X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fcommon%2Fkernel-consumer%2Fkernel-consumer.c;h=32169034095be1b9fe8889e3c9aee0906dc1e58f;hp=86e405158098d1bf9c995681985a5c6893ae86cf;hb=e57427575fc6deabed09cb5b4fae029d05e5bfd9;hpb=f73fabfda365d22e7dd180fb1614e37c446fbd9e

diff --git a/src/common/kernel-consumer/kernel-consumer.c b/src/common/kernel-consumer/kernel-consumer.c
index 86e405158..321690340 100644
--- a/src/common/kernel-consumer/kernel-consumer.c
+++ b/src/common/kernel-consumer/kernel-consumer.c
@@ -16,7 +16,7 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#define _GNU_SOURCE
+#define _LGPL_SOURCE
 #include <assert.h>
 #include <poll.h>
 #include <pthread.h>
@@ -29,12 +29,19 @@
 #include <unistd.h>
 #include <sys/stat.h>
 
+#include <bin/lttng-consumerd/health-consumerd.h>
 #include <common/common.h>
 #include <common/kernel-ctl/kernel-ctl.h>
 #include <common/sessiond-comm/sessiond-comm.h>
 #include <common/sessiond-comm/relayd.h>
 #include <common/compat/fcntl.h>
+#include <common/compat/endian.h>
+#include <common/pipe.h>
 #include <common/relayd/relayd.h>
+#include <common/utils.h>
+#include <common/consumer/consumer-stream.h>
+#include <common/index/index.h>
+#include <common/consumer/consumer-timer.h>
 
 #include "kernel-consumer.h"
 
@@ -47,16 +54,15 @@ extern volatile int consumer_quit;
  *
  * Returns 0 on success, < 0 on error
  */
-int lttng_kconsumer_take_snapshot(struct lttng_consumer_local_data *ctx,
-		struct lttng_consumer_stream *stream)
+int lttng_kconsumer_take_snapshot(struct lttng_consumer_stream *stream)
 {
 	int ret = 0;
 	int infd = stream->wait_fd;
 
 	ret = kernctl_snapshot(infd);
 	if (ret != 0) {
-		errno = -ret;
-		perror("Getting sub-buffer snapshot.");
+		PERROR("Getting sub-buffer snapshot.");
+		ret = -errno;
 	}
 
 	return ret;
@@ -67,9 +73,7 @@ int lttng_kconsumer_take_snapshot(struct lttng_consumer_local_data *ctx,
  *
  * Returns 0 on success, < 0 on error
  */
-int lttng_kconsumer_get_produced_snapshot(
-		struct lttng_consumer_local_data *ctx,
-		struct lttng_consumer_stream *stream,
+int lttng_kconsumer_get_produced_snapshot(struct lttng_consumer_stream *stream,
 		unsigned long *pos)
 {
 	int ret;
@@ -77,27 +81,388 @@ int lttng_kconsumer_get_produced_snapshot(
 
 	ret = kernctl_snapshot_get_produced(infd, pos);
 	if (ret != 0) {
-		errno = -ret;
-		perror("kernctl_snapshot_get_produced");
+		PERROR("kernctl_snapshot_get_produced");
+		ret = -errno;
 	}
 
