X-Git-Url: https://git.liburcu.org/?a=blobdiff_plain;f=src%2Fcommon%2Fconsumer%2Fconsumer.c;h=782ace930c0f7c6cb4952c703202a8fcea4b5e1f;hb=56c86e0a3f16a2f7fd3e473dd8c9d753a13e86ee;hp=cbd99e7ec3ab08146142706383085b2933e314ba;hpb=fa2f196b44f1b8fa07671658b8c74f37477c18cc;p=lttng-tools.git

diff --git a/src/common/consumer/consumer.c b/src/common/consumer/consumer.c
index cbd99e7ec..782ace930 100644
--- a/src/common/consumer/consumer.c
+++ b/src/common/consumer/consumer.c
@@ -63,6 +63,12 @@ struct consumer_channel_msg {
 	uint64_t key;				/* del */
 };
 
+enum open_packet_status {
+	OPEN_PACKET_STATUS_OPENED,
+	OPEN_PACKET_STATUS_NO_SPACE,
+	OPEN_PACKET_STATUS_ERROR,
+};
+
 /* Flag used to temporarily pause data consumption from testpoints. */
 int data_consumption_paused;
 
@@ -3310,11 +3316,145 @@ error_testpoint:
 	return NULL;
 }
 
+static
+int consumer_flush_buffer(struct lttng_consumer_stream *stream,
+		int producer_active)
+{
+	int ret = 0;
+
+	switch (consumer_data.type) {
+	case LTTNG_CONSUMER_KERNEL:
+		if (producer_active) {
+			ret = kernctl_buffer_flush(stream->wait_fd);
+			if (ret < 0) {
+				ERR("Failed to flush kernel stream");
+				goto end;
+			}
+		} else {
+			ret = kernctl_buffer_flush_empty(stream->wait_fd);
+			if (ret < 0) {
+				/*
+				 * Doing a buffer flush which does not take into
+				 * account empty packets. This is not perfect,
+				 * but required as a fall-back when
+				 * "flush_empty" is not implemented by
+				 * lttng-modules.
+				 */
+				ret = kernctl_buffer_flush(stream->wait_fd);
+				if (ret < 0) {
+					ERR("Failed to flush kernel stream");
+					goto end;
+				}
+			}
+		}
+		break;
+	case LTTNG_CONSUMER32_UST:
+	case LTTNG_CONSUMER64_UST:
+		lttng_ustconsumer_flush_buffer(stream, producer_active);
+		break;
+	default:
+		ERR("Unknown consumer_data type");
+		abort();
+	}
+
+end:
+	return ret;
+}
+
+static enum open_packet_status open_packet(struct lttng_consumer_stream *stream)
+{
+	int ret;
+	enum open_packet_status status;
+	unsigned long produced_pos_before, produced_pos_after;
+
+	ret = lttng_consumer_sample_snapshot_positions(stream);
+	if (ret < 0) {
+		ERR("Failed to snapshot positions before post-rotation empty packet flush: stream id = %" PRIu64
+				", channel name = %s, session id = %" PRIu64,
+				stream->key, stream->chan->name,
+				stream->chan->session_id);
+		status = OPEN_PACKET_STATUS_ERROR;
+		goto end;
+	}
+
+	ret = lttng_consumer_get_produced_snapshot(
+			stream, &produced_pos_before);
+	if (ret < 0) {
+		ERR("Failed to read produced position before post-rotation empty packet flush: stream id = %" PRIu64
+				", channel name = %s, session id = %" PRIu64,
+				stream->key, stream->chan->name,
+				stream->chan->session_id);
+		status = OPEN_PACKET_STATUS_ERROR;
+		goto end;
+	}
+
+	ret = consumer_flush_buffer(stream, 0);
+	if (ret) {
+		ERR("Failed to flush an empty packet at rotation point: stream id = %" PRIu64
+				", channel name = %s, session id = %" PRIu64,
+				stream->key, stream->chan->name,
+				stream->chan->session_id);
+		status = OPEN_PACKET_STATUS_ERROR;
+		goto end;
+	}
+
+	ret = lttng_consumer_sample_snapshot_positions(stream);
+	if (ret < 0) {
+		ERR("Failed to snapshot positions after post-rotation empty packet flush: stream id = %" PRIu64
+				", channel name = %s, session id = %" PRIu64,
+				stream->key, stream->chan->name,
+				stream->chan->session_id);
+		status = OPEN_PACKET_STATUS_ERROR;
+		goto end;
+	}
+
+	ret = lttng_consumer_get_produced_snapshot(stream, &produced_pos_after);
+	if (ret < 0) {
+		ERR("Failed to read produced position after post-rotation empty packet flush: stream id = %" PRIu64
+				", channel name = %s, session id = %" PRIu64,
+				stream->key, stream->chan->name,
+				stream->chan->session_id);
+		status = OPEN_PACKET_STATUS_ERROR;
+		goto end;
+	}
+
+	/*
+	 * Determine if the flush had an effect by comparing the produced
+	 * positons before and after the flush.
+	 */
+	status = produced_pos_before != produced_pos_after ?
+			OPEN_PACKET_STATUS_OPENED :
+			OPEN_PACKET_STATUS_NO_SPACE;
+	if (status == OPEN_PACKET_STATUS_OPENED) {
+		stream->opened_packet_in_current_trace_chunk = true;
+	}
+end:
+	return status;
+}
+
+static bool stream_is_rotating_to_null_chunk(
+		const struct lttng_consumer_stream *stream)
+{
+	bool rotating_to_null_chunk = false;
+
+	if (stream->rotate_position == -1ULL) {
+		/* No rotation ongoing. */
+		goto end;
+	}
+
+	if (stream->trace_chunk == stream->chan->trace_chunk ||
+			!stream->chan->trace_chunk) {
+		rotating_to_null_chunk = true;
+	}
+end:
+	return rotating_to_null_chunk;
+}
+
 ssize_t lttng_consumer_read_subbuffer(struct lttng_consumer_stream *stream,
 		struct lttng_consumer_local_data *ctx,
 		bool locked_by_caller)
 {
-	ssize_t ret, written_bytes;
+	ssize_t ret, written_bytes = 0;
 	int rotation_ret;
 	struct stream_subbuffer subbuffer = {};
 
