X-Git-Url: https://git.lttng.org/?a=blobdiff_plain;f=src%2Fbin%2Flttng-sessiond%2Fconsumer.cpp;fp=src%2Fbin%2Flttng-sessiond%2Fconsumer.cpp;h=f7a92cb3d9b282683da3d9ec3060af976b3cada0;hb=7966af5763c4aaca39df9bbfa9277ff15715c720;hp=0000000000000000000000000000000000000000;hpb=3a5f70173aa04d11ccb22694d5d31a702cad33ab;p=lttng-tools.git

diff --git a/src/bin/lttng-sessiond/consumer.cpp b/src/bin/lttng-sessiond/consumer.cpp
new file mode 100644
index 000000000..f7a92cb3d
--- /dev/null
+++ b/src/bin/lttng-sessiond/consumer.cpp
@@ -0,0 +1,2165 @@
+/*
+ * Copyright (C) 2012 David Goulet <dgoulet@efficios.com>
+ * Copyright (C) 2018 Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-only
+ *
+ */
+
+#define _LGPL_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <inttypes.h>
+
+#include <common/common.h>
+#include <common/defaults.h>
+#include <common/uri.h>
+#include <common/relayd/relayd.h>
+#include <common/string-utils/format.h>
+
+#include "consumer.h"
+#include "health-sessiond.h"
+#include "ust-app.h"
+#include "utils.h"
+#include "lttng-sessiond.h"
+
+/*
+ * Return allocated full pathname of the session using the consumer trace path
+ * and subdir if available.
+ *
+ * The caller can safely free(3) the returned value. On error, NULL is
+ * returned.
+ */
+char *setup_channel_trace_path(struct consumer_output *consumer,
+		const char *session_path, size_t *consumer_path_offset)
+{
+	int ret;
+	char *pathname;
+
+	LTTNG_ASSERT(consumer);
+	LTTNG_ASSERT(session_path);
+
+	health_code_update();
+
+	/*
+	 * Allocate the string ourself to make sure we never exceed
+	 * LTTNG_PATH_MAX.
+	 */
+	pathname = (char *) zmalloc(LTTNG_PATH_MAX);
+	if (!pathname) {
+		goto error;
+	}
+
+	/* Get correct path name destination */
+	if (consumer->type == CONSUMER_DST_NET &&
+			consumer->relay_major_version == 2 &&
+			consumer->relay_minor_version < 11) {
+		ret = snprintf(pathname, LTTNG_PATH_MAX, "%s%s/%s/%s",
+				consumer->dst.net.base_dir,
+				consumer->chunk_path, consumer->domain_subdir,
+				session_path);
+		*consumer_path_offset = 0;
+	} else {
+		ret = snprintf(pathname, LTTNG_PATH_MAX, "%s/%s",
+				consumer->domain_subdir, session_path);
+		*consumer_path_offset = strlen(consumer->domain_subdir) + 1;
+	}
+	DBG3("Consumer trace path relative to current trace chunk: \"%s\"",
+			pathname);
+	if (ret < 0) {
+		PERROR("Failed to format channel path");
+		goto error;
+	} else if (ret >= LTTNG_PATH_MAX) {
+		ERR("Truncation occurred while formatting channel path");
+		goto error;
+	}
+
+	return pathname;
+error:
+	free(pathname);
+	return NULL;
+}
+
+/*
+ * Send a data payload using a given consumer socket of size len.
+ *
+ * The consumer socket lock MUST be acquired before calling this since this
+ * function can change the fd value.
+ *
+ * Return 0 on success else a negative value on error.
+ */
+int consumer_socket_send(
+		struct consumer_socket *socket, const void *msg, size_t len)
+{
+	int fd;
+	ssize_t size;
+
+	LTTNG_ASSERT(socket);
+	LTTNG_ASSERT(socket->fd_ptr);
+	LTTNG_ASSERT(msg);
+
+	/* Consumer socket is invalid. Stopping. */
+	fd = *socket->fd_ptr;
+	if (fd < 0) {
+		goto error;
+	}
+
+	size = lttcomm_send_unix_sock(fd, msg, len);
+	if (size < 0) {
+		/* The above call will print a PERROR on error. */
+		DBG("Error when sending data to consumer on sock %d", fd);
+		/*
+		 * At this point, the socket is not usable anymore thus closing it and
+		 * setting the file descriptor to -1 so it is not reused.
+		 */
+
+		/* This call will PERROR on error. */
+		(void) lttcomm_close_unix_sock(fd);
+		*socket->fd_ptr = -1;
+		goto error;
+	}
+
+	return 0;
+
+error:
+	return -1;
+}
+
+/*
+ * Receive a data payload using a given consumer socket of size len.
+ *
+ * The consumer socket lock MUST be acquired before calling this since this
+ * function can change the fd value.
+ *
+ * Return 0 on success else a negative value on error.
+ */
+int consumer_socket_recv(struct consumer_socket *socket, void *msg, size_t len)
+{
+	int fd;
+	ssize_t size;
+
+	LTTNG_ASSERT(socket);
+	LTTNG_ASSERT(socket->fd_ptr);
+	LTTNG_ASSERT(msg);
+
+	/* Consumer socket is invalid. Stopping. */
+	fd = *socket->fd_ptr;
+	if (fd < 0) {
+		goto error;
+	}
+
+	size = lttcomm_recv_unix_sock(fd, msg, len);
+	if (size <= 0) {
+		/* The above call will print a PERROR on error. */
+		DBG("Error when receiving data from the consumer socket %d", fd);
+		/*
+		 * At this point, the socket is not usable anymore thus closing it and
+		 * setting the file descriptor to -1 so it is not reused.
+		 */
+
+		/* This call will PERROR on error. */
+		(void) lttcomm_close_unix_sock(fd);
+		*socket->fd_ptr = -1;
+		goto error;
+	}
+
+	return 0;
+
+error:
+	return -1;
+}
+
+/*
+ * Receive a reply command status message from the consumer. Consumer socket
+ * lock MUST be acquired before calling this function.
+ *
+ * Return 0 on success, -1 on recv error or a negative lttng error code which
+ * was possibly returned by the consumer.
+ */
+int consumer_recv_status_reply(struct consumer_socket *sock)
+{
+	int ret;
+	struct lttcomm_consumer_status_msg reply;
+
+	LTTNG_ASSERT(sock);
+
+	ret = consumer_socket_recv(sock, &reply, sizeof(reply));
+	if (ret < 0) {
+		goto end;
+	}
+
+	if (reply.ret_code == LTTCOMM_CONSUMERD_SUCCESS) {
+		/* All good. */
+		ret = 0;
+	} else {
+		ret = -reply.ret_code;
+		DBG("Consumer ret code %d", ret);
+	}
+
+end:
+	return ret;
+}
+
+/*
+ * Once the ASK_CHANNEL command is sent to the consumer, the channel
+ * information are sent back. This call receives that data and populates key
+ * and stream_count.
+ *
+ * On success return 0 and both key and stream_count are set. On error, a
+ * negative value is sent back and both parameters are untouched.
+ */
+int consumer_recv_status_channel(struct consumer_socket *sock,
+		uint64_t *key, unsigned int *stream_count)
+{
+	int ret;
+	struct lttcomm_consumer_status_channel reply;
+
+	LTTNG_ASSERT(sock);
+	LTTNG_ASSERT(stream_count);
+	LTTNG_ASSERT(key);
+
+	ret = consumer_socket_recv(sock, &reply, sizeof(reply));
+	if (ret < 0) {
+		goto end;
+	}
+
+	/* An error is possible so don't touch the key and stream_count. */
+	if (reply.ret_code != LTTCOMM_CONSUMERD_SUCCESS) {
+		ret = -1;
+		goto end;
+	}
+
+	*key = reply.key;
+	*stream_count = reply.stream_count;
+	ret = 0;
+
+end:
+	return ret;
+}
+
+/*
+ * Send destroy relayd command to consumer.
+ *
+ * On success return positive value. On error, negative value.
+ */
+int consumer_send_destroy_relayd(struct consumer_socket *sock,
+		struct consumer_output *consumer)
+{
+	int ret;
+	struct lttcomm_consumer_msg msg;
+
+	LTTNG_ASSERT(consumer);
+	LTTNG_ASSERT(sock);
+
+	DBG2("Sending destroy relayd command to consumer sock %d", *sock->fd_ptr);
+
+	memset(&msg, 0, sizeof(msg));
+	msg.cmd_type = LTTNG_CONSUMER_DESTROY_RELAYD;
+	msg.u.destroy_relayd.net_seq_idx = consumer->net_seq_index;
+
+	pthread_mutex_lock(sock->lock);
+	ret = consumer_socket_send(sock, &msg, sizeof(msg));
+	if (ret < 0) {
+		goto error;
+	}
+
+	/* Don't check the return value. The caller will do it. */
+	ret = consumer_recv_status_reply(sock);
+
+	DBG2("Consumer send destroy relayd command done");
+
+error:
+	pthread_mutex_unlock(sock->lock);
+	return ret;
+}
+
+/*
+ * For each consumer socket in the consumer output object, send a destroy
+ * relayd command.
