Cleanup: Reduce scope of relayd connections in live thread

[lttng-tools.git] / src / bin / lttng-relayd / main.c

/*
 * Copyright (C) 2012 - Julien Desfossez <jdesfossez@efficios.com>
 *                      David Goulet <dgoulet@efficios.com>
 *               2013 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, version 2 only,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#define _GNU_SOURCE
#define _LGPL_SOURCE
#include <getopt.h>
#include <grp.h>
#include <limits.h>
#include <pthread.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/mount.h>
#include <sys/resource.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <inttypes.h>
#include <urcu/futex.h>
#include <urcu/uatomic.h>
#include <unistd.h>
#include <fcntl.h>
#include <config.h>

#include <lttng/lttng.h>
#include <common/common.h>
#include <common/compat/poll.h>
#include <common/compat/socket.h>
#include <common/compat/endian.h>
#include <common/compat/getenv.h>
#include <common/defaults.h>
#include <common/daemonize.h>
#include <common/futex.h>
#include <common/sessiond-comm/sessiond-comm.h>
#include <common/sessiond-comm/inet.h>
#include <common/sessiond-comm/relayd.h>
#include <common/uri.h>
#include <common/utils.h>
#include <common/config/config.h>

#include "cmd.h"
#include "ctf-trace.h"
#include "index.h"
#include "utils.h"
#include "lttng-relayd.h"
#include "live.h"
#include "health-relayd.h"
#include "testpoint.h"
#include "viewer-stream.h"
#include "session.h"
#include "stream.h"
#include "connection.h"

/* command line options */
char *opt_output_path;
static int opt_daemon, opt_background;

/*
 * We need to wait for listener and live listener threads, as well as
 * health check thread, before being ready to signal readiness.
 */
#define NR_LTTNG_RELAY_READY	3
static int lttng_relay_ready = NR_LTTNG_RELAY_READY;
static int recv_child_signal;	/* Set to 1 when a SIGUSR1 signal is received. */
static pid_t child_ppid;	/* Internal parent PID use with daemonize. */

static struct lttng_uri *control_uri;
static struct lttng_uri *data_uri;
static struct lttng_uri *live_uri;

const char *progname;

const char *tracing_group_name = DEFAULT_TRACING_GROUP;
static int tracing_group_name_override;

const char * const config_section_name = "relayd";

/*
 * Quit pipe for all threads. This permits a single cancellation point
 * for all threads when receiving an event on the pipe.
 */
int thread_quit_pipe[2] = { -1, -1 };

/*
 * This pipe is used to inform the worker thread that a command is queued and
 * ready to be processed.
 */
static int relay_conn_pipe[2] = { -1, -1 };

/* Shared between threads */
static int dispatch_thread_exit;

static pthread_t listener_thread;
static pthread_t dispatcher_thread;
static pthread_t worker_thread;
static pthread_t health_thread;

static uint64_t last_relay_stream_id;

/*
 * Relay command queue.
 *
 * The relay_thread_listener and relay_thread_dispatcher communicate with this
 * queue.
 */
static struct relay_conn_queue relay_conn_queue;

/* buffer allocated at startup, used to store the trace data */
static char *data_buffer;
static unsigned int data_buffer_size;

/* We need those values for the file/dir creation. */
static uid_t relayd_uid;
static gid_t relayd_gid;

/* Global relay stream hash table. */
struct lttng_ht *relay_streams_ht;

/* Global relay viewer stream hash table. */
struct lttng_ht *viewer_streams_ht;

/* Global hash table that stores relay index object. */
struct lttng_ht *indexes_ht;

/* Relayd health monitoring */
struct health_app *health_relayd;

static struct option long_options[] = {
	{ "control-port", 1, 0, 'C', },
	{ "data-port", 1, 0, 'D', },
	{ "live-port", 1, 0, 'L', },
	{ "daemonize", 0, 0, 'd', },
	{ "background", 0, 0, 'b', },
	{ "group", 1, 0, 'g', },
	{ "help", 0, 0, 'h', },
	{ "output", 1, 0, 'o', },
	{ "verbose", 0, 0, 'v', },
	{ "config", 1, 0, 'f' },
	{ NULL, 0, 0, 0, },
};

static const char *config_ignore_options[] = { "help", "config" };

/*
 * usage function on stderr
 */
static
void usage(void)
{
	fprintf(stderr, "Usage: %s OPTIONS\n\nOptions:\n", progname);
	fprintf(stderr, "  -h, --help                Display this usage.\n");
	fprintf(stderr, "  -d, --daemonize           Start as a daemon.\n");
	fprintf(stderr, "  -b, --background          Start as a daemon, keeping console open.\n");
	fprintf(stderr, "  -C, --control-port URL    Control port listening.\n");
	fprintf(stderr, "  -D, --data-port URL       Data port listening.\n");
	fprintf(stderr, "  -L, --live-port URL       Live view port listening.\n");
	fprintf(stderr, "  -o, --output PATH         Output path for traces. Must use an absolute path.\n");
	fprintf(stderr, "  -v, --verbose             Verbose mode. Activate DBG() macro.\n");
	fprintf(stderr, "  -g, --group NAME          Specify the tracing group name. (default: tracing)\n");
	fprintf(stderr, "  -f  --config              Load daemon configuration file\n");
}

/*
 * Take an option from the getopt output and set it in the right variable to be
 * used later.
 *
 * Return 0 on success else a negative value.
 */
static
int set_option(int opt, const char *arg, const char *optname)
{
	int ret;

	switch (opt) {
	case 0:
		fprintf(stderr, "option %s", optname);
		if (arg) {
			fprintf(stderr, " with arg %s\n", arg);
		}
		break;
	case 'C':
		if (lttng_is_setuid_setgid()) {
			WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
				"-C, --control-port");
		} else {
			ret = uri_parse(arg, &control_uri);
			if (ret < 0) {
				ERR("Invalid control URI specified");
				goto end;
			}
			if (control_uri->port == 0) {
				control_uri->port = DEFAULT_NETWORK_CONTROL_PORT;
			}
		}
		break;
	case 'D':
		if (lttng_is_setuid_setgid()) {
			WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
				"-D, -data-port");
		} else {
			ret = uri_parse(arg, &data_uri);
			if (ret < 0) {
				ERR("Invalid data URI specified");
				goto end;
			}
			if (data_uri->port == 0) {
				data_uri->port = DEFAULT_NETWORK_DATA_PORT;
			}
		}
		break;
	case 'L':
		if (lttng_is_setuid_setgid()) {
			WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
				"-L, -live-port");
		} else {
			ret = uri_parse(arg, &live_uri);
			if (ret < 0) {
				ERR("Invalid live URI specified");
				goto end;
			}
			if (live_uri->port == 0) {
				live_uri->port = DEFAULT_NETWORK_VIEWER_PORT;
			}
		}
		break;
	case 'd':
		opt_daemon = 1;
		break;
	case 'b':
		opt_background = 1;
		break;
	case 'g':
		if (lttng_is_setuid_setgid()) {
			WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
				"-g, --group");
		} else {
			tracing_group_name = strdup(arg);
			if (tracing_group_name == NULL) {
				ret = -errno;
				PERROR("strdup");
				goto end;
			}
			tracing_group_name_override = 1;
		}
		break;
	case 'h':
		usage();
		exit(EXIT_FAILURE);
	case 'o':
		if (lttng_is_setuid_setgid()) {
			WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
				"-o, --output");
		} else {
			ret = asprintf(&opt_output_path, "%s", arg);
			if (ret < 0) {
				ret = -errno;
				PERROR("asprintf opt_output_path");
				goto end;
			}
		}
		break;
	case 'v':
		/* Verbose level can increase using multiple -v */
		if (arg) {
			lttng_opt_verbose = config_parse_value(arg);
		} else {
			/* Only 3 level of verbosity (-vvv). */
			if (lttng_opt_verbose < 3) {
				lttng_opt_verbose += 1;
			}
		}
		break;
	default:
		/* Unknown option or other error.
		 * Error is printed by getopt, just return */
		ret = -1;
		goto end;
	}

	/* All good. */
	ret = 0;

end:
	return ret;
}

/*
 * config_entry_handler_cb used to handle options read from a config file.
 * See config_entry_handler_cb comment in common/config/config.h for the
 * return value conventions.
 */
static
int config_entry_handler(const struct config_entry *entry, void *unused)
{
	int ret = 0, i;

	if (!entry || !entry->name || !entry->value) {
		ret = -EINVAL;
		goto end;
	}

	/* Check if the option is to be ignored */
	for (i = 0; i < sizeof(config_ignore_options) / sizeof(char *); i++) {
		if (!strcmp(entry->name, config_ignore_options[i])) {
			goto end;
		}
	}

	for (i = 0; i < (sizeof(long_options) / sizeof(struct option)) - 1; i++) {
		/* Ignore if entry name is not fully matched. */
		if (strcmp(entry->name, long_options[i].name)) {
			continue;
		}

		/*
		 * If the option takes no argument on the command line, we have to
		 * check if the value is "true". We support non-zero numeric values,
		 * true, on and yes.
		 */
		if (!long_options[i].has_arg) {
			ret = config_parse_value(entry->value);
			if (ret <= 0) {
				if (ret) {
					WARN("Invalid configuration value \"%s\" for option %s",
							entry->value, entry->name);
				}
				/* False, skip boolean config option. */
				goto end;
			}
		}

		ret = set_option(long_options[i].val, entry->value, entry->name);
		goto end;
	}

	WARN("Unrecognized option \"%s\" in daemon configuration file.",
			entry->name);

end:
	return ret;
}

static
int set_options(int argc, char **argv)
{
	int c, ret = 0, option_index = 0, retval = 0;
	int orig_optopt = optopt, orig_optind = optind;
	char *default_address, *optstring;
	const char *config_path = NULL;

	optstring = utils_generate_optstring(long_options,
			sizeof(long_options) / sizeof(struct option));
	if (!optstring) {
		retval = -ENOMEM;
		goto exit;
	}

	/* Check for the --config option */

	while ((c = getopt_long(argc, argv, optstring, long_options,
					&option_index)) != -1) {
		if (c == '?') {
			retval = -EINVAL;
			goto exit;
		} else if (c != 'f') {
			continue;
		}

		if (lttng_is_setuid_setgid()) {
			WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
				"-f, --config");
		} else {
			config_path = utils_expand_path(optarg);
			if (!config_path) {
				ERR("Failed to resolve path: %s", optarg);
			}
		}
	}

	ret = config_get_section_entries(config_path, config_section_name,
			config_entry_handler, NULL);
	if (ret) {
		if (ret > 0) {
			ERR("Invalid configuration option at line %i", ret);
		}
		retval = -1;
		goto exit;
	}

