X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fbin%2Flttng-relayd%2Fmain.c;h=25a32a70b7b8488435474461e7a92ea9b161bf73;hp=2ffa75078779b7d0b9986696f5643267ca5ea7aa;hb=7ceefac4c8474606312e25ab822e510c41a3d644;hpb=8d382dd4d4e95ea6ff88d6bd9f8a8fc85970ee3b

diff --git a/src/bin/lttng-relayd/main.c b/src/bin/lttng-relayd/main.c
index 2ffa75078..25a32a70b 100644
--- a/src/bin/lttng-relayd/main.c
+++ b/src/bin/lttng-relayd/main.c
@@ -34,6 +34,7 @@
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <sys/wait.h>
+#include <sys/resource.h>
 #include <inttypes.h>
 #include <urcu/futex.h>
 #include <urcu/uatomic.h>
@@ -41,6 +42,7 @@
 #include <unistd.h>
 #include <fcntl.h>
 #include <strings.h>
+#include <ctype.h>
 
 #include <lttng/lttng.h>
 #include <common/common.h>
@@ -61,22 +63,26 @@
 #include <common/dynamic-buffer.h>
 #include <common/buffer-view.h>
 #include <common/string-utils/format.h>
+#include <common/fd-tracker/fd-tracker.h>
+#include <common/fd-tracker/utils.h>
 
+#include "backward-compatibility-group-by.h"
 #include "cmd.h"
+#include "connection.h"
 #include "ctf-trace.h"
+#include "health-relayd.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 "lttng-relayd.h"
 #include "session.h"
+#include "sessiond-trace-chunks.h"
 #include "stream.h"
-#include "connection.h"
-#include "tracefile-array.h"
 #include "tcp_keep_alive.h"
-#include "sessiond-trace-chunks.h"
+#include "testpoint.h"
+#include "tracefile-array.h"
+#include "utils.h"
+#include "version.h"
+#include "viewer-stream.h"
 
 static const char *help_msg =
 #ifdef LTTNG_EMBED_HELP
@@ -95,8 +101,9 @@ enum relay_connection_status {
 };
 
 /* command line options */
-char *opt_output_path;
-static int opt_daemon, opt_background;
+char *opt_output_path, *opt_working_directory;
+static int opt_daemon, opt_background, opt_print_version, opt_allow_clear = 1;
+enum relay_group_output_by opt_group_output_by = RELAYD_GROUP_OUTPUT_BY_UNKNOWN;
 
 /*
  * We need to wait for listener and live listener threads, as well as
@@ -157,6 +164,9 @@ static uint64_t last_relay_stream_id;
  */
 static struct relay_conn_queue relay_conn_queue;
 
+/* Cap of file desriptors to be in simultaneous use by the relay daemon. */
+static unsigned int lttng_opt_fd_pool_size = -1;
+
 /* Global relay stream hash table. */
 struct lttng_ht *relay_streams_ht;
 
@@ -171,6 +181,9 @@ struct health_app *health_relayd;
 
 struct sessiond_trace_chunk_registry *sessiond_trace_chunk_registry;
 
+/* Global fd tracker. */
+struct fd_tracker *the_fd_tracker;
+
 static struct option long_options[] = {
 	{ "control-port", 1, 0, 'C', },
 	{ "data-port", 1, 0, 'D', },
@@ -178,16 +191,38 @@ static struct option long_options[] = {
 	{ "daemonize", 0, 0, 'd', },
 	{ "background", 0, 0, 'b', },
 	{ "group", 1, 0, 'g', },
+	{ "fd-pool-size", 1, 0, '\0', },
 	{ "help", 0, 0, 'h', },
 	{ "output", 1, 0, 'o', },
 	{ "verbose", 0, 0, 'v', },
 	{ "config", 1, 0, 'f' },
 	{ "version", 0, 0, 'V' },
+	{ "working-directory", 1, 0, 'w', },
+	{ "group-output-by-session", 0, 0, 's', },
+	{ "group-output-by-host", 0, 0, 'p', },
+	{ "disallow-clear", 0, 0, 'x' },
 	{ NULL, 0, 0, 0, },
 };
 
 static const char *config_ignore_options[] = { "help", "config", "version" };
 
+static void print_version(void) {
+	fprintf(stdout, "%s\n", VERSION);
+}
+
+static void relayd_config_log(void)
+{
+	DBG("LTTng-relayd " VERSION " - " VERSION_NAME "%s%s",
+			GIT_VERSION[0] == '\0' ? "" : " - " GIT_VERSION,
+			EXTRA_VERSION_NAME[0] == '\0' ? "" : " - " EXTRA_VERSION_NAME);
+	if (EXTRA_VERSION_DESCRIPTION[0] != '\0') {
+		DBG("LTTng-relayd extra version description:\n\t" EXTRA_VERSION_DESCRIPTION "\n");
+	}
+	if (EXTRA_VERSION_PATCHES[0] != '\0') {
+		DBG("LTTng-relayd extra patches:\n\t" EXTRA_VERSION_PATCHES "\n");
+	}
+}
+
 /*
  * Take an option from the getopt output and set it in the right variable to be
  * used later.
@@ -200,9 +235,27 @@ static int set_option(int opt, const char *arg, const char *optname)
 
