Fix: int printed as uint
[lttng-tools.git] / src / common / ust-consumer / ust-consumer.c
index 5dbd6ba4b4aff3feea113a2092165d13bf5bd160..481bbeba04b2f91eef880335cbd3ac8ef5cb9302 100644 (file)
@@ -17,6 +17,7 @@
  */
 
 #define _GNU_SOURCE
+#define _LGPL_SOURCE
 #include <assert.h>
 #include <lttng/ust-ctl.h>
 #include <poll.h>
 #include <sys/types.h>
 #include <inttypes.h>
 #include <unistd.h>
+#include <urcu/list.h>
+#include <signal.h>
 
+#include <bin/lttng-consumerd/health-consumerd.h>
 #include <common/common.h>
 #include <common/sessiond-comm/sessiond-comm.h>
 #include <common/relayd/relayd.h>
 #include <common/compat/fcntl.h>
+#include <common/compat/endian.h>
+#include <common/consumer-metadata-cache.h>
+#include <common/consumer-stream.h>
+#include <common/consumer-timer.h>
+#include <common/utils.h>
+#include <common/index/index.h>
 
 #include "ust-consumer.h"
 
+#define INT_MAX_STR_LEN 12     /* includes \0 */
+
 extern struct lttng_consumer_global_data consumer_data;
 extern int consumer_poll_timeout;
 extern volatile int consumer_quit;
 
 /*
- * Wrapper over the mmap() read offset from ust-ctl library. Since this can be
- * compiled out, we isolate it in this library.
+ * Free channel object and all streams associated with it. This MUST be used
+ * only and only if the channel has _NEVER_ been added to the global channel
+ * hash table.
  */
-int lttng_ustctl_get_mmap_read_offset(struct lttng_ust_shm_handle *handle,
-               struct lttng_ust_lib_ring_buffer *buf, unsigned long *off)
+static void destroy_channel(struct lttng_consumer_channel *channel)
 {
-       return ustctl_get_mmap_read_offset(handle, buf, off);
-};
+       struct lttng_consumer_stream *stream, *stmp;
+
+       assert(channel);
+
+       DBG("UST consumer cleaning stream list");
+
+       cds_list_for_each_entry_safe(stream, stmp, &channel->streams.head,
+                       send_node) {
+
+               health_code_update();
+
+               cds_list_del(&stream->send_node);
+               ustctl_destroy_stream(stream->ustream);
+               free(stream);
+       }
+
+       /*
+        * If a channel is available meaning that was created before the streams
+        * were, delete it.
+        */
+       if (channel->uchan) {
+               lttng_ustconsumer_del_channel(channel);
+               lttng_ustconsumer_free_channel(channel);
+       }
+       free(channel);
+}
 
 /*
- * Take a snapshot for a specific fd
+ * Add channel to internal consumer state.
  *
- * Returns 0 on success, < 0 on error
+ * Returns 0 on success or else a negative value.
  */
-int lttng_ustconsumer_take_snapshot(struct lttng_consumer_local_data *ctx,
-               struct lttng_consumer_stream *stream)
+static int add_channel(struct lttng_consumer_channel *channel,
+               struct lttng_consumer_local_data *ctx)
 {
        int ret = 0;
 
-       ret = ustctl_snapshot(stream->chan->handle, stream->buf);
-       if (ret != 0) {
-               errno = -ret;
-               PERROR("Getting sub-buffer snapshot.");
+       assert(channel);
+       assert(ctx);
+
+       if (ctx->on_recv_channel != NULL) {
+               ret = ctx->on_recv_channel(channel);
+               if (ret == 0) {
+                       ret = consumer_add_channel(channel, ctx);
+               } else if (ret < 0) {
+                       /* Most likely an ENOMEM. */
+                       lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
+                       goto error;
+               }
+       } else {
+               ret = consumer_add_channel(channel, ctx);
        }
 
+       DBG("UST consumer channel added (key: %" PRIu64 ")", channel->key);
+
+error:
        return ret;
 }
 
 /*
- * Get the produced position
- *
- * Returns 0 on success, < 0 on error
+ * Allocate and return a consumer channel object.
  */
-int lttng_ustconsumer_get_produced_snapshot(
-               struct lttng_consumer_local_data *ctx,
-               struct lttng_consumer_stream *stream,
-               unsigned long *pos)
+static struct lttng_consumer_channel *allocate_channel(uint64_t session_id,
+               const char *pathname, const char *name, uid_t uid, gid_t gid,
+               uint64_t relayd_id, uint64_t key, enum lttng_event_output output,
+               uint64_t tracefile_size, uint64_t tracefile_count,
+               uint64_t session_id_per_pid, unsigned int monitor,
+               unsigned int live_timer_interval,
+               const char *root_shm_path, const char *shm_path)
 {
-       int ret;
+       assert(pathname);
+       assert(name);
 
-       ret = ustctl_snapshot_get_produced(stream->chan->handle,
-                       stream->buf, pos);
-       if (ret != 0) {
-               errno = -ret;
-               PERROR("ustctl_snapshot_get_produced");
-       }
-
-       return ret;
+       return consumer_allocate_channel(key, session_id, pathname, name, uid,
+                       gid, relayd_id, output, tracefile_size,
+                       tracefile_count, session_id_per_pid, monitor,
+                       live_timer_interval, root_shm_path, shm_path);
 }
 
 /*
- * Receive command from session daemon and process it.
+ * Allocate and return a consumer stream object. If _alloc_ret is not NULL, the
+ * error value if applicable is set in it else it is kept untouched.
  *
- * Return 1 on success else a negative value or 0.
+ * Return NULL on error else the newly allocated stream object.
  */
-int lttng_ustconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
-               int sock, struct pollfd *consumer_sockpoll)
+static struct lttng_consumer_stream *allocate_stream(int cpu, int key,
+               struct lttng_consumer_channel *channel,
+               struct lttng_consumer_local_data *ctx, int *_alloc_ret)
 {
-       ssize_t ret;
-       enum lttng_error_code ret_code = LTTNG_OK;
-       struct lttcomm_consumer_msg msg;
-
-       ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
-       if (ret != sizeof(msg)) {
-               DBG("Consumer received unexpected message size %zd (expects %zu)",
-                       ret, sizeof(msg));
-               lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_FD);
-               /*
-                * The ret value might 0 meaning an orderly shutdown but this is ok
-                * since the caller handles this.
-                */
-               return ret;
-       }
-       if (msg.cmd_type == LTTNG_CONSUMER_STOP) {
-               /*
-                * Notify the session daemon that the command is completed.
-                *
-                * On transport layer error, the function call will print an error
-                * message so handling the returned code is a bit useless since we
-                * return an error code anyway.
-                */
-               (void) consumer_send_status_msg(sock, ret_code);
-               return -ENOENT;
+       int alloc_ret;
+       struct lttng_consumer_stream *stream = NULL;
+
+       assert(channel);
+       assert(ctx);
+
+       stream = consumer_allocate_stream(channel->key,
+                       key,
+                       LTTNG_CONSUMER_ACTIVE_STREAM,
+                       channel->name,
+                       channel->uid,
+                       channel->gid,
+                       channel->relayd_id,
+                       channel->session_id,
+                       cpu,
+                       &alloc_ret,
+                       channel->type,
+                       channel->monitor);
+       if (stream == NULL) {
+               switch (alloc_ret) {
+               case -ENOENT:
+                       /*
+                        * We could not find the channel. Can happen if cpu hotplug
+                        * happens while tearing down.
+                        */
+                       DBG3("Could not find channel");
+                       break;
+               case -ENOMEM:
+               case -EINVAL:
+               default:
+                       lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
+                       break;
+               }
+               goto error;
        }
 
-       /* relayd needs RCU read-side lock */
-       rcu_read_lock();
+       stream->chan = channel;
 
-       switch (msg.cmd_type) {
-       case LTTNG_CONSUMER_ADD_RELAYD_SOCKET:
-       {
-               /* Session daemon status message are handled in the following call. */
-               ret = consumer_add_relayd_socket(msg.u.relayd_sock.net_index,
-                               msg.u.relayd_sock.type, ctx, sock, consumer_sockpoll,
-                               &msg.u.relayd_sock.sock, msg.u.relayd_sock.session_id);
-               goto end_nosignal;
+error:
+       if (_alloc_ret) {
+               *_alloc_ret = alloc_ret;
        }
-       case LTTNG_CONSUMER_ADD_CHANNEL:
-       {
-               struct lttng_consumer_channel *new_channel;
-               int fds[1];
-               size_t nb_fd = 1;
-
-               DBG("UST Consumer adding channel");
-
-               /* First send a status message before receiving the fds. */
-               ret = consumer_send_status_msg(sock, ret_code);
-               if (ret < 0) {
-                       /* Somehow, the session daemon is not responding anymore. */
-                       goto end_nosignal;
-               }
+       return stream;
+}
 
-               /* block */
-               if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
-                       rcu_read_unlock();
-                       return -EINTR;
+/*
+ * Send the given stream pointer to the corresponding thread.
+ *
+ * Returns 0 on success else a negative value.
+ */
+static int send_stream_to_thread(struct lttng_consumer_stream *stream,
+               struct lttng_consumer_local_data *ctx)
+{
+       int ret;
+       struct lttng_pipe *stream_pipe;
+
+       /* Get the right pipe where the stream will be sent. */
+       if (stream->metadata_flag) {
+               ret = consumer_add_metadata_stream(stream);
+               if (ret) {
+                       ERR("Consumer add metadata stream %" PRIu64 " failed.",
+                                       stream->key);
+                       goto error;
                }
-               ret = lttcomm_recv_fds_unix_sock(sock, fds, nb_fd);
-               if (ret != sizeof(fds)) {
-                       lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_FD);
-                       rcu_read_unlock();
-                       /*
-                        * The ret value might 0 meaning an orderly shutdown but this is ok
-                        * since the caller handles this.
-                        */
-                       return ret;
+               stream_pipe = ctx->consumer_metadata_pipe;
+       } else {
+               ret = consumer_add_data_stream(stream);
+               if (ret) {
+                       ERR("Consumer add stream %" PRIu64 " failed.",
+                                       stream->key);
+                       goto error;
                }
+               stream_pipe = ctx->consumer_data_pipe;
+       }
 
-               /*
-                * Send status code to session daemon only if the recv works. If the
-                * above recv() failed, the session daemon is notified through the
-                * error socket and the teardown is eventually done.
-                */
-               ret = consumer_send_status_msg(sock, ret_code);
-               if (ret < 0) {
-                       /* Somehow, the session daemon is not responding anymore. */
-                       goto end_nosignal;
+       /*
+        * From this point on, the stream's ownership has been moved away from
+        * the channel and becomes globally visible.
+        */
+       stream->globally_visible = 1;
+
+       ret = lttng_pipe_write(stream_pipe, &stream, sizeof(stream));
+       if (ret < 0) {
+               ERR("Consumer write %s stream to pipe %d",
+                               stream->metadata_flag ? "metadata" : "data",
+                               lttng_pipe_get_writefd(stream_pipe));
+               if (stream->metadata_flag) {
+                       consumer_del_stream_for_metadata(stream);
+               } else {
+                       consumer_del_stream_for_data(stream);
                }
+       }
+error:
+       return ret;
+}
 
-               DBG("consumer_add_channel %d", msg.u.channel.channel_key);
+static
+int get_stream_shm_path(char *stream_shm_path, const char *shm_path, int cpu)
+{
+       char cpu_nr[INT_MAX_STR_LEN];  /* int max len */
+       int ret;
 
