docs: Add supported versions and fix-backport policy

[lttng-tools.git] / src / bin / lttng-relayd / stream.cpp

/*
 * Copyright (C) 2013 Julien Desfossez <jdesfossez@efficios.com>
 * Copyright (C) 2013 David Goulet <dgoulet@efficios.com>
 * Copyright (C) 2015 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 * Copyright (C) 2019 Jérémie Galarneau <jeremie.galarneau@efficios.com>
 *
 * SPDX-License-Identifier: GPL-2.0-only
 *
 */

#define _LGPL_SOURCE
#include <algorithm>
#include <common/common.hpp>
#include <common/defaults.hpp>
#include <common/fs-handle.hpp>
#include <common/sessiond-comm/relayd.hpp>
#include <common/utils.hpp>
#include <sys/stat.h>
#include <urcu/rculist.h>

#include "lttng-relayd.hpp"
#include "index.hpp"
#include "stream.hpp"
#include "viewer-stream.hpp"

#include <sys/types.h>
#include <fcntl.h>

#define FILE_IO_STACK_BUFFER_SIZE               65536

/* Should be called with RCU read-side lock held. */
bool stream_get(struct relay_stream *stream)
{
        ASSERT_RCU_READ_LOCKED();

        return urcu_ref_get_unless_zero(&stream->ref);
}

/*
 * Get stream from stream id from the streams hash table. Return stream
 * if found else NULL. A stream reference is taken when a stream is
 * returned. stream_put() must be called on that stream.
 */
struct relay_stream *stream_get_by_id(uint64_t stream_id)
{
        struct lttng_ht_node_u64 *node;
        struct lttng_ht_iter iter;
        struct relay_stream *stream = NULL;

        rcu_read_lock();
        lttng_ht_lookup(relay_streams_ht, &stream_id, &iter);
        node = lttng_ht_iter_get_node_u64(&iter);
        if (!node) {
                DBG("Relay stream %" PRIu64 " not found", stream_id);
                goto end;
        }
        stream = caa_container_of(node, struct relay_stream, node);
        if (!stream_get(stream)) {
                stream = NULL;
        }
end:
        rcu_read_unlock();
        return stream;
}

static void stream_complete_rotation(struct relay_stream *stream)
{
        DBG("Rotation completed for stream %" PRIu64, stream->stream_handle);
        if (stream->ongoing_rotation.value.next_trace_chunk) {
                tracefile_array_reset(stream->tfa);
                tracefile_array_commit_seq(stream->tfa,
                                stream->index_received_seqcount);
        }
        lttng_trace_chunk_put(stream->trace_chunk);
        stream->trace_chunk = stream->ongoing_rotation.value.next_trace_chunk;
        stream->ongoing_rotation = LTTNG_OPTIONAL_INIT_UNSET;
        stream->completed_rotation_count++;
}

static int stream_create_data_output_file_from_trace_chunk(
                struct relay_stream *stream,
                struct lttng_trace_chunk *trace_chunk,
                bool force_unlink,
                struct fs_handle **out_file)
{
        int ret;
        char stream_path[LTTNG_PATH_MAX];
        enum lttng_trace_chunk_status status;
        const int flags = O_RDWR | O_CREAT | O_TRUNC;
        const mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP;

        ASSERT_LOCKED(stream->lock);

        ret = utils_stream_file_path(stream->path_name, stream->channel_name,
                        stream->tracefile_size, stream->tracefile_current_index,
                        NULL, stream_path, sizeof(stream_path));
        if (ret < 0) {
                goto end;
        }

        if (stream->tracefile_wrapped_around || force_unlink) {
                /*
                 * The on-disk ring-buffer has wrapped around.
                 * Newly created stream files will replace existing files. Since
                 * live clients may be consuming existing files, the file about
                 * to be replaced is unlinked in order to not overwrite its
                 * content.
                 */
                status = (lttng_trace_chunk_status) lttng_trace_chunk_unlink_file(trace_chunk,
                                stream_path);
                if (status != LTTNG_TRACE_CHUNK_STATUS_OK) {
                        PERROR("Failed to unlink stream file \"%s\" during trace file rotation",
                                        stream_path);
                        /*
                         * Don't abort if the file doesn't exist, it is
                         * unexpected, but should not be a fatal error.
                         */
                        if (errno != ENOENT) {
                                ret = -1;
                                goto end;
                        }
                }
        }

        status = lttng_trace_chunk_open_fs_handle(trace_chunk, stream_path,
                        flags, mode, out_file, false);
        if (status != LTTNG_TRACE_CHUNK_STATUS_OK) {
                ERR("Failed to open stream file \"%s\"", stream->channel_name);
                ret = -1;
                goto end;
        }
end:
        return ret;
}

static int stream_rotate_data_file(struct relay_stream *stream)
{
        int ret = 0;

        DBG("Rotating stream %" PRIu64 " data file with size %" PRIu64,
                        stream->stream_handle, stream->tracefile_size_current);

        if (stream->file) {
                fs_handle_close(stream->file);
                stream->file = NULL;
        }

        stream->tracefile_wrapped_around = false;
        stream->tracefile_current_index = 0;

        if (stream->ongoing_rotation.value.next_trace_chunk) {
                enum lttng_trace_chunk_status chunk_status;

                chunk_status = lttng_trace_chunk_create_subdirectory(
                                stream->ongoing_rotation.value.next_trace_chunk,
                                stream->path_name);
                if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
                        ret = -1;
                        goto end;
                }