 	switch (opt) {
 	case 0:
-		fprintf(stderr, "option %s", optname);
-		if (arg) {
-			fprintf(stderr, " with arg %s\n", arg);
+		if (!strcmp(optname, "fd-pool-size")) {
+			unsigned long v;
+
+			errno = 0;
+			v = strtoul(arg, NULL, 0);
+			if (errno != 0 || !isdigit(arg[0])) {
+				ERR("Wrong value in --fd-pool-size parameter: %s", arg);
+				ret = -1;
+				goto end;
+			}
+			if (v >= UINT_MAX) {
+				ERR("File descriptor cap overflow in --fd-pool-size parameter: %s", arg);
+				ret = -1;
+				goto end;
+			}
+			lttng_opt_fd_pool_size = (unsigned int) v;
+		} else {
+			fprintf(stderr, "unknown option %s", optname);
+			if (arg) {
+				fprintf(stderr, " with arg %s\n", arg);
+			}
 		}
 		break;
 	case 'C':
@@ -278,8 +331,8 @@ static int set_option(int opt, const char *arg, const char *optname)
 		}
 		exit(EXIT_FAILURE);
 	case 'V':
-		fprintf(stdout, "%s\n", VERSION);
-		exit(EXIT_SUCCESS);
+		opt_print_version = 1;
+		break;
 	case 'o':
 		if (lttng_is_setuid_setgid()) {
 			WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
@@ -293,6 +346,20 @@ static int set_option(int opt, const char *arg, const char *optname)
 			}
 		}
 		break;
+	case 'w':
+		if (lttng_is_setuid_setgid()) {
+			WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
+				"-w, --working-directory");
+		} else {
+			ret = asprintf(&opt_working_directory, "%s", arg);
+			if (ret < 0) {
+				ret = -errno;
+				PERROR("asprintf opt_working_directory");
+				goto end;
+			}
+		}
+		break;
+
 	case 'v':
 		/* Verbose level can increase using multiple -v */
 		if (arg) {
@@ -304,6 +371,24 @@ static int set_option(int opt, const char *arg, const char *optname)
 			}
 		}
 		break;
+	case 's':
+		if (opt_group_output_by != RELAYD_GROUP_OUTPUT_BY_UNKNOWN) {
+			ERR("Cannot set --group-output-by-session, another --group-output-by argument is present");
+			exit(EXIT_FAILURE);
+		}
+		opt_group_output_by = RELAYD_GROUP_OUTPUT_BY_SESSION;
+		break;
+	case 'p':
+		if (opt_group_output_by != RELAYD_GROUP_OUTPUT_BY_UNKNOWN) {
+			ERR("Cannot set --group-output-by-host, another --group-output-by argument is present");
+			exit(EXIT_FAILURE);
+		}
+		opt_group_output_by = RELAYD_GROUP_OUTPUT_BY_HOST;
+		break;
+	case 'x':
+		/* Disallow clear */
+		opt_allow_clear = 0;
+		break;
 	default:
 		/* Unknown option or other error.
 		 * Error is printed by getopt, just return */
@@ -373,6 +458,73 @@ end:
 	return ret;
 }
 
+static int parse_env_options(void)
+{
+	int ret = 0;
+	char *value = NULL;
+
+	value = lttng_secure_getenv(DEFAULT_LTTNG_RELAYD_WORKING_DIRECTORY_ENV);
+	if (value) {
+		opt_working_directory = strdup(value);
+		if (!opt_working_directory) {
+			ERR("Failed to allocate working directory string (\"%s\")",
+					value);
+			ret = -1;
+		}
+	}
+	return ret;
+}
+
+static int set_fd_pool_size(void)
+{
+	int ret = 0;
+	struct rlimit rlimit;
+
+	ret = getrlimit(RLIMIT_NOFILE, &rlimit);
+	if (ret) {
+		PERROR("Failed to get file descriptor limit");
+		ret = -1;
+		goto end;
+	}
+
+	DBG("File descriptor count limits are %" PRIu64 " (soft) and %" PRIu64 " (hard)",
+			(uint64_t) rlimit.rlim_cur,
+			(uint64_t) rlimit.rlim_max);
+	if (lttng_opt_fd_pool_size == -1) {
+		/* Use default value (soft limit - reserve). */
+		if (rlimit.rlim_cur < DEFAULT_RELAYD_MIN_FD_POOL_SIZE) {
+			ERR("The process' file number limit is too low (%" PRIu64 "). The process' file number limit must be set to at least %i.",
+					(uint64_t) rlimit.rlim_cur, DEFAULT_RELAYD_MIN_FD_POOL_SIZE);
+			ret = -1;
+			goto end;
+		}
+		lttng_opt_fd_pool_size = rlimit.rlim_cur -
+				DEFAULT_RELAYD_FD_POOL_SIZE_RESERVE;
+		goto end;
+	}
+
+	if (lttng_opt_fd_pool_size < DEFAULT_RELAYD_MIN_FD_POOL_SIZE) {
+		ERR("File descriptor pool size must be set to at least %d",
+				DEFAULT_RELAYD_MIN_FD_POOL_SIZE);
+		ret = -1;
+		goto end;
+	}
+
+	if (lttng_opt_fd_pool_size > rlimit.rlim_cur) {
+		ERR("File descriptor pool size argument (%u) exceeds the process' soft limit (%" PRIu64 ").",
+				lttng_opt_fd_pool_size, (uint64_t) rlimit.rlim_cur);
+		ret = -1;
+		goto end;
+	}
+
+	DBG("File descriptor pool size argument (%u) adjusted to %u to accomodate transient fd uses",
+			lttng_opt_fd_pool_size,
+			lttng_opt_fd_pool_size - DEFAULT_RELAYD_FD_POOL_SIZE_RESERVE);
+	lttng_opt_fd_pool_size -= DEFAULT_RELAYD_FD_POOL_SIZE_RESERVE;
+end:
+	return ret;
+}
+
 static int set_options(int argc, char **argv)
 {
 	int c, ret = 0, option_index = 0, retval = 0;
@@ -490,6 +642,28 @@ static int set_options(int argc, char **argv)
 			goto exit;
 		}
 	}
+	ret = set_fd_pool_size();
+	if (ret) {
+		retval = -1;
+		goto exit;
+	}
+
+	if (opt_group_output_by == RELAYD_GROUP_OUTPUT_BY_UNKNOWN) {
+		opt_group_output_by = RELAYD_GROUP_OUTPUT_BY_HOST;
+	}
+	if (opt_allow_clear) {
+		/* Check if env variable exists. */
+		const char *value = lttng_secure_getenv(DEFAULT_LTTNG_RELAYD_DISALLOW_CLEAR_ENV);
+		if (value) {
+			ret = config_parse_value(value);
+			if (ret < 0) {
+				ERR("Invalid value for %s specified", DEFAULT_LTTNG_RELAYD_DISALLOW_CLEAR_ENV);
+				retval = -1;
+				goto exit;
+			}
+			opt_allow_clear = !ret;
+		}
+	}
 
