relayd: do not prioritize control events over data.
[lttng-tools.git] / src / bin / lttng-relayd / main.c
index 0d270d1ca29e5c0e0c5e0d642011d583198ca5bd..19b1342ac5deeffa9ac2fc8c886779c2fa5fbd1d 100644 (file)
@@ -59,6 +59,7 @@
 #include <common/config/session-config.h>
 #include <common/dynamic-buffer.h>
 #include <common/buffer-view.h>
+#include <common/fd-tracker/utils.h>
 #include <urcu/rculist.h>
 
 #include "version.h"
@@ -151,7 +152,7 @@ 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_cap;
+static unsigned int lttng_opt_fd_pool_size = -1;
 
 /* Global relay stream hash table. */
 struct lttng_ht *relay_streams_ht;
@@ -175,7 +176,7 @@ static struct option long_options[] = {
        { "daemonize", 0, 0, 'd', },
        { "background", 0, 0, 'b', },
        { "group", 1, 0, 'g', },
-       { "fd-cap", 1, 0, '\0', },
+       { "fd-pool-size", 1, 0, '\0', },
        { "help", 0, 0, 'h', },
        { "output", 1, 0, 'o', },
        { "verbose", 0, 0, 'v', },
@@ -218,28 +219,22 @@ static int set_option(int opt, const char *arg, const char *optname)
 
        switch (opt) {
        case 0:
-               if (!strcmp(optname, "fd-cap")) {
+               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-cap parameter: %s", arg);
+                               ERR("Wrong value in --fd-pool-size parameter: %s", arg);
                                ret = -1;
                                goto end;
                        }
-                       if (v < DEFAULT_RELAYD_MINIMAL_FD_CAP) {
-                               ERR("File descriptor cap must be set to at least %d",
-                                               DEFAULT_RELAYD_MINIMAL_FD_CAP);
-                       }
                        if (v >= UINT_MAX) {
-                               ERR("File descriptor cap overflow in --fd-cap parameter: %s", arg);
+                               ERR("File descriptor cap overflow in --fd-pool-size parameter: %s", arg);
                                ret = -1;
                                goto end;
                        }
-                       lttng_opt_fd_cap = (unsigned int) v;
-                       DBG3("File descriptor cap set to %u", lttng_opt_fd_cap);
-
+                       lttng_opt_fd_pool_size = (unsigned int) v;
                } else {
                        fprintf(stderr, "unknown option %s", optname);
                        if (arg) {
@@ -453,6 +448,57 @@ static void parse_env_options(void)
        }
 }
 
+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 (%lu).",
+                               lttng_opt_fd_pool_size, 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;
@@ -570,17 +616,10 @@ static int set_options(int argc, char **argv)
                        goto exit;
                }
        }
-       if (lttng_opt_fd_cap == 0) {
-               int ret;
-               struct rlimit rlimit;
-
-               ret = getrlimit(RLIMIT_NOFILE, &rlimit);
-               if (ret) {
-                       PERROR("Failed to get file descriptor limit");
-                       retval = -1;
-               }
-
-               lttng_opt_fd_cap = rlimit.rlim_cur;
+       ret = set_fd_pool_size();
+       if (ret) {
+               retval = -1;
+               goto exit;
        }
 
        if (!opt_group_output_by_session && !opt_group_output_by_host) {
@@ -620,7 +659,7 @@ static void relayd_cleanup(void)
        free(opt_output_path);
 
        /* Close thread quit pipes */
-       utils_close_pipe(thread_quit_pipe);
+       (void) fd_tracker_util_pipe_close(the_fd_tracker, thread_quit_pipe);
 
        uri_free(control_uri);
        uri_free(data_uri);
@@ -629,7 +668,6 @@ static void relayd_cleanup(void)
        if (tracing_group_name_override) {
                free((void *) tracing_group_name);
        }
-       fd_tracker_log(the_fd_tracker);
 }
 
 /*
@@ -783,17 +821,26 @@ 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;
 
