_fds; i++) {
+ int ret;
+
+ ret = close(chan->stream_fds[i]);
+ if (ret) {
+ PERROR("close");
+ }
+ if (chan->shm_path[0]) {
+ char shm_path[PATH_MAX];
+
+ ret = get_stream_shm_path(shm_path, chan->shm_path, i);
+ if (ret) {
+ ERR("Cannot get stream shm path");
+ }
+ ret = run_as_unlink(shm_path,
+ chan->buffer_credentials.value.uid,
+ chan->buffer_credentials.value.gid);
+ if (ret) {
+ PERROR("unlink %s", shm_path);
+ }
+ }
+ }
+}
+
+void lttng_ustconsumer_free_channel(struct lttng_consumer_channel *chan)
+{
+ assert(chan);
+ assert(chan->uchan);
+ assert(chan->buffer_credentials.is_set);
+
+ consumer_metadata_cache_destroy(chan);
+ ustctl_destroy_channel(chan->uchan);
+ /* Try to rmdir all directories under shm_path root. */
+ if (chan->root_shm_path[0]) {
+ (void) run_as_rmdir_recursive(chan->root_shm_path,
+ chan->buffer_credentials.value.uid,
+ chan->buffer_credentials.value.gid,
+ LTTNG_DIRECTORY_HANDLE_SKIP_NON_EMPTY_FLAG);
+ }
+ free(chan->stream_fds);
+}
+
+void lttng_ustconsumer_del_stream(struct lttng_consumer_stream *stream)
+{
+ assert(stream);
+ assert(stream->ustream);
+
+ if (stream->chan->switch_timer_enabled == 1) {
+ consumer_timer_switch_stop(stream->chan);
+ }
+ ustctl_destroy_stream(stream->ustream);
+}
+
+int lttng_ustconsumer_get_wakeup_fd(struct lttng_consumer_stream *stream)
+{
+ assert(stream);
+ assert(stream->ustream);
+
+ return ustctl_stream_get_wakeup_fd(stream->ustream);
+}
+
+int lttng_ustconsumer_close_wakeup_fd(struct lttng_consumer_stream *stream)
+{
+ assert(stream);
+ assert(stream->ustream);
+
+ return ustctl_stream_close_wakeup_fd(stream->ustream);
+}
+
+/*
+ * Populate index values of a UST stream. Values are set in big endian order.
+ *
+ * Return 0 on success or else a negative value.
+ */
+static int get_index_values(struct ctf_packet_index *index,
+ struct ustctl_consumer_stream *ustream)
+{
+ int ret;
+ uint64_t packet_size, content_size, timestamp_begin, timestamp_end,
+ events_discarded, stream_id, stream_instance_id,
+ packet_seq_num;
+
+ ret = ustctl_get_timestamp_begin(ustream, ×tamp_begin);
+ if (ret < 0) {
+ PERROR("ustctl_get_timestamp_begin");
+ goto error;
+ }
+
+ ret = ustctl_get_timestamp_end(ustream, ×tamp_end);
+ if (ret < 0) {
+ PERROR("ustctl_get_timestamp_end");
+ goto error;
+ }
+
+ ret = ustctl_get_events_discarded(ustream, &events_discarded);
+ if (ret < 0) {
+ PERROR("ustctl_get_events_discarded");
+ goto error;
+ }
+
+ ret = ustctl_get_content_size(ustream, &content_size);
+ if (ret < 0) {
+ PERROR("ustctl_get_content_size");
+ goto error;
+ }
+
+ ret = ustctl_get_packet_size(ustream, &packet_size);
+ if (ret < 0) {
+ PERROR("ustctl_get_packet_size");
+ goto error;
+ }
+
+ ret = ustctl_get_stream_id(ustream, &stream_id);
+ if (ret < 0) {
+ PERROR("ustctl_get_stream_id");
+ goto error;
+ }
+
+ ret = ustctl_get_instance_id(ustream, &stream_instance_id);
+ if (ret < 0) {
+ PERROR("ustctl_get_instance_id");
+ goto error;
+ }
+
+ ret = ustctl_get_sequence_number(ustream, &packet_seq_num);
+ if (ret < 0) {
+ PERROR("ustctl_get_sequence_number");
+ goto error;
+ }
+
+ *index = (typeof(*index)) {
+ .offset = index->offset,
+ .packet_size = htobe64(packet_size),
+ .content_size = htobe64(content_size),
+ .timestamp_begin = htobe64(timestamp_begin),
+ .timestamp_end = htobe64(timestamp_end),
+ .events_discarded = htobe64(events_discarded),
+ .stream_id = htobe64(stream_id),
+ .stream_instance_id = htobe64(stream_instance_id),
+ .packet_seq_num = htobe64(packet_seq_num),
+ };
+
+error:
+ return ret;
+}
+
+static
+void metadata_stream_reset_cache(struct lttng_consumer_stream *stream,
+ struct consumer_metadata_cache *cache)
+{
+ DBG("Metadata stream update to version %" PRIu64,
+ cache->version);
+ stream->ust_metadata_pushed = 0;
+ stream->metadata_version = cache->version;
+ stream->reset_metadata_flag = 1;
+}
+
+/*
+ * Check if the version of the metadata stream and metadata cache match.