 exit:
 	free(optstring);
@@ -498,13 +672,26 @@ exit:
 
 static void print_global_objects(void)
 {
-	rcu_register_thread();
-
 	print_viewer_streams();
 	print_relay_streams();
 	print_sessions();
+}
 
-	rcu_unregister_thread();
+static int noop_close(void *data, int *fds)
+{
+	return 0;
+}
+
+static void untrack_stdio(void)
+{
+	int fds[] = { fileno(stdout), fileno(stderr) };
+
+	/*
+	 * noop_close is used since we don't really want to close
+	 * the stdio output fds; we merely want to stop tracking them.
+	 */
+	(void) fd_tracker_close_unsuspendable_fd(the_fd_tracker,
+			fds, 2, noop_close, NULL);
 }
 
 /*
@@ -523,11 +710,33 @@ static void relayd_cleanup(void)
 	if (sessions_ht)
 		lttng_ht_destroy(sessions_ht);
 
-	/* free the dynamically allocated opt_output_path */
 	free(opt_output_path);
+	free(opt_working_directory);
 
+	if (health_relayd) {
+		health_app_destroy(health_relayd);
+	}
 	/* Close thread quit pipes */
-	utils_close_pipe(thread_quit_pipe);
+	if (health_quit_pipe[0] != -1) {
+		(void) fd_tracker_util_pipe_close(
+				the_fd_tracker, health_quit_pipe);
+	}
+	if (thread_quit_pipe[0] != -1) {
+		(void) fd_tracker_util_pipe_close(
+				the_fd_tracker, thread_quit_pipe);
+	}
+	if (sessiond_trace_chunk_registry) {
+		sessiond_trace_chunk_registry_destroy(
+				sessiond_trace_chunk_registry);
+	}
+	if (the_fd_tracker) {
+		untrack_stdio();
+		/*
+		 * fd_tracker_destroy() will log the contents of the fd-tracker
+		 * if a leak is detected.
+		 */
+		fd_tracker_destroy(the_fd_tracker);
+	}
 
 	uri_free(control_uri);
 	uri_free(data_uri);
@@ -689,17 +898,26 @@ void lttng_relay_notify_ready(void)
  */
 static int init_thread_quit_pipe(void)
 {
-	int ret;
-
-	ret = utils_create_pipe_cloexec(thread_quit_pipe);
+	return fd_tracker_util_pipe_open_cloexec(
+			the_fd_tracker, "Quit pipe", thread_quit_pipe);
+}
 
-	return ret;
+/*
+ * Init health quit pipe.
+ *
+ * Return -1 on error or 0 if all pipes are created.
+ */
+static int init_health_quit_pipe(void)
+{
+	return fd_tracker_util_pipe_open_cloexec(the_fd_tracker,
+			"Health quit pipe", health_quit_pipe);
 }
 
 /*
  * 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)
+static int create_named_thread_poll_set(struct lttng_poll_event *events,
+		int size, const char *name)
 {
 	int ret;
 
@@ -708,10 +926,8 @@ static int create_thread_poll_set(struct lttng_poll_event *events, int size)
 		goto error;
 	}
 
-	ret = lttng_poll_create(events, size, LTTNG_CLOEXEC);
-	if (ret < 0) {
-		goto error;
-	}
+	ret = fd_tracker_util_poll_create(the_fd_tracker,
+		        name, events, 1, LTTNG_CLOEXEC);
 
 	/* Add quit pipe */
 	ret = lttng_poll_add(events, thread_quit_pipe[0], LPOLLIN | LPOLLERR);
@@ -739,13 +955,38 @@ static int check_thread_quit_pipe(int fd, uint32_t events)
 	return 0;
 }
 
+static int create_sock(void *data, int *out_fd)
+{
+	int ret;
+	struct lttcomm_sock *sock = data;
+
+	ret = lttcomm_create_sock(sock);
+	if (ret < 0) {
+		goto end;
+	}
+
+	*out_fd = sock->fd;
+end:
+	return ret;
+}
+
+static int close_sock(void *data, int *in_fd)
+{
+	struct lttcomm_sock *sock = data;
+
+	return sock->ops->close(sock);
+}
+
 /*
  * Create and init socket from uri.
  */
-static struct lttcomm_sock *relay_socket_create(struct lttng_uri *uri)
+static struct lttcomm_sock *relay_socket_create(struct lttng_uri *uri,
+		const char *name)
 {
-	int ret;
+	int ret, sock_fd;
 	struct lttcomm_sock *sock = NULL;
+	char uri_str[PATH_MAX];
+	char *formated_name = NULL;
 
 	sock = lttcomm_alloc_sock_from_uri(uri);
 	if (sock == NULL) {
@@ -753,11 +994,25 @@ static struct lttcomm_sock *relay_socket_create(struct lttng_uri *uri)
 		goto error;
 	}
 