 	return ret;
 }
 
+/*
+ * Get the consumerd position
+ *
+ * Returns 0 on success, < 0 on error
+ */
+int lttng_kconsumer_get_consumed_snapshot(struct lttng_consumer_stream *stream,
+		unsigned long *pos)
+{
+	int ret;
+	int infd = stream->wait_fd;
+
+	ret = kernctl_snapshot_get_consumed(infd, pos);
+	if (ret != 0) {
+		PERROR("kernctl_snapshot_get_consumed");
+		ret = -errno;
+	}
+
+	return ret;
+}
+
+/*
+ * Take a snapshot of all the stream of a channel
+ *
+ * Returns 0 on success, < 0 on error
+ */
+int lttng_kconsumer_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 long consumed_pos, produced_pos;
+	struct lttng_consumer_channel *channel;
+	struct lttng_consumer_stream *stream;
+
+	DBG("Kernel consumer snapshot channel %" PRIu64, key);
+
+	rcu_read_lock();
+
+	channel = consumer_find_channel(key);
+	if (!channel) {
+		ERR("No channel found for key %" PRIu64, key);
+		ret = -1;
+		goto end;
+	}
+
+	/* Splice is not supported yet for channel snapshot. */
+	if (channel->output != CONSUMER_CHANNEL_MMAP) {
+		ERR("Unsupported output %d", channel->output);
+		ret = -1;
+		goto end;
+	}
+
+	cds_list_for_each_entry(stream, &channel->streams.head, send_node) {
+		/* Are we at a position _before_ the first available packet ? */
+		bool before_first_packet = true;
+
+		health_code_update();
+
+		/*
+		 * Lock stream because we are about to change its state.
+		 */
+		pthread_mutex_lock(&stream->lock);
+
+		/*
+		 * Assign the received relayd ID so we can use it for streaming. The streams
+		 * are not visible to anyone so this is OK to change it.
+		 */
+		stream->net_seq_idx = relayd_id;
+		channel->relayd_id = relayd_id;
+		if (relayd_id != (uint64_t) -1ULL) {
+			ret = consumer_send_relayd_stream(stream, path);
+			if (ret < 0) {
+				ERR("sending stream to relayd");
+				goto end_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) {
+				ERR("utils_create_stream_file");
+				goto end_unlock;
+			}
+
+			stream->out_fd = ret;
+			stream->tracefile_size_current = 0;
+
+			DBG("Kernel 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) {
+				ERR("sending streams sent to relayd");
+				goto end_unlock;
+			}
+		}
+
+		ret = kernctl_buffer_flush(stream->wait_fd);
+		if (ret < 0) {
+			ERR("Failed to flush kernel stream");
+			ret = -errno;
+			goto end_unlock;
+		}
+
+		ret = lttng_kconsumer_take_snapshot(stream);
+		if (ret < 0) {
+			ERR("Taking kernel snapshot");
+			goto end_unlock;
+		}
+
+		ret = lttng_kconsumer_get_produced_snapshot(stream, &produced_pos);
+		if (ret < 0) {
+			ERR("Produced kernel snapshot position");
+			goto end_unlock;
+		}
+
+		ret = lttng_kconsumer_get_consumed_snapshot(stream, &consumed_pos);
+		if (ret < 0) {
+			ERR("Consumerd kernel snapshot position");
+			goto end_unlock;
+		}
+
+		if (stream->max_sb_size == 0) {
+			ret = kernctl_get_max_subbuf_size(stream->wait_fd,
+					&stream->max_sb_size);
+			if (ret < 0) {
+				ERR("Getting kernel max_sb_size");
+				ret = -errno;
+				goto end_unlock;
+			}
+		}
+
+		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;
+			int lost_packet = 0;
+
+			health_code_update();
+
+			DBG("Kernel consumer taking snapshot at pos %lu", consumed_pos);
+
+			ret = kernctl_get_subbuf(stream->wait_fd, &consumed_pos);
+			if (ret < 0) {
+				if (errno != EAGAIN) {
+					PERROR("kernctl_get_subbuf snapshot");
+					ret = -errno;
+					goto end_unlock;
+				}
+				DBG("Kernel consumer get subbuf failed. Skipping it.");
+				consumed_pos += stream->max_sb_size;
+
+				/*
+				 * Start accounting lost packets only when we
+				 * already have extracted packets (to match the
+				 * content of the final snapshot).
+				 */
+				if (!before_first_packet) {
+					lost_packet = 1;
+				}
+				continue;
+			}
+
+			ret = kernctl_get_subbuf_size(stream->wait_fd, &len);
+			if (ret < 0) {
+				ERR("Snapshot kernctl_get_subbuf_size");
+				ret = -errno;
+				goto error_put_subbuf;
+			}
+
+			ret = kernctl_get_padded_subbuf_size(stream->wait_fd, &padded_len);
+			if (ret < 0) {
+				ERR("Snapshot kernctl_get_padded_subbuf_size");
+				ret = -errno;
+				goto error_put_subbuf;
+			}
+
+			read_len = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len,
+					padded_len - len, NULL);
+			/*
+			 * We write the padded len in local tracefiles but the data len
+			 * when using a relay. Display the error but continue processing
+			 * to try to release the subbuffer.
+			 */
+			if (relayd_id != (uint64_t) -1ULL) {
+				if (read_len != len) {
+					ERR("Error sending to the relay (ret: %zd != len: %lu)",
+							read_len, len);
+				}
+			} else {
+				if (read_len != padded_len) {
+					ERR("Error writing to tracefile (ret: %zd != len: %lu)",
+							read_len, padded_len);
+				}
+			}
+
+			ret = kernctl_put_subbuf(stream->wait_fd);
+			if (ret < 0) {
+				ERR("Snapshot kernctl_put_subbuf");
+				ret = -errno;
+				goto end_unlock;
+			}
+			consumed_pos += stream->max_sb_size;
+
+			/*
+			 * Only account lost packets located between
+			 * succesfully extracted packets (do not account before
+			 * and after since they are not visible in the
+			 * resulting snapshot).
+			 */
+			stream->chan->lost_packets += lost_packet;
+			lost_packet = 0;
+			before_first_packet = false;
+		}
+
+		if (relayd_id == (uint64_t) -1ULL) {
+			if (stream->out_fd >= 0) {
+				ret = close(stream->out_fd);
+				if (ret < 0) {
+					PERROR("Kernel consumer snapshot close out_fd");
+					goto end_unlock;
+				}
+				stream->out_fd = -1;
+			}
+		} else {
+			close_relayd_stream(stream);
+			stream->net_seq_idx = (uint64_t) -1ULL;
+		}
+		pthread_mutex_unlock(&stream->lock);
+	}
+
+	/* All good! */
+	ret = 0;
+	goto end;
+
+error_put_subbuf:
+	ret = kernctl_put_subbuf(stream->wait_fd);
+	if (ret < 0) {
+		ret = -errno;
+		ERR("Snapshot kernctl_put_subbuf error path");
+	}
+end_unlock:
+	pthread_mutex_unlock(&stream->lock);
+end:
+	rcu_read_unlock();
+	return ret;
+}
+
+/*
+ * Read the whole metadata available for a snapshot.
+ *
+ * Returns 0 on success, < 0 on error
+ */
+int lttng_kconsumer_snapshot_metadata(uint64_t key, char *path,
+		uint64_t relayd_id, struct lttng_consumer_local_data *ctx)
+{
+	int ret, use_relayd = 0;
+	ssize_t ret_read;
+	struct lttng_consumer_channel *metadata_channel;
+	struct lttng_consumer_stream *metadata_stream;
+
+	assert(ctx);
+
+	DBG("Kernel consumer snapshot metadata with key %" PRIu64 " at path %s",
+			key, path);
+
+	rcu_read_lock();
+
+	metadata_channel = consumer_find_channel(key);
+	if (!metadata_channel) {
+		ERR("Kernel snapshot metadata not found for key %" PRIu64, key);
+		ret = -1;
+		goto error;
+	}
+
+	metadata_stream = metadata_channel->metadata_stream;
+	assert(metadata_stream);
+
+	/* Flag once that we have a valid relayd for the stream. */
+	if (relayd_id != (uint64_t) -1ULL) {
+		use_relayd = 1;
+	}
+
+	if (use_relayd) {
+		ret = consumer_send_relayd_stream(metadata_stream, path);
+		if (ret < 0) {
+			goto error;
+		}
+	} 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;
+		}
+		metadata_stream->out_fd = ret;
+	}
+
+	do {
+		health_code_update();
+
+		ret_read = lttng_kconsumer_read_subbuffer(metadata_stream, ctx);
+		if (ret_read < 0) {
+			if (ret_read != -EAGAIN) {
+				ERR("Kernel snapshot reading metadata subbuffer (ret: %zd)",
+						ret_read);
+				goto error;
+			}
+			/* ret_read is negative at this point so we will exit the loop. */
+			continue;
+		}
+	} while (ret_read >= 0);
+
+	if (use_relayd) {
+		close_relayd_stream(metadata_stream);
+		metadata_stream->net_seq_idx = (uint64_t) -1ULL;
+	} else {
+		if (metadata_stream->out_fd >= 0) {
+			ret = close(metadata_stream->out_fd);
+			if (ret < 0) {
+				PERROR("Kernel consumer snapshot metadata close out_fd");
+				/*
+				 * Don't go on error here since the snapshot was successful at this
+				 * point but somehow the close failed.
+				 */
+			}
+			metadata_stream->out_fd = -1;
+		}
+	}
+
+	ret = 0;
+
+	cds_list_del(&metadata_stream->send_node);
+	consumer_stream_destroy(metadata_stream, NULL);
+	metadata_channel->metadata_stream = NULL;
+error:
+	rcu_read_unlock();
+	return ret;
+}
+
+/*
+ * Receive command from session daemon and process it.
+ *
+ * Return 1 on success else a negative value or 0.
+ */
 int lttng_kconsumer_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;
 