@@ -802,10 +849,8 @@ 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);
@@ -833,13 +878,55 @@ 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);
+}
+
+static int accept_sock(void *data, int *out_fd)
+{
+       int ret = 0;
+       /* Socks is an array of in_sock, out_sock. */
+       struct lttcomm_sock **socks = data;
+       struct lttcomm_sock *in_sock = socks[0];
+
+        socks[1] = in_sock->ops->accept(in_sock);
+       if (!socks[1]) {
+               ret = -1;
+               goto end;
+       }
+       *out_fd = socks[1]->fd;
+end:
+       return ret;
+}
+
 /*
  * 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) {
@@ -847,11 +934,25 @@ 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) {
@@ -873,6 +974,27 @@ error:
        return NULL;
 }
 
+static
+struct lttcomm_sock *accept_relayd_sock(struct lttcomm_sock *listening_sock,
+               const char *name)
+{
+       int out_fd, ret;
+       struct lttcomm_sock *socks[2] = { listening_sock, NULL };
+       struct lttcomm_sock *new_sock = NULL;
+
+        ret = fd_tracker_open_unsuspendable_fd(
+                       the_fd_tracker, &out_fd,
+                       (const char **) &name,
+                       1, accept_sock, &socks);
+       if (ret) {
+               goto end;
+       }
+       new_sock = socks[1];
+       DBG("%s accepted, socket %d", name, new_sock->fd);
+end:
+       return new_sock;
+}
+
 /*
  * This thread manages the listening for new connections on the network
  */
@@ -889,12 +1011,12 @@ 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;
        }
@@ -903,7 +1025,7 @@ 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;
        }
@@ -979,20 +1101,18 @@ restart:
                                 */
                                int val = 1;
                                struct relay_connection *new_conn;
-                               struct lttcomm_sock *newsock;
+                               struct lttcomm_sock *newsock = NULL;
                                enum connection_type type;
 
                                if (pollfd == data_sock->fd) {
                                        type = RELAY_DATA;
-                                       newsock = data_sock->ops->accept(data_sock);
-                                       DBG("Relay data connection accepted, socket %d",
-                                                       newsock->fd);
+                                       newsock = accept_relayd_sock(data_sock,
+                                                       "Data socket to relayd");
                                } else {
                                        assert(pollfd == control_sock->fd);
                                        type = RELAY_CONTROL;
-                                       newsock = control_sock->ops->accept(control_sock);
-                                       DBG("Relay control connection accepted, socket %d",
-                                                       newsock->fd);
+                                       newsock = accept_relayd_sock(control_sock,
+                                                       "Control socket to relayd");
                                }
                                if (!newsock) {
                                        PERROR("accepting sock");
@@ -1045,10 +1165,12 @@ 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);
+               ret = fd_tracker_close_unsuspendable_fd(the_fd_tracker,
+                               &data_sock->fd, 1, close_sock,
+                               data_sock);
                if (ret) {
                        PERROR("close");
                }
@@ -1056,7 +1178,9 @@ error_create_poll:
        lttcomm_destroy_sock(data_sock);
 error_sock_relay:
        if (control_sock->fd >= 0) {
-               ret = control_sock->ops->close(control_sock);
+               ret = fd_tracker_close_unsuspendable_fd(the_fd_tracker,
+                               &control_sock->fd, 1, close_sock,
+                               control_sock);
                if (ret) {
                        PERROR("close");
                }
@@ -1507,9 +1631,8 @@ int relay_reset_metadata(const struct lttcomm_relayd_hdr *recv_hdr,
                goto end_unlock;
        }
 