+ */
+void consumer_output_send_destroy_relayd(struct consumer_output *consumer)
+{
+	struct lttng_ht_iter iter;
+	struct consumer_socket *socket;
+
+	LTTNG_ASSERT(consumer);
+
+	/* Destroy any relayd connection */
+	if (consumer->type == CONSUMER_DST_NET) {
+		rcu_read_lock();
+		cds_lfht_for_each_entry(consumer->socks->ht, &iter.iter, socket,
+				node.node) {
+			int ret;
+
+			/* Send destroy relayd command */
+			ret = consumer_send_destroy_relayd(socket, consumer);
+			if (ret < 0) {
+				DBG("Unable to send destroy relayd command to consumer");
+				/* Continue since we MUST delete everything at this point. */
+			}
+		}
+		rcu_read_unlock();
+	}
+}
+
+/*
+ * From a consumer_data structure, allocate and add a consumer socket to the
+ * consumer output.
+ *
+ * Return 0 on success, else negative value on error
+ */
+int consumer_create_socket(struct consumer_data *data,
+		struct consumer_output *output)
+{
+	int ret = 0;
+	struct consumer_socket *socket;
+
+	LTTNG_ASSERT(data);
+
+	if (output == NULL || data->cmd_sock < 0) {
+		/*
+		 * Not an error. Possible there is simply not spawned consumer or it's
+		 * disabled for the tracing session asking the socket.
+		 */
+		goto error;
+	}
+
+	rcu_read_lock();
+	socket = consumer_find_socket(data->cmd_sock, output);
+	rcu_read_unlock();
+	if (socket == NULL) {
+		socket = consumer_allocate_socket(&data->cmd_sock);
+		if (socket == NULL) {
+			ret = -1;
+			goto error;
+		}
+
+		socket->registered = 0;
+		socket->lock = &data->lock;
+		rcu_read_lock();
+		consumer_add_socket(socket, output);
+		rcu_read_unlock();
+	}
+
+	socket->type = data->type;
+
+	DBG3("Consumer socket created (fd: %d) and added to output",
+			data->cmd_sock);
+
+error:
+	return ret;
+}
+
+/*
+ * Return the consumer socket from the given consumer output with the right
+ * bitness. On error, returns NULL.
+ *
+ * The caller MUST acquire a rcu read side lock and keep it until the socket
+ * object reference is not needed anymore.
+ */
+struct consumer_socket *consumer_find_socket_by_bitness(int bits,
+		const struct consumer_output *consumer)
+{
+	int consumer_fd;
+	struct consumer_socket *socket = NULL;
+
+	switch (bits) {
+	case 64:
+		consumer_fd = uatomic_read(&the_ust_consumerd64_fd);
+		break;
+	case 32:
+		consumer_fd = uatomic_read(&the_ust_consumerd32_fd);
+		break;
+	default:
+		abort();
+		goto end;
+	}
+
+	socket = consumer_find_socket(consumer_fd, consumer);
+	if (!socket) {
+		ERR("Consumer socket fd %d not found in consumer obj %p",
+				consumer_fd, consumer);
+	}
+
+end:
+	return socket;
+}
+
+/*
+ * Find a consumer_socket in a consumer_output hashtable. Read side lock must
+ * be acquired before calling this function and across use of the
+ * returned consumer_socket.
+ */
+struct consumer_socket *consumer_find_socket(int key,
+		const struct consumer_output *consumer)
+{
+	struct lttng_ht_iter iter;
+	struct lttng_ht_node_ulong *node;
+	struct consumer_socket *socket = NULL;
+
+	/* Negative keys are lookup failures */
+	if (key < 0 || consumer == NULL) {
+		return NULL;
+	}
+
+	lttng_ht_lookup(consumer->socks, (void *)((unsigned long) key),
+			&iter);
+	node = lttng_ht_iter_get_node_ulong(&iter);
+	if (node != NULL) {
+		socket = caa_container_of(node, struct consumer_socket, node);
+	}
+
+	return socket;
+}
+
+/*
+ * Allocate a new consumer_socket and return the pointer.
+ */
+struct consumer_socket *consumer_allocate_socket(int *fd)
+{
+	struct consumer_socket *socket = NULL;
+
+	LTTNG_ASSERT(fd);
+
+	socket = (consumer_socket *) zmalloc(sizeof(struct consumer_socket));
+	if (socket == NULL) {
+		PERROR("zmalloc consumer socket");
+		goto error;
+	}
+
+	socket->fd_ptr = fd;
+	lttng_ht_node_init_ulong(&socket->node, *fd);
+
+error:
+	return socket;
+}
+
+/*
+ * Add consumer socket to consumer output object. Read side lock must be
+ * acquired before calling this function.
+ */
+void consumer_add_socket(struct consumer_socket *sock,
+		struct consumer_output *consumer)
+{
+	LTTNG_ASSERT(sock);
+	LTTNG_ASSERT(consumer);
+
+	lttng_ht_add_unique_ulong(consumer->socks, &sock->node);
+}
+
+/*
+ * Delete consumer socket to consumer output object. Read side lock must be
+ * acquired before calling this function.
+ */
+void consumer_del_socket(struct consumer_socket *sock,
+		struct consumer_output *consumer)
+{
+	int ret;
+	struct lttng_ht_iter iter;
+
+	LTTNG_ASSERT(sock);
+	LTTNG_ASSERT(consumer);
+
+	iter.iter.node = &sock->node.node;
+	ret = lttng_ht_del(consumer->socks, &iter);
+	LTTNG_ASSERT(!ret);
+}
+
+/*
+ * RCU destroy call function.
+ */
+static void destroy_socket_rcu(struct rcu_head *head)
+{
+	struct lttng_ht_node_ulong *node =
+		caa_container_of(head, struct lttng_ht_node_ulong, head);
+	struct consumer_socket *socket =
+		caa_container_of(node, struct consumer_socket, node);
+
+	free(socket);
+}
+
+/*
+ * Destroy and free socket pointer in a call RCU. Read side lock must be
+ * acquired before calling this function.
+ */
+void consumer_destroy_socket(struct consumer_socket *sock)
+{
+	LTTNG_ASSERT(sock);
+
+	/*
+	 * We DO NOT close the file descriptor here since it is global to the
+	 * session daemon and is closed only if the consumer dies or a custom
+	 * consumer was registered,
+	 */
+	if (sock->registered) {
+		DBG3("Consumer socket was registered. Closing fd %d", *sock->fd_ptr);
+		lttcomm_close_unix_sock(*sock->fd_ptr);
+	}
+
+	call_rcu(&sock->node.head, destroy_socket_rcu);
+}
+
+/*
+ * Allocate and assign data to a consumer_output object.
+ *
+ * Return pointer to structure.
+ */
+struct consumer_output *consumer_create_output(enum consumer_dst_type type)
+{
+	struct consumer_output *output = NULL;
+
+	output = (consumer_output *) zmalloc(sizeof(struct consumer_output));
+	if (output == NULL) {
+		PERROR("zmalloc consumer_output");
+		goto error;
+	}
+
+	/* By default, consumer output is enabled */
+	output->enabled = 1;
+	output->type = type;
+	output->net_seq_index = (uint64_t) -1ULL;
+	urcu_ref_init(&output->ref);
+
+	output->socks = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
+
+error:
+	return output;
+}
+
+/*
+ * Iterate over the consumer output socket hash table and destroy them. The
+ * socket file descriptor are only closed if the consumer output was
+ * registered meaning it's an external consumer.
+ */
+void consumer_destroy_output_sockets(struct consumer_output *obj)
+{
+	struct lttng_ht_iter iter;
+	struct consumer_socket *socket;
+
+	if (!obj->socks) {
+		return;
+	}
+
+	rcu_read_lock();
+	cds_lfht_for_each_entry(obj->socks->ht, &iter.iter, socket, node.node) {
+		consumer_del_socket(socket, obj);
+		consumer_destroy_socket(socket);
+	}
+	rcu_read_unlock();
+}
+
+/*
+ * Delete the consumer_output object from the list and free the ptr.
+ *
+ * Should *NOT* be called with RCU read-side lock held.
+ */
+static void consumer_release_output(struct urcu_ref *ref)
+{
+	struct consumer_output *obj =
+		caa_container_of(ref, struct consumer_output, ref);
+
+	consumer_destroy_output_sockets(obj);
+
+	if (obj->socks) {
+		/* Finally destroy HT */
+		ht_cleanup_push(obj->socks);
+	}
+
+	free(obj);
+}
+
+/*
+ * Get the consumer_output object.
+ */
+void consumer_output_get(struct consumer_output *obj)
+{
+	urcu_ref_get(&obj->ref);
+}
+
+/*
+ * Put the consumer_output object.
+ *
+ * Should *NOT* be called with RCU read-side lock held.
+ */
+void consumer_output_put(struct consumer_output *obj)
+{
+	if (!obj) {
+		return;
+	}
+	urcu_ref_put(&obj->ref, consumer_release_output);
+}
+
+/*
+ * Copy consumer output and returned the newly allocated copy.
+ *
+ * Should *NOT* be called with RCU read-side lock held.