	/* Reset getopt's global state */
	optopt = orig_optopt;
	optind = orig_optind;
	while (1) {
		c = getopt_long(argc, argv, optstring, long_options, &option_index);
		if (c == -1) {
			break;
		}

		ret = set_option(c, optarg, long_options[option_index].name);
		if (ret < 0) {
			retval = -1;
			goto exit;
		}
	}

	/* assign default values */
	if (control_uri == NULL) {
		ret = asprintf(&default_address,
			"tcp://" DEFAULT_NETWORK_CONTROL_BIND_ADDRESS ":%d",
			DEFAULT_NETWORK_CONTROL_PORT);
		if (ret < 0) {
			PERROR("asprintf default data address");
			retval = -1;
			goto exit;
		}

		ret = uri_parse(default_address, &control_uri);
		free(default_address);
		if (ret < 0) {
			ERR("Invalid control URI specified");
			retval = -1;
			goto exit;
		}
	}
	if (data_uri == NULL) {
		ret = asprintf(&default_address,
			"tcp://" DEFAULT_NETWORK_DATA_BIND_ADDRESS ":%d",
			DEFAULT_NETWORK_DATA_PORT);
		if (ret < 0) {
			PERROR("asprintf default data address");
			retval = -1;
			goto exit;
		}

		ret = uri_parse(default_address, &data_uri);
		free(default_address);
		if (ret < 0) {
			ERR("Invalid data URI specified");
			retval = -1;
			goto exit;
		}
	}
	if (live_uri == NULL) {
		ret = asprintf(&default_address,
			"tcp://" DEFAULT_NETWORK_VIEWER_BIND_ADDRESS ":%d",
			DEFAULT_NETWORK_VIEWER_PORT);
		if (ret < 0) {
			PERROR("asprintf default viewer control address");
			retval = -1;
			goto exit;
		}

		ret = uri_parse(default_address, &live_uri);
		free(default_address);
		if (ret < 0) {
			ERR("Invalid viewer control URI specified");
			retval = -1;
			goto exit;
		}
	}

exit:
	free(optstring);
	return retval;
}

/*
 * Cleanup the daemon
 */
static
void relayd_cleanup(struct relay_local_data *relay_ctx)
{
	DBG("Cleaning up");

	if (viewer_streams_ht)
		lttng_ht_destroy(viewer_streams_ht);
	if (relay_streams_ht)
		lttng_ht_destroy(relay_streams_ht);
	if (relay_ctx && relay_ctx->sessions_ht)
		lttng_ht_destroy(relay_ctx->sessions_ht);
	free(relay_ctx);

	/* free the dynamically allocated opt_output_path */
	free(opt_output_path);

	/* Close thread quit pipes */
	utils_close_pipe(thread_quit_pipe);

	uri_free(control_uri);
	uri_free(data_uri);
	/* Live URI is freed in the live thread. */

	if (tracing_group_name_override) {
		free((void *) tracing_group_name);
	}
}

/*
 * Write to writable pipe used to notify a thread.
 */
static
int notify_thread_pipe(int wpipe)
{
	ssize_t ret;

	ret = lttng_write(wpipe, "!", 1);
	if (ret < 1) {
		PERROR("write poll pipe");
		goto end;
	}
	ret = 0;
end:
	return ret;
}

static
int notify_health_quit_pipe(int *pipe)
{
	ssize_t ret;

	ret = lttng_write(pipe[1], "4", 1);
	if (ret < 1) {
		PERROR("write relay health quit");
		goto end;
	}
	ret = 0;
end:
	return ret;
}

/*
 * Stop all relayd and relayd-live threads.
 */
int lttng_relay_stop_threads(void)
{
	int retval = 0;

	/* Stopping all threads */
	DBG("Terminating all threads");
	if (notify_thread_pipe(thread_quit_pipe[1])) {
		ERR("write error on thread quit pipe");
		retval = -1;
	}

	if (notify_health_quit_pipe(health_quit_pipe)) {
		ERR("write error on health quit pipe");
	}

	/* Dispatch thread */
	CMM_STORE_SHARED(dispatch_thread_exit, 1);
	futex_nto1_wake(&relay_conn_queue.futex);

	if (relayd_live_stop()) {
		ERR("Error stopping live threads");
		retval = -1;
	}
	return retval;
}

/*
 * Signal handler for the daemon
 *
 * Simply stop all worker threads, leaving main() return gracefully after
 * joining all threads and calling cleanup().
 */
static
void sighandler(int sig)
{
	switch (sig) {
	case SIGPIPE:
		DBG("SIGPIPE caught");
		return;
	case SIGINT:
		DBG("SIGINT caught");
		if (lttng_relay_stop_threads()) {
			ERR("Error stopping threads");
		}
		break;
	case SIGTERM:
		DBG("SIGTERM caught");
		if (lttng_relay_stop_threads()) {
			ERR("Error stopping threads");
		}
		break;
	case SIGUSR1:
		CMM_STORE_SHARED(recv_child_signal, 1);
		break;
	default:
		break;
	}
}

/*
 * Setup signal handler for :
 *		SIGINT, SIGTERM, SIGPIPE
 */
static
int set_signal_handler(void)
{
	int ret = 0;
	struct sigaction sa;
	sigset_t sigset;

	if ((ret = sigemptyset(&sigset)) < 0) {
		PERROR("sigemptyset");
		return ret;
	}

	sa.sa_handler = sighandler;
	sa.sa_mask = sigset;
	sa.sa_flags = 0;
	if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
		PERROR("sigaction");
		return ret;
	}

	if ((ret = sigaction(SIGINT, &sa, NULL)) < 0) {
		PERROR("sigaction");
		return ret;
	}

	if ((ret = sigaction(SIGPIPE, &sa, NULL)) < 0) {
		PERROR("sigaction");
		return ret;
	}

	if ((ret = sigaction(SIGUSR1, &sa, NULL)) < 0) {
		PERROR("sigaction");
		return ret;
	}

	DBG("Signal handler set for SIGTERM, SIGUSR1, SIGPIPE and SIGINT");

	return ret;
}

void lttng_relay_notify_ready(void)
{
	/* Notify the parent of the fork() process that we are ready. */
	if (opt_daemon || opt_background) {
		if (uatomic_sub_return(&lttng_relay_ready, 1) == 0) {
			kill(child_ppid, SIGUSR1);
		}
	}
}

/*
 * Init thread quit pipe.
 *
 * Return -1 on error or 0 if all pipes are created.
 */
static
int init_thread_quit_pipe(void)
{
	int ret;

	ret = utils_create_pipe_cloexec(thread_quit_pipe);

	return ret;
}

/*
 * Create a poll set with O_CLOEXEC and add the thread quit pipe to the set.
 */
static
int create_thread_poll_set(struct lttng_poll_event *events, int size)
{
	int ret;

	if (events == NULL || size == 0) {
		ret = -1;
		goto error;
	}

	ret = lttng_poll_create(events, size, LTTNG_CLOEXEC);
	if (ret < 0) {
		goto error;
	}

	/* Add quit pipe */
	ret = lttng_poll_add(events, thread_quit_pipe[0], LPOLLIN | LPOLLERR);
	if (ret < 0) {
		goto error;
	}

	return 0;

error:
	return ret;
}

/*
 * Check if the thread quit pipe was triggered.
 *
 * Return 1 if it was triggered else 0;
 */
static
int check_thread_quit_pipe(int fd, uint32_t events)
{
	if (fd == thread_quit_pipe[0] && (events & LPOLLIN)) {
		return 1;
	}

	return 0;
}

/*
 * Create and init socket from uri.
 */
static
struct lttcomm_sock *relay_init_sock(struct lttng_uri *uri)
{
	int ret;
	struct lttcomm_sock *sock = NULL;

	sock = lttcomm_alloc_sock_from_uri(uri);
	if (sock == NULL) {
		ERR("Allocating socket");
		goto error;
	}

	ret = lttcomm_create_sock(sock);
	if (ret < 0) {
		goto error;
	}
	DBG("Listening on sock %d", sock->fd);

	ret = sock->ops->bind(sock);
	if (ret < 0) {
		goto error;
	}

	ret = sock->ops->listen(sock, -1);
	if (ret < 0) {
		goto error;

	}

	return sock;

error:
	if (sock) {
		lttcomm_destroy_sock(sock);
	}
	return NULL;
}

/*
 * Return nonzero if stream needs to be closed.
 */
static
int close_stream_check(struct relay_stream *stream)
{
	if (stream->close_flag && stream->prev_seq == stream->last_net_seq_num) {
		/*
		 * We are about to close the stream so set the data pending flag to 1
		 * which will make the end data pending command skip the stream which
		 * is now closed and ready. Note that after proceeding to a file close,
		 * the written file is ready for reading.
		 */
		stream->data_pending_check_done = 1;
		return 1;
	}
	return 0;
}

static void try_close_stream(struct relay_session *session,
		struct relay_stream *stream)
{
	int ret;
	struct ctf_trace *ctf_trace;

	assert(session);
	assert(stream);

	if (!close_stream_check(stream)) {
		/* Can't close it, not ready for that. */
		goto end;
	}

	ctf_trace = ctf_trace_find_by_path(session->ctf_traces_ht,
			stream->path_name);
	assert(ctf_trace);

	pthread_mutex_lock(&session->viewer_ready_lock);
	ctf_trace->invalid_flag = 1;
	pthread_mutex_unlock(&session->viewer_ready_lock);

	ret = stream_close(session, stream);
	if (ret || session->snapshot) {
		/* Already close thus the ctf trace is being or has been destroyed. */
		goto end;
	}

	ctf_trace_try_destroy(session, ctf_trace);

end:
	return;
}

/*
 * This thread manages the listening for new connections on the network
 */
static
void *relay_thread_listener(void *data)
{
	int i, ret, pollfd, err = -1;
	uint32_t revents, nb_fd;
	struct lttng_poll_event events;
	struct lttcomm_sock *control_sock, *data_sock;

	DBG("[thread] Relay listener started");

	health_register(health_relayd, HEALTH_RELAYD_TYPE_LISTENER);

	health_code_update();

	control_sock = relay_init_sock(control_uri);
	if (!control_sock) {
		goto error_sock_control;
	}

	data_sock = relay_init_sock(data_uri);
	if (!data_sock) {
		goto error_sock_relay;
	}