                /* Rotate the data file. */
                ret = stream_create_data_output_file_from_trace_chunk(stream,
                                stream->ongoing_rotation.value.next_trace_chunk,
                                false, &stream->file);
                if (ret < 0) {
                        ERR("Failed to rotate stream data file");
                        goto end;
                }
        }
        DBG("%s: reset tracefile_size_current for stream %" PRIu64 " was %" PRIu64,
                        __func__, stream->stream_handle, stream->tracefile_size_current);
        stream->tracefile_size_current = 0;
        stream->pos_after_last_complete_data_index = 0;
        stream->ongoing_rotation.value.data_rotated = true;

        if (stream->ongoing_rotation.value.index_rotated) {
                /* Rotation completed; reset its state. */
                stream_complete_rotation(stream);
        }
end:
        return ret;
}

/*
 * If too much data has been written in a tracefile before we received the
 * rotation command, we have to move the excess data to the new tracefile and
 * perform the rotation. This can happen because the control and data
 * connections are separate, the indexes as well as the commands arrive from
 * the control connection and we have no control over the order so we could be
 * in a situation where too much data has been received on the data connection
 * before the rotation command on the control connection arrives.
 */
static int rotate_truncate_stream(struct relay_stream *stream)
{
        int ret;
        off_t lseek_ret, previous_stream_copy_origin;
        uint64_t copy_bytes_left, misplaced_data_size;
        bool acquired_reference;
        struct fs_handle *previous_stream_file = NULL;
        struct lttng_trace_chunk *previous_chunk = NULL;

        if (!LTTNG_OPTIONAL_GET(stream->ongoing_rotation).next_trace_chunk) {
                ERR("Protocol error encoutered in %s(): stream rotation "
                        "sequence number is before the current sequence number "
                        "and the next trace chunk is unset. Honoring this "
                        "rotation command would result in data loss",
                                __FUNCTION__);
                ret = -1;
                goto end;
        }

        ASSERT_LOCKED(stream->lock);
        /*
         * Acquire a reference to the current trace chunk to ensure
         * it is not reclaimed when `stream_rotate_data_file` is called.
         * Failing to do so would violate the contract of the trace
         * chunk API as an active file descriptor would outlive the
         * trace chunk.
         */
        acquired_reference = lttng_trace_chunk_get(stream->trace_chunk);
        LTTNG_ASSERT(acquired_reference);
        previous_chunk = stream->trace_chunk;

        /*
         * Steal the stream's reference to its stream_fd. A new
         * stream_fd will be created when the rotation completes and
         * the orinal stream_fd will be used to copy the "extra" data
         * to the new file.
         */
        LTTNG_ASSERT(stream->file);
        previous_stream_file = stream->file;
        stream->file = NULL;

        LTTNG_ASSERT(!stream->is_metadata);
        LTTNG_ASSERT(stream->tracefile_size_current >
                        stream->pos_after_last_complete_data_index);
        misplaced_data_size = stream->tracefile_size_current -
                              stream->pos_after_last_complete_data_index;
        copy_bytes_left = misplaced_data_size;
        previous_stream_copy_origin = stream->pos_after_last_complete_data_index;

        ret = stream_rotate_data_file(stream);
        if (ret) {
                goto end;
        }

        LTTNG_ASSERT(stream->file);
        /*
         * Seek the current tracefile to the position at which the rotation
         * should have occurred.
         */
        lseek_ret = fs_handle_seek(previous_stream_file, previous_stream_copy_origin, SEEK_SET);
        if (lseek_ret < 0) {
                PERROR("Failed to seek to offset %" PRIu64
                       " while copying extra data received before a stream rotation",
                                (uint64_t) previous_stream_copy_origin);
                ret = -1;
                goto end;
        }

        /* Move data from the old file to the new file. */
        while (copy_bytes_left) {
                ssize_t io_ret;
                char copy_buffer[FILE_IO_STACK_BUFFER_SIZE];
                const off_t copy_size_this_pass = std::min<uint64_t>(copy_bytes_left, sizeof(copy_buffer));

                io_ret = fs_handle_read(previous_stream_file, copy_buffer,
                                copy_size_this_pass);
                if (io_ret < (ssize_t) copy_size_this_pass) {
                        if (io_ret == -1) {
                                PERROR("Failed to read %" PRIu64
                                       " bytes from previous stream file in %s(), returned %zi: stream id = %" PRIu64,
                                                copy_size_this_pass,
                                                __FUNCTION__, io_ret,
                                                stream->stream_handle);
                        } else {
                                ERR("Failed to read %" PRIu64
                                       " bytes from previous stream file in %s(), returned %zi: stream id = %" PRIu64,
                                                copy_size_this_pass,
                                                __FUNCTION__, io_ret,
                                                stream->stream_handle);
                        }
                        ret = -1;
                        goto end;
                }

                io_ret = fs_handle_write(
                                stream->file, copy_buffer, copy_size_this_pass);
                if (io_ret < (ssize_t) copy_size_this_pass) {
                        if (io_ret == -1) {
                                PERROR("Failed to write %" PRIu64
                                       " bytes from previous stream file in %s(), returned %zi: stream id = %" PRIu64,
                                                copy_size_this_pass,
                                                __FUNCTION__, io_ret,
                                                stream->stream_handle);
                        } else {
                                ERR("Failed to write %" PRIu64
                                       " bytes from previous stream file in %s(), returned %zi: stream id = %" PRIu64,
                                                copy_size_this_pass,
                                                __FUNCTION__, io_ret,
                                                stream->stream_handle);
                        }
                        ret = -1;
                        goto end;
                }
                copy_bytes_left -= copy_size_this_pass;
        }