-	ret = lttcomm_create_sock(sock);
-	if (ret < 0) {
-		goto error;
+	/*
+	 * Don't fail to create the socket if the name can't be built as it is
+	 * only used for debugging purposes.
+	 */
+	ret = uri_to_str_url(uri, uri_str, sizeof(uri_str));
+	uri_str[sizeof(uri_str) - 1] = '\0';
+	if (ret >= 0) {
+		ret = asprintf(&formated_name, "%s socket @ %s", name,
+				uri_str);
+		if (ret < 0) {
+			formated_name = NULL;
+		}
 	}
-	DBG("Listening on sock %d", sock->fd);
+
+	ret = fd_tracker_open_unsuspendable_fd(the_fd_tracker, &sock_fd,
+			(const char **) (formated_name ? &formated_name : NULL),
+			1, create_sock, sock);
+	free(formated_name);
+	DBG("Listening on %s socket %d", name, sock->fd);
 
 	ret = sock->ops->bind(sock);
 	if (ret < 0) {
@@ -796,12 +1051,12 @@ static void *relay_thread_listener(void *data)
 
 	health_code_update();
 
-	control_sock = relay_socket_create(control_uri);
+	control_sock = relay_socket_create(control_uri, "Control listener");
 	if (!control_sock) {
 		goto error_sock_control;
 	}
 
-	data_sock = relay_socket_create(data_uri);
+	data_sock = relay_socket_create(data_uri, "Data listener");
 	if (!data_sock) {
 		goto error_sock_relay;
 	}
@@ -810,7 +1065,7 @@ static void *relay_thread_listener(void *data)
 	 * Pass 3 as size here for the thread quit pipe, control and
 	 * data socket.
 	 */
-	ret = create_thread_poll_set(&events, 3);
+	ret = create_named_thread_poll_set(&events, 3, "Listener thread epoll");
 	if (ret < 0) {
 		goto error_create_poll;
 	}
@@ -944,21 +1199,31 @@ exit:
 error:
 error_poll_add:
 error_testpoint:
-	lttng_poll_clean(&events);
+	(void) fd_tracker_util_poll_clean(the_fd_tracker, &events);
 error_create_poll:
 	if (data_sock->fd >= 0) {
-		ret = data_sock->ops->close(data_sock);
+		int data_sock_fd = data_sock->fd;
+
+		ret = fd_tracker_close_unsuspendable_fd(the_fd_tracker,
+				&data_sock_fd, 1, close_sock,
+				data_sock);
 		if (ret) {
-			PERROR("close");
+			PERROR("Failed to close the data listener socket file descriptor");
 		}
+		data_sock->fd = -1;
 	}
 	lttcomm_destroy_sock(data_sock);
 error_sock_relay:
 	if (control_sock->fd >= 0) {
-		ret = control_sock->ops->close(control_sock);
+		int control_sock_fd = control_sock->fd;
+
+		ret = fd_tracker_close_unsuspendable_fd(the_fd_tracker,
+				&control_sock_fd, 1, close_sock,
+				control_sock);
 		if (ret) {
-			PERROR("close");
+			PERROR("Failed to close the control listener socket file descriptor");
 		}
+		control_sock->fd = -1;
 	}
 	lttcomm_destroy_sock(control_sock);
 error_sock_control:
@@ -1299,12 +1564,57 @@ static int relay_add_stream(const struct lttcomm_relayd_hdr *recv_hdr,
 		goto send_reply;
 	}
 
+	/*
+	 * Backward compatibility for --group-output-by-session.
+	 * Prior to lttng 2.11, the complete path is passed by the stream.
+	 * Starting at 2.11, lttng-relayd uses chunk. When dealing with producer
+	 * >=2.11 the chunk is responsible for the output path. When dealing
+	 * with producer < 2.11 the chunk output_path is the root output path
+	 * and the stream carries the complete path (path_name).
+	 * To support --group-output-by-session with older producer (<2.11), we
+	 * need to craft the path based on the stream path.
+	 */
+	if (opt_group_output_by == RELAYD_GROUP_OUTPUT_BY_SESSION) {
+		if (conn->minor < 4) {
+			/*
+			 * From 2.1 to 2.3, the session_name is not passed on
+			 * the RELAYD_CREATE_SESSION command. The session name
+			 * is necessary to detect the presence of a base_path
+			 * inside the stream path. Without it we cannot perform
+			 * a valid group-output-by-session transformation.
+			 */
+			WARN("Unable to perform a --group-by-session transformation for session %" PRIu64
+			     " for stream with path \"%s\" as it is produced by a peer using a protocol older than v2.4",
+					session->id, path_name);
+		} else if (conn->minor >= 4 && conn->minor < 11) {
+			char *group_by_session_path_name;
+
+			assert(session->session_name[0] != '\0');
+
+			group_by_session_path_name =
+					backward_compat_group_by_session(
+							path_name,
+							session->session_name);
+			if (!group_by_session_path_name) {
+				ERR("Failed to apply group by session to stream of session %" PRIu64,
+						session->id);
+				goto send_reply;
+			}
+
+			DBG("Transformed session path from \"%s\" to \"%s\" to honor per-session name grouping",
+					path_name, group_by_session_path_name);
+
+			free(path_name);
+			path_name = group_by_session_path_name;
+		}
+	}
+
 	trace = ctf_trace_get_by_path_or_create(session, path_name);
 	if (!trace) {
 		goto send_reply;
 	}
-	/* This stream here has one reference on the trace. */
 