+ */
+struct consumer_output *consumer_copy_output(struct consumer_output *src)
+{
+	int ret;
+	struct consumer_output *output;
+
+	LTTNG_ASSERT(src);
+
+	output = consumer_create_output(src->type);
+	if (output == NULL) {
+		goto end;
+	}
+	output->enabled = src->enabled;
+	output->net_seq_index = src->net_seq_index;
+	memcpy(output->domain_subdir, src->domain_subdir,
+			sizeof(output->domain_subdir));
+	output->snapshot = src->snapshot;
+	output->relay_major_version = src->relay_major_version;
+	output->relay_minor_version = src->relay_minor_version;
+	output->relay_allows_clear = src->relay_allows_clear;
+	memcpy(&output->dst, &src->dst, sizeof(output->dst));
+	ret = consumer_copy_sockets(output, src);
+	if (ret < 0) {
+		goto error_put;
+	}
+end:
+	return output;
+
+error_put:
+	consumer_output_put(output);
+	return NULL;
+}
+
+/*
+ * Copy consumer sockets from src to dst.
+ *
+ * Return 0 on success or else a negative value.
+ */
+int consumer_copy_sockets(struct consumer_output *dst,
+		struct consumer_output *src)
+{
+	int ret = 0;
+	struct lttng_ht_iter iter;
+	struct consumer_socket *socket, *copy_sock;
+
+	LTTNG_ASSERT(dst);
+	LTTNG_ASSERT(src);
+
+	rcu_read_lock();
+	cds_lfht_for_each_entry(src->socks->ht, &iter.iter, socket, node.node) {
+		/* Ignore socket that are already there. */
+		copy_sock = consumer_find_socket(*socket->fd_ptr, dst);
+		if (copy_sock) {
+			continue;
+		}
+
+		/* Create new socket object. */
+		copy_sock = consumer_allocate_socket(socket->fd_ptr);
+		if (copy_sock == NULL) {
+			rcu_read_unlock();
+			ret = -ENOMEM;
+			goto error;
+		}
+
+		copy_sock->registered = socket->registered;
+		/*
+		 * This is valid because this lock is shared accross all consumer
+		 * object being the global lock of the consumer data structure of the
+		 * session daemon.
+		 */
+		copy_sock->lock = socket->lock;
+		consumer_add_socket(copy_sock, dst);
+	}
+	rcu_read_unlock();
+
+error:
+	return ret;
+}
+
+/*
+ * Set network URI to the consumer output.
+ *
+ * Return 0 on success. Return 1 if the URI were equal. Else, negative value on
+ * error.
+ */
+int consumer_set_network_uri(const struct ltt_session *session,
+		struct consumer_output *output,
+		struct lttng_uri *uri)
+{
+	int ret;
+	struct lttng_uri *dst_uri = NULL;
+
+	/* Code flow error safety net. */
+	LTTNG_ASSERT(output);
+	LTTNG_ASSERT(uri);
+
+	switch (uri->stype) {
+	case LTTNG_STREAM_CONTROL:
+		dst_uri = &output->dst.net.control;
+		output->dst.net.control_isset = 1;
+		if (uri->port == 0) {
+			/* Assign default port. */
+			uri->port = DEFAULT_NETWORK_CONTROL_PORT;
+		} else {
+			if (output->dst.net.data_isset && uri->port ==
+					output->dst.net.data.port) {
+				ret = -LTTNG_ERR_INVALID;
+				goto error;
+			}
+		}
+		DBG3("Consumer control URI set with port %d", uri->port);
+		break;
+	case LTTNG_STREAM_DATA:
+		dst_uri = &output->dst.net.data;
+		output->dst.net.data_isset = 1;
+		if (uri->port == 0) {
+			/* Assign default port. */
+			uri->port = DEFAULT_NETWORK_DATA_PORT;
+		} else {
+			if (output->dst.net.control_isset && uri->port ==
+					output->dst.net.control.port) {
+				ret = -LTTNG_ERR_INVALID;
+				goto error;
+			}
+		}
+		DBG3("Consumer data URI set with port %d", uri->port);
+		break;
+	default:
+		ERR("Set network uri type unknown %d", uri->stype);
+		ret = -LTTNG_ERR_INVALID;
+		goto error;
+	}
+
+	ret = uri_compare(dst_uri, uri);
+	if (!ret) {
+		/* Same URI, don't touch it and return success. */
+		DBG3("URI network compare are the same");
+		goto equal;
+	}
+
+	/* URIs were not equal, replacing it. */
+	memcpy(dst_uri, uri, sizeof(struct lttng_uri));
+	output->type = CONSUMER_DST_NET;
+	if (dst_uri->stype != LTTNG_STREAM_CONTROL) {
+		/* Only the control uri needs to contain the path. */
+		goto end;
+	}
+
+	/*
+	 * If the user has specified a subdir as part of the control
+	 * URL, the session's base output directory is:
+	 *   /RELAYD_OUTPUT_PATH/HOSTNAME/USER_SPECIFIED_DIR
+	 *
+	 * Hence, the "base_dir" from which all stream files and
+	 * session rotation chunks are created takes the form
+	 *   /HOSTNAME/USER_SPECIFIED_DIR
+	 *
+	 * If the user has not specified an output directory as part of
+	 * the control URL, the base output directory has the form:
+	 *   /RELAYD_OUTPUT_PATH/HOSTNAME/SESSION_NAME-CREATION_TIME
+	 *
+	 * Hence, the "base_dir" from which all stream files and
+	 * session rotation chunks are created takes the form
+	 *   /HOSTNAME/SESSION_NAME-CREATION_TIME
+	 *
+	 * Note that automatically generated session names already
+	 * contain the session's creation time. In that case, the
+	 * creation time is omitted to prevent it from being duplicated
+	 * in the final directory hierarchy.
+	 */
+	if (*uri->subdir) {
+		if (strstr(uri->subdir, "../")) {
+			ERR("Network URI subdirs are not allowed to walk up the path hierarchy");
+			ret = -LTTNG_ERR_INVALID;
+			goto error;
+		}
+		ret = snprintf(output->dst.net.base_dir,
+				sizeof(output->dst.net.base_dir),
+				"/%s/%s/", session->hostname, uri->subdir);
+	} else {
+		if (session->has_auto_generated_name) {
+			ret = snprintf(output->dst.net.base_dir,
+					sizeof(output->dst.net.base_dir),
+					"/%s/%s/", session->hostname,
+					session->name);
+		} else {
+			char session_creation_datetime[16];
+			size_t strftime_ret;
+			struct tm *timeinfo;
+
+			timeinfo = localtime(&session->creation_time);
+			if (!timeinfo) {
+				ret = -LTTNG_ERR_FATAL;
+				goto error;
+			}
+			strftime_ret = strftime(session_creation_datetime,
+					sizeof(session_creation_datetime),
+					"%Y%m%d-%H%M%S", timeinfo);
+			if (strftime_ret == 0) {
+				ERR("Failed to format session creation timestamp while setting network URI");
+				ret = -LTTNG_ERR_FATAL;
+				goto error;
+			}
+			ret = snprintf(output->dst.net.base_dir,
+					sizeof(output->dst.net.base_dir),
+					"/%s/%s-%s/", session->hostname,
+					session->name,
+					session_creation_datetime);
+		}
+	}
+	if (ret >= sizeof(output->dst.net.base_dir)) {
+		ret = -LTTNG_ERR_INVALID;
+		ERR("Truncation occurred while setting network output base directory");
+		goto error;
+	} else if (ret == -1) {
+		ret = -LTTNG_ERR_INVALID;
+		PERROR("Error occurred while setting network output base directory");
+		goto error;
+	}
+
+	DBG3("Consumer set network uri base_dir path %s",
+			output->dst.net.base_dir);
+
+end:
+	return 0;
+equal:
+	return 1;
+error:
+	return ret;
+}
+
+/*
+ * Send file descriptor to consumer via sock.
+ *
+ * The consumer socket lock must be held by the caller.
+ */
+int consumer_send_fds(struct consumer_socket *sock, const int *fds,
+		size_t nb_fd)
+{
+	int ret;
+
+	LTTNG_ASSERT(fds);
+	LTTNG_ASSERT(sock);
+	LTTNG_ASSERT(nb_fd > 0);
+	LTTNG_ASSERT(pthread_mutex_trylock(sock->lock) == EBUSY);
+
+	ret = lttcomm_send_fds_unix_sock(*sock->fd_ptr, fds, nb_fd);
+	if (ret < 0) {
+		/* The above call will print a PERROR on error. */
+		DBG("Error when sending consumer fds on sock %d", *sock->fd_ptr);
+		goto error;
+	}
+
+	ret = consumer_recv_status_reply(sock);
+error:
+	return ret;
+}
+
+/*
+ * Consumer send communication message structure to consumer.
+ *
+ * The consumer socket lock must be held by the caller.
+ */
+int consumer_send_msg(struct consumer_socket *sock,
+		const struct lttcomm_consumer_msg *msg)
+{
+	int ret;
+
+	LTTNG_ASSERT(msg);
+	LTTNG_ASSERT(sock);
+	LTTNG_ASSERT(pthread_mutex_trylock(sock->lock) == EBUSY);
+
+	ret = consumer_socket_send(sock, msg, sizeof(struct lttcomm_consumer_msg));
+	if (ret < 0) {
+		goto error;
+	}
+
+	ret = consumer_recv_status_reply(sock);
+
+error:
+	return ret;
+}
+
+/*
+ * Consumer send channel communication message structure to consumer.
+ *
+ * The consumer socket lock must be held by the caller.