@@ -3360,24 +3500,10 @@ ssize_t lttng_consumer_read_subbuffer(struct lttng_consumer_stream *stream,
 
 	written_bytes = stream->read_subbuffer_ops.consume_subbuffer(
 			ctx, stream, &subbuffer);
-	/*
-	 * Should write subbuf_size amount of data when network streaming or
-	 * the full padded size when we are not streaming.
-	 */
-	if ((written_bytes != subbuffer.info.data.subbuf_size &&
-			    stream->net_seq_idx != (uint64_t) -1ULL) ||
-			(written_bytes != subbuffer.info.data.padded_subbuf_size &&
-					stream->net_seq_idx ==
-							(uint64_t) -1ULL)) {
-		/*
-		 * Display the error but continue processing to try to
-		 * release the subbuffer. This is a DBG statement
-		 * since this can happen without being a critical
-		 * error.
-		 */
-		DBG("Failed to write to tracefile (written_bytes: %zd != padded subbuffer size: %lu, subbuffer size: %lu)",
-				written_bytes, subbuffer.info.data.subbuf_size,
-				subbuffer.info.data.padded_subbuf_size);
+	if (written_bytes <= 0) {
+		ERR("Error consuming subbuffer: (%zd)", written_bytes);
+		ret = (int) written_bytes;
+		goto error_put_subbuf;
 	}
 
 	ret = stream->read_subbuffer_ops.put_next_subbuffer(stream, &subbuffer);
@@ -3413,7 +3539,45 @@ ssize_t lttng_consumer_read_subbuffer(struct lttng_consumer_stream *stream,
 		goto end;
 	}
 