+	/* This stream here has one reference on the trace. */
 	pthread_mutex_lock(&last_relay_stream_id_lock);
 	stream_handle = ++last_relay_stream_id;
 	pthread_mutex_unlock(&last_relay_stream_id_lock);
@@ -1404,7 +1714,7 @@ static int relay_close_stream(const struct lttcomm_relayd_hdr *recv_hdr,
 
 		vstream = viewer_stream_get_by_id(stream->stream_handle);
 		if (vstream) {
-			if (vstream->metadata_sent == stream->metadata_received) {
+			if (stream->no_new_metadata_notified) {
 				/*
 				 * Since all the metadata has been sent to the
 				 * viewer and that we have a request to close
@@ -2071,6 +2381,9 @@ static int relay_recv_index(const struct lttcomm_relayd_hdr *recv_hdr,
 		index_info.stream_instance_id =
 				be64toh(index_info.stream_instance_id);
 		index_info.packet_seq_num = be64toh(index_info.packet_seq_num);
+	} else {
+		index_info.stream_instance_id = -1ULL;
+		index_info.packet_seq_num = -1ULL;
 	}
 
 	stream = stream_get_by_id(index_info.relay_stream_id);
@@ -2215,7 +2528,7 @@ static int relay_rotate_session_streams(
 				session->sessiond_uuid, session->id,
 				rotate_streams.new_chunk_id.value);
 		if (!next_trace_chunk) {
-			char uuid_str[UUID_STR_LEN];
+			char uuid_str[LTTNG_UUID_STR_LEN];
 
 			lttng_uuid_to_str(session->sessiond_uuid, uuid_str);
 			ERR("Unknown next trace chunk in ROTATE_STREAMS command: sessiond_uuid = {%s}, session_id = %" PRIu64
@@ -2234,7 +2547,6 @@ static int relay_rotate_session_streams(
 		} else {
 			chunk_id_str = chunk_id_buf;
 		}
-		session->has_rotated = true;
 	}
 
 	DBG("Rotate %" PRIu32 " streams of session \"%s\" to chunk \"%s\"",
@@ -2282,6 +2594,7 @@ static int relay_rotate_session_streams(
 	}
 
 	reply_code = LTTNG_OK;
+	ret = 0;
 end:
 	if (stream) {
 		stream_put(stream);
@@ -2295,8 +2608,6 @@ end:
 				send_ret);
 		ret = -1;
 	}
-
-	ret = 0;
 end_no_reply:
 	lttng_trace_chunk_put(next_trace_chunk);
 	return ret;
@@ -2321,7 +2632,7 @@ static int relay_create_trace_chunk(const struct lttcomm_relayd_hdr *recv_hdr,
 	struct lttng_trace_chunk *chunk = NULL, *published_chunk = NULL;
 	enum lttng_error_code reply_code = LTTNG_OK;
 	enum lttng_trace_chunk_status chunk_status;
-	struct lttng_directory_handle session_output;
+	const char *new_path;
 
 	if (!session || !conn->version_check_done) {
 		ERR("Trying to create a trace chunk before version check");
@@ -2348,8 +2659,29 @@ static int relay_create_trace_chunk(const struct lttcomm_relayd_hdr *recv_hdr,
 	msg->creation_timestamp = be64toh(msg->creation_timestamp);
 	msg->override_name_length = be32toh(msg->override_name_length);
 
+	if (session->current_trace_chunk &&
+			!lttng_trace_chunk_get_name_overridden(session->current_trace_chunk)) {
+		chunk_status = lttng_trace_chunk_rename_path(session->current_trace_chunk,
+					DEFAULT_CHUNK_TMP_OLD_DIRECTORY);
+		if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+			ERR("Failed to rename old chunk");
+			ret = -1;
+			reply_code = LTTNG_ERR_UNK;
+			goto end;
+		}
+	}
+	session->ongoing_rotation = true;
+	if (!session->current_trace_chunk) {
+		if (!session->has_rotated) {
+			new_path = "";
+		} else {
+			new_path = NULL;
+		}
+	} else {
+		new_path = DEFAULT_CHUNK_TMP_NEW_DIRECTORY;
+	}
 	chunk = lttng_trace_chunk_create(
-			msg->chunk_id, msg->creation_timestamp);
+			msg->chunk_id, msg->creation_timestamp, new_path);
 	if (!chunk) {
 		ERR("Failed to create trace chunk in trace chunk creation command");
 		ret = -1;
@@ -2396,14 +2728,9 @@ static int relay_create_trace_chunk(const struct lttcomm_relayd_hdr *recv_hdr,
 		goto end;
 	}
 
-	ret = session_init_output_directory_handle(
-			conn->session, &session_output);
-	if (ret) {
-		reply_code = LTTNG_ERR_CREATE_DIR_FAIL;
-		goto end;
-	}
-	chunk_status = lttng_trace_chunk_set_as_owner(chunk, &session_output);
-	lttng_directory_handle_fini(&session_output);
+	assert(conn->session->output_directory);
+	chunk_status = lttng_trace_chunk_set_as_owner(chunk,
+			conn->session->output_directory);
 	if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
 		reply_code = LTTNG_ERR_UNK;
 		ret = -1;
@@ -2416,7 +2743,7 @@ static int relay_create_trace_chunk(const struct lttcomm_relayd_hdr *recv_hdr,
 			conn->session->id,
 			chunk);
 	if (!published_chunk) {
-		char uuid_str[UUID_STR_LEN];
+		char uuid_str[LTTNG_UUID_STR_LEN];
 
 		lttng_uuid_to_str(conn->session->sessiond_uuid, uuid_str);
 		ERR("Failed to publish chunk: sessiond_uuid = %s, session_id = %" PRIu64 ", chunk_id = %" PRIu64,
@@ -2443,6 +2770,9 @@ static int relay_create_trace_chunk(const struct lttcomm_relayd_hdr *recv_hdr,
 			conn->session->current_trace_chunk;
 	conn->session->current_trace_chunk = published_chunk;
 	published_chunk = NULL;
+	if (!conn->session->pending_closure_trace_chunk) {
+		session->ongoing_rotation = false;
+	}
 end_unlock_session:
 	pthread_mutex_unlock(&conn->session->lock);
 end:
@@ -2469,7 +2799,7 @@ static int relay_close_trace_chunk(const struct lttcomm_relayd_hdr *recv_hdr,
 		struct relay_connection *conn,
 		const struct lttng_buffer_view *payload)
 {
-	int ret = 0;
+	int ret = 0, buf_ret;
 	ssize_t send_ret;
 	struct relay_session *session = conn->session;
 	struct lttcomm_relayd_close_trace_chunk *msg;
@@ -2485,6 +2815,7 @@ static int relay_close_trace_chunk(const struct lttcomm_relayd_hdr *recv_hdr,
 	size_t path_length = 0;
 	const char *chunk_name = NULL;
 	struct lttng_dynamic_buffer reply_payload;
+	const char *new_path;
 
 	lttng_dynamic_buffer_init(&reply_payload);
 