+ */
+int consumer_send_channel(struct consumer_socket *sock,
+		struct lttcomm_consumer_msg *msg)
+{
+	int ret;
+
+	LTTNG_ASSERT(msg);
+	LTTNG_ASSERT(sock);
+
+	ret = consumer_send_msg(sock, msg);
+	if (ret < 0) {
+		goto error;
+	}
+
+error:
+	return ret;
+}
+
+/*
+ * Populate the given consumer msg structure with the ask_channel command
+ * information.
+ */
+void consumer_init_ask_channel_comm_msg(struct lttcomm_consumer_msg *msg,
+		uint64_t subbuf_size,
+		uint64_t num_subbuf,
+		int overwrite,
+		unsigned int switch_timer_interval,
+		unsigned int read_timer_interval,
+		unsigned int live_timer_interval,
+		bool is_in_live_session,
+		unsigned int monitor_timer_interval,
+		int output,
+		int type,
+		uint64_t session_id,
+		const char *pathname,
+		const char *name,
+		uint64_t relayd_id,
+		uint64_t key,
+		unsigned char *uuid,
+		uint32_t chan_id,
+		uint64_t tracefile_size,
+		uint64_t tracefile_count,
+		uint64_t session_id_per_pid,
+		unsigned int monitor,
+		uint32_t ust_app_uid,
+		int64_t blocking_timeout,
+		const char *root_shm_path,
+		const char *shm_path,
+		struct lttng_trace_chunk *trace_chunk,
+		const struct lttng_credentials *buffer_credentials)
+{
+	LTTNG_ASSERT(msg);
+
+	/* Zeroed structure */
+	memset(msg, 0, sizeof(struct lttcomm_consumer_msg));
+	msg->u.ask_channel.buffer_credentials.uid = UINT32_MAX;
+	msg->u.ask_channel.buffer_credentials.gid = UINT32_MAX;
+
+	if (trace_chunk) {
+		uint64_t chunk_id;
+		enum lttng_trace_chunk_status chunk_status;
+
+		chunk_status = lttng_trace_chunk_get_id(trace_chunk, &chunk_id);
+		LTTNG_ASSERT(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
+		LTTNG_OPTIONAL_SET(&msg->u.ask_channel.chunk_id, chunk_id);
+	}
+	msg->u.ask_channel.buffer_credentials.uid =
+			lttng_credentials_get_uid(buffer_credentials);
+	msg->u.ask_channel.buffer_credentials.gid =
+			lttng_credentials_get_gid(buffer_credentials);
+
+	msg->cmd_type = LTTNG_CONSUMER_ASK_CHANNEL_CREATION;
+	msg->u.ask_channel.subbuf_size = subbuf_size;
+	msg->u.ask_channel.num_subbuf = num_subbuf ;
+	msg->u.ask_channel.overwrite = overwrite;
+	msg->u.ask_channel.switch_timer_interval = switch_timer_interval;
+	msg->u.ask_channel.read_timer_interval = read_timer_interval;
+	msg->u.ask_channel.live_timer_interval = live_timer_interval;
+	msg->u.ask_channel.is_live = is_in_live_session;
+	msg->u.ask_channel.monitor_timer_interval = monitor_timer_interval;
+	msg->u.ask_channel.output = output;
+	msg->u.ask_channel.type = type;
+	msg->u.ask_channel.session_id = session_id;
+	msg->u.ask_channel.session_id_per_pid = session_id_per_pid;
+	msg->u.ask_channel.relayd_id = relayd_id;
+	msg->u.ask_channel.key = key;
+	msg->u.ask_channel.chan_id = chan_id;
+	msg->u.ask_channel.tracefile_size = tracefile_size;
+	msg->u.ask_channel.tracefile_count = tracefile_count;
+	msg->u.ask_channel.monitor = monitor;
+	msg->u.ask_channel.ust_app_uid = ust_app_uid;
+	msg->u.ask_channel.blocking_timeout = blocking_timeout;
+
+	memcpy(msg->u.ask_channel.uuid, uuid, sizeof(msg->u.ask_channel.uuid));
+
+	if (pathname) {
+		strncpy(msg->u.ask_channel.pathname, pathname,
+				sizeof(msg->u.ask_channel.pathname));
+		msg->u.ask_channel.pathname[sizeof(msg->u.ask_channel.pathname)-1] = '\0';
+	}
+
+	strncpy(msg->u.ask_channel.name, name, sizeof(msg->u.ask_channel.name));
+	msg->u.ask_channel.name[sizeof(msg->u.ask_channel.name) - 1] = '\0';
+
+	if (root_shm_path) {
+		strncpy(msg->u.ask_channel.root_shm_path, root_shm_path,
+			sizeof(msg->u.ask_channel.root_shm_path));
+		msg->u.ask_channel.root_shm_path[sizeof(msg->u.ask_channel.root_shm_path) - 1] = '\0';
+	}
+	if (shm_path) {
+		strncpy(msg->u.ask_channel.shm_path, shm_path,
+			sizeof(msg->u.ask_channel.shm_path));
+		msg->u.ask_channel.shm_path[sizeof(msg->u.ask_channel.shm_path) - 1] = '\0';
+	}
+}
+
+/*
+ * Init channel communication message structure.
+ */
+void consumer_init_add_channel_comm_msg(struct lttcomm_consumer_msg *msg,
+		uint64_t channel_key,
+		uint64_t session_id,
+		const char *pathname,
+		uid_t uid,
+		gid_t gid,
+		uint64_t relayd_id,
+		const char *name,
+		unsigned int nb_init_streams,
+		enum lttng_event_output output,
+		int type,
+		uint64_t tracefile_size,
+		uint64_t tracefile_count,
+		unsigned int monitor,
+		unsigned int live_timer_interval,
+		bool is_in_live_session,
+		unsigned int monitor_timer_interval,
+		struct lttng_trace_chunk *trace_chunk)
+{
+	LTTNG_ASSERT(msg);
+
+	/* Zeroed structure */
+	memset(msg, 0, sizeof(struct lttcomm_consumer_msg));
+
+	if (trace_chunk) {
+		uint64_t chunk_id;
+		enum lttng_trace_chunk_status chunk_status;
+
+		chunk_status = lttng_trace_chunk_get_id(trace_chunk, &chunk_id);
+		LTTNG_ASSERT(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
+		LTTNG_OPTIONAL_SET(&msg->u.channel.chunk_id, chunk_id);
+	}
+
+	/* Send channel */
+	msg->cmd_type = LTTNG_CONSUMER_ADD_CHANNEL;
+	msg->u.channel.channel_key = channel_key;
+	msg->u.channel.session_id = session_id;
+	msg->u.channel.relayd_id = relayd_id;
+	msg->u.channel.nb_init_streams = nb_init_streams;
+	msg->u.channel.output = output;
+	msg->u.channel.type = type;
+	msg->u.channel.tracefile_size = tracefile_size;
+	msg->u.channel.tracefile_count = tracefile_count;
+	msg->u.channel.monitor = monitor;
+	msg->u.channel.live_timer_interval = live_timer_interval;
+	msg->u.channel.is_live = is_in_live_session;
+	msg->u.channel.monitor_timer_interval = monitor_timer_interval;
+
+	strncpy(msg->u.channel.pathname, pathname,
+			sizeof(msg->u.channel.pathname));
+	msg->u.channel.pathname[sizeof(msg->u.channel.pathname) - 1] = '\0';
+
+	strncpy(msg->u.channel.name, name, sizeof(msg->u.channel.name));
+	msg->u.channel.name[sizeof(msg->u.channel.name) - 1] = '\0';
+}
+
+/*
+ * Init stream communication message structure.
+ */
+void consumer_init_add_stream_comm_msg(struct lttcomm_consumer_msg *msg,
+		uint64_t channel_key,
+		uint64_t stream_key,
+		int32_t cpu)
+{
+	LTTNG_ASSERT(msg);
+
+	memset(msg, 0, sizeof(struct lttcomm_consumer_msg));
+
+	msg->cmd_type = LTTNG_CONSUMER_ADD_STREAM;
+	msg->u.stream.channel_key = channel_key;
+	msg->u.stream.stream_key = stream_key;
+	msg->u.stream.cpu = cpu;
+}
+
+void consumer_init_streams_sent_comm_msg(struct lttcomm_consumer_msg *msg,
+		enum lttng_consumer_command cmd,
+		uint64_t channel_key, uint64_t net_seq_idx)
+{
+	LTTNG_ASSERT(msg);
+
+	memset(msg, 0, sizeof(struct lttcomm_consumer_msg));
+
+	msg->cmd_type = cmd;
+	msg->u.sent_streams.channel_key = channel_key;
+	msg->u.sent_streams.net_seq_idx = net_seq_idx;
+}
+
+/*
+ * Send stream communication structure to the consumer.
+ */
+int consumer_send_stream(struct consumer_socket *sock,
+		struct consumer_output *dst, struct lttcomm_consumer_msg *msg,
+		const int *fds, size_t nb_fd)
+{
+	int ret;
+
+	LTTNG_ASSERT(msg);
+	LTTNG_ASSERT(dst);
+	LTTNG_ASSERT(sock);
+	LTTNG_ASSERT(fds);
+
+	ret = consumer_send_msg(sock, msg);
+	if (ret < 0) {
+		goto error;
+	}
+
+	ret = consumer_send_fds(sock, fds, nb_fd);
+	if (ret < 0) {
+		goto error;
+	}
+
+error:
+	return ret;
+}
+
+/*
+ * Send relayd socket to consumer associated with a session name.