+	health_code_update();
+
 	ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
 	if (ret != sizeof(msg)) {
-		lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_CMD);
+		if (ret > 0) {
+			lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_CMD);
+			ret = -1;
+		}
 		return ret;
 	}
-	if (msg.cmd_type == LTTNG_CONSUMER_STOP) {
-		return -ENOENT;
-	}
+
+	health_code_update();
+
+	/* Deprecated command */
+	assert(msg.cmd_type != LTTNG_CONSUMER_STOP);
+
+	health_code_update();
 
 	/* relayd needs RCU read-side protection */
 	rcu_read_lock();
@@ -105,48 +470,145 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 	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.sock, msg.u.relayd_sock.session_id,
+				 msg.u.relayd_sock.relayd_session_id);
 		goto end_nosignal;
 	}
 	case LTTNG_CONSUMER_ADD_CHANNEL:
 	{
 		struct lttng_consumer_channel *new_channel;
+		int ret_recv;
+
+		health_code_update();
+
+		/* 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 error_fatal;
+		}
+
+		health_code_update();
 
-		DBG("consumer_add_channel %d", msg.u.channel.channel_key);
+		DBG("consumer_add_channel %" PRIu64, msg.u.channel.channel_key);
 		new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
-				-1, -1,
-				msg.u.channel.mmap_len,
-				msg.u.channel.max_sb_size);
+				msg.u.channel.session_id, msg.u.channel.pathname,
+				msg.u.channel.name, msg.u.channel.uid, msg.u.channel.gid,
+				msg.u.channel.relayd_id, msg.u.channel.output,
+				msg.u.channel.tracefile_size,
+				msg.u.channel.tracefile_count, 0,
+				msg.u.channel.monitor,
+				msg.u.channel.live_timer_interval,
+				NULL, NULL);
 		if (new_channel == NULL) {
 			lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
 			goto end_nosignal;
 		}
+		new_channel->nb_init_stream_left = msg.u.channel.nb_init_streams;
+		switch (msg.u.channel.output) {
+		case LTTNG_EVENT_SPLICE:
+			new_channel->output = CONSUMER_CHANNEL_SPLICE;
+			break;
+		case LTTNG_EVENT_MMAP:
+			new_channel->output = CONSUMER_CHANNEL_MMAP;
+			break;
+		default:
+			ERR("Channel output unknown %d", msg.u.channel.output);
+			goto end_nosignal;
+		}
+
+		/* Translate and save channel type. */
+		switch (msg.u.channel.type) {
+		case CONSUMER_CHANNEL_TYPE_DATA:
+		case CONSUMER_CHANNEL_TYPE_METADATA:
+			new_channel->type = msg.u.channel.type;
+			break;
+		default:
+			assert(0);
+			goto end_nosignal;
+		};
+
+		health_code_update();
+
 		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) {
+			ret_recv = ctx->on_recv_channel(new_channel);
+			if (ret_recv == 0) {
+				ret = consumer_add_channel(new_channel, ctx);
+			} else if (ret_recv < 0) {
 				goto end_nosignal;
 			}
 		} else {
-			consumer_add_channel(new_channel);
+			ret = consumer_add_channel(new_channel, ctx);
+		}
+		if (CONSUMER_CHANNEL_TYPE_DATA) {
+			consumer_timer_live_start(new_channel,
+					msg.u.channel.live_timer_interval);
+		}
+
+		health_code_update();
+
+		/* If we received an error in add_channel, we need to report it. */
+		if (ret < 0) {
+			ret = consumer_send_status_msg(sock, ret);
+			if (ret < 0) {
+				goto error_fatal;
+			}
+			goto end_nosignal;
 		}
+
 		goto end_nosignal;
 	}
 	case LTTNG_CONSUMER_ADD_STREAM:
 	{
 		int fd;
-		struct consumer_relayd_sock_pair *relayd = NULL;
+		struct lttng_pipe *stream_pipe;
 		struct lttng_consumer_stream *new_stream;
+		struct lttng_consumer_channel *channel;
+		int alloc_ret = 0;
 