        /* Truncate the file to get rid of the excess data. */
        ret = fs_handle_truncate(
                        previous_stream_file, previous_stream_copy_origin);
        if (ret) {
                PERROR("Failed to truncate current stream file to offset %" PRIu64,
                                previous_stream_copy_origin);
                goto end;
        }

        /*
         * Update the offset and FD of all the eventual indexes created by the
         * data connection before the rotation command arrived.
         */
        ret = relay_index_switch_all_files(stream);
        if (ret < 0) {
                ERR("Failed to rotate index file");
                goto end;
        }

        stream->tracefile_size_current = misplaced_data_size;
        /* Index and data contents are back in sync. */
        stream->pos_after_last_complete_data_index = 0;
        ret = 0;
end:
        lttng_trace_chunk_put(previous_chunk);
        return ret;
}

/*
 * Check if a stream's data file (as opposed to index) should be rotated
 * (for session rotation).
 * Must be called with the stream lock held.
 *
 * Return 0 on success, a negative value on error.
 */
static int try_rotate_stream_data(struct relay_stream *stream)
{
        int ret = 0;

        if (caa_likely(!stream->ongoing_rotation.is_set)) {
                /* No rotation expected. */
                goto end;
        }

        if (stream->ongoing_rotation.value.data_rotated) {
                /* Rotation of the data file has already occurred. */
                goto end;
        }

        DBG("%s: Stream %" PRIu64
                                " (rotate_at_index_packet_seq_num = %" PRIu64
                                ", rotate_at_prev_data_net_seq = %" PRIu64
                                ", prev_data_seq = %" PRIu64 ")",
                                __func__, stream->stream_handle,
                                stream->ongoing_rotation.value.packet_seq_num,
                                stream->ongoing_rotation.value.prev_data_net_seq,
                                stream->prev_data_seq);

        if (stream->prev_data_seq == -1ULL ||
                        stream->ongoing_rotation.value.prev_data_net_seq == -1ULL ||
                        stream->prev_data_seq <
                        stream->ongoing_rotation.value.prev_data_net_seq) {
                /*
                 * The next packet that will be written is not part of the next
                 * chunk yet.
                 */
                DBG("Stream %" PRIu64 " data not yet ready for rotation "
                                "(rotate_at_index_packet_seq_num = %" PRIu64
                                ", rotate_at_prev_data_net_seq = %" PRIu64
                                ", prev_data_seq = %" PRIu64 ")",
                                stream->stream_handle,
                                stream->ongoing_rotation.value.packet_seq_num,
                                stream->ongoing_rotation.value.prev_data_net_seq,
                                stream->prev_data_seq);
                goto end;
        } else if (stream->prev_data_seq > stream->ongoing_rotation.value.prev_data_net_seq) {
                /*
                 * prev_data_seq is checked here since indexes and rotation
                 * commands are serialized with respect to each other.
                 */
                DBG("Rotation after too much data has been written in tracefile "
                                "for stream %" PRIu64 ", need to truncate before "
                                "rotating", stream->stream_handle);
                ret = rotate_truncate_stream(stream);
                if (ret) {
                        ERR("Failed to truncate stream");
                        goto end;
                }
        } else {
                ret = stream_rotate_data_file(stream);
        }

end:
        return ret;
}

/*
 * Close the current index file if it is open, and create a new one.
 *
 * Return 0 on success, -1 on error.
 */
static int create_index_file(struct relay_stream *stream,
                struct lttng_trace_chunk *chunk)
{
        int ret;
        uint32_t major, minor;
        char *index_subpath = NULL;
        enum lttng_trace_chunk_status status;

        ASSERT_LOCKED(stream->lock);

        /* Put ref on previous index_file. */
        if (stream->index_file) {
                lttng_index_file_put(stream->index_file);
                stream->index_file = NULL;
        }
        major = stream->trace->session->major;
        minor = stream->trace->session->minor;

        if (!chunk) {
                ret = 0;
                goto end;
        }
        ret = asprintf(&index_subpath, "%s/%s", stream->path_name,
                        DEFAULT_INDEX_DIR);
        if (ret < 0) {
                goto end;
        }

        status = lttng_trace_chunk_create_subdirectory(chunk,
                        index_subpath);
        free(index_subpath);
        if (status != LTTNG_TRACE_CHUNK_STATUS_OK) {
                ret = -1;
                goto end;
        }
        status = lttng_index_file_create_from_trace_chunk(
                        chunk, stream->path_name,
                        stream->channel_name, stream->tracefile_size,
                        stream->tracefile_current_index,
                        lttng_to_index_major(major, minor),
                        lttng_to_index_minor(major, minor), true,
                        &stream->index_file);
        if (status != LTTNG_TRACE_CHUNK_STATUS_OK) {
                ret = -1;
                goto end;
        }

        ret = 0;

end:
        return ret;
}

/*
 * Check if a stream's index file should be rotated (for session rotation).
 * Must be called with the stream lock held.
 *
 * Return 0 on success, a negative value on error.
 */
static int try_rotate_stream_index(struct relay_stream *stream)
{
        int ret = 0;

        if (!stream->ongoing_rotation.is_set) {
                /* No rotation expected. */
                goto end;
        }

        if (stream->ongoing_rotation.value.index_rotated) {
                /* Rotation of the index has already occurred. */
                goto end;
        }