+ *
+ * The consumer socket lock must be held by the caller.
+ *
+ * On success return positive value. On error, negative value.
+ */
+int consumer_send_relayd_socket(struct consumer_socket *consumer_sock,
+		struct lttcomm_relayd_sock *rsock, struct consumer_output *consumer,
+		enum lttng_stream_type type, uint64_t session_id,
+		const char *session_name, const char *hostname,
+		const char *base_path, int session_live_timer,
+		const uint64_t *current_chunk_id, time_t session_creation_time,
+		bool session_name_contains_creation_time)
+{
+	int ret;
+	int fd;
+	struct lttcomm_consumer_msg msg;
+
+	/* Code flow error. Safety net. */
+	LTTNG_ASSERT(rsock);
+	LTTNG_ASSERT(consumer);
+	LTTNG_ASSERT(consumer_sock);
+
+	memset(&msg, 0, sizeof(msg));
+	/* Bail out if consumer is disabled */
+	if (!consumer->enabled) {
+		ret = LTTNG_OK;
+		goto error;
+	}
+
+	if (type == LTTNG_STREAM_CONTROL) {
+		char output_path[LTTNG_PATH_MAX] = {};
+		uint64_t relayd_session_id;
+
+		ret = relayd_create_session(rsock, &relayd_session_id,
+				session_name, hostname, base_path,
+				session_live_timer, consumer->snapshot,
+				session_id, the_sessiond_uuid, current_chunk_id,
+				session_creation_time,
+				session_name_contains_creation_time,
+				output_path);
+		if (ret < 0) {
+			/* Close the control socket. */
+			(void) relayd_close(rsock);
+			goto error;
+		}
+		msg.u.relayd_sock.relayd_session_id = relayd_session_id;
+		DBG("Created session on relay, output path reply: %s",
+			output_path);
+	}
+
+	msg.cmd_type = LTTNG_CONSUMER_ADD_RELAYD_SOCKET;
+	/*
+	 * Assign network consumer output index using the temporary consumer since
+	 * this call should only be made from within a set_consumer_uri() function
+	 * call in the session daemon.
+	 */
+	msg.u.relayd_sock.net_index = consumer->net_seq_index;
+	msg.u.relayd_sock.type = type;
+	msg.u.relayd_sock.session_id = session_id;
+	memcpy(&msg.u.relayd_sock.sock, rsock, sizeof(msg.u.relayd_sock.sock));
+
+	DBG3("Sending relayd sock info to consumer on %d", *consumer_sock->fd_ptr);
+	ret = consumer_send_msg(consumer_sock, &msg);
+	if (ret < 0) {
+		goto error;
+	}
+
+	DBG3("Sending relayd socket file descriptor to consumer");
+	fd = rsock->sock.fd;
+	ret = consumer_send_fds(consumer_sock, &fd, 1);
+	if (ret < 0) {
+		goto error;
+	}
+
+	DBG2("Consumer relayd socket sent");
+
+error:
+	return ret;
+}
+
+static
+int consumer_send_pipe(struct consumer_socket *consumer_sock,
+		enum lttng_consumer_command cmd, int pipe)
+{
+	int ret;
+	struct lttcomm_consumer_msg msg;
+	const char *pipe_name;
+	const char *command_name;
+
+	switch (cmd) {
+	case LTTNG_CONSUMER_SET_CHANNEL_MONITOR_PIPE:
+		pipe_name = "channel monitor";
+		command_name = "SET_CHANNEL_MONITOR_PIPE";
+		break;
+	default:
+		ERR("Unexpected command received in %s (cmd = %d)", __func__,
+				(int) cmd);
+		abort();
+	}
+
+	/* Code flow error. Safety net. */
+
+	memset(&msg, 0, sizeof(msg));
+	msg.cmd_type = cmd;
+
+	pthread_mutex_lock(consumer_sock->lock);
+	DBG3("Sending %s command to consumer", command_name);
+	ret = consumer_send_msg(consumer_sock, &msg);
+	if (ret < 0) {
+		goto error;
+	}
+
+	DBG3("Sending %s pipe %d to consumer on socket %d",
+			pipe_name,
+			pipe, *consumer_sock->fd_ptr);
+	ret = consumer_send_fds(consumer_sock, &pipe, 1);
+	if (ret < 0) {
+		goto error;
+	}
+
+	DBG2("%s pipe successfully sent", pipe_name);
+error:
+	pthread_mutex_unlock(consumer_sock->lock);
+	return ret;
+}
+
+int consumer_send_channel_monitor_pipe(struct consumer_socket *consumer_sock,
+		int pipe)
+{
+	return consumer_send_pipe(consumer_sock,
+			LTTNG_CONSUMER_SET_CHANNEL_MONITOR_PIPE, pipe);
+}
+
+/*
+ * Ask the consumer if the data is pending for the specific session id.
+ * Returns 1 if data is pending, 0 otherwise, or < 0 on error.
+ */
+int consumer_is_data_pending(uint64_t session_id,
+		struct consumer_output *consumer)
+{
+	int ret;
+	int32_t ret_code = 0;  /* Default is that the data is NOT pending */
+	struct consumer_socket *socket;
+	struct lttng_ht_iter iter;
+	struct lttcomm_consumer_msg msg;
+
+	LTTNG_ASSERT(consumer);
+
+	DBG3("Consumer data pending for id %" PRIu64, session_id);
+
+	memset(&msg, 0, sizeof(msg));
+	msg.cmd_type = LTTNG_CONSUMER_DATA_PENDING;
+	msg.u.data_pending.session_id = session_id;
+
+	/* Send command for each consumer */
+	rcu_read_lock();
+	cds_lfht_for_each_entry(consumer->socks->ht, &iter.iter, socket,
+			node.node) {
+		pthread_mutex_lock(socket->lock);
+		ret = consumer_socket_send(socket, &msg, sizeof(msg));
+		if (ret < 0) {
+			pthread_mutex_unlock(socket->lock);
+			goto error_unlock;
+		}
+
+		/*
+		 * No need for a recv reply status because the answer to the command is
+		 * the reply status message.
+		 */
+
+		ret = consumer_socket_recv(socket, &ret_code, sizeof(ret_code));
+		if (ret < 0) {
+			pthread_mutex_unlock(socket->lock);
+			goto error_unlock;
+		}
+		pthread_mutex_unlock(socket->lock);
+
+		if (ret_code == 1) {
+			break;
+		}
+	}
+	rcu_read_unlock();
+
+	DBG("Consumer data is %s pending for session id %" PRIu64,
+			ret_code == 1 ? "" : "NOT", session_id);
+	return ret_code;
+
+error_unlock:
+	rcu_read_unlock();
+	return -1;
+}
+
+/*
+ * Send a flush command to consumer using the given channel key.
+ *
+ * Return 0 on success else a negative value.
+ */
+int consumer_flush_channel(struct consumer_socket *socket, uint64_t key)
+{
+	int ret;
+	struct lttcomm_consumer_msg msg;
+
+	LTTNG_ASSERT(socket);
+
+	DBG2("Consumer flush channel key %" PRIu64, key);
+
+	memset(&msg, 0, sizeof(msg));
+	msg.cmd_type = LTTNG_CONSUMER_FLUSH_CHANNEL;
+	msg.u.flush_channel.key = key;
+
+	pthread_mutex_lock(socket->lock);
+	health_code_update();
+
+	ret = consumer_send_msg(socket, &msg);
+	if (ret < 0) {
+		goto end;
+	}
+
+end:
+	health_code_update();
+	pthread_mutex_unlock(socket->lock);
+	return ret;
+}
+
+/*
+ * Send a clear quiescent command to consumer using the given channel key.
+ *
+ * Return 0 on success else a negative value.
+ */
+int consumer_clear_quiescent_channel(struct consumer_socket *socket, uint64_t key)
+{
+	int ret;
+	struct lttcomm_consumer_msg msg;
+
+	LTTNG_ASSERT(socket);
+
+	DBG2("Consumer clear quiescent channel key %" PRIu64, key);
+
+	memset(&msg, 0, sizeof(msg));
+	msg.cmd_type = LTTNG_CONSUMER_CLEAR_QUIESCENT_CHANNEL;
+	msg.u.clear_quiescent_channel.key = key;
+
+	pthread_mutex_lock(socket->lock);
+	health_code_update();
+
+	ret = consumer_send_msg(socket, &msg);
+	if (ret < 0) {
+		goto end;
+	}
+
+end:
+	health_code_update();
+	pthread_mutex_unlock(socket->lock);
+	return ret;
+}
+
+/*
+ * Send a close metadata command to consumer using the given channel key.
+ * Called with registry lock held.
+ *
+ * Return 0 on success else a negative value.
+ */
+int consumer_close_metadata(struct consumer_socket *socket,
+		uint64_t metadata_key)
+{
+	int ret;
+	struct lttcomm_consumer_msg msg;
+
+	LTTNG_ASSERT(socket);
+
+	DBG2("Consumer close metadata channel key %" PRIu64, metadata_key);
+
+	memset(&msg, 0, sizeof(msg));
+	msg.cmd_type = LTTNG_CONSUMER_CLOSE_METADATA;
+	msg.u.close_metadata.key = metadata_key;
+
+	pthread_mutex_lock(socket->lock);
+	health_code_update();
+
+	ret = consumer_send_msg(socket, &msg);
+	if (ret < 0) {
+		goto end;
+	}
+
+end:
+	health_code_update();
+	pthread_mutex_unlock(socket->lock);
+	return ret;
+}
+
+/*
+ * Send a setup metdata command to consumer using the given channel key.