-               new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
-                               fds[0], -1,
-                               msg.u.channel.mmap_len,
-                               msg.u.channel.max_sb_size,
-                               msg.u.channel.nb_init_streams);
-               if (new_channel == NULL) {
-                       lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
-                       goto end_nosignal;
-               }
-               if (ctx->on_recv_channel != NULL) {
-                       ret = ctx->on_recv_channel(new_channel);
-                       if (ret == 0) {
-                               consumer_add_channel(new_channel);
-                       } else if (ret < 0) {
-                               goto end_nosignal;
-                       }
-               } else {
-                       consumer_add_channel(new_channel);
-               }
-               goto end_nosignal;
+       strncpy(stream_shm_path, shm_path, PATH_MAX);
+       stream_shm_path[PATH_MAX - 1] = '\0';
+       ret = snprintf(cpu_nr, INT_MAX_STR_LEN, "%i", cpu);
+       if (ret < 0) {
+               PERROR("snprintf");
+               goto end;
        }
-       case LTTNG_CONSUMER_ADD_STREAM:
-       {
-               struct lttng_consumer_stream *new_stream;
-               int fds[2], stream_pipe;
-               size_t nb_fd = 2;
-               struct consumer_relayd_sock_pair *relayd = NULL;
-               int alloc_ret = 0;
+       strncat(stream_shm_path, cpu_nr,
+               PATH_MAX - strlen(stream_shm_path) - 1);
+       ret = 0;
+end:
+       return ret;
+}
+
+/*
+ * Create streams for the given channel using liblttng-ust-ctl.
+ *
+ * Return 0 on success else a negative value.
+ */
+static int create_ust_streams(struct lttng_consumer_channel *channel,
+               struct lttng_consumer_local_data *ctx)
+{
+       int ret, cpu = 0;
+       struct ustctl_consumer_stream *ustream;
+       struct lttng_consumer_stream *stream;
 
-               DBG("UST Consumer adding stream");
+       assert(channel);
+       assert(ctx);
 
-               /* First send a status message before receiving the fds. */
-               ret = consumer_send_status_msg(sock, ret_code);
-               if (ret < 0) {
-                       /* Somehow, the session daemon is not responding anymore. */
-                       goto end_nosignal;
-               }
+       /*
+        * While a stream is available from ustctl. When NULL is returned, we've
+        * reached the end of the possible stream for the channel.
+        */
+       while ((ustream = ustctl_create_stream(channel->uchan, cpu))) {
+               int wait_fd;
+               int ust_metadata_pipe[2];
 
-               /* block */
-               if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
-                       rcu_read_unlock();
-                       return -EINTR;
+               health_code_update();
+
+               if (channel->type == CONSUMER_CHANNEL_TYPE_METADATA && channel->monitor) {
+                       ret = utils_create_pipe_cloexec_nonblock(ust_metadata_pipe);
+                       if (ret < 0) {
+                               ERR("Create ust metadata poll pipe");
+                               goto error;
+                       }
+                       wait_fd = ust_metadata_pipe[0];
+               } else {
+                       wait_fd = ustctl_stream_get_wait_fd(ustream);
                }
-               ret = lttcomm_recv_fds_unix_sock(sock, fds, nb_fd);
-               if (ret != sizeof(fds)) {
-                       lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_FD);
-                       rcu_read_unlock();
-                       /*
-                        * The ret value might 0 meaning an orderly shutdown but this is ok
-                        * since the caller handles this.
-                        */
-                       return ret;
+
+               /* Allocate consumer stream object. */
+               stream = allocate_stream(cpu, wait_fd, channel, ctx, &ret);
+               if (!stream) {
+                       goto error_alloc;
                }
+               stream->ustream = ustream;
+               /*
+                * Store it so we can save multiple function calls afterwards since
+                * this value is used heavily in the stream threads. This is UST
+                * specific so this is why it's done after allocation.
+                */
+               stream->wait_fd = wait_fd;
 
                /*
-                * Send status code to session daemon only if the recv works. If the
-                * above recv() failed, the session daemon is notified through the
-                * error socket and the teardown is eventually done.
+                * Increment channel refcount since the channel reference has now been
+                * assigned in the allocation process above.
                 */
-               ret = consumer_send_status_msg(sock, ret_code);
-               if (ret < 0) {
-                       /* Somehow, the session daemon is not responding anymore. */
-                       goto end_nosignal;
+               if (stream->chan->monitor) {
+                       uatomic_inc(&stream->chan->refcount);
                }
 
-               DBG("Consumer command ADD_STREAM chan %d stream %d",
-                               msg.u.stream.channel_key, msg.u.stream.stream_key);
-
-               assert(msg.u.stream.output == LTTNG_EVENT_MMAP);
-               new_stream = consumer_allocate_stream(msg.u.stream.channel_key,
-                               msg.u.stream.stream_key,
-                               fds[0], fds[1],
-                               msg.u.stream.state,
-                               msg.u.stream.mmap_len,
-                               msg.u.stream.output,
-                               msg.u.stream.path_name,
-                               msg.u.stream.uid,
-                               msg.u.stream.gid,
-                               msg.u.stream.net_index,
-                               msg.u.stream.metadata_flag,
-                               msg.u.stream.session_id,
-                               &alloc_ret);
-               if (new_stream == NULL) {
-                       switch (alloc_ret) {
-                       case -ENOMEM:
-                       case -EINVAL:
-                       default:
-                               lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
-                               break;
-                       case -ENOENT:
-                               /*
-                                * We could not find the channel. Can happen if cpu hotplug
-                                * happens while tearing down.
-                                */
-                               DBG3("Could not find channel");
-                               break;
-                       }
-                       goto end_nosignal;
-               }
+               /*
+                * Order is important this is why a list is used. On error, the caller
+                * should clean this list.
+                */
+               cds_list_add_tail(&stream->send_node, &channel->streams.head);
 
-               /* The stream is not metadata. Get relayd reference if exists. */
-               relayd = consumer_find_relayd(msg.u.stream.net_index);
-               if (relayd != NULL) {
-                       pthread_mutex_lock(&relayd->ctrl_sock_mutex);
-                       /* Add stream on the relayd */
-                       ret = relayd_add_stream(&relayd->control_sock,
-                                       msg.u.stream.name, msg.u.stream.path_name,
-                                       &new_stream->relayd_stream_id);
-                       pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
-                       if (ret < 0) {
-                               consumer_del_stream(new_stream, NULL);
-                               goto end_nosignal;
-                       }
-               } else if (msg.u.stream.net_index != -1) {
-                       ERR("Network sequence index %d unknown. Not adding stream.",
-                                       msg.u.stream.net_index);
-                       consumer_del_stream(new_stream, NULL);
-                       goto end_nosignal;
+               ret = ustctl_get_max_subbuf_size(stream->ustream,
+                               &stream->max_sb_size);
+               if (ret < 0) {
+                       ERR("ustctl_get_max_subbuf_size failed for stream %s",
+                                       stream->name);
+                       goto error;
                }
 
                /* Do actions once stream has been received. */
                if (ctx->on_recv_stream) {
-                       ret = ctx->on_recv_stream(new_stream);
+                       ret = ctx->on_recv_stream(stream);
                        if (ret < 0) {
-                               consumer_del_stream(new_stream, NULL);
-                               goto end_nosignal;
+                               goto error;
                        }
                }
 
-               /* Get the right pipe where the stream will be sent. */
-               if (new_stream->metadata_flag) {
-                       stream_pipe = ctx->consumer_metadata_pipe[1];
-               } else {
-                       stream_pipe = ctx->consumer_data_pipe[1];
-               }
+               DBG("UST consumer add stream %s (key: %" PRIu64 ") with relayd id %" PRIu64,
+                               stream->name, stream->key, stream->relayd_stream_id);
 
-               do {
-                       ret = write(stream_pipe, &new_stream, sizeof(new_stream));
-               } while (ret < 0 && errno == EINTR);
-               if (ret < 0) {
-                       PERROR("Consumer write %s stream to pipe %d",
-                                       new_stream->metadata_flag ? "metadata" : "data",
-                                       stream_pipe);
-                       consumer_del_stream(new_stream, NULL);
-                       goto end_nosignal;
+               /* Set next CPU stream. */
+               channel->streams.count = ++cpu;
+
+               /* Keep stream reference when creating metadata. */
+               if (channel->type == CONSUMER_CHANNEL_TYPE_METADATA) {
+                       channel->metadata_stream = stream;
+                       if (channel->monitor) {
+                               /* Set metadata poll pipe if we created one */
+                               memcpy(stream->ust_metadata_poll_pipe,
+                                               ust_metadata_pipe,
+                                               sizeof(ust_metadata_pipe));
+                       }
                }
+       }
 
-               DBG("UST consumer ADD_STREAM %s (%d,%d) with relayd id %" PRIu64,
-                               msg.u.stream.path_name, fds[0], fds[1],
-                               new_stream->relayd_stream_id);
-               break;
+       return 0;
+
+error:
+error_alloc:
+       return ret;
+}
+
+/*
+ * create_posix_shm is never called concurrently within a process.
+ */
+static
+int create_posix_shm(void)
+{
+       char tmp_name[NAME_MAX];
+       int shmfd, ret;
+
+       ret = snprintf(tmp_name, NAME_MAX, "/ust-shm-consumer-%d", getpid());
+       if (ret < 0) {
+               PERROR("snprintf");
+               return -1;
        }
-       case LTTNG_CONSUMER_DESTROY_RELAYD:
-       {
-               uint64_t index = msg.u.destroy_relayd.net_seq_idx;
-               struct consumer_relayd_sock_pair *relayd;
+       /*
+        * Allocate shm, and immediately unlink its shm oject, keeping
+        * only the file descriptor as a reference to the object.
+        * We specifically do _not_ use the / at the beginning of the
+        * pathname so that some OS implementations can keep it local to
+        * the process (POSIX leaves this implementation-defined).
+        */
+       shmfd = shm_open(tmp_name, O_CREAT | O_EXCL | O_RDWR, 0700);
+       if (shmfd < 0) {
+               PERROR("shm_open");
+               goto error_shm_open;
+       }
+       ret = shm_unlink(tmp_name);
+       if (ret < 0 && errno != ENOENT) {
+               PERROR("shm_unlink");
+               goto error_shm_release;
+       }
+       return shmfd;
 
-               DBG("UST consumer destroying relayd %" PRIu64, index);
+error_shm_release:
+       ret = close(shmfd);
+       if (ret) {
+               PERROR("close");
+       }
+error_shm_open:
+       return -1;
+}
 
-               /* Get relayd reference if exists. */
-               relayd = consumer_find_relayd(index);
-               if (relayd == NULL) {
-                       DBG("Unable to find relayd %" PRIu64, index);
-                       ret_code = LTTNG_ERR_NO_CONSUMER;
-               }
+static int open_ust_stream_fd(struct lttng_consumer_channel *channel,
+               struct ustctl_consumer_channel_attr *attr,
+               int cpu)
+{
+       char shm_path[PATH_MAX];
+       int ret;
 