	/*
	 * Pass 3 as size here for the thread quit pipe, control and data socket.
	 */
	ret = create_thread_poll_set(&events, 3);
	if (ret < 0) {
		goto error_create_poll;
	}

	/* Add the control socket */
	ret = lttng_poll_add(&events, control_sock->fd, LPOLLIN | LPOLLRDHUP);
	if (ret < 0) {
		goto error_poll_add;
	}

	/* Add the data socket */
	ret = lttng_poll_add(&events, data_sock->fd, LPOLLIN | LPOLLRDHUP);
	if (ret < 0) {
		goto error_poll_add;
	}

	lttng_relay_notify_ready();

	if (testpoint(relayd_thread_listener)) {
		goto error_testpoint;
	}

	while (1) {
		health_code_update();

		DBG("Listener accepting connections");

restart:
		health_poll_entry();
		ret = lttng_poll_wait(&events, -1);
		health_poll_exit();
		if (ret < 0) {
			/*
			 * Restart interrupted system call.
			 */
			if (errno == EINTR) {
				goto restart;
			}
			goto error;
		}

		nb_fd = ret;

		DBG("Relay new connection received");
		for (i = 0; i < nb_fd; i++) {
			health_code_update();

			/* Fetch once the poll data */
			revents = LTTNG_POLL_GETEV(&events, i);
			pollfd = LTTNG_POLL_GETFD(&events, i);

			if (!revents) {
				/* No activity for this FD (poll implementation). */
				continue;
			}

			/* Thread quit pipe has been closed. Killing thread. */
			ret = check_thread_quit_pipe(pollfd, revents);
			if (ret) {
				err = 0;
				goto exit;
			}

			if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
				ERR("socket poll error");
				goto error;
			} else if (revents & LPOLLIN) {
				/*
				 * Get allocated in this thread, enqueued to a global queue,
				 * dequeued and freed in the worker thread.
				 */
				int val = 1;
				struct relay_connection *new_conn;
				struct lttcomm_sock *newsock;

				new_conn = connection_create();
				if (!new_conn) {
					goto error;
				}

				if (pollfd == data_sock->fd) {
					new_conn->type = RELAY_DATA;
					newsock = data_sock->ops->accept(data_sock);
					DBG("Relay data connection accepted, socket %d",
							newsock->fd);
				} else {
					assert(pollfd == control_sock->fd);
					new_conn->type = RELAY_CONTROL;
					newsock = control_sock->ops->accept(control_sock);
					DBG("Relay control connection accepted, socket %d",
							newsock->fd);
				}
				if (!newsock) {
					PERROR("accepting sock");
					connection_free(new_conn);
					goto error;
				}

				ret = setsockopt(newsock->fd, SOL_SOCKET, SO_REUSEADDR, &val,
						sizeof(val));
				if (ret < 0) {
					PERROR("setsockopt inet");
					lttcomm_destroy_sock(newsock);
					connection_free(new_conn);
					goto error;
				}
				new_conn->sock = newsock;

				/* Enqueue request for the dispatcher thread. */
				cds_wfcq_enqueue(&relay_conn_queue.head, &relay_conn_queue.tail,
						 &new_conn->qnode);

				/*
				 * Wake the dispatch queue futex. Implicit memory barrier with
				 * the exchange in cds_wfcq_enqueue.
				 */
				futex_nto1_wake(&relay_conn_queue.futex);
			}
		}
	}

exit:
error:
error_poll_add:
error_testpoint:
	lttng_poll_clean(&events);
error_create_poll:
	if (data_sock->fd >= 0) {
		ret = data_sock->ops->close(data_sock);
		if (ret) {
			PERROR("close");
		}
	}
	lttcomm_destroy_sock(data_sock);
error_sock_relay:
	if (control_sock->fd >= 0) {
		ret = control_sock->ops->close(control_sock);
		if (ret) {
			PERROR("close");
		}
	}
	lttcomm_destroy_sock(control_sock);
error_sock_control:
	if (err) {
		health_error();
		ERR("Health error occurred in %s", __func__);
	}
	health_unregister(health_relayd);
	DBG("Relay listener thread cleanup complete");
	lttng_relay_stop_threads();
	return NULL;
}

/*
 * This thread manages the dispatching of the requests to worker threads
 */
static
void *relay_thread_dispatcher(void *data)
{
	int err = -1;
	ssize_t ret;
	struct cds_wfcq_node *node;
	struct relay_connection *new_conn = NULL;

	DBG("[thread] Relay dispatcher started");

	health_register(health_relayd, HEALTH_RELAYD_TYPE_DISPATCHER);

	if (testpoint(relayd_thread_dispatcher)) {
		goto error_testpoint;
	}

	health_code_update();

	while (!CMM_LOAD_SHARED(dispatch_thread_exit)) {
		health_code_update();

		/* Atomically prepare the queue futex */
		futex_nto1_prepare(&relay_conn_queue.futex);

		do {
			health_code_update();

			/* Dequeue commands */
			node = cds_wfcq_dequeue_blocking(&relay_conn_queue.head,
							 &relay_conn_queue.tail);
			if (node == NULL) {
				DBG("Woken up but nothing in the relay command queue");
				/* Continue thread execution */
				break;
			}
			new_conn = caa_container_of(node, struct relay_connection, qnode);

			DBG("Dispatching request waiting on sock %d", new_conn->sock->fd);

			/*
			 * Inform worker thread of the new request. This call is blocking
			 * so we can be assured that the data will be read at some point in
			 * time or wait to the end of the world :)
			 */
			ret = lttng_write(relay_conn_pipe[1], &new_conn, sizeof(new_conn));
			if (ret < 0) {
				PERROR("write connection pipe");
				connection_destroy(new_conn);
				goto error;
			}
		} while (node != NULL);

		/* Futex wait on queue. Blocking call on futex() */
		health_poll_entry();
		futex_nto1_wait(&relay_conn_queue.futex);
		health_poll_exit();
	}

	/* Normal exit, no error */
	err = 0;

error:
error_testpoint:
	if (err) {
		health_error();
		ERR("Health error occurred in %s", __func__);
	}
	health_unregister(health_relayd);
	DBG("Dispatch thread dying");
	lttng_relay_stop_threads();
	return NULL;
}

static void try_close_streams(struct relay_session *session)
{
	struct ctf_trace *ctf_trace;
	struct lttng_ht_iter iter;

	assert(session);

	pthread_mutex_lock(&session->viewer_ready_lock);
	rcu_read_lock();
	cds_lfht_for_each_entry(session->ctf_traces_ht->ht, &iter.iter, ctf_trace,
			node.node) {
		struct relay_stream *stream;

		/* Close streams. */
		cds_list_for_each_entry(stream, &ctf_trace->stream_list, trace_list) {
			stream_close(session, stream);
		}

		ctf_trace->invalid_flag = 1;
		ctf_trace_try_destroy(session, ctf_trace);
	}
	rcu_read_unlock();
	pthread_mutex_unlock(&session->viewer_ready_lock);
}

/*
 * Try to destroy a session within a connection.
 */
static void destroy_session(struct relay_session *session,
		struct lttng_ht *sessions_ht)
{
	assert(session);
	assert(sessions_ht);

	/* Indicate that this session can be destroyed from now on. */
	session->close_flag = 1;

	try_close_streams(session);

	/*
	 * This will try to delete and destroy the session if no viewer is attached
	 * to it meaning the refcount is down to zero.
	 */
	session_try_destroy(sessions_ht, session);
}

/*
 * Copy index data from the control port to a given index object.
 */
static void copy_index_control_data(struct relay_index *index,
		struct lttcomm_relayd_index *data)
{
	assert(index);
	assert(data);

	/*
	 * The index on disk is encoded in big endian, so we don't need to convert
	 * the data received on the network. The data_offset value is NEVER
	 * modified here and is updated by the data thread.
	 */
	index->index_data.packet_size = data->packet_size;
	index->index_data.content_size = data->content_size;
	index->index_data.timestamp_begin = data->timestamp_begin;
	index->index_data.timestamp_end = data->timestamp_end;
	index->index_data.events_discarded = data->events_discarded;
	index->index_data.stream_id = data->stream_id;
}

/*
 * Handle the RELAYD_CREATE_SESSION command.
 *
 * On success, send back the session id or else return a negative value.
 */
static
int relay_create_session(struct lttcomm_relayd_hdr *recv_hdr,
		struct relay_connection *conn)
{
	int ret = 0, send_ret;
	struct relay_session *session;
	struct lttcomm_relayd_status_session reply;

	assert(recv_hdr);
	assert(conn);

	memset(&reply, 0, sizeof(reply));

	session = session_create();
	if (!session) {
		ret = -1;
		goto error;
	}
	session->minor = conn->minor;
	session->major = conn->major;
	conn->session_id = session->id;
	conn->session = session;

	reply.session_id = htobe64(session->id);

	switch (conn->minor) {
	case 1:
	case 2:
	case 3:
		break;
	case 4: /* LTTng sessiond 2.4 */
	default:
		ret = cmd_create_session_2_4(conn, session);
	}

	lttng_ht_add_unique_u64(conn->sessions_ht, &session->session_n);
	DBG("Created session %" PRIu64, session->id);

error:
	if (ret < 0) {
		reply.ret_code = htobe32(LTTNG_ERR_FATAL);
	} else {
		reply.ret_code = htobe32(LTTNG_OK);
	}

	send_ret = conn->sock->ops->sendmsg(conn->sock, &reply, sizeof(reply), 0);
	if (send_ret < 0) {
		ERR("Relayd sending session id");
		ret = send_ret;
	}

	return ret;
}

/*
 * When we have received all the streams and the metadata for a channel,
 * we make them visible to the viewer threads.
 */
static
void set_viewer_ready_flag(struct relay_connection *conn)
{
	struct relay_stream *stream, *tmp_stream;

	pthread_mutex_lock(&conn->session->viewer_ready_lock);
	cds_list_for_each_entry_safe(stream, tmp_stream, &conn->recv_head,
			recv_list) {
		stream->viewer_ready = 1;
		cds_list_del(&stream->recv_list);
	}
	pthread_mutex_unlock(&conn->session->viewer_ready_lock);
	return;
}