+ *
+ * Return 0 on success else a negative value.
+ */
+int consumer_setup_metadata(struct consumer_socket *socket,
+		uint64_t metadata_key)
+{
+	int ret;
+	struct lttcomm_consumer_msg msg;
+
+	LTTNG_ASSERT(socket);
+
+	DBG2("Consumer setup metadata channel key %" PRIu64, metadata_key);
+
+	memset(&msg, 0, sizeof(msg));
+	msg.cmd_type = LTTNG_CONSUMER_SETUP_METADATA;
+	msg.u.setup_metadata.key = metadata_key;
+
+	pthread_mutex_lock(socket->lock);
+	health_code_update();
+
+	ret = consumer_send_msg(socket, &msg);
+	if (ret < 0) {
+		goto end;
+	}
+
+end:
+	health_code_update();
+	pthread_mutex_unlock(socket->lock);
+	return ret;
+}
+
+/*
+ * Send metadata string to consumer.
+ * RCU read-side lock must be held to guarantee existence of socket.
+ *
+ * Return 0 on success else a negative value.
+ */
+int consumer_push_metadata(struct consumer_socket *socket,
+		uint64_t metadata_key, char *metadata_str, size_t len,
+		size_t target_offset, uint64_t version)
+{
+	int ret;
+	struct lttcomm_consumer_msg msg;
+
+	LTTNG_ASSERT(socket);
+
+	DBG2("Consumer push metadata to consumer socket %d", *socket->fd_ptr);
+
+	pthread_mutex_lock(socket->lock);
+
+	memset(&msg, 0, sizeof(msg));
+	msg.cmd_type = LTTNG_CONSUMER_PUSH_METADATA;
+	msg.u.push_metadata.key = metadata_key;
+	msg.u.push_metadata.target_offset = target_offset;
+	msg.u.push_metadata.len = len;
+	msg.u.push_metadata.version = version;
+
+	health_code_update();
+	ret = consumer_send_msg(socket, &msg);
+	if (ret < 0 || len == 0) {
+		goto end;
+	}
+
+	DBG3("Consumer pushing metadata on sock %d of len %zu", *socket->fd_ptr,
+			len);
+
+	ret = consumer_socket_send(socket, metadata_str, len);
+	if (ret < 0) {
+		goto end;
+	}
+
+	health_code_update();
+	ret = consumer_recv_status_reply(socket);
+	if (ret < 0) {
+		goto end;
+	}
+
+end:
+	pthread_mutex_unlock(socket->lock);
+	health_code_update();
+	return ret;
+}
+
+/*
+ * Ask the consumer to snapshot a specific channel using the key.
+ *
+ * Returns LTTNG_OK on success or else an LTTng error code.
+ */
+enum lttng_error_code consumer_snapshot_channel(struct consumer_socket *socket,
+		uint64_t key, const struct consumer_output *output, int metadata,
+		uid_t uid, gid_t gid, const char *channel_path, int wait,
+		uint64_t nb_packets_per_stream)
+{
+	int ret;
+	enum lttng_error_code status = LTTNG_OK;
+	struct lttcomm_consumer_msg msg;
+
+	LTTNG_ASSERT(socket);
+	LTTNG_ASSERT(output);
+
+	DBG("Consumer snapshot channel key %" PRIu64, key);
+
+	memset(&msg, 0, sizeof(msg));
+	msg.cmd_type = LTTNG_CONSUMER_SNAPSHOT_CHANNEL;
+	msg.u.snapshot_channel.key = key;
+	msg.u.snapshot_channel.nb_packets_per_stream = nb_packets_per_stream;
+	msg.u.snapshot_channel.metadata = metadata;
+
+	if (output->type == CONSUMER_DST_NET) {
+		msg.u.snapshot_channel.relayd_id =
+				output->net_seq_index;
+		msg.u.snapshot_channel.use_relayd = 1;
+	} else {
+		msg.u.snapshot_channel.relayd_id = (uint64_t) -1ULL;
+	}
+	ret = lttng_strncpy(msg.u.snapshot_channel.pathname,
+			channel_path,
+			sizeof(msg.u.snapshot_channel.pathname));
+	if (ret < 0) {
+		ERR("Snapshot path exceeds the maximal allowed length of %zu bytes (%zu bytes required) with path \"%s\"",
+				sizeof(msg.u.snapshot_channel.pathname),
+				strlen(channel_path),
+				channel_path);
+		status = LTTNG_ERR_SNAPSHOT_FAIL;
+		goto error;
+	}
+
+	health_code_update();
+	pthread_mutex_lock(socket->lock);
+	ret = consumer_send_msg(socket, &msg);
+	pthread_mutex_unlock(socket->lock);
+	if (ret < 0) {
+		switch (-ret) {
+		case LTTCOMM_CONSUMERD_CHAN_NOT_FOUND:
+			status = LTTNG_ERR_CHAN_NOT_FOUND;
+			break;
+		default:
+			status = LTTNG_ERR_SNAPSHOT_FAIL;
+			break;
+		}
+		goto error;
+	}
+
+error:
+	health_code_update();
+	return status;
+}
+
+/*
+ * Ask the consumer the number of discarded events for a channel.
+ */
+int consumer_get_discarded_events(uint64_t session_id, uint64_t channel_key,
+		struct consumer_output *consumer, uint64_t *discarded)
+{
+	int ret;
+	struct consumer_socket *socket;
+	struct lttng_ht_iter iter;
+	struct lttcomm_consumer_msg msg;
+
+	LTTNG_ASSERT(consumer);
+
+	DBG3("Consumer discarded events id %" PRIu64, session_id);
+
+	memset(&msg, 0, sizeof(msg));
+	msg.cmd_type = LTTNG_CONSUMER_DISCARDED_EVENTS;
+	msg.u.discarded_events.session_id = session_id;
+	msg.u.discarded_events.channel_key = channel_key;
+
+	*discarded = 0;
+
+	/* Send command for each consumer */
+	rcu_read_lock();
+	cds_lfht_for_each_entry(consumer->socks->ht, &iter.iter, socket,
+			node.node) {
+		uint64_t consumer_discarded = 0;
+		pthread_mutex_lock(socket->lock);
+		ret = consumer_socket_send(socket, &msg, sizeof(msg));
+		if (ret < 0) {
+			pthread_mutex_unlock(socket->lock);
+			goto end;
+		}
+
+		/*
+		 * No need for a recv reply status because the answer to the
+		 * command is the reply status message.
+		 */
+		ret = consumer_socket_recv(socket, &consumer_discarded,
+				sizeof(consumer_discarded));
+		if (ret < 0) {
+			ERR("get discarded events");
+			pthread_mutex_unlock(socket->lock);
+			goto end;
+		}
+		pthread_mutex_unlock(socket->lock);
+		*discarded += consumer_discarded;
+	}
+	ret = 0;
+	DBG("Consumer discarded %" PRIu64 " events in session id %" PRIu64,
+			*discarded, session_id);
+
+end:
+	rcu_read_unlock();
+	return ret;
+}
+
+/*
+ * Ask the consumer the number of lost packets for a channel.
+ */
+int consumer_get_lost_packets(uint64_t session_id, uint64_t channel_key,
+		struct consumer_output *consumer, uint64_t *lost)
+{
+	int ret;
+	struct consumer_socket *socket;
+	struct lttng_ht_iter iter;
+	struct lttcomm_consumer_msg msg;
+
+	LTTNG_ASSERT(consumer);
+
+	DBG3("Consumer lost packets id %" PRIu64, session_id);
+
+	memset(&msg, 0, sizeof(msg));
+	msg.cmd_type = LTTNG_CONSUMER_LOST_PACKETS;
+	msg.u.lost_packets.session_id = session_id;
+	msg.u.lost_packets.channel_key = channel_key;
+
+	*lost = 0;
+
+	/* Send command for each consumer */
+	rcu_read_lock();
+	cds_lfht_for_each_entry(consumer->socks->ht, &iter.iter, socket,
+			node.node) {
+		uint64_t consumer_lost = 0;
+		pthread_mutex_lock(socket->lock);
+		ret = consumer_socket_send(socket, &msg, sizeof(msg));
+		if (ret < 0) {
+			pthread_mutex_unlock(socket->lock);
+			goto end;
+		}
+
+		/*
+		 * No need for a recv reply status because the answer to the
+		 * command is the reply status message.
+		 */
+		ret = consumer_socket_recv(socket, &consumer_lost,
+				sizeof(consumer_lost));
+		if (ret < 0) {
+			ERR("get lost packets");
+			pthread_mutex_unlock(socket->lock);
+			goto end;
+		}
+		pthread_mutex_unlock(socket->lock);
+		*lost += consumer_lost;
+	}
+	ret = 0;
+	DBG("Consumer lost %" PRIu64 " packets in session id %" PRIu64,
+			*lost, session_id);
+
+end:
+	rcu_read_unlock();
+	return ret;
+}
+
+/*
+ * Ask the consumer to rotate a channel.