-               /*
-                * Each relayd socket pair has a refcount of stream attached to it
-                * which tells if the relayd is still active or not depending on the
-                * refcount value.
-                *
-                * This will set the destroy flag of the relayd object and destroy it
-                * if the refcount reaches zero when called.
-                *
-                * The destroy can happen either here or when a stream fd hangs up.
-                */
-               if (relayd) {
-                       consumer_flag_relayd_for_destroy(relayd);
+       if (!channel->shm_path[0]) {
+               return create_posix_shm();
+       }
+       ret = get_stream_shm_path(shm_path, channel->shm_path, cpu);
+       if (ret) {
+               goto error_shm_path;
+       }
+       return run_as_open(shm_path,
+               O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR,
+               channel->uid, channel->gid);
+
+error_shm_path:
+       return -1;
+}
+
+/*
+ * Create an UST channel with the given attributes and send it to the session
+ * daemon using the ust ctl API.
+ *
+ * Return 0 on success or else a negative value.
+ */
+static int create_ust_channel(struct lttng_consumer_channel *channel,
+               struct ustctl_consumer_channel_attr *attr,
+               struct ustctl_consumer_channel **ust_chanp)
+{
+       int ret, nr_stream_fds, i, j;
+       int *stream_fds;
+       struct ustctl_consumer_channel *ust_channel;
+
+       assert(channel);
+       assert(attr);
+       assert(ust_chanp);
+
+       DBG3("Creating channel to ustctl with attr: [overwrite: %d, "
+                       "subbuf_size: %" PRIu64 ", num_subbuf: %" PRIu64 ", "
+                       "switch_timer_interval: %u, read_timer_interval: %u, "
+                       "output: %d, type: %d", attr->overwrite, attr->subbuf_size,
+                       attr->num_subbuf, attr->switch_timer_interval,
+                       attr->read_timer_interval, attr->output, attr->type);
+
+       if (channel->type == CONSUMER_CHANNEL_TYPE_METADATA)
+               nr_stream_fds = 1;
+       else
+               nr_stream_fds = ustctl_get_nr_stream_per_channel();
+       stream_fds = zmalloc(nr_stream_fds * sizeof(*stream_fds));
+       if (!stream_fds) {
+               ret = -1;
+               goto error_alloc;
+       }
+       for (i = 0; i < nr_stream_fds; i++) {
+               stream_fds[i] = open_ust_stream_fd(channel, attr, i);
+               if (stream_fds[i] < 0) {
+                       ret = -1;
+                       goto error_open;
                }
+       }
+       ust_channel = ustctl_create_channel(attr, stream_fds, nr_stream_fds);
+       if (!ust_channel) {
+               ret = -1;
+               goto error_create;
+       }
+       channel->nr_stream_fds = nr_stream_fds;
+       channel->stream_fds = stream_fds;
+       *ust_chanp = ust_channel;
 
-               ret = consumer_send_status_msg(sock, ret_code);
-               if (ret < 0) {
-                       /* Somehow, the session daemon is not responding anymore. */
-                       goto end_nosignal;
+       return 0;
+
+error_create:
+error_open:
+       for (j = i - 1; j >= 0; j--) {
+               int closeret;
+
+               closeret = close(stream_fds[j]);
+               if (closeret) {
+                       PERROR("close");
                }
+               if (channel->shm_path[0]) {
+                       char shm_path[PATH_MAX];
 