/*
 * Add a recv handle node to the connection recv list with the given stream
 * handle. A new node is allocated thus must be freed when the node is deleted
 * from the list.
 */
static void queue_stream(struct relay_stream *stream,
		struct relay_connection *conn)
{
	assert(conn);
	assert(stream);

	cds_list_add(&stream->recv_list, &conn->recv_head);
}

/*
 * relay_add_stream: allocate a new stream for a session
 */
static
int relay_add_stream(struct lttcomm_relayd_hdr *recv_hdr,
		struct relay_connection *conn)
{
	int ret, send_ret;
	struct relay_session *session = conn->session;
	struct relay_stream *stream = NULL;
	struct lttcomm_relayd_status_stream reply;
	struct ctf_trace *trace;

	if (!session || conn->version_check_done == 0) {
		ERR("Trying to add a stream before version check");
		ret = -1;
		goto end_no_session;
	}

	stream = zmalloc(sizeof(struct relay_stream));
	if (stream == NULL) {
		PERROR("relay stream zmalloc");
		ret = -1;
		goto end_no_session;
	}

	switch (conn->minor) {
	case 1: /* LTTng sessiond 2.1 */
		ret = cmd_recv_stream_2_1(conn, stream);
		break;
	case 2: /* LTTng sessiond 2.2 */
	default:
		ret = cmd_recv_stream_2_2(conn, stream);
		break;
	}
	if (ret < 0) {
		goto err_free_stream;
	}

	rcu_read_lock();
	stream->stream_handle = ++last_relay_stream_id;
	stream->prev_seq = -1ULL;
	stream->session_id = session->id;
	stream->index_fd = -1;
	stream->read_index_fd = -1;
	stream->ctf_stream_id = -1ULL;
	lttng_ht_node_init_u64(&stream->node, stream->stream_handle);
	pthread_mutex_init(&stream->lock, NULL);

	ret = utils_mkdir_recursive(stream->path_name, S_IRWXU | S_IRWXG);
	if (ret < 0) {
		ERR("relay creating output directory");
		goto end;
	}

	/*
	 * No need to use run_as API here because whatever we receives, the relayd
	 * uses its own credentials for the stream files.
	 */
	ret = utils_create_stream_file(stream->path_name, stream->channel_name,
			stream->tracefile_size, 0, relayd_uid, relayd_gid, NULL);
	if (ret < 0) {
		ERR("Create output file");
		goto end;
	}
	stream->fd = ret;
	if (stream->tracefile_size) {
		DBG("Tracefile %s/%s_0 created", stream->path_name, stream->channel_name);
	} else {
		DBG("Tracefile %s/%s created", stream->path_name, stream->channel_name);
	}

	trace = ctf_trace_find_by_path(session->ctf_traces_ht, stream->path_name);
	if (!trace) {
		trace = ctf_trace_create(stream->path_name);
		if (!trace) {
			ret = -1;
			goto end;
		}
		ctf_trace_add(session->ctf_traces_ht, trace);
	}
	ctf_trace_get_ref(trace);

	if (!strncmp(stream->channel_name, DEFAULT_METADATA_NAME, NAME_MAX)) {
		stream->metadata_flag = 1;
		/* Assign quick reference to the metadata stream in the trace. */
		trace->metadata_stream = stream;
	}

	/*
	 * Add the stream in the recv list of the connection. Once the end stream
	 * message is received, this list is emptied and streams are set with the
	 * viewer ready flag.
	 */
	queue_stream(stream, conn);

	/*
	 * Both in the ctf_trace object and the global stream ht since the data
	 * side of the relayd does not have the concept of session.
	 */
	lttng_ht_add_unique_u64(relay_streams_ht, &stream->node);
	cds_list_add_tail(&stream->trace_list, &trace->stream_list);

	session->stream_count++;

	DBG("Relay new stream added %s with ID %" PRIu64, stream->channel_name,
			stream->stream_handle);

end:
	memset(&reply, 0, sizeof(reply));
	reply.handle = htobe64(stream->stream_handle);
	/* send the session id to the client or a negative return code on error */
	if (ret < 0) {
		reply.ret_code = htobe32(LTTNG_ERR_UNK);
		/* stream was not properly added to the ht, so free it */
		free(stream);
	} else {
		reply.ret_code = htobe32(LTTNG_OK);
	}

	send_ret = conn->sock->ops->sendmsg(conn->sock, &reply,
			sizeof(struct lttcomm_relayd_status_stream), 0);
	if (send_ret < 0) {
		ERR("Relay sending stream id");
		ret = send_ret;
	}
	rcu_read_unlock();

end_no_session:
	return ret;

err_free_stream:
	free(stream->path_name);
	free(stream->channel_name);
	free(stream);
	return ret;
}

/*
 * relay_close_stream: close a specific stream
 */
static
int relay_close_stream(struct lttcomm_relayd_hdr *recv_hdr,
		struct relay_connection *conn)
{
	int ret, send_ret;
	struct relay_session *session = conn->session;
	struct lttcomm_relayd_close_stream stream_info;
	struct lttcomm_relayd_generic_reply reply;
	struct relay_stream *stream;

	DBG("Close stream received");

	if (!session || conn->version_check_done == 0) {
		ERR("Trying to close a stream before version check");
		ret = -1;
		goto end_no_session;
	}

	ret = conn->sock->ops->recvmsg(conn->sock, &stream_info,
			sizeof(struct lttcomm_relayd_close_stream), 0);
	if (ret < sizeof(struct lttcomm_relayd_close_stream)) {
		if (ret == 0) {
			/* Orderly shutdown. Not necessary to print an error. */
			DBG("Socket %d did an orderly shutdown", conn->sock->fd);
		} else {
			ERR("Relay didn't receive valid add_stream struct size : %d", ret);
		}
		ret = -1;
		goto end_no_session;
	}

	rcu_read_lock();
	stream = stream_find_by_id(relay_streams_ht,
			be64toh(stream_info.stream_id));
	if (!stream) {
		ret = -1;
		goto end_unlock;
	}

	stream->last_net_seq_num = be64toh(stream_info.last_net_seq_num);
	stream->close_flag = 1;
	session->stream_count--;

	/* Check if we can close it or else the data will do it. */
	try_close_stream(session, stream);

end_unlock:
	rcu_read_unlock();

	memset(&reply, 0, sizeof(reply));
	if (ret < 0) {
		reply.ret_code = htobe32(LTTNG_ERR_UNK);
	} else {
		reply.ret_code = htobe32(LTTNG_OK);
	}
	send_ret = conn->sock->ops->sendmsg(conn->sock, &reply,
			sizeof(struct lttcomm_relayd_generic_reply), 0);
	if (send_ret < 0) {
		ERR("Relay sending stream id");
		ret = send_ret;
	}

end_no_session:
	return ret;
}

/*
 * relay_unknown_command: send -1 if received unknown command
 */
static
void relay_unknown_command(struct relay_connection *conn)
{
	struct lttcomm_relayd_generic_reply reply;
	int ret;

	memset(&reply, 0, sizeof(reply));
	reply.ret_code = htobe32(LTTNG_ERR_UNK);
	ret = conn->sock->ops->sendmsg(conn->sock, &reply,
			sizeof(struct lttcomm_relayd_generic_reply), 0);
	if (ret < 0) {
		ERR("Relay sending unknown command");
	}
}

/*
 * relay_start: send an acknowledgment to the client to tell if we are
 * ready to receive data. We are ready if a session is established.
 */
static
int relay_start(struct lttcomm_relayd_hdr *recv_hdr,
		struct relay_connection *conn)
{
	int ret = htobe32(LTTNG_OK);
	struct lttcomm_relayd_generic_reply reply;
	struct relay_session *session = conn->session;

	if (!session) {
		DBG("Trying to start the streaming without a session established");
		ret = htobe32(LTTNG_ERR_UNK);
	}

	memset(&reply, 0, sizeof(reply));
	reply.ret_code = ret;
	ret = conn->sock->ops->sendmsg(conn->sock, &reply,
			sizeof(struct lttcomm_relayd_generic_reply), 0);
	if (ret < 0) {
		ERR("Relay sending start ack");
	}

	return ret;
}

/*
 * Append padding to the file pointed by the file descriptor fd.
 */
static int write_padding_to_file(int fd, uint32_t size)
{
	ssize_t ret = 0;
	char *zeros;

	if (size == 0) {
		goto end;
	}

	zeros = zmalloc(size);
	if (zeros == NULL) {
		PERROR("zmalloc zeros for padding");
		ret = -1;
		goto end;
	}

	ret = lttng_write(fd, zeros, size);
	if (ret < size) {
		PERROR("write padding to file");
	}

	free(zeros);

end:
	return ret;
}

/*
 * relay_recv_metadata: receive the metada for the session.
 */
static
int relay_recv_metadata(struct lttcomm_relayd_hdr *recv_hdr,
		struct relay_connection *conn)
{
	int ret = htobe32(LTTNG_OK);
	ssize_t size_ret;
	struct relay_session *session = conn->session;
	struct lttcomm_relayd_metadata_payload *metadata_struct;
	struct relay_stream *metadata_stream;
	uint64_t data_size, payload_size;
	struct ctf_trace *ctf_trace;

	if (!session) {
		ERR("Metadata sent before version check");
		ret = -1;
		goto end;
	}

	data_size = payload_size = be64toh(recv_hdr->data_size);
	if (data_size < sizeof(struct lttcomm_relayd_metadata_payload)) {
		ERR("Incorrect data size");
		ret = -1;
		goto end;
	}
	payload_size -= sizeof(struct lttcomm_relayd_metadata_payload);

	if (data_buffer_size < data_size) {
		/* In case the realloc fails, we can free the memory */
		char *tmp_data_ptr;

		tmp_data_ptr = realloc(data_buffer, data_size);
		if (!tmp_data_ptr) {
			ERR("Allocating data buffer");
			free(data_buffer);
			ret = -1;
			goto end;
		}
		data_buffer = tmp_data_ptr;
		data_buffer_size = data_size;
	}
	memset(data_buffer, 0, data_size);
	DBG2("Relay receiving metadata, waiting for %" PRIu64 " bytes", data_size);
	ret = conn->sock->ops->recvmsg(conn->sock, data_buffer, data_size, 0);
	if (ret < 0 || ret != data_size) {
		if (ret == 0) {
			/* Orderly shutdown. Not necessary to print an error. */
			DBG("Socket %d did an orderly shutdown", conn->sock->fd);
		} else {
			ERR("Relay didn't receive the whole metadata");
		}
		ret = -1;
		goto end;
	}
	metadata_struct = (struct lttcomm_relayd_metadata_payload *) data_buffer;

	rcu_read_lock();
	metadata_stream = stream_find_by_id(relay_streams_ht,
			be64toh(metadata_struct->stream_id));
	if (!metadata_stream) {
		ret = -1;
		goto end_unlock;
	}

	size_ret = lttng_write(metadata_stream->fd, metadata_struct->payload,
			payload_size);
	if (size_ret < payload_size) {
		ERR("Relay error writing metadata on file");
		ret = -1;
		goto end_unlock;
	}

	ret = write_padding_to_file(metadata_stream->fd,
			be32toh(metadata_struct->padding_size));
	if (ret < 0) {
		goto end_unlock;
	}

	ctf_trace = ctf_trace_find_by_path(session->ctf_traces_ht,
			metadata_stream->path_name);
	assert(ctf_trace);
	ctf_trace->metadata_received +=
		payload_size + be32toh(metadata_struct->padding_size);