        DBG("%s: Stream %" PRIu64
                        " (rotate_at_packet_seq_num = %" PRIu64
                        ", received_packet_seq_num = "
                        "(value = %" PRIu64 ", is_set = %" PRIu8 "))",
                        __func__, stream->stream_handle,
                        stream->ongoing_rotation.value.packet_seq_num,
                        stream->received_packet_seq_num.value,
                        stream->received_packet_seq_num.is_set);

        if (!stream->received_packet_seq_num.is_set ||
                        LTTNG_OPTIONAL_GET(stream->received_packet_seq_num) + 1 <
                        stream->ongoing_rotation.value.packet_seq_num) {
                DBG("Stream %" PRIu64 " index not yet ready for rotation "
                                "(rotate_at_packet_seq_num = %" PRIu64
                                ", received_packet_seq_num = "
                                "(value = %" PRIu64 ", is_set = %" PRIu8 "))",
                                stream->stream_handle,
                                stream->ongoing_rotation.value.packet_seq_num,
                                stream->received_packet_seq_num.value,
                                stream->received_packet_seq_num.is_set);
                goto end;
        } else {
                /*
                 * The next index belongs to the new trace chunk; rotate.
                 * In overwrite mode, the packet seq num may jump over the
                 * rotation position.
                 */
                LTTNG_ASSERT(LTTNG_OPTIONAL_GET(stream->received_packet_seq_num) + 1 >=
                                stream->ongoing_rotation.value.packet_seq_num);
                DBG("Rotating stream %" PRIu64 " index file",
                                stream->stream_handle);
                if (stream->index_file) {
                        lttng_index_file_put(stream->index_file);
                        stream->index_file = NULL;
                }
                stream->ongoing_rotation.value.index_rotated = true;

                /*
                 * Set the rotation pivot position for the data, now that we have the
                 * net_seq_num matching the packet_seq_num index pivot position.
                 */
                stream->ongoing_rotation.value.prev_data_net_seq =
                        stream->prev_index_seq;
                if (stream->ongoing_rotation.value.data_rotated &&
                                stream->ongoing_rotation.value.index_rotated) {
                        /* Rotation completed; reset its state. */
                        DBG("Rotation completed for stream %" PRIu64,
                                        stream->stream_handle);
                        stream_complete_rotation(stream);
                }
        }

end:
        return ret;
}

static int stream_set_trace_chunk(struct relay_stream *stream,
                struct lttng_trace_chunk *chunk)
{
        int ret = 0;
        enum lttng_trace_chunk_status status;
        bool acquired_reference;

        status = lttng_trace_chunk_create_subdirectory(chunk,
                        stream->path_name);
        if (status != LTTNG_TRACE_CHUNK_STATUS_OK) {
                ret = -1;
                goto end;
        }

        lttng_trace_chunk_put(stream->trace_chunk);
        acquired_reference = lttng_trace_chunk_get(chunk);
        LTTNG_ASSERT(acquired_reference);
        stream->trace_chunk = chunk;

        if (stream->file) {
                fs_handle_close(stream->file);
                stream->file = NULL;
        }
        ret = stream_create_data_output_file_from_trace_chunk(stream, chunk,
                        false, &stream->file);
end:
        return ret;
}

/*
 * We keep ownership of path_name and channel_name.
 */
struct relay_stream *stream_create(struct ctf_trace *trace,
        uint64_t stream_handle, char *path_name,
        char *channel_name, uint64_t tracefile_size,
        uint64_t tracefile_count)
{
        int ret;
        struct relay_stream *stream = NULL;
        struct relay_session *session = trace->session;
        bool acquired_reference = false;
        struct lttng_trace_chunk *current_trace_chunk;

        stream = zmalloc<relay_stream>();
        if (stream == NULL) {
                PERROR("relay stream zmalloc");
                goto error_no_alloc;
        }

        stream->stream_handle = stream_handle;
        stream->prev_data_seq = -1ULL;
        stream->prev_index_seq = -1ULL;
        stream->last_net_seq_num = -1ULL;
        stream->ctf_stream_id = -1ULL;
        stream->tracefile_size = tracefile_size;
        stream->tracefile_count = tracefile_count;
        stream->path_name = path_name;
        stream->channel_name = channel_name;
        stream->beacon_ts_end = -1ULL;
        lttng_ht_node_init_u64(&stream->node, stream->stream_handle);
        pthread_mutex_init(&stream->lock, NULL);
        urcu_ref_init(&stream->ref);
        ctf_trace_get(trace);
        stream->trace = trace;

        pthread_mutex_lock(&trace->session->lock);
        current_trace_chunk = trace->session->current_trace_chunk;
        if (current_trace_chunk) {
                acquired_reference = lttng_trace_chunk_get(current_trace_chunk);
        }
        pthread_mutex_unlock(&trace->session->lock);
        if (!acquired_reference) {
                ERR("Cannot create stream for channel \"%s\" as a reference to the session's current trace chunk could not be acquired",
                                channel_name);
                ret = -1;
                goto end;
        }

        stream->indexes_ht = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
        if (!stream->indexes_ht) {
                ERR("Cannot created indexes_ht");
                ret = -1;
                goto end;
        }

        pthread_mutex_lock(&stream->lock);
        ret = stream_set_trace_chunk(stream, current_trace_chunk);
        pthread_mutex_unlock(&stream->lock);
        if (ret) {
                ERR("Failed to set the current trace chunk of session \"%s\" on newly created stream of channel \"%s\"",
                                trace->session->session_name,
                                stream->channel_name);
                ret = -1;
                goto end;
        }
        stream->tfa = tracefile_array_create(stream->tracefile_count);
        if (!stream->tfa) {
                ret = -1;
                goto end;
        }

        stream->is_metadata = !strcmp(stream->channel_name,
                        DEFAULT_METADATA_NAME);
        stream->in_recv_list = true;