-		/* block */
-		if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
-			rcu_read_unlock();
-			return -EINTR;
+		/*
+		 * Get stream's channel reference. Needed when adding the stream to the
+		 * global hash table.
+		 */
+		channel = consumer_find_channel(msg.u.stream.channel_key);
+		if (!channel) {
+			/*
+			 * We could not find the channel. Can happen if cpu hotplug
+			 * happens while tearing down.
+			 */
+			ERR("Unable to find channel key %" PRIu64, msg.u.stream.channel_key);
+			ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
+		}
+
+		health_code_update();
+
+		/* 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 error_fatal;
+		}
+
+		health_code_update();
+
+		if (ret_code != LTTCOMM_CONSUMERD_SUCCESS) {
+			/* Channel was not found. */
+			goto end_nosignal;
+		}
+
+		/* Blocking call */
+		health_poll_entry();
+		ret = lttng_consumer_poll_socket(consumer_sockpoll);
+		health_poll_exit();
+		if (ret) {
+			goto error_fatal;
 		}
 
+		health_code_update();
+
 		/* Get stream file descriptor from socket */
 		ret = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
 		if (ret != sizeof(fd)) {
@@ -155,53 +617,209 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 			return ret;
 		}
 
-		new_stream = consumer_allocate_stream(msg.u.stream.channel_key,
-				msg.u.stream.stream_key,
-				fd, fd,
-				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);
+		health_code_update();
+
+		/*
+		 * 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;
+		}
+
+		health_code_update();
+
+		new_stream = consumer_allocate_stream(channel->key,
+				fd,
+				LTTNG_CONSUMER_ACTIVE_STREAM,
+				channel->name,
+				channel->uid,
+				channel->gid,
+				channel->relayd_id,
+				channel->session_id,
+				msg.u.stream.cpu,
+				&alloc_ret,
+				channel->type,
+				channel->monitor);
 		if (new_stream == NULL) {
-			lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
+			switch (alloc_ret) {
+			case -ENOMEM:
+			case -EINVAL:
+			default:
+				lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
+				break;
+			}
 			goto end_nosignal;
 		}
 
-		/* The stream is not metadata. Get relayd reference if exists. */
-		relayd = consumer_find_relayd(msg.u.stream.net_index);
-		if (relayd != NULL) {
-			/* Add stream on the relayd */
-			pthread_mutex_lock(&relayd->ctrl_sock_mutex);
-			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);
+		new_stream->chan = channel;
+		new_stream->wait_fd = fd;
+		switch (channel->output) {
+		case CONSUMER_CHANNEL_SPLICE:
+			new_stream->output = LTTNG_EVENT_SPLICE;
+			ret = utils_create_pipe(new_stream->splice_pipe);
 			if (ret < 0) {
 				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);
-			free(new_stream);
+			break;
+		case CONSUMER_CHANNEL_MMAP:
+			new_stream->output = LTTNG_EVENT_MMAP;
+			break;
+		default:
+			ERR("Stream output unknown %d", channel->output);
 			goto end_nosignal;
 		}
 
-		if (ctx->on_recv_stream != NULL) {
+		/*
+		 * We've just assigned the channel to the stream so increment the
+		 * refcount right now. We don't need to increment the refcount for
+		 * streams in no monitor because we handle manually the cleanup of
+		 * those. It is very important to make sure there is NO prior
+		 * consumer_del_stream() calls or else the refcount will be unbalanced.
+		 */
+		if (channel->monitor) {
+			uatomic_inc(&new_stream->chan->refcount);
+		}
+
+		/*
+		 * The buffer flush is done on the session daemon side for the kernel
+		 * so no need for the stream "hangup_flush_done" variable to be
+		 * tracked. This is important for a kernel stream since we don't rely
+		 * on the flush state of the stream to read data. It's not the case for
+		 * user space tracing.
+		 */
+		new_stream->hangup_flush_done = 0;
+
+		health_code_update();
+
+		if (ctx->on_recv_stream) {
 			ret = ctx->on_recv_stream(new_stream);
-			if (ret == 0) {
-				consumer_add_stream(new_stream);
-			} else if (ret < 0) {
+			if (ret < 0) {
+				consumer_stream_free(new_stream);
+				goto end_nosignal;
+			}
+		}
+
+		health_code_update();
+
+		if (new_stream->metadata_flag) {
+			channel->metadata_stream = new_stream;
+		}
+
+		/* Do not monitor this stream. */
+		if (!channel->monitor) {
+			DBG("Kernel consumer add stream %s in no monitor mode with "
+					"relayd id %" PRIu64, new_stream->name,
+					new_stream->net_seq_idx);
+			cds_list_add(&new_stream->send_node, &channel->streams.head);
+			break;
+		}
+
+		/* Send stream to relayd if the stream has an ID. */
+		if (new_stream->net_seq_idx != (uint64_t) -1ULL) {
+			ret = consumer_send_relayd_stream(new_stream,
+					new_stream->chan->pathname);
+			if (ret < 0) {
+				consumer_stream_free(new_stream);
+				goto end_nosignal;
+			}
+		}
+
+		/* Get the right pipe where the stream will be sent. */
+		if (new_stream->metadata_flag) {
+			ret = consumer_add_metadata_stream(new_stream);
+			if (ret) {
+				ERR("Consumer add metadata stream %" PRIu64 " failed. Continuing",
+						new_stream->key);
+				consumer_stream_free(new_stream);
 				goto end_nosignal;
 			}
+			stream_pipe = ctx->consumer_metadata_pipe;
 		} else {
-			consumer_add_stream(new_stream);
+			ret = consumer_add_data_stream(new_stream);
+			if (ret) {
+				ERR("Consumer add stream %" PRIu64 " failed. Continuing",
+						new_stream->key);
+				consumer_stream_free(new_stream);
+				goto end_nosignal;
+			}
+			stream_pipe = ctx->consumer_data_pipe;
+		}
+
+		/* Vitible to other threads */
+		new_stream->globally_visible = 1;
+
+		health_code_update();
+
+		ret = lttng_pipe_write(stream_pipe, &new_stream, sizeof(new_stream));
+		if (ret < 0) {
+			ERR("Consumer write %s stream to pipe %d",
+					new_stream->metadata_flag ? "metadata" : "data",
+					lttng_pipe_get_writefd(stream_pipe));
+			if (new_stream->metadata_flag) {
+				consumer_del_stream_for_metadata(new_stream);
+			} else {
+				consumer_del_stream_for_data(new_stream);
+			}
+			goto end_nosignal;
 		}
 