	DBG2("Relay metadata written");

end_unlock:
	rcu_read_unlock();
end:
	return ret;
}

/*
 * relay_send_version: send relayd version number
 */
static
int relay_send_version(struct lttcomm_relayd_hdr *recv_hdr,
		struct relay_connection *conn)
{
	int ret;
	struct lttcomm_relayd_version reply, msg;

	assert(conn);

	conn->version_check_done = 1;

	/* Get version from the other side. */
	ret = conn->sock->ops->recvmsg(conn->sock, &msg, sizeof(msg), 0);
	if (ret < 0 || ret != sizeof(msg)) {
		if (ret == 0) {
			/* Orderly shutdown. Not necessary to print an error. */
			DBG("Socket %d did an orderly shutdown", conn->sock->fd);
		} else {
			ERR("Relay failed to receive the version values.");
		}
		ret = -1;
		goto end;
	}

	memset(&reply, 0, sizeof(reply));
	reply.major = RELAYD_VERSION_COMM_MAJOR;
	reply.minor = RELAYD_VERSION_COMM_MINOR;

	/* Major versions must be the same */
	if (reply.major != be32toh(msg.major)) {
		DBG("Incompatible major versions (%u vs %u), deleting session",
				reply.major, be32toh(msg.major));
		destroy_session(conn->session, conn->sessions_ht);
		ret = 0;
		goto end;
	}

	conn->major = reply.major;
	/* We adapt to the lowest compatible version */
	if (reply.minor <= be32toh(msg.minor)) {
		conn->minor = reply.minor;
	} else {
		conn->minor = be32toh(msg.minor);
	}

	reply.major = htobe32(reply.major);
	reply.minor = htobe32(reply.minor);
	ret = conn->sock->ops->sendmsg(conn->sock, &reply,
			sizeof(struct lttcomm_relayd_version), 0);
	if (ret < 0) {
		ERR("Relay sending version");
	}

	DBG("Version check done using protocol %u.%u", conn->major,
			conn->minor);

end:
	return ret;
}

/*
 * Check for data pending for a given stream id from the session daemon.
 */
static
int relay_data_pending(struct lttcomm_relayd_hdr *recv_hdr,
		struct relay_connection *conn)
{
	struct relay_session *session = conn->session;
	struct lttcomm_relayd_data_pending msg;
	struct lttcomm_relayd_generic_reply reply;
	struct relay_stream *stream;
	int ret;
	uint64_t last_net_seq_num, stream_id;

	DBG("Data pending command received");

	if (!session || conn->version_check_done == 0) {
		ERR("Trying to check for data before version check");
		ret = -1;
		goto end_no_session;
	}

	ret = conn->sock->ops->recvmsg(conn->sock, &msg, sizeof(msg), 0);
	if (ret < sizeof(msg)) {
		if (ret == 0) {
			/* Orderly shutdown. Not necessary to print an error. */
			DBG("Socket %d did an orderly shutdown", conn->sock->fd);
		} else {
			ERR("Relay didn't receive valid data_pending struct size : %d",
					ret);
		}
		ret = -1;
		goto end_no_session;
	}

	stream_id = be64toh(msg.stream_id);
	last_net_seq_num = be64toh(msg.last_net_seq_num);

	rcu_read_lock();
	stream = stream_find_by_id(relay_streams_ht, stream_id);
	if (stream == NULL) {
		ret = -1;
		goto end_unlock;
	}

	DBG("Data pending for stream id %" PRIu64 " prev_seq %" PRIu64
			" and last_seq %" PRIu64, stream_id, stream->prev_seq,
			last_net_seq_num);

	/* Avoid wrapping issue */
	if (((int64_t) (stream->prev_seq - last_net_seq_num)) >= 0) {
		/* Data has in fact been written and is NOT pending */
		ret = 0;
	} else {
		/* Data still being streamed thus pending */
		ret = 1;
	}

	/* Pending check is now done. */
	stream->data_pending_check_done = 1;

end_unlock:
	rcu_read_unlock();

	memset(&reply, 0, sizeof(reply));
	reply.ret_code = htobe32(ret);
	ret = conn->sock->ops->sendmsg(conn->sock, &reply, sizeof(reply), 0);
	if (ret < 0) {
		ERR("Relay data pending ret code failed");
	}

end_no_session:
	return ret;
}

/*
 * Wait for the control socket to reach a quiescent state.
 *
 * Note that for now, when receiving this command from the session daemon, this
 * means that every subsequent commands or data received on the control socket
 * has been handled. So, this is why we simply return OK here.
 */
static
int relay_quiescent_control(struct lttcomm_relayd_hdr *recv_hdr,
		struct relay_connection *conn)
{
	int ret;
	uint64_t stream_id;
	struct relay_stream *stream;
	struct lttng_ht_iter iter;
	struct lttcomm_relayd_quiescent_control msg;
	struct lttcomm_relayd_generic_reply reply;

	DBG("Checking quiescent state on control socket");

	if (!conn->session || conn->version_check_done == 0) {
		ERR("Trying to check for data before version check");
		ret = -1;
		goto end_no_session;
	}

	ret = conn->sock->ops->recvmsg(conn->sock, &msg, sizeof(msg), 0);
	if (ret < sizeof(msg)) {
		if (ret == 0) {
			/* Orderly shutdown. Not necessary to print an error. */
			DBG("Socket %d did an orderly shutdown", conn->sock->fd);
		} else {
			ERR("Relay didn't receive valid begin data_pending struct size: %d",
					ret);
		}
		ret = -1;
		goto end_no_session;
	}

	stream_id = be64toh(msg.stream_id);

	rcu_read_lock();
	cds_lfht_for_each_entry(relay_streams_ht->ht, &iter.iter, stream,
			node.node) {
		if (stream->stream_handle == stream_id) {
			stream->data_pending_check_done = 1;
			DBG("Relay quiescent control pending flag set to %" PRIu64,
					stream_id);
			break;
		}
	}
	rcu_read_unlock();

	memset(&reply, 0, sizeof(reply));
	reply.ret_code = htobe32(LTTNG_OK);
	ret = conn->sock->ops->sendmsg(conn->sock, &reply, sizeof(reply), 0);
	if (ret < 0) {
		ERR("Relay data quiescent control ret code failed");
	}

end_no_session:
	return ret;
}

/*
 * Initialize a data pending command. This means that a client is about to ask
 * for data pending for each stream he/she holds. Simply iterate over all
 * streams of a session and set the data_pending_check_done flag.
 *
 * This command returns to the client a LTTNG_OK code.
 */
static
int relay_begin_data_pending(struct lttcomm_relayd_hdr *recv_hdr,
		struct relay_connection *conn)
{
	int ret;
	struct lttng_ht_iter iter;
	struct lttcomm_relayd_begin_data_pending msg;
	struct lttcomm_relayd_generic_reply reply;
	struct relay_stream *stream;
	uint64_t session_id;

	assert(recv_hdr);
	assert(conn);

	DBG("Init streams for data pending");

	if (!conn->session || conn->version_check_done == 0) {
		ERR("Trying to check for data before version check");
		ret = -1;
		goto end_no_session;
	}

	ret = conn->sock->ops->recvmsg(conn->sock, &msg, sizeof(msg), 0);
	if (ret < sizeof(msg)) {
		if (ret == 0) {
			/* Orderly shutdown. Not necessary to print an error. */
			DBG("Socket %d did an orderly shutdown", conn->sock->fd);
		} else {
			ERR("Relay didn't receive valid begin data_pending struct size: %d",
					ret);
		}
		ret = -1;
		goto end_no_session;
	}

	session_id = be64toh(msg.session_id);

	/*
	 * Iterate over all streams to set the begin data pending flag. For now, the
	 * streams are indexed by stream handle so we have to iterate over all
	 * streams to find the one associated with the right session_id.
	 */
	rcu_read_lock();
	cds_lfht_for_each_entry(relay_streams_ht->ht, &iter.iter, stream,
			node.node) {
		if (stream->session_id == session_id) {
			stream->data_pending_check_done = 0;
			DBG("Set begin data pending flag to stream %" PRIu64,
					stream->stream_handle);
		}
	}
	rcu_read_unlock();

	memset(&reply, 0, sizeof(reply));
	/* All good, send back reply. */
	reply.ret_code = htobe32(LTTNG_OK);

	ret = conn->sock->ops->sendmsg(conn->sock, &reply, sizeof(reply), 0);
	if (ret < 0) {
		ERR("Relay begin data pending send reply failed");
	}

end_no_session:
	return ret;
}

/*
 * End data pending command. This will check, for a given session id, if each
 * stream associated with it has its data_pending_check_done flag set. If not,
 * this means that the client lost track of the stream but the data is still
 * being streamed on our side. In this case, we inform the client that data is
 * inflight.
 *
 * Return to the client if there is data in flight or not with a ret_code.
 */
static
int relay_end_data_pending(struct lttcomm_relayd_hdr *recv_hdr,
		struct relay_connection *conn)
{
	int ret;
	struct lttng_ht_iter iter;
	struct lttcomm_relayd_end_data_pending msg;
	struct lttcomm_relayd_generic_reply reply;
	struct relay_stream *stream;
	uint64_t session_id;
	uint32_t is_data_inflight = 0;

	assert(recv_hdr);
	assert(conn);

	DBG("End data pending command");

	if (!conn->session || conn->version_check_done == 0) {
		ERR("Trying to check for data before version check");
		ret = -1;
		goto end_no_session;
	}

	ret = conn->sock->ops->recvmsg(conn->sock, &msg, sizeof(msg), 0);
	if (ret < sizeof(msg)) {
		if (ret == 0) {
			/* Orderly shutdown. Not necessary to print an error. */
			DBG("Socket %d did an orderly shutdown", conn->sock->fd);
		} else {
			ERR("Relay didn't receive valid end data_pending struct size: %d",
					ret);
		}
		ret = -1;
		goto end_no_session;
	}

	session_id = be64toh(msg.session_id);