-               goto end_nosignal;
+                       closeret = get_stream_shm_path(shm_path,
+                                       channel->shm_path, j);
+                       if (closeret) {
+                               ERR("Cannot get stream shm path");
+                       }
+                       closeret = run_as_unlink(shm_path,
+                                       channel->uid, channel->gid);
+                       if (closeret) {
+                               PERROR("unlink %s", shm_path);
+                       }
+               }
        }
-       case LTTNG_CONSUMER_UPDATE_STREAM:
-       {
-               rcu_read_unlock();
-               return -ENOSYS;
+       /* Try to rmdir all directories under shm_path root. */
+       if (channel->root_shm_path[0]) {
+               (void) run_as_recursive_rmdir(channel->root_shm_path,
+                               channel->uid, channel->gid);
        }
-       case LTTNG_CONSUMER_DATA_PENDING:
-       {
-               int ret, is_data_pending;
-               uint64_t id = msg.u.data_pending.session_id;
+       free(stream_fds);
+error_alloc:
+       return ret;
+}
+
+/*
+ * Send a single given stream to the session daemon using the sock.
+ *
+ * Return 0 on success else a negative value.
+ */
+static int send_sessiond_stream(int sock, struct lttng_consumer_stream *stream)
+{
+       int ret;
+
+       assert(stream);
+       assert(sock >= 0);
+
+       DBG("UST consumer sending stream %" PRIu64 " to sessiond", stream->key);
+
+       /* Send stream to session daemon. */
+       ret = ustctl_send_stream_to_sessiond(sock, stream->ustream);
+       if (ret < 0) {
+               goto error;
+       }
+
+error:
+       return ret;
+}
+
+/*
+ * Send channel to sessiond.
+ *
+ * Return 0 on success or else a negative value.
+ */
+static int send_sessiond_channel(int sock,
+               struct lttng_consumer_channel *channel,
+               struct lttng_consumer_local_data *ctx, int *relayd_error)
+{
+       int ret, ret_code = LTTCOMM_CONSUMERD_SUCCESS;
+       struct lttng_consumer_stream *stream;
+       uint64_t net_seq_idx = -1ULL;
+
+       assert(channel);
+       assert(ctx);
+       assert(sock >= 0);
+
+       DBG("UST consumer sending channel %s to sessiond", channel->name);
+
+       if (channel->relayd_id != (uint64_t) -1ULL) {
+               cds_list_for_each_entry(stream, &channel->streams.head, send_node) {
+
+                       health_code_update();
+
+                       /* Try to send the stream to the relayd if one is available. */
+                       ret = consumer_send_relayd_stream(stream, stream->chan->pathname);
+                       if (ret < 0) {
+                               /*
+                                * Flag that the relayd was the problem here probably due to a
+                                * communicaton error on the socket.
+                                */
+                               if (relayd_error) {
+                                       *relayd_error = 1;
+                               }
+                               ret_code = LTTCOMM_CONSUMERD_RELAYD_FAIL;
+                       }
+                       if (net_seq_idx == -1ULL) {
+                               net_seq_idx = stream->net_seq_idx;
+                       }
+               }
+       }
+
+       /* Inform sessiond that we are about to send channel and streams. */
+       ret = consumer_send_status_msg(sock, ret_code);
+       if (ret < 0 || ret_code != LTTCOMM_CONSUMERD_SUCCESS) {
+               /*
+                * Either the session daemon is not responding or the relayd died so we
+                * stop now.
+                */
+               goto error;
+       }
+
+       /* Send channel to sessiond. */
+       ret = ustctl_send_channel_to_sessiond(sock, channel->uchan);
+       if (ret < 0) {
+               goto error;
+       }
+
+       ret = ustctl_channel_close_wakeup_fd(channel->uchan);
+       if (ret < 0) {
+               goto error;
+       }
+
+       /* The channel was sent successfully to the sessiond at this point. */
+       cds_list_for_each_entry(stream, &channel->streams.head, send_node) {
+
+               health_code_update();
+
+               /* Send stream to session daemon. */
+               ret = send_sessiond_stream(sock, stream);
+               if (ret < 0) {
+                       goto error;
+               }
+       }
+
+       /* Tell sessiond there is no more stream. */
+       ret = ustctl_send_stream_to_sessiond(sock, NULL);
+       if (ret < 0) {
+               goto error;
+       }
+
+       DBG("UST consumer NULL stream sent to sessiond");
+
+       return 0;
+
+error:
+       if (ret_code != LTTCOMM_CONSUMERD_SUCCESS) {
+               ret = -1;
+       }
+       return ret;
+}
+
+/*
+ * Creates a channel and streams and add the channel it to the channel internal
+ * state. The created stream must ONLY be sent once the GET_CHANNEL command is
+ * received.
+ *
+ * Return 0 on success or else, a negative value is returned and the channel
+ * MUST be destroyed by consumer_del_channel().
+ */
+static int ask_channel(struct lttng_consumer_local_data *ctx, int sock,
+               struct lttng_consumer_channel *channel,
+               struct ustctl_consumer_channel_attr *attr)
+{
+       int ret;
+
+       assert(ctx);
+       assert(channel);
+       assert(attr);
+
+       /*
+        * This value is still used by the kernel consumer since for the kernel,
+        * the stream ownership is not IN the consumer so we need to have the
+        * number of left stream that needs to be initialized so we can know when
+        * to delete the channel (see consumer.c).
+        *
+        * As for the user space tracer now, the consumer creates and sends the
+        * stream to the session daemon which only sends them to the application
+        * once every stream of a channel is received making this value useless
+        * because we they will be added to the poll thread before the application
+        * receives them. This ensures that a stream can not hang up during
+        * initilization of a channel.
+        */
+       channel->nb_init_stream_left = 0;
+
+       /* The reply msg status is handled in the following call. */
+       ret = create_ust_channel(channel, attr, &channel->uchan);
+       if (ret < 0) {
+               goto end;
+       }
+
+       channel->wait_fd = ustctl_channel_get_wait_fd(channel->uchan);
+
+       /*
+        * For the snapshots (no monitor), we create the metadata streams
+        * on demand, not during the channel creation.
+        */
+       if (channel->type == CONSUMER_CHANNEL_TYPE_METADATA && !channel->monitor) {
+               ret = 0;
+               goto end;
+       }
+
+       /* Open all streams for this channel. */
+       ret = create_ust_streams(channel, ctx);
+       if (ret < 0) {
+               goto end;
+       }
+
+end:
+       return ret;
+}
+
+/*
+ * Send all stream of a channel to the right thread handling it.
+ *
+ * On error, return a negative value else 0 on success.
+ */
+static int send_streams_to_thread(struct lttng_consumer_channel *channel,
+               struct lttng_consumer_local_data *ctx)
+{
+       int ret = 0;
+       struct lttng_consumer_stream *stream, *stmp;
+
+       assert(channel);
+       assert(ctx);
+
+       /* Send streams to the corresponding thread. */
+       cds_list_for_each_entry_safe(stream, stmp, &channel->streams.head,
+                       send_node) {
+
+               health_code_update();
+
+               /* Sending the stream to the thread. */
+               ret = send_stream_to_thread(stream, ctx);
+               if (ret < 0) {
+                       /*
+                        * If we are unable to send the stream to the thread, there is
+                        * a big problem so just stop everything.
+                        */
+                       /* Remove node from the channel stream list. */
+                       cds_list_del(&stream->send_node);
+                       goto error;
+               }
+
+               /* Remove node from the channel stream list. */
+               cds_list_del(&stream->send_node);
+
+       }
+
+error:
+       return ret;
+}
+
+/*
+ * Flush channel's streams using the given key to retrieve the channel.
+ *
+ * Return 0 on success else an LTTng error code.
+ */
+static int flush_channel(uint64_t chan_key)
+{
+       int ret = 0;
+       struct lttng_consumer_channel *channel;
+       struct lttng_consumer_stream *stream;
+       struct lttng_ht *ht;
+       struct lttng_ht_iter iter;
+
+       DBG("UST consumer flush channel key %" PRIu64, chan_key);
+
+       rcu_read_lock();
+       channel = consumer_find_channel(chan_key);
+       if (!channel) {
+               ERR("UST consumer flush channel %" PRIu64 " not found", chan_key);
+               ret = LTTNG_ERR_UST_CHAN_NOT_FOUND;
+               goto error;
+       }
+
+       ht = consumer_data.stream_per_chan_id_ht;
+
+       /* For each stream of the channel id, flush it. */
+       cds_lfht_for_each_entry_duplicate(ht->ht,
+                       ht->hash_fct(&channel->key, lttng_ht_seed), ht->match_fct,
+                       &channel->key, &iter.iter, stream, node_channel_id.node) {
+
+               health_code_update();
+
+               ustctl_flush_buffer(stream->ustream, 1);
+       }
+error:
+       rcu_read_unlock();
+       return ret;
+}
+
+/*
+ * Close metadata stream wakeup_fd using the given key to retrieve the channel.
+ * RCU read side lock MUST be acquired before calling this function.
+ *
+ * Return 0 on success else an LTTng error code.
+ */
+static int close_metadata(uint64_t chan_key)
+{
+       int ret = 0;
+       struct lttng_consumer_channel *channel;
+
+       DBG("UST consumer close metadata key %" PRIu64, chan_key);
+
+       channel = consumer_find_channel(chan_key);
+       if (!channel) {
+               /*
+                * This is possible if the metadata thread has issue a delete because
+                * the endpoint point of the stream hung up. There is no way the
+                * session daemon can know about it thus use a DBG instead of an actual
+                * error.
+                */
+               DBG("UST consumer close metadata %" PRIu64 " not found", chan_key);
+               ret = LTTNG_ERR_UST_CHAN_NOT_FOUND;
+               goto error;
+       }
+
+       pthread_mutex_lock(&consumer_data.lock);
+       pthread_mutex_lock(&channel->lock);
+
+       if (cds_lfht_is_node_deleted(&channel->node.node)) {
+               goto error_unlock;
+       }
+
+       lttng_ustconsumer_close_metadata(channel);
+
+error_unlock:
+       pthread_mutex_unlock(&channel->lock);
+       pthread_mutex_unlock(&consumer_data.lock);
+error:
+       return ret;
+}
+
+/*
+ * RCU read side lock MUST be acquired before calling this function.
+ *
+ * Return 0 on success else an LTTng error code.
+ */
+static int setup_metadata(struct lttng_consumer_local_data *ctx, uint64_t key)
+{
+       int ret;
+       struct lttng_consumer_channel *metadata;
+
+       DBG("UST consumer setup metadata key %" PRIu64, key);
+
+       metadata = consumer_find_channel(key);
+       if (!metadata) {
+               ERR("UST consumer push metadata %" PRIu64 " not found", key);
+               ret = LTTNG_ERR_UST_CHAN_NOT_FOUND;
+               goto end;
+       }
+
+       /*
+        * In no monitor mode, the metadata channel has no stream(s) so skip the
+        * ownership transfer to the metadata thread.
+        */
+       if (!metadata->monitor) {
+               DBG("Metadata channel in no monitor");
+               ret = 0;
+               goto end;
+       }
+
+       /*
+        * Send metadata stream to relayd if one available. Availability is
+        * known if the stream is still in the list of the channel.
+        */
+       if (cds_list_empty(&metadata->streams.head)) {
+               ERR("Metadata channel key %" PRIu64 ", no stream available.", key);
+               ret = LTTCOMM_CONSUMERD_ERROR_METADATA;
+               goto error_no_stream;
+       }
+
+       /* Send metadata stream to relayd if needed. */
+       if (metadata->metadata_stream->net_seq_idx != (uint64_t) -1ULL) {
+               ret = consumer_send_relayd_stream(metadata->metadata_stream,
+                               metadata->pathname);
+               if (ret < 0) {
+                       ret = LTTCOMM_CONSUMERD_ERROR_METADATA;
+                       goto error;
+               }
+               ret = consumer_send_relayd_streams_sent(
+                               metadata->metadata_stream->net_seq_idx);
+               if (ret < 0) {
+                       ret = LTTCOMM_CONSUMERD_RELAYD_FAIL;
+                       goto error;
+               }
+       }
+
+       ret = send_streams_to_thread(metadata, ctx);
+       if (ret < 0) {
+               /*
+                * If we are unable to send the stream to the thread, there is
+                * a big problem so just stop everything.
+                */
+               ret = LTTCOMM_CONSUMERD_FATAL;
+               goto error;
+       }
+       /* List MUST be empty after or else it could be reused. */
+       assert(cds_list_empty(&metadata->streams.head));
+
+       ret = 0;
+       goto end;
+
+error:
+       /*
+        * Delete metadata channel on error. At this point, the metadata stream can
+        * NOT be monitored by the metadata thread thus having the guarantee that
+        * the stream is still in the local stream list of the channel. This call
+        * will make sure to clean that list.
+        */
+       consumer_stream_destroy(metadata->metadata_stream, NULL);
+       cds_list_del(&metadata->metadata_stream->send_node);
+       metadata->metadata_stream = NULL;
+error_no_stream:
+end:
+       return ret;
+}
+
+/*
+ * Snapshot the whole metadata.
+ *
+ * Returns 0 on success, < 0 on error
+ */
+static int snapshot_metadata(uint64_t key, char *path, uint64_t relayd_id,
+               struct lttng_consumer_local_data *ctx)
+{
+       int ret = 0;
+       struct lttng_consumer_channel *metadata_channel;
+       struct lttng_consumer_stream *metadata_stream;
+
+       assert(path);
+       assert(ctx);
+
+       DBG("UST consumer snapshot metadata with key %" PRIu64 " at path %s",
+                       key, path);
+
+       rcu_read_lock();
+
+       metadata_channel = consumer_find_channel(key);
+       if (!metadata_channel) {
+               ERR("UST snapshot metadata channel not found for key %" PRIu64,
+                       key);
+               ret = -1;
+               goto error;
+       }
+       assert(!metadata_channel->monitor);
+
+       health_code_update();
+
+       /*
+        * Ask the sessiond if we have new metadata waiting and update the
+        * consumer metadata cache.
+        */
+       ret = lttng_ustconsumer_request_metadata(ctx, metadata_channel, 0, 1);
+       if (ret < 0) {
+               goto error;
+       }
+
+       health_code_update();
+
+       /*
+        * The metadata stream is NOT created in no monitor mode when the channel
+        * is created on a sessiond ask channel command.
+        */
+       ret = create_ust_streams(metadata_channel, ctx);
+       if (ret < 0) {
+               goto error;
+       }
+
+       metadata_stream = metadata_channel->metadata_stream;
+       assert(metadata_stream);
+
+       if (relayd_id != (uint64_t) -1ULL) {
+               metadata_stream->net_seq_idx = relayd_id;
+               ret = consumer_send_relayd_stream(metadata_stream, path);
+               if (ret < 0) {
+                       goto error_stream;
+               }
+       } else {
+               ret = utils_create_stream_file(path, metadata_stream->name,
+                               metadata_stream->chan->tracefile_size,
+                               metadata_stream->tracefile_count_current,
+                               metadata_stream->uid, metadata_stream->gid, NULL);