        /*
         * Add the stream in the recv list of the session. Once the end stream
         * message is received, all session streams are published.
         */
        pthread_mutex_lock(&session->recv_list_lock);
        cds_list_add_rcu(&stream->recv_node, &session->recv_list);
        session->stream_count++;
        pthread_mutex_unlock(&session->recv_list_lock);

        /*
         * 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);
        stream->in_stream_ht = true;

        DBG("Relay new stream added %s with ID %" PRIu64, stream->channel_name,
                        stream->stream_handle);
        ret = 0;

end:
        if (ret) {
                if (stream->file) {
                        fs_handle_close(stream->file);
                        stream->file = NULL;
                }
                stream_put(stream);
                stream = NULL;
        }
        if (acquired_reference) {
                lttng_trace_chunk_put(current_trace_chunk);
        }
        return stream;

error_no_alloc:
        /*
         * path_name and channel_name need to be freed explicitly here
         * because we cannot rely on stream_put().
         */
        free(path_name);
        free(channel_name);
        return NULL;
}

/*
 * Called with the session lock held.
 */
void stream_publish(struct relay_stream *stream)
{
        struct relay_session *session;

        pthread_mutex_lock(&stream->lock);
        if (stream->published) {
                goto unlock;
        }

        session = stream->trace->session;

        pthread_mutex_lock(&session->recv_list_lock);
        if (stream->in_recv_list) {
                cds_list_del_rcu(&stream->recv_node);
                stream->in_recv_list = false;
        }
        pthread_mutex_unlock(&session->recv_list_lock);

        pthread_mutex_lock(&stream->trace->stream_list_lock);
        cds_list_add_rcu(&stream->stream_node, &stream->trace->stream_list);
        pthread_mutex_unlock(&stream->trace->stream_list_lock);

        stream->published = true;
unlock:
        pthread_mutex_unlock(&stream->lock);
}

/*
 * Stream must be protected by holding the stream lock or by virtue of being
 * called from stream_destroy.
 */
static void stream_unpublish(struct relay_stream *stream)
{
        if (stream->in_stream_ht) {
                struct lttng_ht_iter iter;
                int ret;

                iter.iter.node = &stream->node.node;
                ret = lttng_ht_del(relay_streams_ht, &iter);
                LTTNG_ASSERT(!ret);
                stream->in_stream_ht = false;
        }
        if (stream->published) {
                pthread_mutex_lock(&stream->trace->stream_list_lock);
                cds_list_del_rcu(&stream->stream_node);
                pthread_mutex_unlock(&stream->trace->stream_list_lock);
                stream->published = false;
        }
}

static void stream_destroy(struct relay_stream *stream)
{
        if (stream->indexes_ht) {
                /*
                 * Calling lttng_ht_destroy in call_rcu worker thread so
                 * we don't hold the RCU read-side lock while calling
                 * it.
                 */
                lttng_ht_destroy(stream->indexes_ht);
        }
        if (stream->tfa) {
                tracefile_array_destroy(stream->tfa);
        }
        free(stream->path_name);
        free(stream->channel_name);
        free(stream);
}

static void stream_destroy_rcu(struct rcu_head *rcu_head)
{
        struct relay_stream *stream =
                caa_container_of(rcu_head, struct relay_stream, rcu_node);

        stream_destroy(stream);
}

/*
 * No need to take stream->lock since this is only called on the final
 * stream_put which ensures that a single thread may act on the stream.
 */
static void stream_release(struct urcu_ref *ref)
{
        struct relay_stream *stream =
                caa_container_of(ref, struct relay_stream, ref);
        struct relay_session *session;

        session = stream->trace->session;

        DBG("Releasing stream id %" PRIu64, stream->stream_handle);

        pthread_mutex_lock(&session->recv_list_lock);
        session->stream_count--;
        if (stream->in_recv_list) {
                cds_list_del_rcu(&stream->recv_node);
                stream->in_recv_list = false;
        }
        pthread_mutex_unlock(&session->recv_list_lock);

        stream_unpublish(stream);

        if (stream->file) {
                fs_handle_close(stream->file);
                stream->file = NULL;
        }
        if (stream->index_file) {
                lttng_index_file_put(stream->index_file);
                stream->index_file = NULL;
        }
        if (stream->trace) {
                ctf_trace_put(stream->trace);
                stream->trace = NULL;
        }
        stream_complete_rotation(stream);
        lttng_trace_chunk_put(stream->trace_chunk);
        stream->trace_chunk = NULL;

        call_rcu(&stream->rcu_node, stream_destroy_rcu);
}

void stream_put(struct relay_stream *stream)
{
        rcu_read_lock();
        LTTNG_ASSERT(stream->ref.refcount != 0);
        /*
         * Wait until we have processed all the stream packets before
         * actually putting our last stream reference.
         */
        urcu_ref_put(&stream->ref, stream_release);
        rcu_read_unlock();
}

int stream_set_pending_rotation(struct relay_stream *stream,
                struct lttng_trace_chunk *next_trace_chunk,
                uint64_t rotation_sequence_number)
{
        int ret = 0;
        const struct relay_stream_rotation rotation = {
                .data_rotated = false,
                .index_rotated = false,
                .packet_seq_num = rotation_sequence_number,
                .prev_data_net_seq = -1ULL,
                .next_trace_chunk = next_trace_chunk,
        };

        if (stream->ongoing_rotation.is_set) {
                ERR("Attempted to set a pending rotation on a stream already being rotated (protocol error)");
                ret = -1;
                goto end;
        }

        if (next_trace_chunk) {
                const bool reference_acquired =
                                lttng_trace_chunk_get(next_trace_chunk);