	/* Iterate over all streams to see if the begin data pending flag is set. */
	rcu_read_lock();
	cds_lfht_for_each_entry(relay_streams_ht->ht, &iter.iter, stream,
			node.node) {
		if (stream->session_id == session_id &&
				!stream->data_pending_check_done && !stream->terminated_flag) {
			is_data_inflight = 1;
			DBG("Data is still in flight for stream %" PRIu64,
					stream->stream_handle);
			break;
		}
	}
	rcu_read_unlock();

	memset(&reply, 0, sizeof(reply));
	/* All good, send back reply. */
	reply.ret_code = htobe32(is_data_inflight);

	ret = conn->sock->ops->sendmsg(conn->sock, &reply, sizeof(reply), 0);
	if (ret < 0) {
		ERR("Relay end data pending send reply failed");
	}

end_no_session:
	return ret;
}

/*
 * Receive an index for a specific stream.
 *
 * Return 0 on success else a negative value.
 */
static
int relay_recv_index(struct lttcomm_relayd_hdr *recv_hdr,
		struct relay_connection *conn)
{
	int ret, send_ret, index_created = 0;
	struct relay_session *session = conn->session;
	struct lttcomm_relayd_index index_info;
	struct relay_index *index, *wr_index = NULL;
	struct lttcomm_relayd_generic_reply reply;
	struct relay_stream *stream;
	uint64_t net_seq_num;

	assert(conn);

	DBG("Relay receiving index");

	if (!session || conn->version_check_done == 0) {
		ERR("Trying to close a stream before version check");
		ret = -1;
		goto end_no_session;
	}

	ret = conn->sock->ops->recvmsg(conn->sock, &index_info,
			sizeof(index_info), 0);
	if (ret < sizeof(index_info)) {
		if (ret == 0) {
			/* Orderly shutdown. Not necessary to print an error. */
			DBG("Socket %d did an orderly shutdown", conn->sock->fd);
		} else {
			ERR("Relay didn't receive valid index struct size : %d", ret);
		}
		ret = -1;
		goto end_no_session;
	}

	net_seq_num = be64toh(index_info.net_seq_num);

	rcu_read_lock();
	stream = stream_find_by_id(relay_streams_ht,
			be64toh(index_info.relay_stream_id));
	if (!stream) {
		ret = -1;
		goto end_rcu_unlock;
	}

	/* Live beacon handling */
	if (index_info.packet_size == 0) {
		DBG("Received live beacon for stream %" PRIu64, stream->stream_handle);

		/*
		 * Only flag a stream inactive when it has already received data
		 * and no indexes are in flight.
		 */
		if (stream->total_index_received > 0 && stream->indexes_in_flight == 0) {
			stream->beacon_ts_end = be64toh(index_info.timestamp_end);
		}
		ret = 0;
		goto end_rcu_unlock;
	} else {
		stream->beacon_ts_end = -1ULL;
	}

	index = relay_index_find(stream->stream_handle, net_seq_num);
	if (!index) {
		/* A successful creation will add the object to the HT. */
		index = relay_index_create(stream->stream_handle, net_seq_num);
		if (!index) {
			goto end_rcu_unlock;
		}
		index_created = 1;
		stream->indexes_in_flight++;
	}

	copy_index_control_data(index, &index_info);
	if (stream->ctf_stream_id == -1ULL) {
		stream->ctf_stream_id = be64toh(index_info.stream_id);
	}

	if (index_created) {
		/*
		 * Try to add the relay index object to the hash table. If an object
		 * already exist, destroy back the index created, set the data in this
		 * object and write it on disk.
		 */
		relay_index_add(index, &wr_index);
		if (wr_index) {
			copy_index_control_data(wr_index, &index_info);
			free(index);
		}
	} else {
		/* The index already exists so write it on disk. */
		wr_index = index;
	}

	/* Do we have a writable ready index to write on disk. */
	if (wr_index) {
		ret = relay_index_write(wr_index->fd, wr_index);
		if (ret < 0) {
			goto end_rcu_unlock;
		}
		stream->total_index_received++;
		stream->indexes_in_flight--;
		assert(stream->indexes_in_flight >= 0);
	}

end_rcu_unlock:
	rcu_read_unlock();

	memset(&reply, 0, sizeof(reply));
	if (ret < 0) {
		reply.ret_code = htobe32(LTTNG_ERR_UNK);
	} else {
		reply.ret_code = htobe32(LTTNG_OK);
	}
	send_ret = conn->sock->ops->sendmsg(conn->sock, &reply, sizeof(reply), 0);
	if (send_ret < 0) {
		ERR("Relay sending close index id reply");
		ret = send_ret;
	}

end_no_session:
	return ret;
}

/*
 * Receive the streams_sent message.
 *
 * Return 0 on success else a negative value.
 */
static
int relay_streams_sent(struct lttcomm_relayd_hdr *recv_hdr,
		struct relay_connection *conn)
{
	int ret, send_ret;
	struct lttcomm_relayd_generic_reply reply;

	assert(conn);

	DBG("Relay receiving streams_sent");

	if (!conn->session || conn->version_check_done == 0) {
		ERR("Trying to close a stream before version check");
		ret = -1;
		goto end_no_session;
	}

	/*
	 * Flag every pending stream in the connection recv list that they are
	 * ready to be used by the viewer.
	 */
	set_viewer_ready_flag(conn);

	/*
	 * Inform the viewer that there are new streams in the session.
	 */
	if (conn->session->viewer_refcount) {
		uatomic_set(&conn->session->new_streams, 1);
	}

	memset(&reply, 0, sizeof(reply));
	reply.ret_code = htobe32(LTTNG_OK);
	send_ret = conn->sock->ops->sendmsg(conn->sock, &reply, sizeof(reply), 0);
	if (send_ret < 0) {
		ERR("Relay sending sent_stream reply");
		ret = send_ret;
	} else {
		/* Success. */
		ret = 0;
	}

end_no_session:
	return ret;
}

/*
 * Process the commands received on the control socket
 */
static
int relay_process_control(struct lttcomm_relayd_hdr *recv_hdr,
		struct relay_connection *conn)
{
	int ret = 0;

	switch (be32toh(recv_hdr->cmd)) {
	case RELAYD_CREATE_SESSION:
		ret = relay_create_session(recv_hdr, conn);
		break;
	case RELAYD_ADD_STREAM:
		ret = relay_add_stream(recv_hdr, conn);
		break;
	case RELAYD_START_DATA:
		ret = relay_start(recv_hdr, conn);
		break;
	case RELAYD_SEND_METADATA:
		ret = relay_recv_metadata(recv_hdr, conn);
		break;
	case RELAYD_VERSION:
		ret = relay_send_version(recv_hdr, conn);
		break;
	case RELAYD_CLOSE_STREAM:
		ret = relay_close_stream(recv_hdr, conn);
		break;
	case RELAYD_DATA_PENDING:
		ret = relay_data_pending(recv_hdr, conn);
		break;
	case RELAYD_QUIESCENT_CONTROL:
		ret = relay_quiescent_control(recv_hdr, conn);
		break;
	case RELAYD_BEGIN_DATA_PENDING:
		ret = relay_begin_data_pending(recv_hdr, conn);
		break;
	case RELAYD_END_DATA_PENDING:
		ret = relay_end_data_pending(recv_hdr, conn);
		break;
	case RELAYD_SEND_INDEX:
		ret = relay_recv_index(recv_hdr, conn);
		break;
	case RELAYD_STREAMS_SENT:
		ret = relay_streams_sent(recv_hdr, conn);
		break;
	case RELAYD_UPDATE_SYNC_INFO:
	default:
		ERR("Received unknown command (%u)", be32toh(recv_hdr->cmd));
		relay_unknown_command(conn);
		ret = -1;
		goto end;
	}

end:
	return ret;
}

/*
 * Handle index for a data stream.
 *
 * RCU read side lock MUST be acquired.
 *
 * Return 0 on success else a negative value.
 */
static int handle_index_data(struct relay_stream *stream, uint64_t net_seq_num,
		int rotate_index)
{
	int ret = 0, index_created = 0;
	uint64_t stream_id, data_offset;
	struct relay_index *index, *wr_index = NULL;

	assert(stream);

	stream_id = stream->stream_handle;
	/* Get data offset because we are about to update the index. */
	data_offset = htobe64(stream->tracefile_size_current);

	/*
	 * Lookup for an existing index for that stream id/sequence number. If on
	 * exists, the control thread already received the data for it thus we need
	 * to write it on disk.
	 */
	index = relay_index_find(stream_id, net_seq_num);
	if (!index) {
		/* A successful creation will add the object to the HT. */
		index = relay_index_create(stream_id, net_seq_num);
		if (!index) {
			ret = -1;
			goto error;
		}
		index_created = 1;
		stream->indexes_in_flight++;
	}

	if (rotate_index || stream->index_fd < 0) {
		index->to_close_fd = stream->index_fd;
		ret = index_create_file(stream->path_name, stream->channel_name,
				relayd_uid, relayd_gid, stream->tracefile_size,
				stream->tracefile_count_current);
		if (ret < 0) {
			/* This will close the stream's index fd if one. */
			relay_index_free_safe(index);
			goto error;
		}
		stream->index_fd = ret;
	}
	index->fd = stream->index_fd;
	index->index_data.offset = data_offset;

	if (index_created) {
		/*
		 * Try to add the relay index object to the hash table. If an object
		 * already exist, destroy back the index created and set the data.
		 */
		relay_index_add(index, &wr_index);
		if (wr_index) {
			/* Copy back data from the created index. */
			wr_index->fd = index->fd;
			wr_index->to_close_fd = index->to_close_fd;
			wr_index->index_data.offset = data_offset;
			free(index);
		}
	} else {
		/* The index already exists so write it on disk. */
		wr_index = index;
	}

