Fix: consumer data pending for empty streams

[lttng-tools.git] / src / common / consumer.c

diff --git a/src/common/consumer.c b/src/common/consumer.c
index 59207da2f2f99f03a27b8a014f682025b03e39f7..7acb8560ca4e07bfdccc89518477dad6a8d79051 100644 (file)
--- a/src/common/consumer.c
+++ b/src/common/consumer.c
@@ -498,6 +498,7 @@ struct lttng_consumer_stream *consumer_allocate_stream(uint64_t channel_key,
        stream->key = stream_key;
        stream->out_fd = -1;
        stream->out_fd_offset = 0;
+       stream->output_written = 0;
        stream->state = state;
        stream->uid = uid;
        stream->gid = gid;
@@ -1475,6 +1476,7 @@ ssize_t lttng_consumer_on_read_subbuffer_mmap(
                                        SYNC_FILE_RANGE_WRITE);
                        stream->out_fd_offset += ret;
                }
+               stream->output_written += ret;
                written += ret;
        }
        lttng_consumer_sync_trace_file(stream, orig_offset);
@@ -1688,6 +1690,7 @@ ssize_t lttng_consumer_on_read_subbuffer_splice(
                                        SYNC_FILE_RANGE_WRITE);
                        stream->out_fd_offset += ret_splice;
                }
+               stream->output_written += ret_splice;
                written += ret_splice;
        }
        lttng_consumer_sync_trace_file(stream, orig_offset);
@@ -3400,6 +3403,15 @@ int consumer_data_pending(uint64_t id)
                 */
                ret = cds_lfht_is_node_deleted(&stream->node.node);
                if (!ret) {
+                       /*
+                        * An empty output file is not valid. We need at least one packet
+                        * generated per stream, even if it contains no event, so it
+                        * contains at least one packet header.
+                        */
+                       if (stream->output_written == 0) {
+                               pthread_mutex_unlock(&stream->lock);
+                               goto data_pending;
+                       }
                        /* Check the stream if there is data in the buffers. */
                        ret = data_pending(stream);
                        if (ret == 1) {