-       ret = utils_rotate_stream_file(stream->path_name, stream->channel_name,
-                       0, 0, -1, -1, stream->stream_fd->fd, NULL,
-                       &stream->stream_fd->fd);
+       ret = stream_fd_rotate(stream->stream_fd,
+                       stream->path_name, stream->channel_name, 0, 0, NULL);
        if (ret < 0) {
                ERR("Failed to rotate metadata file %s of channel %s",
                                stream->path_name, stream->channel_name);
@@ -1629,6 +1752,7 @@ static int relay_recv_metadata(const struct lttcomm_relayd_hdr *recv_hdr,
        struct lttcomm_relayd_metadata_payload metadata_payload_header;
        struct relay_stream *metadata_stream;
        uint64_t metadata_payload_size;
+       int metadata_fd = -1;
 
        if (!session) {
                ERR("Metadata sent before version check");
@@ -1659,20 +1783,24 @@ static int relay_recv_metadata(const struct lttcomm_relayd_hdr *recv_hdr,
 
        pthread_mutex_lock(&metadata_stream->lock);
 
-       size_ret = lttng_write(metadata_stream->stream_fd->fd,
+       metadata_fd = stream_fd_get_fd(metadata_stream->stream_fd);
+       if (metadata_fd < 0) {
+               goto end_put;
+       }
+       size_ret = lttng_write(metadata_fd,
                        payload->data + sizeof(metadata_payload_header),
                        metadata_payload_size);
        if (size_ret < metadata_payload_size) {
                ERR("Relay error writing metadata on file");
                ret = -1;
-               goto end_put;
+               goto end_put_fd;
        }
 
-       size_ret = write_padding_to_file(metadata_stream->stream_fd->fd,
+       size_ret = write_padding_to_file(metadata_fd,
                        metadata_payload_header.padding_size);
        if (size_ret < (int64_t) metadata_payload_header.padding_size) {
                ret = -1;
-               goto end_put;
+               goto end_put_fd;
        }
 
        metadata_stream->metadata_received +=
@@ -1680,6 +1808,8 @@ static int relay_recv_metadata(const struct lttcomm_relayd_hdr *recv_hdr,
        DBG2("Relay metadata written. Updated metadata_received %" PRIu64,
                metadata_stream->metadata_received);
 
+end_put_fd:
+       stream_fd_put_fd(metadata_stream->stream_fd);
 end_put:
        pthread_mutex_unlock(&metadata_stream->lock);
        stream_put(metadata_stream);
@@ -2156,8 +2286,13 @@ static int relay_recv_index(const struct lttcomm_relayd_hdr *recv_hdr,
                /* no flush. */
                ret = 0;
        } else {
+               /*
+                * ret < 0
+                *
+                * relay_index_try_flush is responsible for the self-reference
+                * put of the index object on error.
+                */
                ERR("relay_index_try_flush error %d", ret);
-               relay_index_put(index);
                ret = -1;
        }
 
@@ -2525,14 +2660,14 @@ static int handle_index_data(struct relay_stream *stream, uint64_t net_seq_num,
 
                /* Put ref on previous index_file. */
                if (stream->index_file) {
-                       lttng_index_file_put(stream->index_file);
+                       relay_index_file_put(stream->index_file);
                        stream->index_file = NULL;
                }
                major = stream->trace->session->major;
                minor = stream->trace->session->minor;
-               stream->index_file = lttng_index_file_create(stream->path_name,
+               stream->index_file = relay_index_file_create(stream->path_name,
                                stream->channel_name,
-                               -1, -1, stream->tracefile_size,
+                               stream->tracefile_size,
                                tracefile_array_get_file_index_head(stream->tfa),
                                lttng_to_index_major(major, minor),
                                lttng_to_index_minor(major, minor));
@@ -2561,9 +2696,13 @@ static int handle_index_data(struct relay_stream *stream, uint64_t net_seq_num,
                /* No flush. */
                ret = 0;
        } else {
-               /* Put self-ref for this index due to error. */
-               relay_index_put(index);
-               index = NULL;
+               /*
+                * ret < 0
+                *
+                * relay_index_try_flush is responsible for the self-reference
+                * put of the index object on error.
+                */
+               ERR("relay_index_try_flush error %d", ret);
                ret = -1;
        }
 end:
@@ -2660,11 +2799,9 @@ static enum relay_connection_status relay_process_data_receive_header(
                /* new_id is updated by utils_rotate_stream_file. */
                new_id = old_id;
 