                LTTNG_ASSERT(reference_acquired);
        }
        LTTNG_OPTIONAL_SET(&stream->ongoing_rotation, rotation);

        DBG("Setting pending rotation: stream_id = %" PRIu64
                        ", rotate_at_packet_seq_num = %" PRIu64,
                        stream->stream_handle, rotation_sequence_number);
        if (stream->is_metadata) {
                /*
                 * A metadata stream has no index; consider it already rotated.
                 */
                stream->ongoing_rotation.value.index_rotated = true;
                if (next_trace_chunk) {
                        /*
                         * The metadata will be received again in the new chunk.
                         */
                        stream->metadata_received = 0;
                }
                ret = stream_rotate_data_file(stream);
        } else {
                ret = try_rotate_stream_index(stream);
                if (ret < 0) {
                        goto end;
                }

                ret = try_rotate_stream_data(stream);
                if (ret < 0) {
                        goto end;
                }
        }
end:
        return ret;
}

void try_stream_close(struct relay_stream *stream)
{
        bool session_aborted;
        struct relay_session *session = stream->trace->session;

        DBG("Trying to close stream %" PRIu64, stream->stream_handle);

        pthread_mutex_lock(&session->lock);
        session_aborted = session->aborted;
        pthread_mutex_unlock(&session->lock);

        pthread_mutex_lock(&stream->lock);
        /*
         * Can be called concurently by connection close and reception of last
         * pending data.
         */
        if (stream->closed) {
                pthread_mutex_unlock(&stream->lock);
                DBG("closing stream %" PRIu64 " aborted since it is already marked as closed", stream->stream_handle);
                return;
        }

        stream->close_requested = true;

        if (stream->last_net_seq_num == -1ULL) {
                /*
                 * Handle connection close without explicit stream close
                 * command.
                 *
                 * We can be clever about indexes partially received in
                 * cases where we received the data socket part, but not
                 * the control socket part: since we're currently closing
                 * the stream on behalf of the control socket, we *know*
                 * there won't be any more control information for this
                 * socket. Therefore, we can destroy all indexes for
                 * which we have received only the file descriptor (from
                 * data socket). This takes care of consumerd crashes
                 * between sending the data and control information for
                 * a packet. Since those are sent in that order, we take
                 * care of consumerd crashes.
                 */
                DBG("relay_index_close_partial_fd");
                relay_index_close_partial_fd(stream);
                /*
                 * Use the highest net_seq_num we currently have pending
                 * As end of stream indicator.  Leave last_net_seq_num
                 * at -1ULL if we cannot find any index.
                 */
                stream->last_net_seq_num = relay_index_find_last(stream);
                DBG("Updating stream->last_net_seq_num to %" PRIu64, stream->last_net_seq_num);
                /* Fall-through into the next check. */
        }

        if (stream->last_net_seq_num != -1ULL &&
                        ((int64_t) (stream->prev_data_seq - stream->last_net_seq_num)) < 0
                        && !session_aborted) {
                /*
                 * Don't close since we still have data pending. This
                 * handles cases where an explicit close command has
                 * been received for this stream, and cases where the
                 * connection has been closed, and we are awaiting for
                 * index information from the data socket. It is
                 * therefore expected that all the index fd information
                 * we need has already been received on the control
                 * socket. Matching index information from data socket
                 * should be Expected Soon(TM).
                 *
                 * TODO: We should implement a timer to garbage collect
                 * streams after a timeout to be resilient against a
                 * consumerd implementation that would not match this
                 * expected behavior.
                 */
                pthread_mutex_unlock(&stream->lock);
                DBG("closing stream %" PRIu64 " aborted since it still has data pending", stream->stream_handle);
                return;
        }
        /*
         * We received all the indexes we can expect.
         */
        stream_unpublish(stream);
        stream->closed = true;
        /* Relay indexes are only used by the "consumer/sessiond" end. */
        relay_index_close_all(stream);

        /*
         * If we are closed by an application exiting (per-pid buffers),
         * we need to put our reference on the stream trace chunk right
         * away, because otherwise still holding the reference on the
         * trace chunk could allow a viewer stream (which holds a reference
         * to the stream) to postpone destroy waiting for the chunk to cease
         * to exist endlessly until the viewer is detached.
         */

        /* Put stream fd before put chunk. */
        if (stream->file) {
                fs_handle_close(stream->file);
                stream->file = NULL;
        }
        if (stream->index_file) {
                lttng_index_file_put(stream->index_file);
                stream->index_file = NULL;
        }
        lttng_trace_chunk_put(stream->trace_chunk);
        stream->trace_chunk = NULL;
        pthread_mutex_unlock(&stream->lock);
        DBG("Succeeded in closing stream %" PRIu64, stream->stream_handle);
        stream_put(stream);
}

int stream_init_packet(struct relay_stream *stream, size_t packet_size,
                bool *file_rotated)
{
        int ret = 0;

        ASSERT_LOCKED(stream->lock);

        if (!stream->file || !stream->trace_chunk) {
                ERR("Protocol error: received a packet for a stream that doesn't have a current trace chunk: stream_id = %" PRIu64 ", channel_name = %s",
                                stream->stream_handle, stream->channel_name);
                ret = -1;
                goto end;
        }

        if (caa_likely(stream->tracefile_size == 0)) {
                /* No size limit set; nothing to check. */
                goto end;
        }

