X-Git-Url: https://git.lttng.org/?a=blobdiff_plain;ds=sidebyside;f=src%2Fcommon%2Fconsumer.c;h=41f8ae53fe67adde7552b54dfb31aa89d4abedcb;hb=6d805429e9cb049eb0c9205fcf742a53e3166caf;hp=d245ed7eecb385cb72b76841a14944810f9a72c1;hpb=8994307fa7ccf9b61cc0157f2c5d34e248c56641;p=lttng-tools.git

diff --git a/src/common/consumer.c b/src/common/consumer.c
index d245ed7ee..41f8ae53f 100644
--- a/src/common/consumer.c
+++ b/src/common/consumer.c
@@ -2671,33 +2671,61 @@ error:
 	return ret;
 }
 
+/*
+ * Try to lock the stream mutex.
+ *
+ * On success, 1 is returned else 0 indicating that the mutex is NOT lock.
+ */
+static int stream_try_lock(struct lttng_consumer_stream *stream)
+{
+	int ret;
+
+	assert(stream);
+
+	/*
+	 * Try to lock the stream mutex. On failure, we know that the stream is
+	 * being used else where hence there is data still being extracted.
+	 */
+	ret = pthread_mutex_trylock(&stream->lock);
+	if (ret) {
+		/* For both EBUSY and EINVAL error, the mutex is NOT locked. */
+		ret = 0;
+		goto end;
+	}
+
+	ret = 1;
+
+end:
+	return ret;
+}
+
 /*
  * Check if for a given session id there is still data needed to be extract
  * from the buffers.
  *
- * Return 1 if data is in fact available to be read or else 0.
+ * Return 1 if data is pending or else 0 meaning ready to be read.
  */
-int consumer_data_available(uint64_t id)
+int consumer_data_pending(uint64_t id)
 {
 	int ret;
 	struct lttng_ht_iter iter;
 	struct lttng_ht *ht;
 	struct lttng_consumer_stream *stream;
 	struct consumer_relayd_sock_pair *relayd;
-	int (*data_available)(struct lttng_consumer_stream *);
+	int (*data_pending)(struct lttng_consumer_stream *);
 
-	DBG("Consumer data available command on session id %" PRIu64, id);
+	DBG("Consumer data pending command on session id %" PRIu64, id);
 
 	rcu_read_lock();
 	pthread_mutex_lock(&consumer_data.lock);
 
 	switch (consumer_data.type) {
 	case LTTNG_CONSUMER_KERNEL:
-		data_available = lttng_kconsumer_data_available;
+		data_pending = lttng_kconsumer_data_pending;
 		break;
 	case LTTNG_CONSUMER32_UST:
 	case LTTNG_CONSUMER64_UST:
-		data_available = lttng_ustconsumer_data_available;
+		data_pending = lttng_ustconsumer_data_pending;
 		break;
 	default:
 		ERR("Unknown consumer data type");
@@ -2711,30 +2739,56 @@ int consumer_data_available(uint64_t id)
 			ht->hash_fct((void *)((unsigned long) id), 0x42UL),
 			ht->match_fct, (void *)((unsigned long) id),
 			&iter.iter, stream, node_session_id.node) {
-		/* Check the stream for data. */
-		ret = data_available(stream);
-		if (ret == 0) {
-			goto data_not_available;
+		/* If this call fails, the stream is being used hence data pending. */
+		ret = stream_try_lock(stream);
+		if (!ret) {
+			goto data_not_pending;
+		}
+
+		/*
+		 * A removed node from the hash table indicates that the stream has
+		 * been deleted thus having a guarantee that the buffers are closed
+		 * on the consumer side. However, data can still be transmitted
+		 * over the network so don't skip the relayd check.
+		 */
+		ret = cds_lfht_is_node_deleted(&stream->node.node);
+		if (!ret) {
+			/* Check the stream if there is data in the buffers. */
+			ret = data_pending(stream);
+			if (ret == 1) {
+				pthread_mutex_unlock(&stream->lock);
+				goto data_not_pending;
+			}
 		}
 
+		/* Relayd check */
 		if (stream->net_seq_idx != -1) {
 			relayd = consumer_find_relayd(stream->net_seq_idx);
-			assert(relayd);
+			if (!relayd) {
+				/*
+				 * At this point, if the relayd object is not available for the
+				 * given stream, it is because the relayd is being cleaned up
+				 * so every stream associated with it (for a session id value)
+				 * are or will be marked for deletion hence no data pending.
+				 */
+				pthread_mutex_unlock(&stream->lock);
+				goto data_not_pending;
+			}
 
-			pthread_mutex_lock(&stream->lock);
 			pthread_mutex_lock(&relayd->ctrl_sock_mutex);
 			if (stream->metadata_flag) {
 				ret = relayd_quiescent_control(&relayd->control_sock);
 			} else {
-				ret = relayd_data_available(&relayd->control_sock,
+				ret = relayd_data_pending(&relayd->control_sock,
 						stream->relayd_stream_id, stream->next_net_seq_num);
 			}
 			pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
-			pthread_mutex_unlock(&stream->lock);
-			if (ret == 0) {
-				goto data_not_available;
+			if (ret == 1) {
+				pthread_mutex_unlock(&stream->lock);
+				goto data_not_pending;
 			}
 		}
+		pthread_mutex_unlock(&stream->lock);
 	}
 
 	/*
@@ -2747,11 +2801,11 @@ int consumer_data_available(uint64_t id)
 	/* Data is available to be read by a viewer. */
 	pthread_mutex_unlock(&consumer_data.lock);
 	rcu_read_unlock();
-	return 1;
+	return 0;
 
-data_not_available:
+data_not_pending:
 	/* Data is still being extracted from buffers. */
 	pthread_mutex_unlock(&consumer_data.lock);
 	rcu_read_unlock();
-	return 0;
+	return 1;
 }