+               if (ret < 0) {
+                       goto error_stream;
+               }
+               metadata_stream->out_fd = ret;
+               metadata_stream->tracefile_size_current = 0;
+       }
+
+       do {
+               health_code_update();
+
+               ret = lttng_consumer_read_subbuffer(metadata_stream, ctx);
+               if (ret < 0) {
+                       goto error_stream;
+               }
+       } while (ret > 0);
+
+error_stream:
+       /*
+        * Clean up the stream completly because the next snapshot will use a new
+        * metadata stream.
+        */
+       consumer_stream_destroy(metadata_stream, NULL);
+       cds_list_del(&metadata_stream->send_node);
+       metadata_channel->metadata_stream = NULL;
+
+error:
+       rcu_read_unlock();
+       return ret;
+}
+
+/*
+ * Take a snapshot of all the stream of a channel.
+ *
+ * Returns 0 on success, < 0 on error
+ */
+static int snapshot_channel(uint64_t key, char *path, uint64_t relayd_id,
+               uint64_t nb_packets_per_stream, struct lttng_consumer_local_data *ctx)
+{
+       int ret;
+       unsigned use_relayd = 0;
+       unsigned long consumed_pos, produced_pos;
+       struct lttng_consumer_channel *channel;
+       struct lttng_consumer_stream *stream;
+
+       assert(path);
+       assert(ctx);
+
+       rcu_read_lock();
+
+       if (relayd_id != (uint64_t) -1ULL) {
+               use_relayd = 1;
+       }
+
+       channel = consumer_find_channel(key);
+       if (!channel) {
+               ERR("UST snapshot channel not found for key %" PRIu64, key);
+               ret = -1;
+               goto error;
+       }
+       assert(!channel->monitor);
+       DBG("UST consumer snapshot channel %" PRIu64, key);
+
+       cds_list_for_each_entry(stream, &channel->streams.head, send_node) {
+
+               health_code_update();
+
+               /* Lock stream because we are about to change its state. */
+               pthread_mutex_lock(&stream->lock);
+               stream->net_seq_idx = relayd_id;
+
+               if (use_relayd) {
+                       ret = consumer_send_relayd_stream(stream, path);
+                       if (ret < 0) {
+                               goto error_unlock;
+                       }
+               } else {
+                       ret = utils_create_stream_file(path, stream->name,
+                                       stream->chan->tracefile_size,
+                                       stream->tracefile_count_current,
+                                       stream->uid, stream->gid, NULL);
+                       if (ret < 0) {
+                               goto error_unlock;
+                       }
+                       stream->out_fd = ret;
+                       stream->tracefile_size_current = 0;
+
+                       DBG("UST consumer snapshot stream %s/%s (%" PRIu64 ")", path,
+                                       stream->name, stream->key);
+               }
+               if (relayd_id != -1ULL) {
+                       ret = consumer_send_relayd_streams_sent(relayd_id);
+                       if (ret < 0) {
+                               goto error_unlock;
+                       }
+               }
+
+               ustctl_flush_buffer(stream->ustream, 1);
+
+               ret = lttng_ustconsumer_take_snapshot(stream);
+               if (ret < 0) {
+                       ERR("Taking UST snapshot");
+                       goto error_unlock;
+               }
+
+               ret = lttng_ustconsumer_get_produced_snapshot(stream, &produced_pos);
+               if (ret < 0) {
+                       ERR("Produced UST snapshot position");
+                       goto error_unlock;
+               }
+
+               ret = lttng_ustconsumer_get_consumed_snapshot(stream, &consumed_pos);
+               if (ret < 0) {
+                       ERR("Consumerd UST snapshot position");
+                       goto error_unlock;
+               }
+
+               /*
+                * The original value is sent back if max stream size is larger than
+                * the possible size of the snapshot. Also, we assume that the session
+                * daemon should never send a maximum stream size that is lower than
+                * subbuffer size.
+                */
+               consumed_pos = consumer_get_consume_start_pos(consumed_pos,
+                               produced_pos, nb_packets_per_stream,
+                               stream->max_sb_size);
+
+               while (consumed_pos < produced_pos) {
+                       ssize_t read_len;
+                       unsigned long len, padded_len;
+
+                       health_code_update();
+
+                       DBG("UST consumer taking snapshot at pos %lu", consumed_pos);
+
+                       ret = ustctl_get_subbuf(stream->ustream, &consumed_pos);
+                       if (ret < 0) {
+                               if (ret != -EAGAIN) {
+                                       PERROR("ustctl_get_subbuf snapshot");
+                                       goto error_close_stream;
+                               }
+                               DBG("UST consumer get subbuf failed. Skipping it.");
+                               consumed_pos += stream->max_sb_size;
+                               continue;
+                       }
+
+                       ret = ustctl_get_subbuf_size(stream->ustream, &len);
+                       if (ret < 0) {
+                               ERR("Snapshot ustctl_get_subbuf_size");
+                               goto error_put_subbuf;
+                       }
+
+                       ret = ustctl_get_padded_subbuf_size(stream->ustream, &padded_len);
+                       if (ret < 0) {
+                               ERR("Snapshot ustctl_get_padded_subbuf_size");
+                               goto error_put_subbuf;
+                       }
+
+                       read_len = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len,
+                                       padded_len - len, NULL);
+                       if (use_relayd) {
+                               if (read_len != len) {
+                                       ret = -EPERM;
+                                       goto error_put_subbuf;
+                               }
+                       } else {
+                               if (read_len != padded_len) {
+                                       ret = -EPERM;
+                                       goto error_put_subbuf;
+                               }
+                       }
+
+                       ret = ustctl_put_subbuf(stream->ustream);
+                       if (ret < 0) {
+                               ERR("Snapshot ustctl_put_subbuf");
+                               goto error_close_stream;
+                       }
+                       consumed_pos += stream->max_sb_size;
+               }
+
+               /* Simply close the stream so we can use it on the next snapshot. */
+               consumer_stream_close(stream);
+               pthread_mutex_unlock(&stream->lock);
+       }
+
+       rcu_read_unlock();
+       return 0;
+
+error_put_subbuf:
+       if (ustctl_put_subbuf(stream->ustream) < 0) {
+               ERR("Snapshot ustctl_put_subbuf");
+       }
+error_close_stream:
+       consumer_stream_close(stream);
+error_unlock:
+       pthread_mutex_unlock(&stream->lock);
+error:
+       rcu_read_unlock();
+       return ret;
+}
+
+/*
+ * Receive the metadata updates from the sessiond. Supports receiving
+ * overlapping metadata, but is needs to always belong to a contiguous
+ * range starting from 0.
+ * Be careful about the locks held when calling this function: it needs
+ * the metadata cache flush to concurrently progress in order to
+ * complete.
+ */
+int lttng_ustconsumer_recv_metadata(int sock, uint64_t key, uint64_t offset,
+               uint64_t len, struct lttng_consumer_channel *channel,
+               int timer, int wait)
+{
+       int ret, ret_code = LTTCOMM_CONSUMERD_SUCCESS;
+       char *metadata_str;
+
+       DBG("UST consumer push metadata key %" PRIu64 " of len %" PRIu64, key, len);
+
+       metadata_str = zmalloc(len * sizeof(char));
+       if (!metadata_str) {
+               PERROR("zmalloc metadata string");
+               ret_code = LTTCOMM_CONSUMERD_ENOMEM;
+               goto end;
+       }
+
+       health_code_update();
+
+       /* Receive metadata string. */
+       ret = lttcomm_recv_unix_sock(sock, metadata_str, len);
+       if (ret < 0) {
+               /* Session daemon is dead so return gracefully. */
+               ret_code = ret;
+               goto end_free;
+       }
+
+       health_code_update();
+
+       pthread_mutex_lock(&channel->metadata_cache->lock);
+       ret = consumer_metadata_cache_write(channel, offset, len, metadata_str);
+       if (ret < 0) {
+               /* Unable to handle metadata. Notify session daemon. */
+               ret_code = LTTCOMM_CONSUMERD_ERROR_METADATA;
+               /*
+                * Skip metadata flush on write error since the offset and len might
+                * not have been updated which could create an infinite loop below when
+                * waiting for the metadata cache to be flushed.
+                */
+               pthread_mutex_unlock(&channel->metadata_cache->lock);
+               goto end_free;
+       }
+       pthread_mutex_unlock(&channel->metadata_cache->lock);
+
+       if (!wait) {
+               goto end_free;
+       }
+       while (consumer_metadata_cache_flushed(channel, offset + len, timer)) {
+               DBG("Waiting for metadata to be flushed");
+
+               health_code_update();
+
+               usleep(DEFAULT_METADATA_AVAILABILITY_WAIT_TIME);
+       }
+
+end_free:
+       free(metadata_str);
+end:
+       return ret_code;
+}
+
+/*
+ * Receive command from session daemon and process it.
+ *
+ * Return 1 on success else a negative value or 0.
+ */
+int lttng_ustconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
+               int sock, struct pollfd *consumer_sockpoll)
+{
+       ssize_t ret;
+       enum lttcomm_return_code ret_code = LTTCOMM_CONSUMERD_SUCCESS;
+       struct lttcomm_consumer_msg msg;
+       struct lttng_consumer_channel *channel = NULL;
+
+       health_code_update();
+
+       ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
+       if (ret != sizeof(msg)) {
+               DBG("Consumer received unexpected message size %zd (expects %zu)",
+                       ret, sizeof(msg));
+               /*
+                * The ret value might 0 meaning an orderly shutdown but this is ok
+                * since the caller handles this.
+                */
+               if (ret > 0) {
+                       lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_CMD);
+                       ret = -1;
+               }
+               return ret;
+       }
+
+       health_code_update();
+
+       /* deprecated */
+       assert(msg.cmd_type != LTTNG_CONSUMER_STOP);
+
+       health_code_update();
+
+       /* relayd needs RCU read-side lock */
+       rcu_read_lock();
+
+       switch (msg.cmd_type) {
+       case LTTNG_CONSUMER_ADD_RELAYD_SOCKET:
+       {
+               /* Session daemon status message are handled in the following call. */
+               ret = consumer_add_relayd_socket(msg.u.relayd_sock.net_index,
+                               msg.u.relayd_sock.type, ctx, sock, consumer_sockpoll,
+                               &msg.u.relayd_sock.sock, msg.u.relayd_sock.session_id,
+                               msg.u.relayd_sock.relayd_session_id);
+               goto end_nosignal;
+       }
+       case LTTNG_CONSUMER_DESTROY_RELAYD:
+       {
+               uint64_t index = msg.u.destroy_relayd.net_seq_idx;
+               struct consumer_relayd_sock_pair *relayd;
+
+               DBG("UST consumer destroying relayd %" PRIu64, index);
+
+               /* Get relayd reference if exists. */
+               relayd = consumer_find_relayd(index);
+               if (relayd == NULL) {
+                       DBG("Unable to find relayd %" PRIu64, index);
+                       ret_code = LTTCOMM_CONSUMERD_RELAYD_FAIL;
+               }
+
+               /*
+                * Each relayd socket pair has a refcount of stream attached to it
+                * which tells if the relayd is still active or not depending on the
+                * refcount value.
+                *
+                * This will set the destroy flag of the relayd object and destroy it
+                * if the refcount reaches zero when called.
+                *
+                * The destroy can happen either here or when a stream fd hangs up.
+                */
+               if (relayd) {
+                       consumer_flag_relayd_for_destroy(relayd);
+               }
+
+               goto end_msg_sessiond;
+       }
+       case LTTNG_CONSUMER_UPDATE_STREAM:
+       {
+               rcu_read_unlock();
+               return -ENOSYS;
+       }
+       case LTTNG_CONSUMER_DATA_PENDING:
+       {
+               int ret, is_data_pending;
+               uint64_t id = msg.u.data_pending.session_id;
+
+               DBG("UST consumer data pending command for id %" PRIu64, id);
+
+               is_data_pending = consumer_data_pending(id);
+
+               /* Send back returned value to session daemon */
+               ret = lttcomm_send_unix_sock(sock, &is_data_pending,
+                               sizeof(is_data_pending));
+               if (ret < 0) {
+                       DBG("Error when sending the data pending ret code: %d", ret);
+                       goto error_fatal;
+               }
+
+               /*
+                * No need to send back a status message since the data pending
+                * returned value is the response.
+                */
+               break;
+       }
+       case LTTNG_CONSUMER_ASK_CHANNEL_CREATION:
+       {
+               int ret;
+               struct ustctl_consumer_channel_attr attr;
+
+               /* Create a plain object and reserve a channel key. */
+               channel = allocate_channel(msg.u.ask_channel.session_id,
+                               msg.u.ask_channel.pathname, msg.u.ask_channel.name,
+                               msg.u.ask_channel.uid, msg.u.ask_channel.gid,
+                               msg.u.ask_channel.relayd_id, msg.u.ask_channel.key,
+                               (enum lttng_event_output) msg.u.ask_channel.output,
+                               msg.u.ask_channel.tracefile_size,
+                               msg.u.ask_channel.tracefile_count,
+                               msg.u.ask_channel.session_id_per_pid,
+                               msg.u.ask_channel.monitor,
+                               msg.u.ask_channel.live_timer_interval,
+                               msg.u.ask_channel.root_shm_path,
+                               msg.u.ask_channel.shm_path);
+               if (!channel) {
+                       goto end_channel_error;
+               }
+
+               /*
+                * Assign UST application UID to the channel. This value is ignored for
+                * per PID buffers. This is specific to UST thus setting this after the
+                * allocation.
+                */
+               channel->ust_app_uid = msg.u.ask_channel.ust_app_uid;
+
+               /* Build channel attributes from received message. */
+               attr.subbuf_size = msg.u.ask_channel.subbuf_size;
+               attr.num_subbuf = msg.u.ask_channel.num_subbuf;
+               attr.overwrite = msg.u.ask_channel.overwrite;
+               attr.switch_timer_interval = msg.u.ask_channel.switch_timer_interval;
+               attr.read_timer_interval = msg.u.ask_channel.read_timer_interval;
+               attr.chan_id = msg.u.ask_channel.chan_id;
+               memcpy(attr.uuid, msg.u.ask_channel.uuid, sizeof(attr.uuid));
+
+               /* Match channel buffer type to the UST abi. */