-		DBG("Kernel consumer_add_stream (%d)", fd);
+		DBG("Kernel consumer ADD_STREAM %s (fd: %d) with relayd id %" PRIu64,
+				new_stream->name, fd, new_stream->relayd_stream_id);
+		break;
+	}
+	case LTTNG_CONSUMER_STREAMS_SENT:
+	{
+		struct lttng_consumer_channel *channel;
+
+		/*
+		 * Get stream's channel reference. Needed when adding the stream to the
+		 * global hash table.
+		 */
+		channel = consumer_find_channel(msg.u.sent_streams.channel_key);
+		if (!channel) {
+			/*
+			 * We could not find the channel. Can happen if cpu hotplug
+			 * happens while tearing down.
+			 */
+			ERR("Unable to find channel key %" PRIu64,
+					msg.u.sent_streams.channel_key);
+			ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
+		}
+
+		health_code_update();
+
+		/*
+		 * Send status code to session daemon.
+		 */
+		ret = consumer_send_status_msg(sock, ret_code);
+		if (ret < 0 || ret_code != LTTCOMM_CONSUMERD_SUCCESS) {
+			/* Somehow, the session daemon is not responding anymore. */
+			goto end_nosignal;
+		}
+
+		health_code_update();
+
+		/*
+		 * We should not send this message if we don't monitor the
+		 * streams in this channel.
+		 */
+		if (!channel->monitor) {
+			break;
+		}
+
+		health_code_update();
+		/* Send stream to relayd if the stream has an ID. */
+		if (msg.u.sent_streams.net_seq_idx != (uint64_t) -1ULL) {
+			ret = consumer_send_relayd_streams_sent(
+					msg.u.sent_streams.net_seq_idx);
+			if (ret < 0) {
+				goto end_nosignal;
+			}
+		}
 		break;
 	}
 	case LTTNG_CONSUMER_UPDATE_STREAM:
@@ -219,8 +837,8 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 		/* Get relayd reference if exists. */
 		relayd = consumer_find_relayd(index);
 		if (relayd == NULL) {
-			ERR("Unable to find relayd %" PRIu64, index);
-			goto end_nosignal;
+			DBG("Unable to find relayd %" PRIu64, index);
+			ret_code = LTTCOMM_CONSUMERD_RELAYD_FAIL;
 		}
 
 		/*
@@ -233,31 +851,386 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 		 *
 		 * The destroy can happen either here or when a stream fd hangs up.
 		 */
-		consumer_flag_relayd_for_destroy(relayd);
+		if (relayd) {
+			consumer_flag_relayd_for_destroy(relayd);
+		}
+
+		health_code_update();
+
+		ret = consumer_send_status_msg(sock, ret_code);
+		if (ret < 0) {
+			/* Somehow, the session daemon is not responding anymore. */
+			goto error_fatal;
+		}
+
+		goto end_nosignal;
+	}
+	case LTTNG_CONSUMER_DATA_PENDING:
+	{
+		int32_t ret;
+		uint64_t id = msg.u.data_pending.session_id;
+
+		DBG("Kernel consumer data pending command for id %" PRIu64, id);
+
+		ret = consumer_data_pending(id);
+
+		health_code_update();
+
+		/* Send back returned value to session daemon */
+		ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
+		if (ret < 0) {
+			PERROR("send data pending ret code");
+			goto error_fatal;
+		}
+
+		/*
+		 * No need to send back a status message since the data pending
+		 * returned value is the response.
+		 */
+		break;
+	}
+	case LTTNG_CONSUMER_SNAPSHOT_CHANNEL:
+	{
+		if (msg.u.snapshot_channel.metadata == 1) {
+			ret = lttng_kconsumer_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 = lttng_kconsumer_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_CHAN_NOT_FOUND;
+			}
+		}
+
+		health_code_update();
+
+		ret = consumer_send_status_msg(sock, ret_code);
+		if (ret < 0) {
+			/* Somehow, the session daemon is not responding anymore. */
+			goto end_nosignal;
+		}
+		break;
+	}
+	case LTTNG_CONSUMER_DESTROY_CHANNEL:
+	{
+		uint64_t key = msg.u.destroy_channel.key;
+		struct lttng_consumer_channel *channel;
+
+		channel = consumer_find_channel(key);
+		if (!channel) {
+			ERR("Kernel consumer destroy channel %" PRIu64 " not found", key);
+			ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
+		}
+
+		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();
+
+		/* Stop right now if no channel was found. */
+		if (!channel) {
+			goto end_nosignal;
+		}
+
+		/*
+		 * This command should ONLY be issued for channel with streams set in
+		 * no monitor mode.
+		 */
+		assert(!channel->monitor);
+
+		/*
+		 * The refcount should ALWAYS be 0 in the case of a channel in no
+		 * monitor mode.
+		 */
+		assert(!uatomic_sub_return(&channel->refcount, 1));
+
+		consumer_del_channel(channel);
 
