Fix: Wait for in-flight data before closing a stream

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

diff --git a/src/bin/lttng-relayd/stream.c b/src/bin/lttng-relayd/stream.c
index af4ef1bbb80d9e17fe331298c4fac558d0795d3c..2a59d1ed3e166edd319209ea97065eebf81e3876 100644 (file)
--- a/src/bin/lttng-relayd/stream.c
+++ b/src/bin/lttng-relayd/stream.c
@@ -93,6 +93,7 @@ struct relay_stream *stream_create(struct ctf_trace *trace,
 
        stream->stream_handle = stream_handle;
        stream->prev_seq = -1ULL;
+       stream->last_net_seq_num = -1ULL;
        stream->ctf_stream_id = -1ULL;
        stream->tracefile_size = tracefile_size;
        stream->tracefile_count = tracefile_count;
@@ -137,6 +138,11 @@ struct relay_stream *stream_create(struct ctf_trace *trace,
                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 {
@@ -163,6 +169,7 @@ struct relay_stream *stream_create(struct ctf_trace *trace,
         * 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);
@@ -220,20 +227,27 @@ unlock:
 }
 
 /*
- * Only called from destroy. No stream lock needed, since there is a
- * single user at this point. This is ensured by having the refcount
- * reaching 0.
+ * 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->published) {
-               return;
+       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;
        }
-       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)
@@ -241,6 +255,9 @@ static void stream_destroy(struct relay_stream *stream)
        if (stream->indexes_ht) {
                lttng_ht_destroy(stream->indexes_ht);
        }
+       if (stream->tfa) {
+               tracefile_array_destroy(stream->tfa);
+       }
        free(stream->path_name);
        free(stream->channel_name);
        free(stream);
@@ -266,8 +283,6 @@ static void stream_release(struct urcu_ref *ref)
        struct relay_stream *stream =
                caa_container_of(ref, struct relay_stream, ref);
        struct relay_session *session;
-       int ret;
-       struct lttng_ht_iter iter;
 
        session = stream->trace->session;
 
@@ -281,10 +296,6 @@ static void stream_release(struct urcu_ref *ref)
        }
        pthread_mutex_unlock(&session->recv_list_lock);
 
-       iter.iter.node = &stream->node.node;
-       ret = lttng_ht_del(relay_streams_ht, &iter);
-       assert(!ret);
-
        stream_unpublish(stream);
 
        if (stream->stream_fd) {
@@ -328,12 +339,47 @@ void stream_put(struct relay_stream *stream)
        rcu_read_unlock();
 }
 
-void stream_close(struct relay_stream *stream)
+void try_stream_close(struct relay_stream *stream)
 {
-       DBG("closing stream %" PRIu64, stream->stream_handle);
+       DBG("Trying to close stream %" PRIu64, stream->stream_handle);
        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;
+       /*
+        * We shortcut the data pending check if no bound is known for this
+        * stream. This prevents us from never closing the stream in the case
+        * where a connection would be closed before a "close" command has
+        * been received.
+        *
+        * TODO
+        * This still leaves open the question of handling missing data after
+        * a bound has been set by a stream close command. Since we have no
+        * way of pairing data and control connection, and that a data
+        * connection has no ownership of a stream, it is likely that a
+        * timeout approach would be appropriate to handle dangling streams.
+        */
+       if (stream->last_net_seq_num != -1ULL &&
+                       ((int64_t) (stream->prev_seq - stream->last_net_seq_num)) < 0) {
+               /* Don't close since we still have data pending. */
+               pthread_mutex_unlock(&stream->lock);
+               DBG("closing stream %" PRIu64 " aborted since it still has data pending", stream->stream_handle);
+               return;
+       }
+       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);
 }