-stream_sleep:
+	/*
+	 * TODO roll into a post_consume op as this doesn't apply to metadata
+	 * streams.
+	 */
+	if (!stream->opened_packet_in_current_trace_chunk &&
+			stream->trace_chunk && !stream->metadata_flag &&
+			!stream_is_rotating_to_null_chunk(stream)) {
+		const enum open_packet_status status = open_packet(stream);
+
+		switch (status) {
+		case OPEN_PACKET_STATUS_OPENED:
+			DBG("Opened a packet after consuming a packet rotation: stream id = %" PRIu64
+					", channel name = %s, session id = %" PRIu64,
+					stream->key, stream->chan->name,
+					stream->chan->session_id);
+			break;
+		case OPEN_PACKET_STATUS_NO_SPACE:
+			/*
+			 * Can't open a packet as there is no space left.
+			 * This means that new events were produced, resulting
+			 * in a packet being opened, which is what we wanted
+			 * anyhow.
+			 */
+			DBG("No space left to open a packet after consuming a packet: stream id = %" PRIu64
+					", channel name = %s, session id = %" PRIu64,
+					stream->key, stream->chan->name,
+					stream->chan->session_id);
+			stream->opened_packet_in_current_trace_chunk = true;
+			break;
+		case OPEN_PACKET_STATUS_ERROR:
+			/* Logged by callee. */
+			ret = -1;
+			goto end;
+		default:
+			abort();
+		}
+	}
+
+sleep_stream:
 	if (stream->read_subbuffer_ops.on_sleep) {
 		stream->read_subbuffer_ops.on_sleep(stream, ctx);
 	}
@@ -3901,50 +4065,6 @@ unsigned long consumer_get_consume_start_pos(unsigned long consumed_pos,
 	return start_pos;
 }
 
-static
-int consumer_flush_buffer(struct lttng_consumer_stream *stream, int producer_active)
-{
-	int ret = 0;
-
-	switch (consumer_data.type) {
-	case LTTNG_CONSUMER_KERNEL:
-		if (producer_active) {
-			ret = kernctl_buffer_flush(stream->wait_fd);
-			if (ret < 0) {
-				ERR("Failed to flush kernel stream");
-				goto end;
-			}
-		} else {
-			ret = kernctl_buffer_flush_empty(stream->wait_fd);
-			if (ret < 0) {
-				/*
-				 * Doing a buffer flush which does not take into
-				 * account empty packets. This is not perfect,
-				 * but required as a fall-back when
-				 * "flush_empty" is not implemented by
-				 * lttng-modules.
-				 */
-				ret = kernctl_buffer_flush(stream->wait_fd);
-				if (ret < 0) {
-					ERR("Failed to flush kernel stream");
-					goto end;
-				}
-			}
-		}
-		break;
-	case LTTNG_CONSUMER32_UST:
-	case LTTNG_CONSUMER64_UST:
-		lttng_ustconsumer_flush_buffer(stream, producer_active);
-		break;
-	default:
-		ERR("Unknown consumer_data type");
-		abort();
-	}
-
-end:
-	return ret;
-}
-
 /*
  * Sample the rotate position for all the streams of a channel. If a stream
  * is already at the rotate position (produced == consumed), we flag it as
@@ -3968,11 +4088,15 @@ int lttng_consumer_rotate_channel(struct lttng_consumer_channel *channel,
 	const bool is_local_trace = relayd_id == -1ULL;
 	struct consumer_relayd_sock_pair *relayd = NULL;
 	bool rotating_to_new_chunk = true;
+	/* Array of `struct lttng_consumer_stream *` */
+	struct lttng_dynamic_pointer_array streams_packet_to_open;
+	size_t stream_idx;
 
 	DBG("Consumer sample rotate position for channel %" PRIu64, key);
 
 	lttng_dynamic_array_init(&stream_rotation_positions,
 			sizeof(struct relayd_stream_rotation_position), NULL);
+	lttng_dynamic_pointer_array_init(&streams_packet_to_open, NULL);
 
 	rcu_read_lock();
 