+               switch (msg.u.ask_channel.output) {
+               case LTTNG_EVENT_MMAP:
+               default:
+                       attr.output = LTTNG_UST_MMAP;
+                       break;
+               }
+
+               /* Translate and save channel type. */
+               switch (msg.u.ask_channel.type) {
+               case LTTNG_UST_CHAN_PER_CPU:
+                       channel->type = CONSUMER_CHANNEL_TYPE_DATA;
+                       attr.type = LTTNG_UST_CHAN_PER_CPU;
+                       /*
+                        * Set refcount to 1 for owner. Below, we will
+                        * pass ownership to the
+                        * consumer_thread_channel_poll() thread.
+                        */
+                       channel->refcount = 1;
+                       break;
+               case LTTNG_UST_CHAN_METADATA:
+                       channel->type = CONSUMER_CHANNEL_TYPE_METADATA;
+                       attr.type = LTTNG_UST_CHAN_METADATA;
+                       break;
+               default:
+                       assert(0);
+                       goto error_fatal;
+               };
+
+               health_code_update();
+
+               ret = ask_channel(ctx, sock, channel, &attr);
+               if (ret < 0) {
+                       goto end_channel_error;
+               }
+
+               if (msg.u.ask_channel.type == LTTNG_UST_CHAN_METADATA) {
+                       ret = consumer_metadata_cache_allocate(channel);
+                       if (ret < 0) {
+                               ERR("Allocating metadata cache");
+                               goto end_channel_error;
+                       }
+                       consumer_timer_switch_start(channel, attr.switch_timer_interval);
+                       attr.switch_timer_interval = 0;
+               } else {
+                       consumer_timer_live_start(channel,
+                                       msg.u.ask_channel.live_timer_interval);
+               }
+
+               health_code_update();
+
+               /*
+                * Add the channel to the internal state AFTER all streams were created
+                * and successfully sent to session daemon. This way, all streams must
+                * be ready before this channel is visible to the threads.
+                * If add_channel succeeds, ownership of the channel is
+                * passed to consumer_thread_channel_poll().
+                */
+               ret = add_channel(channel, ctx);
+               if (ret < 0) {
+                       if (msg.u.ask_channel.type == LTTNG_UST_CHAN_METADATA) {
+                               if (channel->switch_timer_enabled == 1) {
+                                       consumer_timer_switch_stop(channel);
+                               }
+                               consumer_metadata_cache_destroy(channel);
+                       }
+                       if (channel->live_timer_enabled == 1) {
+                               consumer_timer_live_stop(channel);
+                       }
+                       goto end_channel_error;
+               }
+
+               health_code_update();
+
+               /*
+                * Channel and streams are now created. Inform the session daemon that
+                * everything went well and should wait to receive the channel and
+                * streams with ustctl API.
+                */
+               ret = consumer_send_status_channel(sock, channel);
+               if (ret < 0) {
+                       /*
+                        * There is probably a problem on the socket.
+                        */
+                       goto error_fatal;
+               }
+
+               break;
+       }
+       case LTTNG_CONSUMER_GET_CHANNEL:
+       {
+               int ret, relayd_err = 0;
+               uint64_t key = msg.u.get_channel.key;
+               struct lttng_consumer_channel *channel;
+
+               channel = consumer_find_channel(key);
+               if (!channel) {
+                       ERR("UST consumer get channel key %" PRIu64 " not found", key);
+                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
+                       goto end_msg_sessiond;
+               }
+
+               health_code_update();
+
+               /* Send everything to sessiond. */
+               ret = send_sessiond_channel(sock, channel, ctx, &relayd_err);
+               if (ret < 0) {
+                       if (relayd_err) {
+                               /*
+                                * We were unable to send to the relayd the stream so avoid
+                                * sending back a fatal error to the thread since this is OK
+                                * and the consumer can continue its work. The above call
+                                * has sent the error status message to the sessiond.
+                                */
+                               goto end_nosignal;
+                       }
+                       /*
+                        * The communicaton was broken hence there is a bad state between
+                        * the consumer and sessiond so stop everything.
+                        */
+                       goto error_fatal;
+               }
+
+               health_code_update();
+
+               /*
+                * In no monitor mode, the streams ownership is kept inside the channel
+                * so don't send them to the data thread.
+                */
+               if (!channel->monitor) {
+                       goto end_msg_sessiond;
+               }
+
+               ret = send_streams_to_thread(channel, ctx);
+               if (ret < 0) {
+                       /*
+                        * If we are unable to send the stream to the thread, there is
+                        * a big problem so just stop everything.
+                        */
+                       goto error_fatal;
+               }
+               /* List MUST be empty after or else it could be reused. */
+               assert(cds_list_empty(&channel->streams.head));
+               goto end_msg_sessiond;
+       }
+       case LTTNG_CONSUMER_DESTROY_CHANNEL:
+       {
+               uint64_t key = msg.u.destroy_channel.key;
+
+               /*
+                * Only called if streams have not been sent to stream
+                * manager thread. However, channel has been sent to
+                * channel manager thread.
+                */
+               notify_thread_del_channel(ctx, key);
+               goto end_msg_sessiond;
+       }
+       case LTTNG_CONSUMER_CLOSE_METADATA:
+       {
+               int ret;
+
+               ret = close_metadata(msg.u.close_metadata.key);
+               if (ret != 0) {
+                       ret_code = ret;
+               }
+
+               goto end_msg_sessiond;
+       }
+       case LTTNG_CONSUMER_FLUSH_CHANNEL:
+       {
+               int ret;
+
+               ret = flush_channel(msg.u.flush_channel.key);
+               if (ret != 0) {
+                       ret_code = ret;
+               }
+
+               goto end_msg_sessiond;
+       }
+       case LTTNG_CONSUMER_PUSH_METADATA:
+       {
+               int ret;
+               uint64_t len = msg.u.push_metadata.len;
+               uint64_t key = msg.u.push_metadata.key;
+               uint64_t offset = msg.u.push_metadata.target_offset;
+               struct lttng_consumer_channel *channel;
+
+               DBG("UST consumer push metadata key %" PRIu64 " of len %" PRIu64, key,
+                               len);
+
+               channel = consumer_find_channel(key);
+               if (!channel) {
+                       /*
+                        * This is possible if the metadata creation on the consumer side
+                        * is in flight vis-a-vis a concurrent push metadata from the
+                        * session daemon.  Simply return that the channel failed and the
+                        * session daemon will handle that message correctly considering
+                        * that this race is acceptable thus the DBG() statement here.
+                        */
+                       DBG("UST consumer push metadata %" PRIu64 " not found", key);
+                       ret_code = LTTCOMM_CONSUMERD_CHANNEL_FAIL;
+                       goto end_msg_sessiond;
+               }
+
+               health_code_update();
+
+               if (!len) {
+                       /*
+                        * There is nothing to receive. We have simply
+                        * checked whether the channel can be found.
+                        */
+                       ret_code = LTTCOMM_CONSUMERD_SUCCESS;
+                       goto end_msg_sessiond;
+               }
+
+               /* Tell session daemon we are ready to receive the metadata. */
+               ret = consumer_send_status_msg(sock, LTTCOMM_CONSUMERD_SUCCESS);
+               if (ret < 0) {
+                       /* Somehow, the session daemon is not responding anymore. */
+                       goto error_fatal;
+               }
+
+               health_code_update();
+
+               /* Wait for more data. */
+               health_poll_entry();
+               ret = lttng_consumer_poll_socket(consumer_sockpoll);
+               health_poll_exit();
+               if (ret) {
+                       goto error_fatal;
+               }
+
+               health_code_update();
+
+               ret = lttng_ustconsumer_recv_metadata(sock, key, offset,
+                               len, channel, 0, 1);
+               if (ret < 0) {
+                       /* error receiving from sessiond */
+                       goto error_fatal;
+               } else {
+                       ret_code = ret;
+                       goto end_msg_sessiond;
+               }
+       }
+       case LTTNG_CONSUMER_SETUP_METADATA:
+       {
+               int ret;
+
+               ret = setup_metadata(ctx, msg.u.setup_metadata.key);
+               if (ret) {
+                       ret_code = ret;
+               }
+               goto end_msg_sessiond;
+       }
+       case LTTNG_CONSUMER_SNAPSHOT_CHANNEL:
+       {
+               if (msg.u.snapshot_channel.metadata) {
+                       ret = snapshot_metadata(msg.u.snapshot_channel.key,
+                                       msg.u.snapshot_channel.pathname,
+                                       msg.u.snapshot_channel.relayd_id,
+                                       ctx);
+                       if (ret < 0) {
+                               ERR("Snapshot metadata failed");
+                               ret_code = LTTCOMM_CONSUMERD_ERROR_METADATA;
+                       }
+               } else {
+                       ret = snapshot_channel(msg.u.snapshot_channel.key,
+                                       msg.u.snapshot_channel.pathname,
+                                       msg.u.snapshot_channel.relayd_id,
+                                       msg.u.snapshot_channel.nb_packets_per_stream,
+                                       ctx);
+                       if (ret < 0) {
+                               ERR("Snapshot channel failed");
+                               ret_code = LTTCOMM_CONSUMERD_CHANNEL_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_nosignal;
+               }
+               health_code_update();
+               break;
+       }
+       default:
+               break;
+       }
+
+end_nosignal:
+       rcu_read_unlock();
+
+       health_code_update();
+
+       /*
+        * Return 1 to indicate success since the 0 value can be a socket
+        * shutdown during the recv() or send() call.
+        */
+       return 1;
+
+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;
+       }
+       rcu_read_unlock();
+
+       health_code_update();
+
+       return 1;
+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;
+       }
+       rcu_read_unlock();
+
+       health_code_update();
+
+       return 1;
+error_fatal:
+       rcu_read_unlock();
+       /* This will issue a consumer stop. */
+       return -1;
+}
+
+/*
+ * Wrapper over the mmap() read offset from ust-ctl library. Since this can be
+ * compiled out, we isolate it in this library.
+ */
+int lttng_ustctl_get_mmap_read_offset(struct lttng_consumer_stream *stream,
+               unsigned long *off)
+{
+       assert(stream);
+       assert(stream->ustream);
+
+       return ustctl_get_mmap_read_offset(stream->ustream, off);
+}
+
+/*
+ * Wrapper over the mmap() read offset from ust-ctl library. Since this can be
+ * compiled out, we isolate it in this library.
+ */
+void *lttng_ustctl_get_mmap_base(struct lttng_consumer_stream *stream)
+{
+       assert(stream);
+       assert(stream->ustream);
+
+       return ustctl_get_mmap_base(stream->ustream);
+}
+
+/*
+ * Take a snapshot for a specific fd
+ *
+ * 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);
+}
+
+/*
+ * 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);
+}
+
+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);
+}
+
+/*
+ * Called when the stream signal the consumer that it has hang up.
+ */
+void lttng_ustconsumer_on_stream_hangup(struct lttng_consumer_stream *stream)
+{
+       assert(stream);
+       assert(stream->ustream);
+
+       ustctl_flush_buffer(stream->ustream, 0);
+       stream->hangup_flush_done = 1;
+}
+
+void lttng_ustconsumer_del_channel(struct lttng_consumer_channel *chan)
+{
+       int i;
+
+       assert(chan);
+       assert(chan->uchan);
+
+       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->uid, chan->gid);
+                       if (ret) {
+                               PERROR("unlink %s", shm_path);
+                       }
+               }
+       }
+       /* Try to rmdir all directories under shm_path root. */
+       if (chan->root_shm_path[0]) {
+               (void) run_as_recursive_rmdir(chan->root_shm_path,
+                               chan->uid, chan->gid);
+       }
+}
+
+void lttng_ustconsumer_free_channel(struct lttng_consumer_channel *chan)
+{
+       assert(chan);
+       assert(chan->uchan);
+
+       consumer_metadata_cache_destroy(chan);
+       ustctl_destroy_channel(chan->uchan);
+       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;
+
+       ret = ustctl_get_timestamp_begin(ustream, &index->timestamp_begin);
+       if (ret < 0) {
+               PERROR("ustctl_get_timestamp_begin");
+               goto error;
+       }
+       index->timestamp_begin = htobe64(index->timestamp_begin);
+
+       ret = ustctl_get_timestamp_end(ustream, &index->timestamp_end);
+       if (ret < 0) {
+               PERROR("ustctl_get_timestamp_end");
+               goto error;
+       }
+       index->timestamp_end = htobe64(index->timestamp_end);
+
+       ret = ustctl_get_events_discarded(ustream, &index->events_discarded);
+       if (ret < 0) {
+               PERROR("ustctl_get_events_discarded");
+               goto error;
+       }
+       index->events_discarded = htobe64(index->events_discarded);
+
+       ret = ustctl_get_content_size(ustream, &index->content_size);
+       if (ret < 0) {
+               PERROR("ustctl_get_content_size");
+               goto error;
+       }
+       index->content_size = htobe64(index->content_size);
+
+       ret = ustctl_get_packet_size(ustream, &index->packet_size);
+       if (ret < 0) {
+               PERROR("ustctl_get_packet_size");
+               goto error;
+       }
+       index->packet_size = htobe64(index->packet_size);
+
+       ret = ustctl_get_stream_id(ustream, &index->stream_id);
+       if (ret < 0) {
+               PERROR("ustctl_get_stream_id");
+               goto error;
+       }
+       index->stream_id = htobe64(index->stream_id);
+
+error:
+       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);
+       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;
+
+end:
+       pthread_mutex_unlock(&stream->chan->metadata_cache->lock);
+       return ret;
+}
 
