Fix: stream intersection fails on snapshot of cleared session

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

diff --git a/src/common/ust-consumer/ust-consumer.c b/src/common/ust-consumer/ust-consumer.c
index 6a561b4ca7b3be844c7ae2d306b70b473da9eebb..209931f5644a3d74dc27ed1a8f7dbb3d3863d387 100644 (file)
--- a/src/common/ust-consumer/ust-consumer.c
+++ b/src/common/ust-consumer/ust-consumer.c
@@ -78,6 +78,11 @@ static void destroy_channel(struct lttng_consumer_channel *channel)
                lttng_ustconsumer_del_channel(channel);
                lttng_ustconsumer_free_channel(channel);
        }
+
+       if (channel->trace_chunk) {
+               lttng_trace_chunk_put(channel->trace_chunk);
+       }
+
        free(channel);
 }
 
@@ -2176,6 +2181,28 @@ end_rotate_channel_nosignal:
                                msg.u.trace_chunk_exists.chunk_id);
                goto end_msg_sessiond;
        }
+       case LTTNG_CONSUMER_OPEN_CHANNEL_PACKETS:
+       {
+               const uint64_t key = msg.u.open_channel_packets.key;
+               struct lttng_consumer_channel *channel =
+                               consumer_find_channel(key);
+
+               if (channel) {
+                       pthread_mutex_lock(&channel->lock);
+                       ret_code = lttng_consumer_open_channel_packets(channel);
+                       pthread_mutex_unlock(&channel->lock);
+               } else {
+                       /*
+                        * The channel could have disappeared in per-pid
+                        * buffering mode.
+                        */
+                       DBG("Channel %" PRIu64 " not found", key);
+                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
+               }
+
+               health_code_update();
+               goto end_msg_sessiond;
+       }
        default:
                break;
        }
@@ -2441,8 +2468,8 @@ void metadata_stream_reset_cache_consumed_position(
 /*
  * Write up to one packet from the metadata cache to the channel.
  *
- * Returns the number of bytes pushed in the cache, or a negative value
- * on error.
+ * Returns the number of bytes pushed from the cache into the ring buffer, or a
+ * negative value on error.
  */
 static
 int commit_one_metadata_packet(struct lttng_consumer_stream *stream)
@@ -2526,15 +2553,13 @@ end:
  * awaiting on metadata to be pushed out.
  *
  * The RCU read side lock must be held by the caller.
- *
- * Return 0 if new metadatda is available, EAGAIN if the metadata stream
- * is empty or a negative value on error.
  */
-int lttng_ustconsumer_sync_metadata(struct lttng_consumer_local_data *ctx,
+enum sync_metadata_status lttng_ustconsumer_sync_metadata(
+               struct lttng_consumer_local_data *ctx,
                struct lttng_consumer_stream *metadata_stream)
 {
        int ret;
-       int retry = 0;
+       enum sync_metadata_status status;
        struct lttng_consumer_channel *metadata_channel;
 
        assert(ctx);
@@ -2549,6 +2574,7 @@ int lttng_ustconsumer_sync_metadata(struct lttng_consumer_local_data *ctx,
        ret = lttng_ustconsumer_request_metadata(ctx, metadata_channel, 0, 0);
        pthread_mutex_lock(&metadata_stream->lock);
        if (ret < 0) {
+               status = SYNC_METADATA_STATUS_ERROR;
                goto end;
        }
 
@@ -2566,38 +2592,30 @@ int lttng_ustconsumer_sync_metadata(struct lttng_consumer_local_data *ctx,
        if (consumer_stream_is_deleted(metadata_stream)) {
                DBG("Metadata stream %" PRIu64 " was deleted during the metadata synchronization",
                                metadata_stream->key);
-               ret = 0;
+               status = SYNC_METADATA_STATUS_NO_DATA;
                goto end;
        }
 
        ret = commit_one_metadata_packet(metadata_stream);
-       if (ret <= 0) {
+       if (ret < 0) {
+               status = SYNC_METADATA_STATUS_ERROR;
                goto end;
        } else if (ret > 0) {
-               retry = 1;
+               status = SYNC_METADATA_STATUS_NEW_DATA;
+       } else /* ret == 0 */ {
+               status = SYNC_METADATA_STATUS_NO_DATA;
+               goto end;
        }
 
        ret = ustctl_snapshot(metadata_stream->ustream);
        if (ret < 0) {
-               if (errno != EAGAIN) {
-                       ERR("Sync metadata, taking UST snapshot");
-                       goto end;
-               }
-               DBG("No new metadata when syncing them.");
-               /* No new metadata, exit. */
-               ret = ENODATA;
+               ERR("Failed to take a snapshot of the metadata ring-buffer positions, ret = %d", ret);
+               status = SYNC_METADATA_STATUS_ERROR;
                goto end;
        }
 
-       /*
-        * After this flush, we still need to extract metadata.
-        */
-       if (retry) {
-               ret = EAGAIN;
-       }
-
 end:
-       return ret;
+       return status;
 }
 
 /*