 		goto end_nosignal;
 	}
+	case LTTNG_CONSUMER_DISCARDED_EVENTS:
+	{
+		uint64_t ret;
+		struct lttng_consumer_channel *channel;
+		uint64_t id = msg.u.discarded_events.session_id;
+		uint64_t key = msg.u.discarded_events.channel_key;
+
+		DBG("Kernel consumer discarded events command for session id %"
+				PRIu64 ", channel key %" PRIu64, id, key);
+
+		channel = consumer_find_channel(key);
+		if (!channel) {
+			ERR("Kernel consumer discarded events channel %"
+					PRIu64 " not found", key);
+			ret = 0;
+		} else {
+			ret = channel->discarded_events;
+		}
+
+		health_code_update();
+
+		/* Send back returned value to session daemon */
+		ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
+		if (ret < 0) {
+			PERROR("send discarded events");
+			goto error_fatal;
+		}
+
+		break;
+	}
+	case LTTNG_CONSUMER_LOST_PACKETS:
+	{
+		uint64_t ret;
+		struct lttng_consumer_channel *channel;
+		uint64_t id = msg.u.lost_packets.session_id;
+		uint64_t key = msg.u.lost_packets.channel_key;
+
+		DBG("Kernel consumer lost packets command for session id %"
+				PRIu64 ", channel key %" PRIu64, id, key);
+
+		channel = consumer_find_channel(key);
+		if (!channel) {
+			ERR("Kernel consumer lost packets channel %"
+					PRIu64 " not found", key);
+			ret = 0;
+		} else {
+			ret = channel->lost_packets;
+		}
+
+		health_code_update();
+
+		/* Send back returned value to session daemon */
+		ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
+		if (ret < 0) {
+			PERROR("send lost packets");
+			goto error_fatal;
+		}
+
+		break;
+	}
 	default:
 		goto end_nosignal;
 	}
 
+end_nosignal:
+	rcu_read_unlock();
+
 	/*
-	 * Wake-up the other end by writing a null byte in the pipe (non-blocking).
-	 * Important note: Because writing into the pipe is non-blocking (and
-	 * therefore we allow dropping wakeup data, as long as there is wakeup data
-	 * present in the pipe buffer to wake up the other end), the other end
-	 * should perform the following sequence for waiting:
-	 *
-	 * 1) empty the pipe (reads).
-	 * 2) perform update operation.
-	 * 3) wait on the pipe (poll).
+	 * Return 1 to indicate success since the 0 value can be a socket
+	 * shutdown during the recv() or send() call.
 	 */
-	do {
-		ret = write(ctx->consumer_poll_pipe[1], "", 1);
-	} while (ret < 0 && errno == EINTR);
-end_nosignal:
+	health_code_update();
+	return 1;
+
+error_fatal:
 	rcu_read_unlock();
-	return 0;
+	/* This will issue a consumer stop. */
+	return -1;
+}
+
+/*
+ * Populate index values of a kernel 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, int infd)
+{
+	int ret;
+
+	ret = kernctl_get_timestamp_begin(infd, &index->timestamp_begin);
+	if (ret < 0) {
+		PERROR("kernctl_get_timestamp_begin");
+		goto error;
+	}
+	index->timestamp_begin = htobe64(index->timestamp_begin);
+
+	ret = kernctl_get_timestamp_end(infd, &index->timestamp_end);
+	if (ret < 0) {
+		PERROR("kernctl_get_timestamp_end");
+		goto error;
+	}
+	index->timestamp_end = htobe64(index->timestamp_end);
+
+	ret = kernctl_get_events_discarded(infd, &index->events_discarded);
+	if (ret < 0) {
+		PERROR("kernctl_get_events_discarded");
+		goto error;
+	}
+	index->events_discarded = htobe64(index->events_discarded);
+
+	ret = kernctl_get_content_size(infd, &index->content_size);
+	if (ret < 0) {
+		PERROR("kernctl_get_content_size");
+		goto error;
+	}
+	index->content_size = htobe64(index->content_size);
+
+	ret = kernctl_get_packet_size(infd, &index->packet_size);
+	if (ret < 0) {
+		PERROR("kernctl_get_packet_size");
+		goto error;
+	}
+	index->packet_size = htobe64(index->packet_size);
+
+	ret = kernctl_get_stream_id(infd, &index->stream_id);
+	if (ret < 0) {
+		PERROR("kernctl_get_stream_id");
+		goto error;
+	}
+	index->stream_id = htobe64(index->stream_id);
+
+	ret = kernctl_get_instance_id(infd, &index->stream_instance_id);
+	if (ret < 0) {
+		PERROR("kernctl_get_instance_id");
+		goto error;
+	}
+	index->stream_instance_id = htobe64(index->stream_instance_id);
+
+	ret = kernctl_get_sequence_number(infd, &index->packet_seq_num);
+	if (ret < 0) {
+		PERROR("kernctl_get_sequence_number");
+		goto error;
+	}
+	index->packet_seq_num = htobe64(index->packet_seq_num);
+
+error:
+	return ret;
+}
+/*
+ * Sync metadata meaning request them to the session daemon and snapshot to the
+ * metadata thread can consumer them.
+ *
+ * Metadata stream lock MUST be acquired.
+ *
+ * Return 0 if new metadatda is available, EAGAIN if the metadata stream
+ * is empty or a negative value on error.
+ */
+int lttng_kconsumer_sync_metadata(struct lttng_consumer_stream *metadata)
+{
+	int ret;
+
+	assert(metadata);
+
+	ret = kernctl_buffer_flush(metadata->wait_fd);
+	if (ret < 0) {
+		ERR("Failed to flush kernel stream");
+		goto end;
+	}
+
+	ret = kernctl_snapshot(metadata->wait_fd);
+	if (ret < 0) {
+		if (errno != EAGAIN) {
+			ERR("Sync metadata, taking kernel snapshot failed.");
+			goto end;
+		}
+		DBG("Sync metadata, no new kernel metadata");
+		/* No new metadata, exit. */
+		ret = ENODATA;
+		goto end;
+	}
+
+end:
+	return ret;
+}
+
+static
+int update_stream_stats(struct lttng_consumer_stream *stream)
+{
+	int ret;
+	uint64_t seq, discarded;
+
+	ret = kernctl_get_sequence_number(stream->wait_fd, &seq);
+	if (ret < 0) {
+		PERROR("kernctl_get_sequence_number");
+		goto end;
+	}
+
+	/*
+	 * Start the sequence when we extract the first packet in case we don't
+	 * start at 0 (for example if a consumer is not connected to the
+	 * session immediately after the beginning).
+	 */
+	if (stream->last_sequence_number == -1ULL) {
+		stream->last_sequence_number = seq;
+	} else if (seq > stream->last_sequence_number) {
+		stream->chan->lost_packets += seq -
+				stream->last_sequence_number - 1;
+	} else {
+		/* seq <= last_sequence_number */
+		ERR("Sequence number inconsistent : prev = %" PRIu64
+				", current = %" PRIu64,
+				stream->last_sequence_number, seq);
+		ret = -1;
+		goto end;
+	}
+	stream->last_sequence_number = seq;
+
+	ret = kernctl_get_events_discarded(stream->wait_fd, &discarded);
+	if (ret < 0) {
+		PERROR("kernctl_get_events_discarded");
+		goto end;
+	}
+	if (discarded < stream->last_discarded_events) {
+		/*
+		 * Overflow has occured. We assume only one wrap-around
+		 * has occured.
+		 */
+		stream->chan->discarded_events += (1ULL << (CAA_BITS_PER_LONG - 1)) -
+			stream->last_discarded_events + discarded;
+	} else {
+		stream->chan->discarded_events += discarded -
+			stream->last_discarded_events;
+	}
+	stream->last_discarded_events = discarded;
+	ret = 0;
+
+end:
+	return ret;
+}
+
+/*
+ * Check if the local version of the metadata stream matches with the version
+ * of the metadata stream in the kernel. If it was updated, set the reset flag
+ * on the stream.
+ */
+static
+int metadata_stream_check_version(int infd, struct lttng_consumer_stream *stream)
+{
+	int ret;
+	uint64_t cur_version;
+
+	ret = kernctl_get_metadata_version(infd, &cur_version);
+	if (ret < 0) {
+		ERR("Failed to get the metadata version");
+		goto end;
+	}
+
+	if (stream->metadata_version == cur_version) {
+		ret = 0;
+		goto end;
+	}
+
+	DBG("New metadata version detected");
+	stream->metadata_version = cur_version;
+	stream->reset_metadata_flag = 1;
+	ret = 0;
+
+end:
+	return ret;
 }
 
