relayd: Implement custom EfficiOS session clear

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

/*
 * Copyright (C) 2013 - Julien Desfossez <jdesfossez@efficios.com>
 *                      David Goulet <dgoulet@efficios.com>
 *               2015 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License, version 2 only, as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 51
 * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#define _LGPL_SOURCE
#include <common/common.h>
#include <common/utils.h>
#include <common/defaults.h>
#include <urcu/rculist.h>
#include <sys/stat.h>

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

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

        pthread_mutex_lock(&stream->reflock);
        if (stream->ref.refcount != 0) {
                has_ref = true;
                urcu_ref_get(&stream->ref);
        }
        pthread_mutex_unlock(&stream->reflock);

        return has_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;
}

/*
 * 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;

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

        stream->stream_handle = stream_handle;
        stream->prev_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);
        pthread_mutex_init(&stream->reflock, NULL);
        urcu_ref_init(&stream->ref);
        ctf_trace_get(trace);
        stream->trace = trace;

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

        ret = utils_mkdir_recursive(stream->path_name, S_IRWXU | S_IRWXG,
                        -1, -1);
        if (ret < 0) {
                ERR("relay creating output directory");
                goto end;
        }

        /*
         * No need to use run_as API here because whatever we receive,
         * the relayd uses its own credentials for the stream files.
         */
        ret = utils_create_stream_file(stream->path_name, stream->channel_name,
                        stream->tracefile_size, 0, -1, -1, NULL);
        if (ret < 0) {
                ERR("Create output file");
                goto end;
        }
        stream->stream_fd = stream_fd_create(ret);
        if (!stream->stream_fd) {
                if (close(ret)) {
                        PERROR("Error closing file %d", ret);
                }
                ret = -1;
                goto end;
        }
        stream->tfa = tracefile_array_create(stream->tracefile_count);
        if (!stream->tfa) {
                ret = -1;
                goto end;
        }
        if (stream->tracefile_size) {
                DBG("Tracefile %s/%s_0 created", stream->path_name, stream->channel_name);
        } else {
                DBG("Tracefile %s/%s created", stream->path_name, stream->channel_name);
        }

        if (!strncmp(stream->channel_name, DEFAULT_METADATA_NAME, LTTNG_NAME_MAX)) {
                stream->is_metadata = 1;
        }

        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->stream_fd) {
                        stream_fd_put(stream->stream_fd);
                        stream->stream_fd = NULL;
                }
                stream_put(stream);
                stream = NULL;
        }
        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, in which case it is guaranteed to be accessed
 * from a single thread by the reflock.
 */
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);
                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.
 *
 * At that point, the object is also protected by the reflock which
 * guarantees that no other thread may share ownership of this 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->stream_fd) {
                stream_fd_put(stream->stream_fd);
                stream->stream_fd = 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;
        }

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

void stream_put(struct relay_stream *stream)
{
        DBG("stream put for stream id %" PRIu64, stream->stream_handle);
        /*
         * Ensure existence of stream->reflock for stream unlock.
         */
        rcu_read_lock();
        /*
         * Stream reflock ensures that concurrent test and update of
         * stream ref is atomic.
         */
        pthread_mutex_lock(&stream->reflock);
        assert(stream->ref.refcount != 0);
        /*
         * Wait until we have processed all the stream packets before
         * actually putting our last stream reference.
         */
        DBG("stream put stream id %" PRIu64 " refcount %d",
                        stream->stream_handle,
                        (int) stream->ref.refcount);
        urcu_ref_put(&stream->ref, stream_release);
        pthread_mutex_unlock(&stream->reflock);
        rcu_read_unlock();
}

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.
                 */
                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);
                /* Fall-through into the next check. */
        }

        if (stream->last_net_seq_num != -1ULL &&
                        ((int64_t) (stream->prev_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);
        pthread_mutex_unlock(&stream->lock);
        DBG("Succeeded in closing stream %" PRIu64, stream->stream_handle);
        stream_put(stream);
}

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();
}

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();
}

static int relay_unlink_stream_files_rotation(struct relay_stream *stream)
{
        uint64_t tracefile_size = stream->tracefile_size;
        uint64_t tracefile_count = stream->tracefile_count;
        uint64_t count;
        int ret;

        /*
         * If the channel is configured to have an open-ended number of tracefiles,
         * use the current tracefile count number as upper-bound.
         */
        if (!tracefile_count) {
                tracefile_count = stream->tracefile_count_current + 1;
        }

        /*
         * Try to unlink each file and each index for this stream. They may not exist,
         * in which case ENOENT is fine.
         */
        for (count = 0; count < tracefile_count; count++) {
                ret = utils_unlink_stream_file(stream->path_name, stream->channel_name,
                                tracefile_size, count, -1, -1, NULL);
                if (ret < 0 && errno != ENOENT) {
                        return -1;
                }
        }
        return 0;
}

static int relay_unlink_index_files_rotation(struct relay_stream *stream)
{
        uint64_t tracefile_size = stream->tracefile_size;
        uint64_t tracefile_count = stream->tracefile_count;
        uint64_t count;
        int ret;

        /*
         * If the channel is configured to have an open-ended number of tracefiles,
         * use the current tracefile count number as upper-bound.
         */
        if (!tracefile_count) {
                tracefile_count = stream->tracefile_count_current + 1;
        }