	/* Do we have a writable ready index to write on disk. */
	if (wr_index) {
		ret = relay_index_write(wr_index->fd, wr_index);
		if (ret < 0) {
			goto error;
		}
		stream->total_index_received++;
		stream->indexes_in_flight--;
		assert(stream->indexes_in_flight >= 0);
	}

error:
	return ret;
}

/*
 * relay_process_data: Process the data received on the data socket
 */
static
int relay_process_data(struct relay_connection *conn)
{
	int ret = 0, rotate_index = 0;
	ssize_t size_ret;
	struct relay_stream *stream;
	struct lttcomm_relayd_data_hdr data_hdr;
	uint64_t stream_id;
	uint64_t net_seq_num;
	uint32_t data_size;
	struct relay_session *session;

	assert(conn);

	ret = conn->sock->ops->recvmsg(conn->sock, &data_hdr,
			sizeof(struct lttcomm_relayd_data_hdr), 0);
	if (ret <= 0) {
		if (ret == 0) {
			/* Orderly shutdown. Not necessary to print an error. */
			DBG("Socket %d did an orderly shutdown", conn->sock->fd);
		} else {
			ERR("Unable to receive data header on sock %d", conn->sock->fd);
		}
		ret = -1;
		goto end;
	}

	stream_id = be64toh(data_hdr.stream_id);

	rcu_read_lock();
	stream = stream_find_by_id(relay_streams_ht, stream_id);
	if (!stream) {
		ret = -1;
		goto end_rcu_unlock;
	}

	session = session_find_by_id(conn->sessions_ht, stream->session_id);
	assert(session);

	data_size = be32toh(data_hdr.data_size);
	if (data_buffer_size < data_size) {
		char *tmp_data_ptr;

		tmp_data_ptr = realloc(data_buffer, data_size);
		if (!tmp_data_ptr) {
			ERR("Allocating data buffer");
			free(data_buffer);
			ret = -1;
			goto end_rcu_unlock;
		}
		data_buffer = tmp_data_ptr;
		data_buffer_size = data_size;
	}
	memset(data_buffer, 0, data_size);

	net_seq_num = be64toh(data_hdr.net_seq_num);

	DBG3("Receiving data of size %u for stream id %" PRIu64 " seqnum %" PRIu64,
		data_size, stream_id, net_seq_num);
	ret = conn->sock->ops->recvmsg(conn->sock, data_buffer, data_size, 0);
	if (ret <= 0) {
		if (ret == 0) {
			/* Orderly shutdown. Not necessary to print an error. */
			DBG("Socket %d did an orderly shutdown", conn->sock->fd);
		}
		ret = -1;
		goto end_rcu_unlock;
	}

	/* Check if a rotation is needed. */
	if (stream->tracefile_size > 0 &&
			(stream->tracefile_size_current + data_size) >
			stream->tracefile_size) {
		struct relay_viewer_stream *vstream;
		uint64_t new_id;

		new_id = (stream->tracefile_count_current + 1) %
			stream->tracefile_count;
		/*
		 * When we wrap-around back to 0, we start overwriting old
		 * trace data.
		 */
		if (!stream->tracefile_overwrite && new_id == 0) {
			stream->tracefile_overwrite = 1;
		}
		pthread_mutex_lock(&stream->viewer_stream_rotation_lock);
		if (stream->tracefile_overwrite) {
			stream->oldest_tracefile_id =
				(stream->oldest_tracefile_id + 1) %
				stream->tracefile_count;
		}
		vstream = viewer_stream_find_by_id(stream->stream_handle);
		if (vstream) {
			/*
			 * The viewer is reading a file about to be
			 * overwritten. Close the FDs it is
			 * currently using and let it handle the fault.
			 */
			if (vstream->tracefile_count_current == new_id) {
				pthread_mutex_lock(&vstream->overwrite_lock);
				vstream->abort_flag = 1;
				pthread_mutex_unlock(&vstream->overwrite_lock);
				DBG("Streaming side setting abort_flag on stream %s_%" PRIu64 "\n",
						stream->channel_name, new_id);
			} else if (vstream->tracefile_count_current ==
					stream->tracefile_count_current) {
				/*
				 * The reader and writer were in the
				 * same trace file, inform the viewer
				 * that no new index will ever be added
				 * to this file.
				 */
				vstream->close_write_flag = 1;
			}
		}
		ret = utils_rotate_stream_file(stream->path_name, stream->channel_name,
				stream->tracefile_size, stream->tracefile_count,
				relayd_uid, relayd_gid, stream->fd,
				&(stream->tracefile_count_current), &stream->fd);
		pthread_mutex_unlock(&stream->viewer_stream_rotation_lock);
		if (ret < 0) {
			ERR("Rotating stream output file");
			goto end_rcu_unlock;
		}
		/* Reset current size because we just perform a stream rotation. */
		stream->tracefile_size_current = 0;
		rotate_index = 1;
	}

	/*
	 * Index are handled in protocol version 2.4 and above. Also, snapshot and
	 * index are NOT supported.
	 */
	if (session->minor >= 4 && !session->snapshot) {
		ret = handle_index_data(stream, net_seq_num, rotate_index);
		if (ret < 0) {
			goto end_rcu_unlock;
		}
	}

	/* Write data to stream output fd. */
	size_ret = lttng_write(stream->fd, data_buffer, data_size);
	if (size_ret < data_size) {
		ERR("Relay error writing data to file");
		ret = -1;
		goto end_rcu_unlock;
	}

	DBG2("Relay wrote %d bytes to tracefile for stream id %" PRIu64,
			ret, stream->stream_handle);

	ret = write_padding_to_file(stream->fd, be32toh(data_hdr.padding_size));
	if (ret < 0) {
		goto end_rcu_unlock;
	}
	stream->tracefile_size_current += data_size + be32toh(data_hdr.padding_size);

	stream->prev_seq = net_seq_num;

	try_close_stream(session, stream);

end_rcu_unlock:
	rcu_read_unlock();
end:
	return ret;
}

static
void cleanup_connection_pollfd(struct lttng_poll_event *events, int pollfd)
{
	int ret;

	assert(events);

	(void) lttng_poll_del(events, pollfd);

	ret = close(pollfd);
	if (ret < 0) {
		ERR("Closing pollfd %d", pollfd);
	}
}

static void destroy_connection(struct lttng_ht *relay_connections_ht,
		struct relay_connection *conn)
{
	assert(relay_connections_ht);
	assert(conn);

	connection_delete(relay_connections_ht, conn);

	/* For the control socket, we try to destroy the session. */
	if (conn->type == RELAY_CONTROL && conn->session) {
		destroy_session(conn->session, conn->sessions_ht);
	}

	connection_destroy(conn);
}

/*
 * This thread does the actual work
 */
static
void *relay_thread_worker(void *data)
{
	int ret, err = -1, last_seen_data_fd = -1;
	uint32_t nb_fd;
	struct relay_connection *conn;
	struct lttng_poll_event events;
	struct lttng_ht *relay_connections_ht;
	struct lttng_ht_iter iter;
	struct lttcomm_relayd_hdr recv_hdr;
	struct relay_local_data *relay_ctx = (struct relay_local_data *) data;
	struct lttng_ht *sessions_ht = relay_ctx->sessions_ht;
	struct relay_index *index;

	DBG("[thread] Relay worker started");

	rcu_register_thread();

	health_register(health_relayd, HEALTH_RELAYD_TYPE_WORKER);

	if (testpoint(relayd_thread_worker)) {
		goto error_testpoint;
	}

	health_code_update();

	/* table of connections indexed on socket */
	relay_connections_ht = lttng_ht_new(0, LTTNG_HT_TYPE_ULONG);
	if (!relay_connections_ht) {
		goto relay_connections_ht_error;
	}

	/* Tables of received indexes indexed by index handle and net_seq_num. */
	indexes_ht = lttng_ht_new(0, LTTNG_HT_TYPE_TWO_U64);
	if (!indexes_ht) {
		goto indexes_ht_error;
	}

	ret = create_thread_poll_set(&events, 2);
	if (ret < 0) {
		goto error_poll_create;
	}

	ret = lttng_poll_add(&events, relay_conn_pipe[0], LPOLLIN | LPOLLRDHUP);
	if (ret < 0) {
		goto error;
	}

restart:
	while (1) {
		int idx = -1, i, seen_control = 0, last_notdel_data_fd = -1;

		health_code_update();

		/* Infinite blocking call, waiting for transmission */
		DBG3("Relayd worker thread polling...");
		health_poll_entry();
		ret = lttng_poll_wait(&events, -1);
		health_poll_exit();
		if (ret < 0) {
			/*
			 * Restart interrupted system call.
			 */
			if (errno == EINTR) {
				goto restart;
			}
			goto error;
		}

		nb_fd = ret;

		/*
		 * Process control. The control connection is prioritised so we don't
		 * starve it with high throughout put tracing data on the data
		 * connection.
		 */
		for (i = 0; i < nb_fd; i++) {
			/* Fetch once the poll data */
			uint32_t revents = LTTNG_POLL_GETEV(&events, i);
			int pollfd = LTTNG_POLL_GETFD(&events, i);

			health_code_update();

			if (!revents) {
				/* No activity for this FD (poll implementation). */
				continue;
			}

			/* Thread quit pipe has been closed. Killing thread. */
			ret = check_thread_quit_pipe(pollfd, revents);
			if (ret) {
				err = 0;
				goto exit;
			}

			/* Inspect the relay conn pipe for new connection */
			if (pollfd == relay_conn_pipe[0]) {
				if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
					ERR("Relay connection pipe error");
					goto error;
				} else if (revents & LPOLLIN) {
					ret = lttng_read(relay_conn_pipe[0], &conn, sizeof(conn));
					if (ret < 0) {
						goto error;
					}
					conn->sessions_ht = sessions_ht;
					connection_init(conn);
					lttng_poll_add(&events, conn->sock->fd,
							LPOLLIN | LPOLLRDHUP);
					rcu_read_lock();
					lttng_ht_add_unique_ulong(relay_connections_ht,
							&conn->sock_n);
					rcu_read_unlock();
					DBG("Connection socket %d added", conn->sock->fd);
				}
			} else {
				rcu_read_lock();
				conn = connection_find_by_sock(relay_connections_ht, pollfd);
				/* If not found, there is a synchronization issue. */
				assert(conn);

				if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
					cleanup_connection_pollfd(&events, pollfd);
					destroy_connection(relay_connections_ht, conn);
					if (last_seen_data_fd == pollfd) {
						last_seen_data_fd = last_notdel_data_fd;
					}
				} else if (revents & LPOLLIN) {
					if (conn->type == RELAY_CONTROL) {
						ret = conn->sock->ops->recvmsg(conn->sock, &recv_hdr,
								sizeof(recv_hdr), 0);
						if (ret <= 0) {
							/* Connection closed */
							cleanup_connection_pollfd(&events, pollfd);
							destroy_connection(relay_connections_ht, conn);
							DBG("Control connection closed with %d", pollfd);
						} else {
							ret = relay_process_control(&recv_hdr, conn);
							if (ret < 0) {
								/* Clear the session on error. */
								cleanup_connection_pollfd(&events, pollfd);
								destroy_connection(relay_connections_ht, conn);
								DBG("Connection closed with %d", pollfd);
							}
							seen_control = 1;
						}
					} else {
						/*
						 * Flag the last seen data fd not deleted. It will be
						 * used as the last seen fd if any fd gets deleted in
						 * this first loop.
						 */
						last_notdel_data_fd = pollfd;
					}
				} else {
					ERR("Unknown poll events %u for sock %d", revents, pollfd);
				}
				rcu_read_unlock();
			}
		}