-               ret = utils_rotate_stream_file(stream->path_name,
+               ret = stream_fd_rotate(stream->stream_fd, stream->path_name,
                                stream->channel_name, stream->tracefile_size,
-                               stream->tracefile_count, -1,
-                               -1, stream->stream_fd->fd,
-                               &new_id, &stream->stream_fd->fd);
+                               stream->tracefile_count, &new_id);
                if (ret < 0) {
                        ERR("Failed to rotate stream output file");
                        status = RELAY_CONNECTION_STATUS_ERROR;
@@ -2701,6 +2838,7 @@ static enum relay_connection_status relay_process_data_receive_payload(
        bool new_stream = false, close_requested = false;
        uint64_t left_to_receive = state->left_to_receive;
        struct relay_session *session;
+       int stream_fd = -1;
 
        DBG3("Receiving data for stream id %" PRIu64 " seqnum %" PRIu64 ", %" PRIu64" bytes received, %" PRIu64 " bytes left to receive",
                        state->header.stream_id, state->header.net_seq_num,
@@ -2725,6 +2863,12 @@ static enum relay_connection_status relay_process_data_receive_payload(
                }
        }
 
+       stream_fd = stream_fd_get_fd(stream->stream_fd);
+       if (stream_fd < 0) {
+               status = RELAY_CONNECTION_STATUS_ERROR;
+               goto end_stream_unlock;
+       }
+
        /*
         * The size of the "chunk" received on any iteration is bounded by:
         *   - the data left to receive,
@@ -2742,7 +2886,7 @@ static enum relay_connection_status relay_process_data_receive_payload(
                                PERROR("Socket %d error", conn->sock->fd);
                                status = RELAY_CONNECTION_STATUS_ERROR;
                        }
-                       goto end_stream_unlock;
+                       goto end_put_fd;
                } else if (ret == 0) {
                        /* No more data ready to be consumed on socket. */
                        DBG3("No more data ready for consumption on data socket of stream id %" PRIu64,
@@ -2760,12 +2904,12 @@ static enum relay_connection_status relay_process_data_receive_payload(
                recv_size = ret;
 
                /* Write data to stream output fd. */
-               write_ret = lttng_write(stream->stream_fd->fd, data_buffer,
+               write_ret = lttng_write(stream_fd, data_buffer,
                                recv_size);
                if (write_ret < (ssize_t) recv_size) {
                        ERR("Relay error writing data to file");
                        status = RELAY_CONNECTION_STATUS_ERROR;
-                       goto end_stream_unlock;
+                       goto end_put_fd;
                }
 
                left_to_receive -= recv_size;
@@ -2784,17 +2928,17 @@ static enum relay_connection_status relay_process_data_receive_payload(
                DBG3("Partial receive on data connection of stream id %" PRIu64 ", %" PRIu64 " bytes received, %" PRIu64 " bytes left to receive",
                                state->header.stream_id, state->received,
                                state->left_to_receive);
-               goto end_stream_unlock;
+               goto end_put_fd;
        }
 
-       ret = write_padding_to_file(stream->stream_fd->fd,
+       ret = write_padding_to_file(stream_fd,
                        state->header.padding_size);
        if ((int64_t) ret < (int64_t) state->header.padding_size) {
                ERR("write_padding_to_file: fail stream %" PRIu64 " net_seq_num %" PRIu64 " ret %d",
                                stream->stream_handle,
                                state->header.net_seq_num, ret);
                status = RELAY_CONNECTION_STATUS_ERROR;
-               goto end_stream_unlock;
+               goto end_put_fd;
        }
 
 
@@ -2806,7 +2950,7 @@ static enum relay_connection_status relay_process_data_receive_payload(
                                        stream->stream_handle,
                                        state->header.net_seq_num, ret);
                        status = RELAY_CONNECTION_STATUS_ERROR;
-                       goto end_stream_unlock;
+                       goto end_put_fd;
                }
        }
 
@@ -2827,6 +2971,8 @@ static enum relay_connection_status relay_process_data_receive_payload(
        connection_reset_protocol_state(conn);
        state = NULL;
 