-               DBG("UST consumer data pending command for id %" PRIu64, id);
 
-               is_data_pending = consumer_data_pending(id);
+/*
+ * 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.
+ *
+ * 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)
+{
+       int ret;
+       int retry = 0;
 
-               /* Send back returned value to session daemon */
-               ret = lttcomm_send_unix_sock(sock, &is_data_pending,
-                               sizeof(is_data_pending));
-               if (ret < 0) {
-                       DBG("Error when sending the data pending ret code: %d", ret);
-               }
+       assert(ctx);
+       assert(metadata);
 
-               /*
-                * No need to send back a status message since the data pending
-                * returned value is the response.
-                */
-               break;
+       pthread_mutex_unlock(&metadata->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->chan, 0, 0);
+       if (ret < 0) {
+               goto end;
        }
-       default:
-               break;
+       pthread_mutex_lock(&metadata->lock);
+
+       ret = commit_one_metadata_packet(metadata);
+       if (ret <= 0) {
+               goto end;
+       } else if (ret > 0) {
+               retry = 1;
        }
 
-end_nosignal:
-       rcu_read_unlock();
+       ustctl_flush_buffer(metadata->ustream, 1);
+       ret = ustctl_snapshot(metadata->ustream);
+       if (ret < 0) {
+               if (errno != EAGAIN) {
+                       ERR("Sync metadata, taking UST snapshot");
+                       goto end;
+               }
+               DBG("No new metadata when syncing them.");
+               /* No new metadata, exit. */
+               ret = ENODATA;
+               goto end;
+       }
 
        /*
-        * Return 1 to indicate success since the 0 value can be a socket
-        * shutdown during the recv() or send() call.
+        * After this flush, we still need to extract metadata.
         */
-       return 1;
-}
-
-int lttng_ustconsumer_allocate_channel(struct lttng_consumer_channel *chan)
-{
-       struct lttng_ust_object_data obj;
-
-       obj.handle = -1;
-       obj.shm_fd = chan->shm_fd;
-       obj.wait_fd = chan->wait_fd;
-       obj.memory_map_size = chan->mmap_len;
-       chan->handle = ustctl_map_channel(&obj);
-       if (!chan->handle) {
-               return -ENOMEM;
+       if (retry) {
+               ret = EAGAIN;
        }
-       chan->wait_fd_is_copy = 1;
-       chan->shm_fd = -1;
 
-       return 0;
+end:
+       return ret;
 }
 
-void lttng_ustconsumer_on_stream_hangup(struct lttng_consumer_stream *stream)
+/*
+ * Return 0 on success else a negative value.
+ */
+static int notify_if_more_data(struct lttng_consumer_stream *stream,
+               struct lttng_consumer_local_data *ctx)
 {
-       ustctl_flush_buffer(stream->chan->handle, stream->buf, 0);
-       stream->hangup_flush_done = 1;
-}
+       int ret;
+       struct ustctl_consumer_stream *ustream;
 
-void lttng_ustconsumer_del_channel(struct lttng_consumer_channel *chan)
-{
-       ustctl_unmap_channel(chan->handle);
-}
+       assert(stream);
+       assert(ctx);
 
-int lttng_ustconsumer_add_stream(struct lttng_consumer_stream *stream)
-{
-       struct lttng_ust_object_data obj;
-       int ret;
+       ustream = stream->ustream;
 
-       obj.handle = -1;
-       obj.shm_fd = stream->shm_fd;
-       obj.wait_fd = stream->wait_fd;
-       obj.memory_map_size = stream->mmap_len;
-       ret = ustctl_add_stream(stream->chan->handle, &obj);
+       /*
+        * First, we are going to check if there is a new subbuffer available
+        * before reading the stream wait_fd.
+        */
+       /* Get the next subbuffer */
+       ret = ustctl_get_next_subbuf(ustream);
        if (ret) {
-               ERR("UST ctl add_stream failed with ret %d", ret);
-               goto error;
+               /* No more data found, flag the stream. */
+               stream->has_data = 0;
+               ret = 0;
+               goto end;
        }
 
-       stream->buf = ustctl_open_stream_read(stream->chan->handle, stream->cpu);
-       if (!stream->buf) {
-               ERR("UST ctl open_stream_read failed");
-               ret = -EBUSY;
-               goto error;
-       }
+       ret = ustctl_put_subbuf(ustream);
+       assert(!ret);
 
-       /* ustctl_open_stream_read has closed the shm fd. */
-       stream->wait_fd_is_copy = 1;
-       stream->shm_fd = -1;
+       /* This stream still has data. Flag it and wake up the data thread. */
+       stream->has_data = 1;
 
-       stream->mmap_base = ustctl_get_mmap_base(stream->chan->handle, stream->buf);
-       if (!stream->mmap_base) {
-               ERR("UST ctl get_mmap_base failed");
-               ret = -EINVAL;
-               goto mmap_error;
-       }
+       if (stream->monitor && !stream->hangup_flush_done && !ctx->has_wakeup) {
+               ssize_t writelen;
 
-       return 0;
+               writelen = lttng_pipe_write(ctx->consumer_wakeup_pipe, "!", 1);
+               if (writelen < 0 && errno != EAGAIN && errno != EWOULDBLOCK) {
+                       ret = writelen;
+                       goto end;
+               }
 
-mmap_error:
-       ustctl_close_stream_read(stream->chan->handle, stream->buf);
-error:
-       return ret;
-}
+               /* The wake up pipe has been notified. */
+               ctx->has_wakeup = 1;
+       }
+       ret = 0;
 
-void lttng_ustconsumer_del_stream(struct lttng_consumer_stream *stream)
-{
-       ustctl_close_stream_read(stream->chan->handle, stream->buf);
+end:
+       return ret;
 }
 
-
+/*
+ * Read subbuffer from the given stream.
+ *
+ * Stream lock MUST be acquired.
+ *
+ * Return 0 on success else a negative value.
+ */
 int lttng_ustconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
                struct lttng_consumer_local_data *ctx)
 {
        unsigned long len, subbuf_size, padding;
-       int err;
+       int err, write_index = 1;
        long ret = 0;
-       struct lttng_ust_shm_handle *handle;
-       struct lttng_ust_lib_ring_buffer *buf;
-       char dummy;
+       struct ustctl_consumer_stream *ustream;
+       struct ctf_packet_index index;
 
-       DBG("In read_subbuffer (wait_fd: %d, stream key: %d)",
-               stream->wait_fd, stream->key);
+       assert(stream);
+       assert(stream->ustream);
+       assert(ctx);
+
+       DBG("In UST read_subbuffer (wait_fd: %d, name: %s)", stream->wait_fd,
+                       stream->name);
 
-       /* We can consume the 1 byte written into the wait_fd by UST */
-       if (!stream->hangup_flush_done) {
+       /* Ease our life for what's next. */
+       ustream = stream->ustream;
+
+       /*
+        * We can consume the 1 byte written into the wait_fd by UST. Don't trigger
+        * error if we cannot read this one byte (read returns 0), or if the error
+        * is EAGAIN or EWOULDBLOCK.
+        *
+        * This is only done when the stream is monitored by a thread, before the
+        * flush is done after a hangup and if the stream is not flagged with data
+        * since there might be nothing to consume in the wait fd but still have
+        * data available flagged by the consumer wake up pipe.
+        */
+       if (stream->monitor && !stream->hangup_flush_done && !stream->has_data) {
+               char dummy;
                ssize_t readlen;
 
-               do {
-                       readlen = read(stream->wait_fd, &dummy, 1);
-               } while (readlen == -1 && errno == EINTR);
-               if (readlen == -1) {
+               readlen = lttng_read(stream->wait_fd, &dummy, 1);
+               if (readlen < 0 && errno != EAGAIN && errno != EWOULDBLOCK) {
                        ret = readlen;
                        goto end;
                }
        }
 
-       buf = stream->buf;
-       handle = stream->chan->handle;
+retry:
        /* Get the next subbuffer */
-       err = ustctl_get_next_subbuf(handle, buf);
+       err = ustctl_get_next_subbuf(ustream);
        if (err != 0) {
+               /*
+                * Populate metadata info if the existing info has
+                * already been read.
+                */
+               if (stream->metadata_flag) {
+                       ret = commit_one_metadata_packet(stream);
+                       if (ret <= 0) {
+                               goto end;
+                       }
+                       ustctl_flush_buffer(stream->ustream, 1);
+                       goto retry;
+               }
+
                ret = err;      /* ustctl_get_next_subbuf returns negative, caller expect positive. */
                /*
                 * This is a debug message even for single-threaded consumer,
@@ -527,16 +2177,27 @@ int lttng_ustconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
                 * would issue wakeups.
                 */
                DBG("Reserving sub buffer failed (everything is normal, "
-                               "it is due to concurrency)");
+                               "it is due to concurrency) [ret: %d]", err);
                goto end;
        }
-       assert(stream->output == LTTNG_EVENT_MMAP);
+       assert(stream->chan->output == CONSUMER_CHANNEL_MMAP);
+
+       if (!stream->metadata_flag) {
+               index.offset = htobe64(stream->out_fd_offset);
+               ret = get_index_values(&index, ustream);
+               if (ret < 0) {
+                       goto end;
+               }
+       } else {
+               write_index = 0;
+       }
+
        /* Get the full padded subbuffer size */
-       err = ustctl_get_padded_subbuf_size(handle, buf, &len);
+       err = ustctl_get_padded_subbuf_size(ustream, &len);
        assert(err == 0);
 
        /* Get subbuffer data size (without padding) */
-       err = ustctl_get_subbuf_size(handle, buf, &subbuf_size);
+       err = ustctl_get_subbuf_size(ustream, &subbuf_size);
        assert(err == 0);
 
        /* Make sure we don't get a subbuffer size bigger than the padded */
@@ -544,13 +2205,13 @@ int lttng_ustconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
 
        padding = len - subbuf_size;
        /* write the subbuffer to the tracefile */
-       ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, subbuf_size, padding);
+       ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, subbuf_size, padding, &index);
        /*
         * The mmap operation should write subbuf_size amount of data when network
         * streaming or the full padding (len) size when we are _not_ streaming.
         */
-       if ((ret != subbuf_size && stream->net_seq_idx != -1) ||
-                       (ret != len && stream->net_seq_idx == -1)) {
+       if ((ret != subbuf_size && stream->net_seq_idx != (uint64_t) -1ULL) ||
+                       (ret != len && stream->net_seq_idx == (uint64_t) -1ULL)) {
                /*
                 * Display the error but continue processing to try to release the
                 * subbuffer. This is a DBG statement since any unexpected kill or
@@ -560,42 +2221,99 @@ int lttng_ustconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
                 * happen and it is OK with the code flow.
                 */
                DBG("Error writing to tracefile "
-                               "(ret: %zd != len: %lu != subbuf_size: %lu)",
+                               "(ret: %ld != len: %lu != subbuf_size: %lu)",
                                ret, len, subbuf_size);
+               write_index = 0;
        }
-       err = ustctl_put_next_subbuf(handle, buf);
+       err = ustctl_put_next_subbuf(ustream);
        assert(err == 0);
+
+       /*
+        * This will consumer the byte on the wait_fd if and only if there is not
+        * next subbuffer to be acquired.
+        */
+       if (!stream->metadata_flag) {
+               ret = notify_if_more_data(stream, ctx);
+               if (ret < 0) {
+                       goto end;
+               }
+       }
+
+       /* Write index if needed. */
+       if (!write_index) {
+               goto end;
+       }
+
+       if (stream->chan->live_timer_interval && !stream->metadata_flag) {
+               /*
+                * In live, block until all the metadata is sent.
+                */
+               pthread_mutex_lock(&stream->metadata_timer_lock);
+               assert(!stream->missed_metadata_flush);
+               stream->waiting_on_metadata = true;
+               pthread_mutex_unlock(&stream->metadata_timer_lock);
+
+               err = consumer_stream_sync_metadata(ctx, stream->session_id);
+
+               pthread_mutex_lock(&stream->metadata_timer_lock);
+               stream->waiting_on_metadata = false;
+               if (stream->missed_metadata_flush) {
+                       stream->missed_metadata_flush = false;
+                       pthread_mutex_unlock(&stream->metadata_timer_lock);
+                       (void) consumer_flush_ust_index(stream);
+               } else {
+                       pthread_mutex_unlock(&stream->metadata_timer_lock);
+               }
+
+               if (err < 0) {
+                       goto end;
+               }
+       }
+
+       assert(!stream->metadata_flag);
+       err = consumer_stream_write_index(stream, &index);
+       if (err < 0) {
+               goto end;
+       }
+
 end:
        return ret;
 }
 