@@ -2522,7 +2853,7 @@ static int relay_close_trace_chunk(const struct lttcomm_relayd_hdr *recv_hdr,
 			conn->session->id,
 			chunk_id);
 	if (!chunk) {
-		char uuid_str[UUID_STR_LEN];
+		char uuid_str[LTTNG_UUID_STR_LEN];
 
 		lttng_uuid_to_str(conn->session->sessiond_uuid, uuid_str);
 		ERR("Failed to find chunk to close: sessiond_uuid = %s, session_id = %" PRIu64 ", chunk_id = %" PRIu64,
@@ -2535,6 +2866,20 @@ static int relay_close_trace_chunk(const struct lttcomm_relayd_hdr *recv_hdr,
 	}
 
 	pthread_mutex_lock(&session->lock);
+	if (close_command.is_set &&
+			close_command.value == LTTNG_TRACE_CHUNK_COMMAND_TYPE_DELETE) {
+		/*
+		 * Clear command. It is a protocol error to ask for a
+		 * clear on a relay which does not allow it. Querying
+		 * the configuration allows figuring out whether
+		 * clearing is allowed before doing the clear.
+		 */
+		if (!opt_allow_clear) {
+			ret = -1;
+			reply_code = LTTNG_ERR_INVALID_PROTOCOL;
+			goto end_unlock_session;
+		}
+	}
 	if (session->pending_closure_trace_chunk &&
 			session->pending_closure_trace_chunk != chunk) {
 		ERR("Trace chunk close command for session \"%s\" does not target the trace chunk pending closure",
@@ -2544,6 +2889,43 @@ static int relay_close_trace_chunk(const struct lttcomm_relayd_hdr *recv_hdr,
 		goto end_unlock_session;
 	}
 
+	if (session->current_trace_chunk && session->current_trace_chunk != chunk &&
+			!lttng_trace_chunk_get_name_overridden(session->current_trace_chunk)) {
+		if (close_command.is_set &&
+				close_command.value == LTTNG_TRACE_CHUNK_COMMAND_TYPE_DELETE &&
+				!session->has_rotated) {
+			/* New chunk stays in session output directory. */
+			new_path = "";
+		} else {
+			/* Use chunk name for new chunk. */
+			new_path = NULL;
+		}
+		/* Rename new chunk path. */
+		chunk_status = lttng_trace_chunk_rename_path(session->current_trace_chunk,
+				new_path);
+		if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+			ret = -1;
+			goto end;
+		}
+		session->ongoing_rotation = false;
+	}
+	if ((!close_command.is_set ||
+			close_command.value == LTTNG_TRACE_CHUNK_COMMAND_TYPE_NO_OPERATION) &&
+			!lttng_trace_chunk_get_name_overridden(chunk)) {
+		const char *old_path;
+
+		if (!session->has_rotated) {
+			old_path = "";
+		} else {
+			old_path = NULL;
+		}
+		/* We need to move back the .tmp_old_chunk to its rightful place. */
+		chunk_status = lttng_trace_chunk_rename_path(chunk, old_path);
+		if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+			ret = -1;
+			goto end;
+		}
+	}
 	chunk_status = lttng_trace_chunk_set_close_timestamp(
 			chunk, close_timestamp);
 	if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
@@ -2601,6 +2983,10 @@ static int relay_close_trace_chunk(const struct lttcomm_relayd_hdr *recv_hdr,
 			goto end_unlock_session;
 		}
 	}
+	if (close_command.is_set &&
+			close_command.value == LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED) {
+		session->has_rotated = true;
+	}
 	DBG("Reply chunk path on close: %s", closed_trace_chunk_path);
 	path_length = strlen(closed_trace_chunk_path) + 1;
 	if (path_length > UINT32_MAX) {
@@ -2630,17 +3016,17 @@ end_unlock_session:
 end:
 	reply.generic.ret_code = htobe32((uint32_t) reply_code);
 	reply.path_length = htobe32((uint32_t) path_length);
-	ret = lttng_dynamic_buffer_append(
+	buf_ret = lttng_dynamic_buffer_append(
 			&reply_payload, &reply, sizeof(reply));
-	if (ret) {
+	if (buf_ret) {
 		ERR("Failed to append \"close trace chunk\" command reply header to payload buffer");
 		goto end_no_reply;
 	}
 
 	if (reply_code == LTTNG_OK) {
-		ret = lttng_dynamic_buffer_append(&reply_payload,
+		buf_ret = lttng_dynamic_buffer_append(&reply_payload,
 				closed_trace_chunk_path, path_length);
-		if (ret) {
+		if (buf_ret) {
 			ERR("Failed to append \"close trace chunk\" command reply path to payload buffer");
 			goto end_no_reply;
 		}
@@ -2675,8 +3061,8 @@ static int relay_trace_chunk_exists(const struct lttcomm_relayd_hdr *recv_hdr,
 	struct lttcomm_relayd_trace_chunk_exists *msg;
 	struct lttcomm_relayd_trace_chunk_exists_reply reply = {};
 	struct lttng_buffer_view header_view;
-	struct lttng_trace_chunk *chunk = NULL;
 	uint64_t chunk_id;
+	bool chunk_exists;
 
 	if (!session || !conn->version_check_done) {
 		ERR("Trying to close a trace chunk before version check");
@@ -2701,25 +3087,80 @@ static int relay_trace_chunk_exists(const struct lttcomm_relayd_hdr *recv_hdr,
 	msg = (typeof(msg)) header_view.data;
 	chunk_id = be64toh(msg->chunk_id);
 