 /*
@@ -266,12 +1239,14 @@ end_nosignal:
 ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
 		struct lttng_consumer_local_data *ctx)
 {
-	unsigned long len;
-	int err;
+	unsigned long len, subbuf_size, padding;
+	int err, write_index = 1;
 	ssize_t ret = 0;
 	int infd = stream->wait_fd;
+	struct ctf_packet_index index;
 
 	DBG("In read_subbuffer (infd : %d)", infd);
+
 	/* Get the next subbuffer */
 	err = kernctl_get_next_subbuf(infd);
 	if (err != 0) {
@@ -283,63 +1258,179 @@ ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
 		 */
 		DBG("Reserving sub buffer failed (everything is normal, "
 				"it is due to concurrency)");
+		ret = -errno;
 		goto end;
 	}
 
-	switch (stream->output) {
-		case LTTNG_EVENT_SPLICE:
-			/* read the whole subbuffer */
-			err = kernctl_get_padded_subbuf_size(infd, &len);
+	/* Get the full subbuffer size including padding */
+	err = kernctl_get_padded_subbuf_size(infd, &len);
+	if (err != 0) {
+		PERROR("Getting sub-buffer len failed.");
+		err = kernctl_put_subbuf(infd);
+		if (err != 0) {
+			if (errno == EFAULT) {
+				PERROR("Error in unreserving sub buffer\n");
+			} else if (errno == EIO) {
+				/* Should never happen with newer LTTng versions */
+				PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
+			}
+			ret = -errno;
+			goto end;
+		}
+		ret = -errno;
+		goto end;
+	}
+
+	if (!stream->metadata_flag) {
+		ret = get_index_values(&index, infd);
+		if (ret < 0) {
+			err = kernctl_put_subbuf(infd);
 			if (err != 0) {
-				errno = -ret;
-				perror("Getting sub-buffer len failed.");
+				if (errno == EFAULT) {
+					PERROR("Error in unreserving sub buffer\n");
+				} else if (errno == EIO) {
+					/* Should never happen with newer LTTng versions */
+					PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
+				}
+				ret = -errno;
 				goto end;
 			}
+			goto end;
+		}
+		ret = update_stream_stats(stream);
+		if (ret < 0) {
+			goto end;
+		}
+	} else {
+		write_index = 0;
+		ret = metadata_stream_check_version(infd, stream);
+		if (ret < 0) {
+			goto end;
+		}
+	}
 
-			/* splice the subbuffer to the tracefile */
-			ret = lttng_consumer_on_read_subbuffer_splice(ctx, stream, len);
-			if (ret != len) {
-				/*
-				 * display the error but continue processing to try
-				 * to release the subbuffer
-				 */
-				ERR("Error splicing to tracefile (ret: %zd != len: %lu)",
-						ret, len);
-			}
+	switch (stream->chan->output) {
+	case CONSUMER_CHANNEL_SPLICE:
+		/*
+		 * XXX: The lttng-modules splice "actor" does not handle copying
+		 * partial pages hence only using the subbuffer size without the
+		 * padding makes the splice fail.
+		 */
+		subbuf_size = len;
+		padding = 0;
 