+/*
+ * Called when a stream is created.
+ *
+ * Return 0 on success or else a negative value.
+ */
 int lttng_ustconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
 {
        int ret;
 
-       /* Opening the tracefile in write mode */
-       if (stream->path_name != NULL && stream->net_seq_idx == -1) {
-               ret = run_as_open(stream->path_name,
-                               O_WRONLY|O_CREAT|O_TRUNC,
-                               S_IRWXU|S_IRWXG|S_IRWXO,
-                               stream->uid, stream->gid);
+       assert(stream);
+
+       /* Don't create anything if this is set for streaming. */
+       if (stream->net_seq_idx == (uint64_t) -1ULL && stream->chan->monitor) {
+               ret = utils_create_stream_file(stream->chan->pathname, stream->name,
+                               stream->chan->tracefile_size, stream->tracefile_count_current,
+                               stream->uid, stream->gid, NULL);
                if (ret < 0) {
-                       ERR("Opening %s", stream->path_name);
-                       PERROR("open");
                        goto error;
                }
                stream->out_fd = ret;
-       }
+               stream->tracefile_size_current = 0;
 
-       ret = lttng_ustconsumer_add_stream(stream);
-       if (ret) {
-               consumer_del_stream(stream, NULL);
-               ret = -1;
-               goto error;
+               if (!stream->metadata_flag) {
+                       ret = index_create_file(stream->chan->pathname,
+                                       stream->name, stream->uid, stream->gid,
+                                       stream->chan->tracefile_size,
+                                       stream->tracefile_count_current);
+                       if (ret < 0) {
+                               goto error;
+                       }
+                       stream->index_fd = ret;
+               }
        }
-
-       /* we return 0 to let the library handle the FD internally */
-       return 0;
+       ret = 0;
 
 error:
        return ret;
@@ -614,21 +2332,286 @@ int lttng_ustconsumer_data_pending(struct lttng_consumer_stream *stream)
        int ret;
 
        assert(stream);
+       assert(stream->ustream);
 
        DBG("UST consumer checking data pending");
 
-       ret = ustctl_get_next_subbuf(stream->chan->handle, stream->buf);
-       if (ret == 0) {
-               /* There is still data so let's put back this subbuffer. */
-               ret = ustctl_put_subbuf(stream->chan->handle, stream->buf);
-               assert(ret == 0);
-               ret = 1;  /* Data is pending */
+       if (stream->endpoint_status != CONSUMER_ENDPOINT_ACTIVE) {
+               ret = 0;
                goto end;
        }
 
+       if (stream->chan->type == CONSUMER_CHANNEL_TYPE_METADATA) {
+               uint64_t contiguous, pushed;
+
+               /* Ease our life a bit. */
+               contiguous = stream->chan->metadata_cache->max_offset;
+               pushed = stream->ust_metadata_pushed;
+
+               /*
+                * We can simply check whether all contiguously available data
+                * has been pushed to the ring buffer, since the push operation
+                * is performed within get_next_subbuf(), and because both
+                * get_next_subbuf() and put_next_subbuf() are issued atomically
+                * thanks to the stream lock within
+                * lttng_ustconsumer_read_subbuffer(). This basically means that
+                * whetnever ust_metadata_pushed is incremented, the associated
+                * metadata has been consumed from the metadata stream.
+                */
+               DBG("UST consumer metadata pending check: contiguous %" PRIu64 " vs pushed %" PRIu64,
+                               contiguous, pushed);
+               assert(((int64_t) (contiguous - pushed)) >= 0);
+               if ((contiguous != pushed) ||
+                               (((int64_t) contiguous - pushed) > 0 || contiguous == 0)) {
+                       ret = 1;        /* Data is pending */
+                       goto end;
+               }
+       } else {
+               ret = ustctl_get_next_subbuf(stream->ustream);
+               if (ret == 0) {
+                       /*
+                        * There is still data so let's put back this
+                        * subbuffer.
+                        */
+                       ret = ustctl_put_subbuf(stream->ustream);
+                       assert(ret == 0);
+                       ret = 1;        /* Data is pending */
+                       goto end;
+               }
+       }
+
        /* Data is NOT pending so ready to be read. */
        ret = 0;
 
 end:
        return ret;
 }
+
+/*
+ * Stop a given metadata channel timer if enabled and close the wait fd which
+ * is the poll pipe of the metadata stream.
+ *
+ * This MUST be called with the metadata channel acquired.
+ */
+void lttng_ustconsumer_close_metadata(struct lttng_consumer_channel *metadata)
+{
+       int ret;
+
+       assert(metadata);
+       assert(metadata->type == CONSUMER_CHANNEL_TYPE_METADATA);
+
+       DBG("Closing metadata channel key %" PRIu64, metadata->key);
+
+       if (metadata->switch_timer_enabled == 1) {
+               consumer_timer_switch_stop(metadata);
+       }
+
+       if (!metadata->metadata_stream) {
+               goto end;
+       }
+
+       /*
+        * Closing write side so the thread monitoring the stream wakes up if any
+        * and clean the metadata stream.
+        */
+       if (metadata->metadata_stream->ust_metadata_poll_pipe[1] >= 0) {
+               ret = close(metadata->metadata_stream->ust_metadata_poll_pipe[1]);
+               if (ret < 0) {
+                       PERROR("closing metadata pipe write side");
+               }
+               metadata->metadata_stream->ust_metadata_poll_pipe[1] = -1;
+       }
+
+end:
+       return;
+}
+
+/*
+ * Close every metadata stream wait fd of the metadata hash table. This
+ * function MUST be used very carefully so not to run into a race between the
+ * metadata thread handling streams and this function closing their wait fd.
+ *
+ * For UST, this is used when the session daemon hangs up. Its the metadata
+ * producer so calling this is safe because we are assured that no state change
+ * can occur in the metadata thread for the streams in the hash table.
+ */
+void lttng_ustconsumer_close_all_metadata(struct lttng_ht *metadata_ht)
+{
+       struct lttng_ht_iter iter;
+       struct lttng_consumer_stream *stream;
+
+       assert(metadata_ht);
+       assert(metadata_ht->ht);
+
+       DBG("UST consumer closing all metadata streams");
+
+       rcu_read_lock();
+       cds_lfht_for_each_entry(metadata_ht->ht, &iter.iter, stream,
+                       node.node) {
+
+               health_code_update();
+
+               pthread_mutex_lock(&stream->chan->lock);
+               lttng_ustconsumer_close_metadata(stream->chan);
+               pthread_mutex_unlock(&stream->chan->lock);
+
+       }
+       rcu_read_unlock();
+}
+
+void lttng_ustconsumer_close_stream_wakeup(struct lttng_consumer_stream *stream)
+{
+       int ret;
+
+       ret = ustctl_stream_close_wakeup_fd(stream->ustream);
+       if (ret < 0) {
+               ERR("Unable to close wakeup fd");
+       }
+}
+
+/*
+ * Please refer to consumer-timer.c before adding any lock within this
+ * function or any of its callees. Timers have a very strict locking
+ * semantic with respect to teardown. Failure to respect this semantic
+ * introduces deadlocks.
+ *
+ * DON'T hold the metadata lock when calling this function, else this
+ * can cause deadlock involving consumer awaiting for metadata to be
+ * pushed out due to concurrent interaction with the session daemon.
+ */
+int lttng_ustconsumer_request_metadata(struct lttng_consumer_local_data *ctx,
+               struct lttng_consumer_channel *channel, int timer, int wait)
+{
+       struct lttcomm_metadata_request_msg request;
+       struct lttcomm_consumer_msg msg;
+       enum lttcomm_return_code ret_code = LTTCOMM_CONSUMERD_SUCCESS;
+       uint64_t len, key, offset;
+       int ret;
+
+       assert(channel);
+       assert(channel->metadata_cache);
+
+       memset(&request, 0, sizeof(request));
+
+       /* send the metadata request to sessiond */
+       switch (consumer_data.type) {
+       case LTTNG_CONSUMER64_UST:
+               request.bits_per_long = 64;
+               break;
+       case LTTNG_CONSUMER32_UST:
+               request.bits_per_long = 32;
+               break;
+       default:
+               request.bits_per_long = 0;
+               break;
+       }
+
+       request.session_id = channel->session_id;
+       request.session_id_per_pid = channel->session_id_per_pid;
+       /*
+        * Request the application UID here so the metadata of that application can
+        * be sent back. The channel UID corresponds to the user UID of the session
+        * used for the rights on the stream file(s).
+        */
+       request.uid = channel->ust_app_uid;
+       request.key = channel->key;
+
+       DBG("Sending metadata request to sessiond, session id %" PRIu64
+                       ", per-pid %" PRIu64 ", app UID %u and channek key %" PRIu64,
+                       request.session_id, request.session_id_per_pid, request.uid,
+                       request.key);
+
+       pthread_mutex_lock(&ctx->metadata_socket_lock);
+
+       health_code_update();
+
+       ret = lttcomm_send_unix_sock(ctx->consumer_metadata_socket, &request,
+                       sizeof(request));
+       if (ret < 0) {
+               ERR("Asking metadata to sessiond");
+               goto end;
+       }
+
+       health_code_update();
+
+       /* Receive the metadata from sessiond */
+       ret = lttcomm_recv_unix_sock(ctx->consumer_metadata_socket, &msg,
+                       sizeof(msg));
+       if (ret != sizeof(msg)) {
+               DBG("Consumer received unexpected message size %d (expects %zu)",
+                       ret, sizeof(msg));
+               lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_CMD);
+               /*
+                * The ret value might 0 meaning an orderly shutdown but this is ok
+                * since the caller handles this.
+                */
+               goto end;
+       }
+
+       health_code_update();
+
+       if (msg.cmd_type == LTTNG_ERR_UND) {
+               /* No registry found */
+               (void) consumer_send_status_msg(ctx->consumer_metadata_socket,
+                               ret_code);
+               ret = 0;
+               goto end;
+       } else if (msg.cmd_type != LTTNG_CONSUMER_PUSH_METADATA) {
+               ERR("Unexpected cmd_type received %d", msg.cmd_type);
+               ret = -1;
+               goto end;
+       }
+
+       len = msg.u.push_metadata.len;
+       key = msg.u.push_metadata.key;
+       offset = msg.u.push_metadata.target_offset;
+
+       assert(key == channel->key);
+       if (len == 0) {
+               DBG("No new metadata to receive for key %" PRIu64, key);
+       }
+
+       health_code_update();
+
+       /* Tell session daemon we are ready to receive the metadata. */
+       ret = consumer_send_status_msg(ctx->consumer_metadata_socket,
+                       LTTCOMM_CONSUMERD_SUCCESS);
+       if (ret < 0 || len == 0) {
+               /*
+                * Somehow, the session daemon is not responding anymore or there is
+                * nothing to receive.
+                */
+               goto end;
+       }
+
+       health_code_update();
+
+       ret = lttng_ustconsumer_recv_metadata(ctx->consumer_metadata_socket,
+                       key, offset, len, channel, timer, wait);
+       if (ret >= 0) {
+               /*
+                * Only send the status msg if the sessiond is alive meaning a positive
+                * ret code.
+                */
+               (void) consumer_send_status_msg(ctx->consumer_metadata_socket, ret);
+       }
+       ret = 0;
+
+end:
+       health_code_update();
+
+       pthread_mutex_unlock(&ctx->metadata_socket_lock);
+       return ret;
+}
+
+/*
+ * Return the ustctl call for the get stream id.
+ */
+int lttng_ustconsumer_get_stream_id(struct lttng_consumer_stream *stream,
+               uint64_t *stream_id)
+{
+       assert(stream);
+       assert(stream_id);
+
+       return ustctl_get_stream_id(stream->ustream, stream_id);
+}
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