+ *
+ * The new_chunk_id is the session->rotate_count that has been incremented
+ * when the rotation started. On the relay, this allows to keep track in which
+ * chunk each stream is currently writing to (for the rotate_pending operation).
+ */
+int consumer_rotate_channel(struct consumer_socket *socket, uint64_t key,
+		uid_t uid, gid_t gid, struct consumer_output *output,
+		bool is_metadata_channel)
+{
+	int ret;
+	struct lttcomm_consumer_msg msg;
+
+	LTTNG_ASSERT(socket);
+
+	DBG("Consumer rotate channel key %" PRIu64, key);
+
+	pthread_mutex_lock(socket->lock);
+	memset(&msg, 0, sizeof(msg));
+	msg.cmd_type = LTTNG_CONSUMER_ROTATE_CHANNEL;
+	msg.u.rotate_channel.key = key;
+	msg.u.rotate_channel.metadata = !!is_metadata_channel;
+
+	if (output->type == CONSUMER_DST_NET) {
+		msg.u.rotate_channel.relayd_id = output->net_seq_index;
+	} else {
+		msg.u.rotate_channel.relayd_id = (uint64_t) -1ULL;
+	}
+
+	health_code_update();
+	ret = consumer_send_msg(socket, &msg);
+	if (ret < 0) {
+		switch (-ret) {
+		case LTTCOMM_CONSUMERD_CHAN_NOT_FOUND:
+			ret = -LTTNG_ERR_CHAN_NOT_FOUND;
+			break;
+		default:
+			ret = -LTTNG_ERR_ROTATION_FAIL_CONSUMER;
+			break;
+		}
+		goto error;
+	}
+error:
+	pthread_mutex_unlock(socket->lock);
+	health_code_update();
+	return ret;
+}
+
+int consumer_open_channel_packets(struct consumer_socket *socket, uint64_t key)
+{
+	int ret;
+	lttcomm_consumer_msg msg = {
+		.cmd_type = LTTNG_CONSUMER_OPEN_CHANNEL_PACKETS,
+	};
+	msg.u.open_channel_packets.key = key;
+
+	LTTNG_ASSERT(socket);
+
+	DBG("Consumer open channel packets: channel key = %" PRIu64, key);
+
+	health_code_update();
+
+	pthread_mutex_lock(socket->lock);
+	ret = consumer_send_msg(socket, &msg);
+	pthread_mutex_unlock(socket->lock);
+	if (ret < 0) {
+		goto error_socket;
+	}
+
+error_socket:
+	health_code_update();
+	return ret;
+}
+
+int consumer_clear_channel(struct consumer_socket *socket, uint64_t key)
+{
+	int ret;
+	struct lttcomm_consumer_msg msg;
+
+	LTTNG_ASSERT(socket);
+
+	DBG("Consumer clear channel %" PRIu64, key);
+
+	memset(&msg, 0, sizeof(msg));
+	msg.cmd_type = LTTNG_CONSUMER_CLEAR_CHANNEL;
+	msg.u.clear_channel.key = key;
+
+	health_code_update();
+
+	pthread_mutex_lock(socket->lock);
+	ret = consumer_send_msg(socket, &msg);
+	if (ret < 0) {
+		goto error_socket;
+	}
+
+error_socket:
+	pthread_mutex_unlock(socket->lock);
+
+	health_code_update();
+	return ret;
+}
+
+int consumer_init(struct consumer_socket *socket,
+		const lttng_uuid sessiond_uuid)
+{
+	int ret;
+	struct lttcomm_consumer_msg msg = {
+		.cmd_type = LTTNG_CONSUMER_INIT,
+	};
+
+	LTTNG_ASSERT(socket);
+
+	DBG("Sending consumer initialization command");
+	lttng_uuid_copy(msg.u.init.sessiond_uuid, sessiond_uuid);
+
+	health_code_update();
+	ret = consumer_send_msg(socket, &msg);
+	if (ret < 0) {
+		goto error;
+	}
+
+error:
+	health_code_update();
+	return ret;
+}
+
+/*
+ * Ask the consumer to create a new chunk for a given session.
+ *
+ * Called with the consumer socket lock held.
+ */
+int consumer_create_trace_chunk(struct consumer_socket *socket,
+		uint64_t relayd_id, uint64_t session_id,
+		struct lttng_trace_chunk *chunk,
+		const char *domain_subdir)
+{
+	int ret;
+	enum lttng_trace_chunk_status chunk_status;
+	struct lttng_credentials chunk_credentials;
+	const struct lttng_directory_handle *chunk_directory_handle = NULL;
+	struct lttng_directory_handle *domain_handle = NULL;
+	int domain_dirfd;
+	const char *chunk_name;
+	bool chunk_name_overridden;
+	uint64_t chunk_id;
+	time_t creation_timestamp;
+	char creation_timestamp_buffer[ISO8601_STR_LEN];
+	const char *creation_timestamp_str = "(none)";
+	const bool chunk_has_local_output = relayd_id == -1ULL;
+	enum lttng_trace_chunk_status tc_status;
+	struct lttcomm_consumer_msg msg = {
+		.cmd_type = LTTNG_CONSUMER_CREATE_TRACE_CHUNK,
+	};
+	msg.u.create_trace_chunk.session_id = session_id;
+
+	LTTNG_ASSERT(socket);
+	LTTNG_ASSERT(chunk);
+
+	if (relayd_id != -1ULL) {
+		LTTNG_OPTIONAL_SET(&msg.u.create_trace_chunk.relayd_id,
+				relayd_id);
+	}
+
+	chunk_status = lttng_trace_chunk_get_name(chunk, &chunk_name,
+			&chunk_name_overridden);
+	if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK &&
+			chunk_status != LTTNG_TRACE_CHUNK_STATUS_NONE) {
+		ERR("Failed to get name of trace chunk");
+		ret = -LTTNG_ERR_FATAL;
+		goto error;
+	}
+	if (chunk_name_overridden) {
+		ret = lttng_strncpy(msg.u.create_trace_chunk.override_name,
+				chunk_name,
+				sizeof(msg.u.create_trace_chunk.override_name));
+		if (ret) {
+			ERR("Trace chunk name \"%s\" exceeds the maximal length allowed by the consumer protocol",
+					chunk_name);
+			ret = -LTTNG_ERR_FATAL;
+			goto error;
+		}
+	}
+
+	chunk_status = lttng_trace_chunk_get_creation_timestamp(chunk,
+			&creation_timestamp);
+	if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+		ret = -LTTNG_ERR_FATAL;
+		goto error;
+	}
+	msg.u.create_trace_chunk.creation_timestamp =
+			(uint64_t) creation_timestamp;
+	/* Only used for logging purposes. */
+	ret = time_to_iso8601_str(creation_timestamp,
+			creation_timestamp_buffer,
+			sizeof(creation_timestamp_buffer));
+	creation_timestamp_str = !ret ? creation_timestamp_buffer :
+			"(formatting error)";
+
+	chunk_status = lttng_trace_chunk_get_id(chunk, &chunk_id);
+	if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+		/*
+		 * Anonymous trace chunks should never be transmitted
+		 * to remote peers (consumerd and relayd). They are used
+		 * internally for backward-compatibility purposes.
+		 */
+		ret = -LTTNG_ERR_FATAL;
+		goto error;
+	}
+	msg.u.create_trace_chunk.chunk_id = chunk_id;
+
+	if (chunk_has_local_output) {
+		chunk_status = lttng_trace_chunk_borrow_chunk_directory_handle(
+				chunk, &chunk_directory_handle);
+		if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+			ret = -LTTNG_ERR_FATAL;
+			goto error;
+		}
+		chunk_status = lttng_trace_chunk_get_credentials(
+				chunk, &chunk_credentials);
+		if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+			/*
+			 * Not associating credentials to a sessiond chunk is a
+			 * fatal internal error.
+			 */
+			ret = -LTTNG_ERR_FATAL;
+			goto error;
+		}
+		tc_status = lttng_trace_chunk_create_subdirectory(
+				chunk, domain_subdir);
+		if (tc_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+			PERROR("Failed to create chunk domain output directory \"%s\"",
+				domain_subdir);
+			ret = -LTTNG_ERR_FATAL;
+			goto error;
+		}
+		domain_handle = lttng_directory_handle_create_from_handle(
+				domain_subdir,
+				chunk_directory_handle);
+		if (!domain_handle) {
+			ret = -LTTNG_ERR_FATAL;
+			goto error;
+		}
+
+		/*
+		 * This will only compile on platforms that support
+		 * dirfd (POSIX.2008). This is fine as the session daemon
+		 * is only built for such platforms.
+		 *
+		 * The ownership of the chunk directory handle's is maintained
+		 * by the trace chunk.