        /*
         * Check if writing the new packet would exceed the maximal file size.
         */
        if (caa_unlikely((stream->tracefile_size_current + packet_size) >
                        stream->tracefile_size)) {
                const uint64_t new_file_index =
                                (stream->tracefile_current_index + 1) %
                                stream->tracefile_count;

                if (new_file_index < stream->tracefile_current_index) {
                        stream->tracefile_wrapped_around = true;
                }
                DBG("New stream packet causes stream file rotation: stream_id = %" PRIu64
                                ", current_file_size = %" PRIu64
                                ", packet_size = %zu, current_file_index = %" PRIu64
                                " new_file_index = %" PRIu64,
                                stream->stream_handle,
                                stream->tracefile_size_current, packet_size,
                                stream->tracefile_current_index, new_file_index);
                tracefile_array_file_rotate(stream->tfa, TRACEFILE_ROTATE_WRITE);
                stream->tracefile_current_index = new_file_index;

                if (stream->file) {
                        fs_handle_close(stream->file);
                        stream->file = NULL;
                }
                ret = stream_create_data_output_file_from_trace_chunk(stream,
                                stream->trace_chunk, false, &stream->file);
                if (ret) {
                        ERR("Failed to perform trace file rotation of stream %" PRIu64,
                                        stream->stream_handle);
                        goto end;
                }

                /*
                 * Reset current size because we just performed a stream
                 * rotation.
                 */
                DBG("%s: reset tracefile_size_current for stream %" PRIu64 " was %" PRIu64,
                        __func__, stream->stream_handle, stream->tracefile_size_current);
                stream->tracefile_size_current = 0;
                *file_rotated = true;
        } else {
                *file_rotated = false;
        }
end:
        return ret;
}

/* Note that the packet is not necessarily complete. */
int stream_write(struct relay_stream *stream,
                const struct lttng_buffer_view *packet, size_t padding_len)
{
        int ret = 0;
        ssize_t write_ret;
        size_t padding_to_write = padding_len;
        char padding_buffer[FILE_IO_STACK_BUFFER_SIZE];

        ASSERT_LOCKED(stream->lock);
        memset(padding_buffer, 0,
                        std::min(sizeof(padding_buffer), padding_to_write));

        if (!stream->file || !stream->trace_chunk) {
                ERR("Protocol error: received a packet for a stream that doesn't have a current trace chunk: stream_id = %" PRIu64 ", channel_name = %s",
                                stream->stream_handle, stream->channel_name);
                ret = -1;
                goto end;
        }
        if (packet) {
                write_ret = fs_handle_write(
                                stream->file, packet->data, packet->size);
                if (write_ret != packet->size) {
                        PERROR("Failed to write to stream file of %sstream %" PRIu64,
                                        stream->is_metadata ? "metadata " : "",
                                        stream->stream_handle);
                        ret = -1;
                        goto end;
                }
        }

        while (padding_to_write > 0) {
                const size_t padding_to_write_this_pass =
                                std::min(padding_to_write, sizeof(padding_buffer));

                write_ret = fs_handle_write(stream->file, padding_buffer,
                                padding_to_write_this_pass);
                if (write_ret != padding_to_write_this_pass) {
                        PERROR("Failed to write padding to file of %sstream %" PRIu64,
                                        stream->is_metadata ? "metadata " : "",
                                        stream->stream_handle);
                        ret = -1;
                        goto end;
                }
                padding_to_write -= padding_to_write_this_pass;
        }

        if (stream->is_metadata) {
                size_t recv_len;

                recv_len = packet ? packet->size : 0;
                recv_len += padding_len;
                stream->metadata_received += recv_len;
                if (recv_len) {
                        stream->no_new_metadata_notified = false;
                }
        }

        DBG("Wrote to %sstream %" PRIu64 ": data_length = %zu, padding_length = %zu",
                        stream->is_metadata ? "metadata " : "",
                        stream->stream_handle,
                        packet ? packet->size : (size_t) 0, padding_len);
end:
        return ret;
}

/*
 * Update index after receiving a packet for a data stream.
 *
 * Called with the stream lock held.
 *
 * Return 0 on success else a negative value.
 */
int stream_update_index(struct relay_stream *stream, uint64_t net_seq_num,
                bool rotate_index, bool *flushed, uint64_t total_size)
{
        int ret = 0;
        uint64_t data_offset;
        struct relay_index *index;

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

        DBG("handle_index_data: stream %" PRIu64 " net_seq_num %" PRIu64 " data offset %" PRIu64,
                        stream->stream_handle, net_seq_num, stream->tracefile_size_current);

        /*
         * Lookup for an existing index for that stream id/sequence
         * number. If it exists, the control thread has already received the
         * data for it, thus we need to write it to disk.
         */
        index = relay_index_get_by_id_or_create(stream, net_seq_num);
        if (!index) {
                ret = -1;
                goto end;
        }

        if (rotate_index || !stream->index_file) {
                ret = create_index_file(stream, stream->trace_chunk);
                if (ret) {
                        ERR("Failed to create index file for stream %" PRIu64,
                                        stream->stream_handle);
                        /* Put self-ref for this index due to error. */
                        relay_index_put(index);
                        index = NULL;
                        goto end;
                }
        }

        if (relay_index_set_file(index, stream->index_file, data_offset)) {
                ret = -1;
                /* Put self-ref for this index due to error. */
                relay_index_put(index);
                index = NULL;
                goto end;
        }

        ret = relay_index_try_flush(index);
        if (ret == 0) {
                tracefile_array_file_rotate(stream->tfa, TRACEFILE_ROTATE_READ);
                tracefile_array_commit_seq(stream->tfa, stream->index_received_seqcount);
                stream->index_received_seqcount++;
                LTTNG_OPTIONAL_SET(&stream->received_packet_seq_num,
                        be64toh(index->index_data.packet_seq_num));
                *flushed = true;
        } else if (ret > 0) {
                index->total_size = total_size;
                /* 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);
                ret = -1;
        }
end:
        return ret;
}

int stream_complete_packet(struct relay_stream *stream, size_t packet_total_size,
                uint64_t sequence_number, bool index_flushed)
{
        int ret = 0;