+ * If the cache got updated, reset the metadata stream.
+ * The stream lock and metadata cache lock MUST be held.
+ * Return 0 on success, a negative value on error.
+ */
+static
+int metadata_stream_check_version(struct lttng_consumer_stream *stream)
+{
+ int ret = 0;
+ struct consumer_metadata_cache *cache = stream->chan->metadata_cache;
+
+ if (cache->version == stream->metadata_version) {
+ goto end;
+ }
+ metadata_stream_reset_cache(stream, cache);
+
+end:
+ return ret;
+}
+
+/*
+ * Write up to one packet from the metadata cache to the channel.
+ *
+ * Returns the number of bytes pushed in the cache, or a negative value
+ * on error.
+ */
+static
+int commit_one_metadata_packet(struct lttng_consumer_stream *stream)
+{
+ ssize_t write_len;
+ int ret;
+
+ pthread_mutex_lock(&stream->chan->metadata_cache->lock);
+ ret = metadata_stream_check_version(stream);
+ if (ret < 0) {
+ goto end;
+ }
+ if (stream->chan->metadata_cache->max_offset
+ == stream->ust_metadata_pushed) {
+ ret = 0;
+ goto end;
+ }
+
+ write_len = ustctl_write_one_packet_to_channel(stream->chan->uchan,
+ &stream->chan->metadata_cache->data[stream->ust_metadata_pushed],
+ stream->chan->metadata_cache->max_offset
+ - stream->ust_metadata_pushed);
+ assert(write_len != 0);
+ if (write_len < 0) {
+ ERR("Writing one metadata packet");
+ ret = -1;
+ goto end;
+ }
+ stream->ust_metadata_pushed += write_len;
+
+ assert(stream->chan->metadata_cache->max_offset >=
+ stream->ust_metadata_pushed);
+ ret = write_len;
+
+ /*
+ * Switch packet (but don't open the next one) on every commit of
+ * a metadata packet. Since the subbuffer is fully filled (with padding,
+ * if needed), the stream is "quiescent" after this commit.
+ */
+ ustctl_flush_buffer(stream->ustream, 1);
+ stream->quiescent = true;
+end:
+ pthread_mutex_unlock(&stream->chan->metadata_cache->lock);
+ return ret;
+}
+
+
+/*
+ * Sync metadata meaning request them to the session daemon and snapshot to the
+ * metadata thread can consumer them.
+ *
+ * Metadata stream lock is held here, but we need to release it when
+ * interacting with sessiond, else we cause a deadlock with live
+ * awaiting on metadata to be pushed out.
+ *
+ * The RCU read side lock must be held by the caller.
+ *
+ * Return 0 if new metadatda is available, EAGAIN if the metadata stream
+ * is empty or a negative value on error.
+ */
+int lttng_ustconsumer_sync_metadata(struct lttng_consumer_local_data *ctx,
+ struct lttng_consumer_stream *metadata_stream)
+{
+ int ret;
+ int retry = 0;
+ struct lttng_consumer_channel *metadata_channel;
+
+ assert(ctx);
+ assert(metadata_stream);
+
+ metadata_channel = metadata_stream->chan;
+ pthread_mutex_unlock(&metadata_stream->lock);
+ /*
+ * Request metadata from the sessiond, but don't wait for the flush
+ * because we locked the metadata thread.
+ */
+ ret = lttng_ustconsumer_request_metadata(ctx, metadata_channel, 0, 0);
+ pthread_mutex_lock(&metadata_stream->lock);
+ if (ret < 0) {
+ goto end;
+ }
+
+ /*
+ * The metadata stream and channel can be deleted while the
+ * metadata stream lock was released. The streamed is checked
+ * for deletion before we use it further.
+ *
+ * Note that it is safe to access a logically-deleted stream since its
+ * existence is still guaranteed by the RCU read side lock. However,
+ * it should no longer be used. The close/deletion of the metadata
+ * channel and stream already guarantees that all metadata has been
+ * consumed. Therefore, there is nothing left to do in this function.
+ */
+ if (consumer_stream_is_deleted(metadata_stream)) {
+ DBG("Metadata stream %" PRIu64 " was deleted during the metadata synchronization",
+ metadata_stream->key);
+ ret = 0;
+ goto end;