@@ -4102,36 +4226,135 @@ int lttng_consumer_rotate_channel(struct lttng_consumer_channel *channel,
 			}
 			stream_count++;
 		}
+
+		stream->opened_packet_in_current_trace_chunk = false;
+
+		if (rotating_to_new_chunk && !stream->metadata_flag) {
+			/*
+			 * Attempt to flush an empty packet as close to the
+			 * rotation point as possible. In the event where a
+			 * stream remains inactive after the rotation point,
+			 * this ensures that the new trace chunk has a
+			 * beginning timestamp set at the begining of the
+			 * trace chunk instead of only creating an empty
+			 * packet when the trace chunk is stopped.
+			 *
+			 * This indicates to the viewers that the stream
+			 * was being recorded, but more importantly it
+			 * allows viewers to determine a useable trace
+			 * intersection.
+			 *
+			 * This presents a problem in the case where the
+			 * ring-buffer is completely full.
+			 *
+			 * Consider the following scenario:
+			 *   - The consumption of data is slow (slow network,
+			 *     for instance),
+			 *   - The ring buffer is full,
+			 *   - A rotation is initiated,
+			 *     - The flush below does nothing (no space left to
+			 *       open a new packet),
+			 *   - The other streams rotate very soon, and new
+			 *     data is produced in the new chunk,
+			 *   - This stream completes its rotation long after the
+			 *     rotation was initiated
+			 *   - The session is stopped before any event can be
+			 *     produced	in this stream's buffers.
+			 *
+			 * The resulting trace chunk will have a single packet
+			 * temporaly at the end of the trace chunk for this
+			 * stream making the stream intersection more narrow
+			 * than it should be.
+			 *
+			 * To work-around this, an empty flush is performed
+			 * after the first consumption of a packet during a
+			 * rotation if open_packet fails. The idea is that
+			 * consuming a packet frees enough space to switch
+			 * packets in this scenario and allows the tracer to
+			 * "stamp" the beginning of the new trace chunk at the
+			 * earliest possible point.
+			 *
+			 * The packet open is performed after the channel
+			 * rotation to ensure that no attempt to open a packet
+			 * is performed in a stream that has no active trace
+			 * chunk.
+			 */
+			ret = lttng_dynamic_pointer_array_add_pointer(
+					&streams_packet_to_open, stream);
+			if (ret) {
+				PERROR("Failed to add a stream pointer to array of streams in which to open a packet");
+				ret = -1;
+				goto end_unlock_stream;
+			}
+		}
+
 		pthread_mutex_unlock(&stream->lock);
 	}
 	stream = NULL;
-	pthread_mutex_unlock(&channel->lock);
 
-	if (is_local_trace) {
-		ret = 0;
-		goto end;
-	}
+	if (!is_local_trace) {
+		relayd = consumer_find_relayd(relayd_id);
+		if (!relayd) {
+			ERR("Failed to find relayd %" PRIu64, relayd_id);
+			ret = -1;
+			goto end_unlock_channel;
+		}
 
-	relayd = consumer_find_relayd(relayd_id);
-	if (!relayd) {
-		ERR("Failed to find relayd %" PRIu64, relayd_id);
-		ret = -1;
-		goto end;
+		pthread_mutex_lock(&relayd->ctrl_sock_mutex);
+		ret = relayd_rotate_streams(&relayd->control_sock, stream_count,
+				rotating_to_new_chunk ? &next_chunk_id : NULL,
+				(const struct relayd_stream_rotation_position *)
+						stream_rotation_positions.buffer
+								.data);
+		pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
+		if (ret < 0) {
+			ERR("Relayd rotate stream failed. Cleaning up relayd %" PRIu64,
+					relayd->net_seq_idx);
+			lttng_consumer_cleanup_relayd(relayd);
+			goto end_unlock_channel;
+		}
 	}
 