+end_put_fd:
+       stream_fd_put_fd(stream->stream_fd);
 end_stream_unlock:
        close_requested = stream->close_requested;
        pthread_mutex_unlock(&stream->lock);
@@ -2874,7 +3020,8 @@ static void cleanup_connection_pollfd(struct lttng_poll_event *events, int pollf
 
        (void) lttng_poll_del(events, pollfd);
 
-       ret = close(pollfd);
+       ret = fd_tracker_close_unsuspendable_fd(the_fd_tracker, &pollfd, 1,
+                       fd_tracker_util_close_fd, NULL);
        if (ret < 0) {
                ERR("Closing pollfd %d", pollfd);
        }
@@ -2911,12 +3058,14 @@ static void relay_thread_close_connection(struct lttng_poll_event *events,
  */
 static void *relay_thread_worker(void *data)
 {
-       int ret, err = -1, last_seen_data_fd = -1;
+       int ret, err = -1;
        uint32_t nb_fd;
        struct lttng_poll_event events;
        struct lttng_ht *relay_connections_ht;
        struct lttng_ht_iter iter;
-       struct relay_connection *destroy_conn = NULL;
+       struct relay_connection *tmp_conn = NULL;
+       uint64_t relay_conn_pipe_activity_phase = 0;
+       uint64_t current_activity_phase = 1;
 
        DBG("[thread] Relay worker started");
 
@@ -2936,7 +3085,7 @@ 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;
        }
@@ -2948,7 +3097,8 @@ static void *relay_thread_worker(void *data)
 
 restart:
        while (1) {
-               int idx = -1, i, seen_control = 0, last_notdel_data_fd = -1;
+               int i;
+               bool at_least_one_event_processed = false;
 
                health_code_update();
 
@@ -2970,9 +3120,11 @@ restart:
                nb_fd = ret;
 
                /*
-                * Process control. The control connection is
-                * prioritized so we don't starve it with high
-                * throughput tracing data on the data connection.
+                * Processes FDs that were not yet active during the
+                * current activity phase. Increment the activity phase when all
+                * events are already processed for the current activity
+                * phase. This result in fairness across all connections and
+                * connection pipe.
                 */
                for (i = 0; i < nb_fd; i++) {
                        /* Fetch once the poll data */
@@ -3001,14 +3153,32 @@ restart:
                                if (revents & LPOLLIN) {
                                        struct relay_connection *conn;
 
+                                       if (relay_conn_pipe_activity_phase == current_activity_phase) {
+                                               /*
+                                                * Only consider once per
+                                                * activity phase for fairness.
+                                                */
+                                               DBG("Skipping adding reception, already happened in activity phase %" PRIu64, current_activity_phase);
+                                               continue;
+                                       }
+
                                        ret = lttng_read(relay_conn_pipe[0], &conn, sizeof(conn));
                                        if (ret < 0) {
                                                goto error;
                                        }
+                                       /*
+                                        * For now we prefer fairness over
+                                        * "immediate" action of new
+                                        * connection. Set activity phase to the
+                                        * current phase.
+                                        */
+                                       conn->activity_phase = current_activity_phase;
                                        lttng_poll_add(&events, conn->sock->fd,
                                                        LPOLLIN | LPOLLRDHUP);
                                        connection_ht_add(relay_connections_ht, conn);
                                        DBG("Connection socket %d added", conn->sock->fd);
+                                       relay_conn_pipe_activity_phase = current_activity_phase;
+                                       at_least_one_event_processed = true;
                                } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
                                        ERR("Relay connection pipe error");
                                        goto error;
@@ -3017,29 +3187,27 @@ restart:
                                        goto error;
                                }
                        } else {
-                               struct relay_connection *ctrl_conn;
+                               struct relay_connection *connection;
 