-	chunk = sessiond_trace_chunk_registry_get_chunk(
+	ret = sessiond_trace_chunk_registry_chunk_exists(
 			sessiond_trace_chunk_registry,
 			conn->session->sessiond_uuid,
 			conn->session->id,
-			chunk_id);
-
-	reply = (typeof(reply)) {
-		.generic.ret_code = htobe32((uint32_t) LTTNG_OK),
-		.trace_chunk_exists = !!chunk,
+			chunk_id, &chunk_exists);
+	/*
+	 * If ret is not 0, send the reply and report the error to the caller.
+	 * It is a protocol (or internal) error and the session/connection
+	 * should be torn down.
+	 */
+	reply = (typeof(reply)){
+		.generic.ret_code = htobe32((uint32_t)
+			(ret == 0 ? LTTNG_OK : LTTNG_ERR_INVALID_PROTOCOL)),
+		.trace_chunk_exists = ret == 0 ? chunk_exists : 0,
 	};
-	send_ret = conn->sock->ops->sendmsg(conn->sock,
-			&reply, sizeof(reply), 0);
+	send_ret = conn->sock->ops->sendmsg(
+			conn->sock, &reply, sizeof(reply), 0);
 	if (send_ret < (ssize_t) sizeof(reply)) {
 		ERR("Failed to send \"create trace chunk\" command reply (ret = %zd)",
 				send_ret);
 		ret = -1;
 	}
 end_no_reply:
-	lttng_trace_chunk_put(chunk);
+	return ret;
+}
+
+/*
+ * relay_get_configuration: query whether feature is available
+ */
+static int relay_get_configuration(const struct lttcomm_relayd_hdr *recv_hdr,
+		struct relay_connection *conn,
+		const struct lttng_buffer_view *payload)
+{
+	int ret = 0;
+	ssize_t send_ret;
+	struct lttcomm_relayd_get_configuration *msg;
+	struct lttcomm_relayd_get_configuration_reply reply = {};
+	struct lttng_buffer_view header_view;
+	uint64_t query_flags = 0;
+	uint64_t result_flags = 0;
+
+	header_view = lttng_buffer_view_from_view(payload, 0, sizeof(*msg));
+	if (!header_view.data) {
+		ERR("Failed to receive payload of chunk close command");
+		ret = -1;
+		goto end_no_reply;
+	}
+
+	/* Convert to host endianness. */
+	msg = (typeof(msg)) header_view.data;
+	query_flags = be64toh(msg->query_flags);
+
+	if (query_flags) {
+		ret = LTTNG_ERR_INVALID_PROTOCOL;
+		goto reply;
+	}
+	if (opt_allow_clear) {
+		result_flags |= LTTCOMM_RELAYD_CONFIGURATION_FLAG_CLEAR_ALLOWED;
+	}
+	ret = 0;
+reply:
+	reply = (typeof(reply)){
+		.generic.ret_code = htobe32((uint32_t)
+			(ret == 0 ? LTTNG_OK : LTTNG_ERR_INVALID_PROTOCOL)),
+		.relayd_configuration_flags = htobe64(result_flags),
+	};
+	send_ret = conn->sock->ops->sendmsg(
+			conn->sock, &reply, sizeof(reply), 0);
+	if (send_ret < (ssize_t) sizeof(reply)) {
+		ERR("Failed to send \"get configuration\" command reply (ret = %zd)",
+				send_ret);
+		ret = -1;
+	}
+end_no_reply:
 	return ret;
 }
 
@@ -2801,6 +3242,10 @@ static int relay_process_control_command(struct relay_connection *conn,
 		DBG_CMD("RELAYD_TRACE_CHUNK_EXISTS", conn);
 		ret = relay_trace_chunk_exists(header, conn, payload);
 		break;
+	case RELAYD_GET_CONFIGURATION:
+		DBG_CMD("RELAYD_GET_CONFIGURATION", conn);
+		ret = relay_get_configuration(header, conn, payload);
+		break;
 	case RELAYD_UPDATE_SYNC_INFO:
 	default:
 		ERR("Received unknown command (%u)", header->cmd);
@@ -3339,7 +3784,7 @@ static void *relay_thread_worker(void *data)
 		goto relay_connections_ht_error;
 	}
 
-	ret = create_thread_poll_set(&events, 2);
+	ret = create_named_thread_poll_set(&events, 2, "Worker thread epoll");
 	if (ret < 0) {
 		goto error_poll_create;
 	}
@@ -3400,8 +3845,13 @@ restart:
 					if (ret < 0) {
 						goto error;
 					}
-					lttng_poll_add(&events, conn->sock->fd,
+					ret = lttng_poll_add(&events,
+							conn->sock->fd,
 							LPOLLIN | LPOLLRDHUP);
+					if (ret) {
+						ERR("Failed to add new connection file descriptor to poll set");
+						goto error;
+					}
 					connection_ht_add(relay_connections_ht, conn);
 					DBG("Connection socket %d added", conn->sock->fd);
 				} else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
@@ -3603,12 +4053,13 @@ error:
 	}
 	rcu_read_unlock();
 