-	pthread_mutex_lock(&relayd->ctrl_sock_mutex);
-	ret = relayd_rotate_streams(&relayd->control_sock, stream_count,
-			rotating_to_new_chunk ? &next_chunk_id : NULL,
-			(const struct relayd_stream_rotation_position *)
-					stream_rotation_positions.buffer.data);
-	pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
-	if (ret < 0) {
-		ERR("Relayd rotate stream failed. Cleaning up relayd %" PRIu64,
-				relayd->net_seq_idx);
-		lttng_consumer_cleanup_relayd(relayd);
-		goto end;
+	for (stream_idx = 0;
+			stream_idx < lttng_dynamic_pointer_array_get_count(
+				&streams_packet_to_open);
+			stream_idx++) {
+		enum open_packet_status status;
+
+		stream = lttng_dynamic_pointer_array_get_pointer(
+				&streams_packet_to_open, stream_idx);
+
+		pthread_mutex_lock(&stream->lock);
+		status = open_packet(stream);
+		pthread_mutex_unlock(&stream->lock);
+		switch (status) {
+		case OPEN_PACKET_STATUS_OPENED:
+			DBG("Opened a packet after a rotation: stream id = %" PRIu64
+			    ", channel name = %s, session id = %" PRIu64,
+					stream->key, stream->chan->name,
+					stream->chan->session_id);
+			break;
+		case OPEN_PACKET_STATUS_NO_SPACE:
+			/*
+			 * Can't open a packet as there is no space left
+			 * in the buffer. A new packet will be opened
+			 * once one has been consumed.
+			 */
+			DBG("No space left to open a packet after a rotation: stream id = %" PRIu64
+			    ", channel name = %s, session id = %" PRIu64,
+					stream->key, stream->chan->name,
+					stream->chan->session_id);
+			break;
+		case OPEN_PACKET_STATUS_ERROR:
+			/* Logged by callee. */
+			ret = -1;
+			goto end_unlock_channel;
+		default:
+			abort();
+		}
 	}
 
+	pthread_mutex_unlock(&channel->lock);
 	ret = 0;
 	goto end;
 
@@ -4142,6 +4365,7 @@ end_unlock_channel:
 end:
 	rcu_read_unlock();
 	lttng_dynamic_array_reset(&stream_rotation_positions);
+	lttng_dynamic_pointer_array_reset(&streams_packet_to_open);
 	return ret;
 }
 
@@ -4957,3 +5181,70 @@ int lttng_consumer_clear_channel(struct lttng_consumer_channel *channel)
 end:
 	return ret;
 }
+
+enum lttcomm_return_code lttng_consumer_open_channel_packets(
+		struct lttng_consumer_channel *channel)
+{
+	struct lttng_consumer_stream *stream;
+	enum lttcomm_return_code ret = LTTCOMM_CONSUMERD_SUCCESS;
+
+	if (channel->metadata_stream) {
+		ERR("Open channel packets command attempted on a metadata channel");
+		ret = LTTCOMM_CONSUMERD_INVALID_PARAMETERS;
+		goto end;
+	}
+
+	rcu_read_lock();
+	cds_list_for_each_entry(stream, &channel->streams.head, send_node) {
+		enum open_packet_status status;
+
+		pthread_mutex_lock(&stream->lock);
+		if (cds_lfht_is_node_deleted(&stream->node.node)) {
+			goto next;
+		}
+
+		status = open_packet(stream);
+		switch (status) {
+		case OPEN_PACKET_STATUS_OPENED:
+			DBG("Opened a packet in \"open channel packets\" command: stream id = %" PRIu64
+					", channel name = %s, session id = %" PRIu64,
+					stream->key, stream->chan->name,
+					stream->chan->session_id);
+			stream->opened_packet_in_current_trace_chunk = true;
+			break;
+		case OPEN_PACKET_STATUS_NO_SPACE:
+			DBG("No space left to open a packet in \"open channel packets\" command: stream id = %" PRIu64
+					", channel name = %s, session id = %" PRIu64,
+					stream->key, stream->chan->name,
+					stream->chan->session_id);
+			break;
+		case OPEN_PACKET_STATUS_ERROR:
+			/*
+			 * Only unexpected internal errors can lead to this
+			 * failing. Report an unknown error.
+			 */
+			ERR("Failed to flush empty buffer in \"open channel packets\" command: stream id = %" PRIu64
+					", channel id = %" PRIu64
+					", channel name = %s"
+					", session id = %" PRIu64,
+					stream->key, channel->key,
+					channel->name, channel->session_id);
+			ret = LTTCOMM_CONSUMERD_UNKNOWN_ERROR;
+			goto error_unlock;
+		default:
+			abort();
+		}
+
+	next:
+		pthread_mutex_unlock(&stream->lock);
+	}
+
+end_rcu_unlock:
+	rcu_read_unlock();
+end:
+	return ret;
+
+error_unlock:
+	pthread_mutex_unlock(&stream->lock);
+	goto end_rcu_unlock;
+}