-                               ctrl_conn = connection_get_by_sock(relay_connections_ht, pollfd);
+                               connection = connection_get_by_sock(relay_connections_ht, pollfd);
                                /* If not found, there is a synchronization issue. */
-                               assert(ctrl_conn);
-
-                               if (ctrl_conn->type == RELAY_DATA) {
-                                       if (revents & LPOLLIN) {
-                                               /*
-                                                * 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;
-                                       }
-                                       goto put_ctrl_connection;
+                               assert(connection);
+                               if (connection->activity_phase == current_activity_phase) {
+                                       DBG3("Skipping connection %d, already processed in activity phase %" PRIu64, connection->sock->fd, current_activity_phase);
+                                       goto connection_put;
                                }
-                               assert(ctrl_conn->type == RELAY_CONTROL);
 
                                if (revents & LPOLLIN) {
                                        enum relay_connection_status status;
 
-                                       status = relay_process_control(ctrl_conn);
+                                       at_least_one_event_processed = true;
+                                       connection->activity_phase = current_activity_phase;
+
+                                       if (connection->type == RELAY_DATA) {
+                                               status = relay_process_data(connection);
+                                       } else {
+                                               status = relay_process_control(connection);
+                                       }
                                        if (status != RELAY_CONNECTION_STATUS_OK) {
                                                /*
                                                 * On socket error flag the session as aborted to force
@@ -3052,137 +3220,38 @@ restart:
                                                 * connection is closed (uncleanly) before the packet's
                                                 * data provided.
                                                 *
-                                                * Since the control connection encountered an error,
+                                                * Since the connection encountered an error,
                                                 * it is okay to be conservative and close the
                                                 * session right now as we can't rely on the protocol
                                                 * being respected anymore.
                                                 */
                                                if (status == RELAY_CONNECTION_STATUS_ERROR) {
-                                                       session_abort(ctrl_conn->session);
+                                                       session_abort(connection->session);
                                                }
 
                                                /* Clear the connection on error or close. */
                                                relay_thread_close_connection(&events,
                                                                pollfd,
-                                                               ctrl_conn);
+                                                               connection);
                                        }
-                                       seen_control = 1;
                                } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
                                        relay_thread_close_connection(&events,
-                                                       pollfd, ctrl_conn);
-                                       if (last_seen_data_fd == pollfd) {
-                                               last_seen_data_fd = last_notdel_data_fd;
-                                       }
+                                                       pollfd, connection);
                                } else {
-                                       ERR("Unexpected poll events %u for control sock %d",
+                                       ERR("Unexpected poll events %u for sock %d",
                                                        revents, pollfd);
-                                       connection_put(ctrl_conn);
+                                       connection_put(connection);
                                        goto error;
                                }
-                       put_ctrl_connection:
-                               connection_put(ctrl_conn);
+                       connection_put:
+                               connection_put(connection);
                        }
                }
 
-               /*
-                * The last loop handled a control request, go back to poll to make
-                * sure we prioritise the control socket.
-                */
-               if (seen_control) {
-                       continue;
+               if (!at_least_one_event_processed) {
+                       current_activity_phase++;
+                       DBG3("Incrementing activity phase: %" PRIu64, current_activity_phase);
                }
-
-               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);
-                       struct relay_connection *data_conn;
-
-                       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;
-                       }
-
-                       data_conn = connection_get_by_sock(relay_connections_ht, pollfd);
-                       if (!data_conn) {
-                               /* Skip it. Might be removed before. */
-                               continue;
-                       }
-                       if (data_conn->type == RELAY_CONTROL) {
-                               goto put_data_connection;
-                       }
-                       assert(data_conn->type == RELAY_DATA);
-
-                       if (revents & LPOLLIN) {
-                               enum relay_connection_status status;
-
-                               status = relay_process_data(data_conn);
-                               /* Connection closed or error. */
-                               if (status != RELAY_CONNECTION_STATUS_OK) {
-                                       /*
-                                        * On socket error flag the session as aborted to force
-                                        * the cleanup of its stream otherwise it can leak
-                                        * during the lifetime of the relayd.
-                                        *
-                                        * This prevents situations in which streams can be
-                                        * left opened because an index was received, the
-                                        * control connection is closed, and the data
-                                        * connection is closed (uncleanly) before the packet's
-                                        * data provided.
-                                        *
-                                        * Since the data connection encountered an error,
-                                        * it is okay to be conservative and close the
-                                        * session right now as we can't rely on the protocol
-                                        * being respected anymore.
-                                        */
-                                       if (status == RELAY_CONNECTION_STATUS_ERROR) {
-                                               session_abort(data_conn->session);
-                                       }
-                                       relay_thread_close_connection(&events, pollfd,
-                                                       data_conn);
-                                       /*
-                                        * 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;
-                                       connection_put(data_conn);
-                                       goto restart;
-                               }
-                       } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
-                               relay_thread_close_connection(&events, pollfd,
-                                               data_conn);
-                       } else {
-                               ERR("Unknown poll events %u for data sock %d",
-                                               revents, pollfd);
-                       }
-               put_data_connection:
-                       connection_put(data_conn);
-               }
-               last_seen_data_fd = -1;
        }
 