        /*
         * Try to unlink each file and each index for this stream. They may not exist,
         * in which case ENOENT is fine.
         */
        for (count = 0; count < tracefile_count; count++) {
                if (stream->index_file) {
                        ret = lttng_index_file_unlink(stream->path_name, stream->channel_name,
                                        -1, -1, tracefile_size, count);
                        if (ret < 0 && errno != ENOENT) {
                                return -1;
                        }
                }
        }
        return 0;
}

static int relay_unlink_stream_files(struct relay_stream *stream)
{
        int ret;

        ret = utils_unlink_stream_file(stream->path_name, stream->channel_name,
                        stream->tracefile_size, 0, -1, -1, NULL);
        if (ret < 0 && errno != ENOENT) {
                return -1;
        }
        return 0;
}

static int relay_unlink_index_files(struct relay_stream *stream)
{
        int ret;

        ret = lttng_index_file_unlink(stream->path_name, stream->channel_name,
                        -1, -1, stream->tracefile_size, 0);
        if (ret < 0 && errno != ENOENT) {
                return -1;
        }
        return 0;
}

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

        DBG("try stream clear for handle %" PRIu64 " recv %" PRIu64 " clear_pos_idx %" PRIu64 " clear_pos_data %" PRIu64,
                        stream->stream_handle, stream->index_received_seqcount, stream->clear_position_index_seqcount,
                        stream->clear_position_data_seqcount);
        if (!stream->index_received_seqcount) {
                return 0;
        }
        if (stream->index_received_seqcount <= stream->clear_position_index_seqcount) {
                /*
                 * Put ref on current index file. The new index file will be created upon
                 * reception of next index data beyond the clear position.
                 */
                if (stream->index_file) {
                        lttng_index_file_put(stream->index_file);
                        if (stream->tracefile_size > 0) {
                                ret = relay_unlink_index_files_rotation(stream);
                        } else {
                                ret = relay_unlink_index_files(stream);
                        }
                        if (ret) {
                                return ret;
                        }
                        stream->index_file = NULL;
                }
                tracefile_array_reset(stream->tfa);
        }
        if (stream->index_received_seqcount == stream->clear_position_data_seqcount) {
                ret = close(stream->stream_fd->fd);
                if (ret < 0) {
                        PERROR("Closing tracefile");
                        return -1;
                }
                stream->stream_fd->fd = -1;
                stream->tracefile_size_current = 0;

                if (stream->tracefile_size > 0) {
                        ret = relay_unlink_stream_files_rotation(stream);
                } else {
                        ret = relay_unlink_stream_files(stream);
                }

                /* Create new files. */
                ret = utils_create_stream_file(stream->path_name, stream->channel_name,
                                stream->tracefile_size, 0, -1, -1, NULL);
                if (ret < 0) {
                        ERR("Create output file");
                        return -1;
                }
                stream->stream_fd->fd = ret;
        }
        return 0;
}

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

        pthread_mutex_lock(&stream->lock);

        if (stream->is_metadata) {
                /* Do not clear metadata streams. */
                goto end;
        }

        /*
         * Clear index and data for all packets up to and including the
         * clear position index seqcount.
         *
         * Clearing the index is straightforward: we can remove the entire
         * on-disk index for this stream because the control port is an ordered
         * protocol. We may also have in-flight indexes within the indexes_ht
         * (pending data reception). We need to mark those so they get
         * discarded (as well as their associated data content) upon reception
         * of matching data.
         *
         * Clearing the data: because data is written directly into the output files,
         * we need to carefully handle cases where index or data positions are ahead
         * of the other.
         *
         * In tracefile rotation mode, we need to move the seq_tail to the head
         * position.
         */

        /*
         * If the data received is beyond indexes received, unlink data immediately and
         * discard indexes when they arrive (up to the clear position).
         *
         * If indexes received is beyond data, we will reach the sync point when the
         * indexes are received, so it will be safe to unlink the data and index files
         * at that point.
         *
         * Clear index and data file(s) immediately if reaching the clear
         * position (no in-flight indexes).
         */
        DBG("stream clear for handle %" PRIu64 " prev_seq %" PRIu64 " prev_index_seq %" PRIu64 " indexes in flight %d",
                        stream->stream_handle, stream->prev_seq, stream->prev_index_seq,
                        stream->indexes_in_flight);
        if (stream->prev_seq > stream->prev_index_seq) {
                stream->clear_position_data_seqcount = stream->index_received_seqcount;
                stream->clear_position_index_seqcount = stream->index_received_seqcount +
                                                        stream->indexes_in_flight;
        } else if (stream->prev_seq < stream->prev_index_seq) {
                stream->clear_position_data_seqcount = stream->index_received_seqcount +
                                                        stream->indexes_in_flight;
                stream->clear_position_index_seqcount = stream->index_received_seqcount +
                                                        stream->indexes_in_flight;
        } else {
                assert(stream->indexes_in_flight == 0);
                stream->clear_position_data_seqcount = stream->index_received_seqcount;
                stream->clear_position_index_seqcount = stream->index_received_seqcount;

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

end:
        pthread_mutex_unlock(&stream->lock);
        return ret;
}