-			break;
-		case LTTNG_EVENT_MMAP:
-			/* read the used subbuffer size */
-			err = kernctl_get_padded_subbuf_size(infd, &len);
+		/* splice the subbuffer to the tracefile */
+		ret = lttng_consumer_on_read_subbuffer_splice(ctx, stream, subbuf_size,
+				padding, &index);
+		/*
+		 * XXX: Splice does not support network streaming so the return value
+		 * is simply checked against subbuf_size and not like the mmap() op.
+		 */
+		if (ret != subbuf_size) {
+			/*
+			 * display the error but continue processing to try
+			 * to release the subbuffer
+			 */
+			ERR("Error splicing to tracefile (ret: %zd != len: %lu)",
+					ret, subbuf_size);
+			write_index = 0;
+		}
+		break;
+	case CONSUMER_CHANNEL_MMAP:
+		/* Get subbuffer size without padding */
+		err = kernctl_get_subbuf_size(infd, &subbuf_size);
+		if (err != 0) {
+			PERROR("Getting sub-buffer len failed.");
+			err = kernctl_put_subbuf(infd);
 			if (err != 0) {
-				errno = -ret;
-				perror("Getting sub-buffer len failed.");
+				if (errno == EFAULT) {
+					PERROR("Error in unreserving sub buffer\n");
+				} else if (errno == EIO) {
+					/* Should never happen with newer LTTng versions */
+					PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
+				}
+				ret = -errno;
 				goto end;
 			}
-			/* write the subbuffer to the tracefile */
-			ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len);
-			if (ret != len) {
-				/*
-				 * display the error but continue processing to try
-				 * to release the subbuffer
-				 */
-				ERR("Error writing to tracefile");
-			}
-			break;
-		default:
-			ERR("Unknown output method");
-			ret = -1;
+			ret = -errno;
+			goto end;
+		}
+
+		/* Make sure the tracer is not gone mad on us! */
+		assert(len >= subbuf_size);
+
+		padding = len - subbuf_size;
+
+		/* write the subbuffer to the tracefile */
+		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 != (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 this is possible to
+			 * happen without being a critical error.
+			 */
+			DBG("Error writing to tracefile "
+					"(ret: %zd != len: %lu != subbuf_size: %lu)",
+					ret, len, subbuf_size);
+			write_index = 0;
+		}
+		break;
+	default:
+		ERR("Unknown output method");
+		ret = -EPERM;
 	}
 
 	err = kernctl_put_next_subbuf(infd);
 	if (err != 0) {
-		errno = -ret;
 		if (errno == EFAULT) {
-			perror("Error in unreserving sub buffer\n");
+			PERROR("Error in unreserving sub buffer\n");
 		} else if (errno == EIO) {
 			/* Should never happen with newer LTTng versions */
-			perror("Reader has been pushed by the writer, last sub-buffer corrupted.");
+			PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
 		}
+		ret = -errno;
+		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_kernel_index(stream);
+		} else {
+			pthread_mutex_unlock(&stream->metadata_timer_lock);
+		}
+		if (err < 0) {
+			goto end;
+		}
+	}
+
+	err = consumer_stream_write_index(stream, &index);
+	if (err < 0) {
 		goto end;
 	}
 
@@ -351,18 +1442,32 @@ int lttng_kconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
 {
 	int ret;
 
-	/* Opening the tracefile in write mode */
-	if (strlen(stream->path_name) > 0 && 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 or should not be
+	 * monitored.
+	 */
+	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;
+
+		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;
+		}
 	}
 
 	if (stream->output == LTTNG_EVENT_MMAP) {
@@ -371,16 +1476,16 @@ int lttng_kconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
 
 		ret = kernctl_get_mmap_len(stream->wait_fd, &mmap_len);
 		if (ret != 0) {
-			errno = -ret;
-			perror("kernctl_get_mmap_len");
+			PERROR("kernctl_get_mmap_len");
+			ret = -errno;
 			goto error_close_fd;
 		}
 		stream->mmap_len = (size_t) mmap_len;
 
-		stream->mmap_base = mmap(NULL, stream->mmap_len,
-				PROT_READ, MAP_PRIVATE, stream->wait_fd, 0);
+		stream->mmap_base = mmap(NULL, stream->mmap_len, PROT_READ,
+				MAP_PRIVATE, stream->wait_fd, 0);
 		if (stream->mmap_base == MAP_FAILED) {
-			perror("Error mmaping");
+			PERROR("Error mmaping");
 			ret = -1;
 			goto error_close_fd;
 		}
@@ -390,13 +1495,48 @@ int lttng_kconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
 	return 0;
 
 error_close_fd:
-	{
+	if (stream->out_fd >= 0) {
 		int err;
 
 		err = close(stream->out_fd);
 		assert(!err);
+		stream->out_fd = -1;
 	}
 error:
 	return ret;
 }
 
+/*
+ * Check if data is still being extracted from the buffers for a specific
+ * stream. Consumer data lock MUST be acquired before calling this function
+ * and the stream lock.
+ *
+ * Return 1 if the traced data are still getting read else 0 meaning that the
+ * data is available for trace viewer reading.
+ */
+int lttng_kconsumer_data_pending(struct lttng_consumer_stream *stream)
+{
+	int ret;
+
+	assert(stream);
+
+	if (stream->endpoint_status != CONSUMER_ENDPOINT_ACTIVE) {
+		ret = 0;
+		goto end;
+	}
+
+	ret = kernctl_get_next_subbuf(stream->wait_fd);
+	if (ret == 0) {
+		/* There is still data so let's put back this subbuffer. */
+		ret = kernctl_put_subbuf(stream->wait_fd);
+		assert(ret == 0);
+		ret = 1;   /* Data is pending */
+		goto end;
+	}
+
+	/* Data is NOT pending and ready to be read. */
+	ret = 0;
+
+end:
+	return ret;
+}