-	lttng_poll_clean(&events);
+	(void) fd_tracker_util_poll_clean(the_fd_tracker, &events);
 error_poll_create:
 	lttng_ht_destroy(relay_connections_ht);
 relay_connections_ht_error:
 	/* Close relay conn pipes */
-	utils_close_pipe(relay_conn_pipe);
+	(void) fd_tracker_util_pipe_close(the_fd_tracker,
+			relay_conn_pipe);
 	if (err) {
 		DBG("Thread exited with error");
 	}
@@ -3630,11 +4081,24 @@ error_testpoint:
  */
 static int create_relay_conn_pipe(void)
 {
-	int ret;
+	return fd_tracker_util_pipe_open_cloexec(the_fd_tracker,
+			"Relayd connection pipe", relay_conn_pipe);
+}
+
+static int stdio_open(void *data, int *fds)
+{
+	fds[0] = fileno(stdout);
+	fds[1] = fileno(stderr);
+	return 0;
+}
 
-	ret = utils_create_pipe_cloexec(relay_conn_pipe);
+static int track_stdio(void)
+{
+	int fds[2];
+	const char *names[] = { "stdout", "stderr" };
 
-	return ret;
+	return fd_tracker_open_unsuspendable_fd(the_fd_tracker, fds,
+			names, 2, stdio_open, NULL);
 }
 
 /*
@@ -3642,10 +4106,21 @@ static int create_relay_conn_pipe(void)
  */
 int main(int argc, char **argv)
 {
+	bool thread_is_rcu_registered = false;
 	int ret = 0, retval = 0;
 	void *status;
 
-	/* Parse arguments */
+	/* Parse environment variables */
+	ret = parse_env_options();
+	if (ret) {
+		retval = -1;
+		goto exit_options;
+	}
+
+	/*
+	 * Parse arguments.
+	 * Command line arguments overwrite environment.
+	 */
 	progname = argv[0];
 	if (set_options(argc, argv)) {
 		retval = -1;
@@ -3657,6 +4132,22 @@ int main(int argc, char **argv)
 		goto exit_options;
 	}
 
+	relayd_config_log();
+
+	if (opt_print_version) {
+		print_version();
+		retval = 0;
+		goto exit_options;
+	}
+
+	ret = fclose(stdin);
+	if (ret) {
+		PERROR("Failed to close stdin");
+		goto exit_options;
+	}
+
+	DBG("Clear command %s", opt_allow_clear ? "allowed" : "disallowed");
+
 	/* Try to create directory if -o, --output is specified. */
 	if (opt_output_path) {
 		if (*opt_output_path != '/') {
@@ -3676,22 +4167,19 @@ int main(int argc, char **argv)
 
 	/* 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);
+	if (opt_working_directory) {
+		ret = utils_change_working_directory(opt_working_directory);
+		if (ret) {
+			/* All errors are already logged. */
+			goto exit_options;
 		}
 	}
 
@@ -3699,7 +4187,28 @@ int main(int argc, char **argv)
 	if (!sessiond_trace_chunk_registry) {
 		ERR("Failed to initialize session daemon trace chunk registry");
 		retval = -1;
-		goto exit_sessiond_trace_chunk_registry;
+		goto exit_options;
+	}
+
+	/*
+	 * The RCU thread registration (and use, through the fd-tracker's
+	 * creation) is done after the daemonization to allow us to not
+	 * deal with liburcu's fork() management as the call RCU needs to
+	 * be restored.
+	 */
+	rcu_register_thread();
+	thread_is_rcu_registered = true;
+
+	the_fd_tracker = fd_tracker_create(lttng_opt_fd_pool_size);
+	if (!the_fd_tracker) {
+		retval = -1;
+		goto exit_options;
+	}
+
+	ret = track_stdio();
+	if (ret) {
+		retval = -1;
+		goto exit_options;
 	}
 
 	/* Initialize thread health monitoring */
@@ -3707,19 +4216,19 @@ int main(int argc, char **argv)
 	if (!health_relayd) {
 		PERROR("health_app_create error");
 		retval = -1;
-		goto exit_health_app_create;
+		goto exit_options;
 	}
 
 	/* Create thread quit pipe */
 	if (init_thread_quit_pipe()) {
 		retval = -1;
-		goto exit_init_data;
+		goto exit_options;
 	}
 
 	/* Setup the thread apps communication pipe. */
 	if (create_relay_conn_pipe()) {
 		retval = -1;
-		goto exit_init_data;
+		goto exit_options;
 	}
 
 	/* Init relay command queue. */
@@ -3733,27 +4242,27 @@ int main(int argc, char **argv)
 	sessions_ht = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
 	if (!sessions_ht) {
 		retval = -1;
-		goto exit_init_data;
+		goto exit_options;
 	}
 
 	/* 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;
+		goto exit_options;
 	}
 
 	/* 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;
+		goto exit_options;
 	}
 
-	ret = utils_create_pipe(health_quit_pipe);
+	ret = init_health_quit_pipe();
 	if (ret) {
 		retval = -1;
-		goto exit_health_quit_pipe;
+		goto exit_options;
 	}
 
 	/* Create thread to manage the client socket */
@@ -3763,7 +4272,7 @@ int main(int argc, char **argv)
 		errno = ret;
 		PERROR("pthread_create health");
 		retval = -1;
-		goto exit_health_thread;
+		goto exit_options;
 	}
 
 	/* Setup the dispatcher thread */
@@ -3844,16 +4353,6 @@ exit_dispatcher_thread:
 		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);
-	sessiond_trace_chunk_registry_destroy(sessiond_trace_chunk_registry);
-exit_health_app_create:
-exit_sessiond_trace_chunk_registry:
 exit_options:
 	/*
 	 * Wait for all pending call_rcu work to complete before tearing
@@ -3866,6 +4365,10 @@ exit_options:
 	/* Ensure all prior call_rcu are done. */
 	rcu_barrier();
 
+	if (thread_is_rcu_registered) {
+		rcu_unregister_thread();
+	}
+
 	if (!retval) {
 		exit(EXIT_SUCCESS);
 	} else {