+		 */
+		domain_dirfd = lttng_directory_handle_get_dirfd(
+				domain_handle);
+		LTTNG_ASSERT(domain_dirfd >= 0);
+
+		msg.u.create_trace_chunk.credentials.value.uid =
+				lttng_credentials_get_uid(&chunk_credentials);
+		msg.u.create_trace_chunk.credentials.value.gid =
+				lttng_credentials_get_gid(&chunk_credentials);
+		msg.u.create_trace_chunk.credentials.is_set = 1;
+	}
+
+	DBG("Sending consumer create trace chunk command: relayd_id = %" PRId64
+			", session_id = %" PRIu64 ", chunk_id = %" PRIu64
+			", creation_timestamp = %s",
+			relayd_id, session_id, chunk_id,
+			creation_timestamp_str);
+	health_code_update();
+	ret = consumer_send_msg(socket, &msg);
+	health_code_update();
+	if (ret < 0) {
+		ERR("Trace chunk creation error on consumer");
+		ret = -LTTNG_ERR_CREATE_TRACE_CHUNK_FAIL_CONSUMER;
+		goto error;
+	}
+
+	if (chunk_has_local_output) {
+		DBG("Sending trace chunk domain directory fd to consumer");
+		health_code_update();
+		ret = consumer_send_fds(socket, &domain_dirfd, 1);
+		health_code_update();
+		if (ret < 0) {
+			ERR("Trace chunk creation error on consumer");
+			ret = -LTTNG_ERR_CREATE_TRACE_CHUNK_FAIL_CONSUMER;
+			goto error;
+		}
+	}
+error:
+	lttng_directory_handle_put(domain_handle);
+	return ret;
+}
+
+/*
+ * Ask the consumer to close a trace chunk for a given session.
+ *
+ * Called with the consumer socket lock held.
+ */
+int consumer_close_trace_chunk(struct consumer_socket *socket,
+		uint64_t relayd_id, uint64_t session_id,
+		struct lttng_trace_chunk *chunk,
+		char *closed_trace_chunk_path)
+{
+	int ret;
+	enum lttng_trace_chunk_status chunk_status;
+	lttcomm_consumer_msg msg = {
+		.cmd_type = LTTNG_CONSUMER_CLOSE_TRACE_CHUNK,
+	};
+	msg.u.close_trace_chunk.session_id = session_id;
+
+	struct lttcomm_consumer_close_trace_chunk_reply reply;
+	uint64_t chunk_id;
+	time_t close_timestamp;
+	enum lttng_trace_chunk_command_type close_command;
+	const char *close_command_name = "none";
+	struct lttng_dynamic_buffer path_reception_buffer;
+
+	LTTNG_ASSERT(socket);
+	lttng_dynamic_buffer_init(&path_reception_buffer);
+
+	if (relayd_id != -1ULL) {
+		LTTNG_OPTIONAL_SET(
+				&msg.u.close_trace_chunk.relayd_id, relayd_id);
+	}
+
+	chunk_status = lttng_trace_chunk_get_close_command(
+			chunk, &close_command);
+	switch (chunk_status) {
+	case LTTNG_TRACE_CHUNK_STATUS_OK:
+		LTTNG_OPTIONAL_SET(&msg.u.close_trace_chunk.close_command,
+				(uint32_t) close_command);
+		break;
+	case LTTNG_TRACE_CHUNK_STATUS_NONE:
+		break;
+	default:
+		ERR("Failed to get trace chunk close command");
+		ret = -1;
+		goto error;
+	}
+
+	chunk_status = lttng_trace_chunk_get_id(chunk, &chunk_id);
+	/*
+	 * Anonymous trace chunks should never be transmitted to remote peers
+	 * (consumerd and relayd). They are used internally for
+	 * backward-compatibility purposes.
+	 */
+	LTTNG_ASSERT(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
+	msg.u.close_trace_chunk.chunk_id = chunk_id;
+
+	chunk_status = lttng_trace_chunk_get_close_timestamp(chunk,
+			&close_timestamp);
+	/*
+	 * A trace chunk should be closed locally before being closed remotely.
+	 * Otherwise, the close timestamp would never be transmitted to the
+	 * peers.
+	 */
+	LTTNG_ASSERT(chunk_status == LTTNG_TRACE_CHUNK_STATUS_OK);
+	msg.u.close_trace_chunk.close_timestamp = (uint64_t) close_timestamp;
+
+	if (msg.u.close_trace_chunk.close_command.is_set) {
+		close_command_name = lttng_trace_chunk_command_type_get_name(
+				close_command);
+	}
+	DBG("Sending consumer close trace chunk command: relayd_id = %" PRId64
+			", session_id = %" PRIu64 ", chunk_id = %" PRIu64
+			", close command = \"%s\"",
+			relayd_id, session_id, chunk_id, close_command_name);
+
+	health_code_update();
+	ret = consumer_socket_send(socket, &msg, sizeof(struct lttcomm_consumer_msg));
+	if (ret < 0) {
+		ret = -LTTNG_ERR_CLOSE_TRACE_CHUNK_FAIL_CONSUMER;
+		goto error;
+	}
+	ret = consumer_socket_recv(socket, &reply, sizeof(reply));
+	if (ret < 0) {
+		ret = -LTTNG_ERR_CLOSE_TRACE_CHUNK_FAIL_CONSUMER;
+		goto error;
+	}
+	if (reply.path_length >= LTTNG_PATH_MAX) {
+		ERR("Invalid path returned by relay daemon: %" PRIu32 "bytes exceeds maximal allowed length of %d bytes",
+				reply.path_length, LTTNG_PATH_MAX);
+		ret = -LTTNG_ERR_INVALID_PROTOCOL;
+		goto error;
+	}
+	ret = lttng_dynamic_buffer_set_size(&path_reception_buffer,
+			reply.path_length);
+	if (ret) {
+		ERR("Failed to allocate reception buffer of path returned by the \"close trace chunk\" command");
+		ret = -LTTNG_ERR_NOMEM;
+		goto error;
+	}
+	ret = consumer_socket_recv(socket, path_reception_buffer.data,
+			path_reception_buffer.size);
+	if (ret < 0) {
+		ERR("Communication error while receiving path of closed trace chunk");
+		ret = -LTTNG_ERR_CLOSE_TRACE_CHUNK_FAIL_CONSUMER;
+		goto error;
+	}
+	if (path_reception_buffer.data[path_reception_buffer.size - 1] != '\0') {
+		ERR("Invalid path returned by relay daemon: not null-terminated");
+		ret = -LTTNG_ERR_INVALID_PROTOCOL;
+		goto error;
+	}
+	if (closed_trace_chunk_path) {
+		/*
+		 * closed_trace_chunk_path is assumed to have a length >=
+		 * LTTNG_PATH_MAX
+		 */
+		memcpy(closed_trace_chunk_path, path_reception_buffer.data,
+				path_reception_buffer.size);
+	}
+error:
+	lttng_dynamic_buffer_reset(&path_reception_buffer);
+	health_code_update();
+	return ret;
+}
+
+/*
+ * Ask the consumer if a trace chunk exists.
+ *
+ * Called with the consumer socket lock held.
+ * Returns 0 on success, or a negative value on error.
+ */
+int consumer_trace_chunk_exists(struct consumer_socket *socket,
+		uint64_t relayd_id, uint64_t session_id,
+		struct lttng_trace_chunk *chunk,
+		enum consumer_trace_chunk_exists_status *result)
+{
+	int ret;
+	enum lttng_trace_chunk_status chunk_status;
+	lttcomm_consumer_msg msg = {
+		.cmd_type = LTTNG_CONSUMER_TRACE_CHUNK_EXISTS,
+	};
+	msg.u.trace_chunk_exists.session_id = session_id;
+
+	uint64_t chunk_id;
+	const char *consumer_reply_str;
+
+	LTTNG_ASSERT(socket);
+
+	if (relayd_id != -1ULL) {
+		LTTNG_OPTIONAL_SET(&msg.u.trace_chunk_exists.relayd_id,
+				relayd_id);
+	}
+
+	chunk_status = lttng_trace_chunk_get_id(chunk, &chunk_id);
+	if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+		/*
+		 * Anonymous trace chunks should never be transmitted
+		 * to remote peers (consumerd and relayd). They are used
+		 * internally for backward-compatibility purposes.
+		 */
+		ret = -LTTNG_ERR_FATAL;
+		goto error;
+	}
+	msg.u.trace_chunk_exists.chunk_id = chunk_id;
+
+	DBG("Sending consumer trace chunk exists command: relayd_id = %" PRId64
+			", session_id = %" PRIu64
+			", chunk_id = %" PRIu64, relayd_id, session_id, chunk_id);
+
+	health_code_update();
+	ret = consumer_send_msg(socket, &msg);
+	switch (-ret) {
+	case LTTCOMM_CONSUMERD_UNKNOWN_TRACE_CHUNK:
+		consumer_reply_str = "unknown trace chunk";
+		*result = CONSUMER_TRACE_CHUNK_EXISTS_STATUS_UNKNOWN_CHUNK;
+		break;
+	case LTTCOMM_CONSUMERD_TRACE_CHUNK_EXISTS_LOCAL:
+		consumer_reply_str = "trace chunk exists locally";
+		*result = CONSUMER_TRACE_CHUNK_EXISTS_STATUS_EXISTS_LOCAL;
+		break;
+	case LTTCOMM_CONSUMERD_TRACE_CHUNK_EXISTS_REMOTE:
+		consumer_reply_str = "trace chunk exists on remote peer";
+		*result = CONSUMER_TRACE_CHUNK_EXISTS_STATUS_EXISTS_REMOTE;
+		break;
+	default:
+		ERR("Consumer returned an error from TRACE_CHUNK_EXISTS command");
+		ret = -1;
+		goto error;
+	}
+	DBG("Consumer reply to TRACE_CHUNK_EXISTS command: %s",
+			consumer_reply_str);
+	ret = 0;
+error:
+	health_code_update();
+	return ret;
+}