        /* Normal exit, no error */
@@ -3193,27 +3262,28 @@ error:
        /* Cleanup reamaining connection object. */
        rcu_read_lock();
        cds_lfht_for_each_entry(relay_connections_ht->ht, &iter.iter,
-                       destroy_conn,
+                       tmp_conn,
                        sock_n.node) {
                health_code_update();
 
-               session_abort(destroy_conn->session);
+               session_abort(tmp_conn->session);
 
                /*
                 * No need to grab another ref, because we own
-                * destroy_conn.
+                * tmp conn.
                 */
-               relay_thread_close_connection(&events, destroy_conn->sock->fd,
-                               destroy_conn);
+               relay_thread_close_connection(&events, tmp_conn->sock->fd,
+                               tmp_conn);
        }
        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");
        }
@@ -3235,11 +3305,45 @@ 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);
+}
 
-       ret = utils_create_pipe_cloexec(relay_conn_pipe);
+static
+int stdio_open(void *data, int *fds)
+{
+       fds[0] = fileno(stdout);
+       fds[1] = fileno(stderr);
+       return 0;
+}
 
-       return ret;
+static
+int noop_close(void *data, int *fds)
+{
+       return 0;
+}
+
+static
+int track_stdio(void)
+{
+       int fds[2];
+       const char *names[] = { "stdout", "stderr" };
+
+       return fd_tracker_open_unsuspendable_fd(the_fd_tracker, fds,
+                       names, 2, stdio_open, NULL);
+}
+
+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);
 }
 
 /*
@@ -3323,12 +3427,18 @@ int main(int argc, char **argv)
         */
        rcu_register_thread();
 
-       the_fd_tracker = fd_tracker_create(lttng_opt_fd_cap);
+       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_tracker;
+       }
+
        /* Initialize thread health monitoring */
        health_relayd = health_app_create(NR_HEALTH_RELAYD_TYPES);
        if (!health_relayd) {
@@ -3377,7 +3487,7 @@ int main(int argc, char **argv)
                goto exit_init_data;
        }
 
-       ret = utils_create_pipe(health_quit_pipe);
+       ret = init_health_quit_pipe();
        if (ret) {
                retval = -1;
                goto exit_health_quit_pipe;
@@ -3473,13 +3583,13 @@ exit_dispatcher_thread:
        }
 exit_health_thread:
 
-       utils_close_pipe(health_quit_pipe);
+       (void) fd_tracker_util_pipe_close(the_fd_tracker, health_quit_pipe);
 exit_health_quit_pipe:
 
 exit_init_data:
        health_app_destroy(health_relayd);
 exit_health_app_create:
-exit_options:
+
        /*
         * Wait for all pending call_rcu work to complete before tearing
         * down data structures. call_rcu worker may be trying to
@@ -3490,10 +3600,15 @@ exit_options:
 
        /* Ensure all prior call_rcu are done. */
        rcu_barrier();
-
+exit_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);
        rcu_unregister_thread();
-
+exit_options:
        if (!retval) {
                exit(EXIT_SUCCESS);
        } else {
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