        ASSERT_LOCKED(stream->lock);

        stream->tracefile_size_current += packet_total_size;
        if (index_flushed) {
                stream->pos_after_last_complete_data_index =
                                stream->tracefile_size_current;
                stream->prev_index_seq = sequence_number;
                ret = try_rotate_stream_index(stream);
                if (ret < 0) {
                        goto end;
                }
        }

        stream->prev_data_seq = sequence_number;
        ret = try_rotate_stream_data(stream);

end:
        return ret;
}

int stream_add_index(struct relay_stream *stream,
                const struct lttcomm_relayd_index *index_info)
{
        int ret = 0;
        struct relay_index *index;

        ASSERT_LOCKED(stream->lock);

        DBG("stream_add_index for stream %" PRIu64, stream->stream_handle);

        /* 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->index_received_seqcount > 0
                                && stream->indexes_in_flight == 0) {
                        stream->beacon_ts_end = index_info->timestamp_end;
                }
                ret = 0;
                goto end;
        } else {
                stream->beacon_ts_end = -1ULL;
        }

        if (stream->ctf_stream_id == -1ULL) {
                stream->ctf_stream_id = index_info->stream_id;
        }

        index = relay_index_get_by_id_or_create(stream, index_info->net_seq_num);
        if (!index) {
                ret = -1;
                ERR("Failed to get or create index %" PRIu64,
                                index_info->net_seq_num);
                goto end;
        }
        if (relay_index_set_control_data(index, index_info,
                        stream->trace->session->minor)) {
                ERR("set_index_control_data error");
                relay_index_put(index);
                ret = -1;
                goto end;
        }
        ret = relay_index_try_flush(index);
        if (ret == 0) {
                tracefile_array_file_rotate(stream->tfa, TRACEFILE_ROTATE_READ);
                tracefile_array_commit_seq(stream->tfa, stream->index_received_seqcount);
                stream->index_received_seqcount++;
                stream->pos_after_last_complete_data_index += index->total_size;
                stream->prev_index_seq = index_info->net_seq_num;
                LTTNG_OPTIONAL_SET(&stream->received_packet_seq_num,
                                index_info->packet_seq_num);

                ret = try_rotate_stream_index(stream);
                if (ret < 0) {
                        goto end;
                }
                ret = try_rotate_stream_data(stream);
                if (ret < 0) {
                        goto end;
                }
        } else if (ret > 0) {
                /* 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);
                ret = -1;
        }
end:
        return ret;
}

static void print_stream_indexes(struct relay_stream *stream)
{
        struct lttng_ht_iter iter;
        struct relay_index *index;

        rcu_read_lock();
        cds_lfht_for_each_entry(stream->indexes_ht->ht, &iter.iter, index,
                        index_n.node) {
                DBG("index %p net_seq_num %" PRIu64 " refcount %ld"
                                " stream %" PRIu64 " trace %" PRIu64
                                " session %" PRIu64,
                                index,
                                index->index_n.key,
                                stream->ref.refcount,
                                index->stream->stream_handle,
                                index->stream->trace->id,
                                index->stream->trace->session->id);
        }
        rcu_read_unlock();
}

int stream_reset_file(struct relay_stream *stream)
{
        ASSERT_LOCKED(stream->lock);

        if (stream->file) {
                int ret;

                ret = fs_handle_close(stream->file);
                if (ret) {
                        ERR("Failed to close stream file handle: channel name = \"%s\", id = %" PRIu64,
                                        stream->channel_name,
                                        stream->stream_handle);
                }
                stream->file = NULL;
        }

        DBG("%s: reset tracefile_size_current for stream %" PRIu64 " was %" PRIu64,
                        __func__, stream->stream_handle, stream->tracefile_size_current);
        stream->tracefile_size_current = 0;
        stream->prev_data_seq = 0;
        stream->prev_index_seq = 0;
        /* Note that this does not reset the tracefile array. */
        stream->tracefile_current_index = 0;
        stream->pos_after_last_complete_data_index = 0;

        return stream_create_data_output_file_from_trace_chunk(stream,
                        stream->trace_chunk, true, &stream->file);
}

void print_relay_streams(void)
{
        struct lttng_ht_iter iter;
        struct relay_stream *stream;

        if (!relay_streams_ht) {
                return;
        }

        rcu_read_lock();
        cds_lfht_for_each_entry(relay_streams_ht->ht, &iter.iter, stream,
                        node.node) {
                if (!stream_get(stream)) {
                        continue;
                }
                DBG("stream %p refcount %ld stream %" PRIu64 " trace %" PRIu64
                                " session %" PRIu64,
                                stream,
                                stream->ref.refcount,
                                stream->stream_handle,
                                stream->trace->id,
                                stream->trace->session->id);
                print_stream_indexes(stream);
                stream_put(stream);
        }
        rcu_read_unlock();
}