		/*
		 * The last loop handled a control request, go back to poll to make
		 * sure we prioritise the control socket.
		 */
		if (seen_control) {
			continue;
		}

		if (last_seen_data_fd >= 0) {
			for (i = 0; i < nb_fd; i++) {
				int pollfd = LTTNG_POLL_GETFD(&events, i);

				health_code_update();

				if (last_seen_data_fd == pollfd) {
					idx = i;
					break;
				}
			}
		}

		/* Process data connection. */
		for (i = idx + 1; i < nb_fd; i++) {
			/* Fetch the poll data. */
			uint32_t revents = LTTNG_POLL_GETEV(&events, i);
			int pollfd = LTTNG_POLL_GETFD(&events, i);

			health_code_update();

			if (!revents) {
				/* No activity for this FD (poll implementation). */
				continue;
			}

			/* Skip the command pipe. It's handled in the first loop. */
			if (pollfd == relay_conn_pipe[0]) {
				continue;
			}

			rcu_read_lock();
			conn = connection_find_by_sock(relay_connections_ht, pollfd);
			if (!conn) {
				/* Skip it. Might be removed before. */
				rcu_read_unlock();
				continue;
			}

			if (revents & LPOLLIN) {
				if (conn->type != RELAY_DATA) {
					rcu_read_unlock();
					continue;
				}

				ret = relay_process_data(conn);
				/* Connection closed */
				if (ret < 0) {
					cleanup_connection_pollfd(&events, pollfd);
					destroy_connection(relay_connections_ht, conn);
					DBG("Data connection closed with %d", pollfd);
					/*
					 * Every goto restart call sets the last seen fd where
					 * here we don't really care since we gracefully
					 * continue the loop after the connection is deleted.
					 */
				} else {
					/* Keep last seen port. */
					last_seen_data_fd = pollfd;
					rcu_read_unlock();
					goto restart;
				}
			}
			rcu_read_unlock();
		}
		last_seen_data_fd = -1;
	}

	/* Normal exit, no error */
	ret = 0;

exit:
error:
	lttng_poll_clean(&events);

	/* Cleanup reamaining connection object. */
	rcu_read_lock();
	cds_lfht_for_each_entry(relay_connections_ht->ht, &iter.iter, conn,
			sock_n.node) {
		health_code_update();
		destroy_connection(relay_connections_ht, conn);
	}
	rcu_read_unlock();
error_poll_create:
	rcu_read_lock();
	cds_lfht_for_each_entry(indexes_ht->ht, &iter.iter, index,
			index_n.node) {
		health_code_update();
		relay_index_delete(index);
		relay_index_free_safe(index);
	}
	rcu_read_unlock();
	lttng_ht_destroy(indexes_ht);
indexes_ht_error:
	lttng_ht_destroy(relay_connections_ht);
relay_connections_ht_error:
	/* Close relay conn pipes */
	utils_close_pipe(relay_conn_pipe);
	if (err) {
		DBG("Thread exited with error");
	}
	DBG("Worker thread cleanup complete");
	free(data_buffer);
error_testpoint:
	if (err) {
		health_error();
		ERR("Health error occurred in %s", __func__);
	}
	health_unregister(health_relayd);
	rcu_unregister_thread();
	lttng_relay_stop_threads();
	return NULL;
}

/*
 * Create the relay command pipe to wake thread_manage_apps.
 * Closed in cleanup().
 */
static int create_relay_conn_pipe(void)
{
	int ret;

	ret = utils_create_pipe_cloexec(relay_conn_pipe);

	return ret;
}

/*
 * main
 */
int main(int argc, char **argv)
{
	int ret = 0, retval = 0;
	void *status;
	struct relay_local_data *relay_ctx = NULL;

	/* Parse arguments */
	progname = argv[0];
	if (set_options(argc, argv)) {
		retval = -1;
		goto exit_options;
	}

	if (set_signal_handler()) {
		retval = -1;
		goto exit_options;
	}

	/* Try to create directory if -o, --output is specified. */
	if (opt_output_path) {
		if (*opt_output_path != '/') {
			ERR("Please specify an absolute path for -o, --output PATH");
			retval = -1;
			goto exit_options;
		}

		ret = utils_mkdir_recursive(opt_output_path, S_IRWXU | S_IRWXG);
		if (ret < 0) {
			ERR("Unable to create %s", opt_output_path);
			retval = -1;
			goto exit_options;
		}
	}

	/* Daemonize */
	if (opt_daemon || opt_background) {
		int i;

		ret = lttng_daemonize(&child_ppid, &recv_child_signal,
			!opt_background);
		if (ret < 0) {
			retval = -1;
			goto exit_options;
		}

		/*
		 * We are in the child. Make sure all other file
		 * descriptors are closed, in case we are called with
		 * more opened file descriptors than the standard ones.
		 */
		for (i = 3; i < sysconf(_SC_OPEN_MAX); i++) {
			(void) close(i);
		}
	}


	/* Initialize thread health monitoring */
	health_relayd = health_app_create(NR_HEALTH_RELAYD_TYPES);
	if (!health_relayd) {
		PERROR("health_app_create error");
		retval = -1;
		goto exit_health_app_create;
	}

	/* Create thread quit pipe */
	if (init_thread_quit_pipe()) {
		retval = -1;
		goto exit_init_data;
	}

	/* We need those values for the file/dir creation. */
	relayd_uid = getuid();
	relayd_gid = getgid();

	/* Check if daemon is UID = 0 */
	if (relayd_uid == 0) {
		if (control_uri->port < 1024 || data_uri->port < 1024 || live_uri->port < 1024) {
			ERR("Need to be root to use ports < 1024");
			retval = -1;
			goto exit_init_data;
		}
	}

	/* Setup the thread apps communication pipe. */
	if (create_relay_conn_pipe()) {
		retval = -1;
		goto exit_init_data;
	}

	/* Init relay command queue. */
	cds_wfcq_init(&relay_conn_queue.head, &relay_conn_queue.tail);

	/* Set up max poll set size */
	if (lttng_poll_set_max_size()) {
		retval = -1;
		goto exit_init_data;
	}

	/* Initialize communication library */
	lttcomm_init();
	lttcomm_inet_init();

	relay_ctx = zmalloc(sizeof(struct relay_local_data));
	if (!relay_ctx) {
		PERROR("relay_ctx");
		retval = -1;
		goto exit_init_data;
	}

	/* tables of sessions indexed by session ID */
	relay_ctx->sessions_ht = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
	if (!relay_ctx->sessions_ht) {
		retval = -1;
		goto exit_init_data;
	}

	/* tables of streams indexed by stream ID */
	relay_streams_ht = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
	if (!relay_streams_ht) {
		retval = -1;
		goto exit_init_data;
	}

	/* tables of streams indexed by stream ID */
	viewer_streams_ht = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
	if (!viewer_streams_ht) {
		retval = -1;
		goto exit_init_data;
	}

	ret = utils_create_pipe(health_quit_pipe);
	if (ret) {
		retval = -1;
		goto exit_health_quit_pipe;
	}

	/* Create thread to manage the client socket */
	ret = pthread_create(&health_thread, NULL,
			thread_manage_health, (void *) NULL);
	if (ret) {
		errno = ret;
		PERROR("pthread_create health");
		retval = -1;
		goto exit_health_thread;
	}

	/* Setup the dispatcher thread */
	ret = pthread_create(&dispatcher_thread, NULL,
			relay_thread_dispatcher, (void *) NULL);
	if (ret) {
		errno = ret;
		PERROR("pthread_create dispatcher");
		retval = -1;
		goto exit_dispatcher_thread;
	}

	/* Setup the worker thread */
	ret = pthread_create(&worker_thread, NULL,
			relay_thread_worker, (void *) relay_ctx);
	if (ret) {
		errno = ret;
		PERROR("pthread_create worker");
		retval = -1;
		goto exit_worker_thread;
	}

	/* Setup the listener thread */
	ret = pthread_create(&listener_thread, NULL,
			relay_thread_listener, (void *) NULL);
	if (ret) {
		errno = ret;
		PERROR("pthread_create listener");
		retval = -1;
		goto exit_listener_thread;
	}

	ret = relayd_live_create(live_uri, relay_ctx);
	if (ret) {
		ERR("Starting live viewer threads");
		retval = -1;
		goto exit_live;
	}

	/*
	 * This is where we start awaiting program completion (e.g. through
	 * signal that asks threads to teardown).
	 */

	ret = relayd_live_join();
	if (ret) {
		retval = -1;
	}
exit_live:

	ret = pthread_join(listener_thread, &status);
	if (ret) {
		errno = ret;
		PERROR("pthread_join listener_thread");
		retval = -1;
	}

exit_listener_thread:
	ret = pthread_join(worker_thread, &status);
	if (ret) {
		errno = ret;
		PERROR("pthread_join worker_thread");
		retval = -1;
	}

exit_worker_thread:
	ret = pthread_join(dispatcher_thread, &status);
	if (ret) {
		errno = ret;
		PERROR("pthread_join dispatcher_thread");
		retval = -1;
	}
exit_dispatcher_thread:

	ret = pthread_join(health_thread, &status);
	if (ret) {
		errno = ret;
		PERROR("pthread_join health_thread");
		retval = -1;
	}
exit_health_thread:

	utils_close_pipe(health_quit_pipe);
exit_health_quit_pipe:

exit_init_data:
	health_app_destroy(health_relayd);
exit_health_app_create:
exit_options:
	relayd_cleanup(relay_ctx);

	if (!retval) {
		exit(EXIT_SUCCESS);
	} else {
		exit(EXIT_FAILURE);
	}
}