From: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Date: Fri, 8 Feb 2019 22:05:10 +0000 (-0500)
Subject: Consumer: Implement lttng_consumer_clear_channel
X-Git-Url: http://git.efficios.com/?p=lttng-tools.git;a=commitdiff_plain;h=a9c7eac7b27c5f0bc7895fd77f6f11ee5d5e8751

Consumer: Implement lttng_consumer_clear_channel

This function is responsible for performing all actions needed to
clear a given channel.

It only supports clear operation on unmonitored channel
(snapshot mode) for now.

To do so, flush and clear all the channel streams.

We use an active flush (consumer_flush_buffer(..., 1)) since we consider
the producer active at all time. No reason so far to check for the
quiescent state of the channel. This might need to be revisited.

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
---

diff --git a/src/common/consumer/consumer.c b/src/common/consumer/consumer.c
index cb1414979..3e3c30487 100644
--- a/src/common/consumer/consumer.c
+++ b/src/common/consumer/consumer.c
@@ -3767,3 +3767,134 @@ 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:
+		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
+int consumer_clear_buffer(struct lttng_consumer_stream *stream)
+{
+	int ret = 0;
+
+	switch (consumer_data.type) {
+	case LTTNG_CONSUMER_KERNEL:
+		ret = kernctl_buffer_clear(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_clear_buffer(stream);
+		break;
+	default:
+		ERR("Unknown consumer_data type");
+		abort();
+	}
+
+end:
+	return ret;
+}
+
+static
+int clear_unmonitored_channel(struct lttng_consumer_channel *channel)
+{
+
+	int ret;
+	struct lttng_consumer_stream *stream;
+
+	assert(!channel->monitor);
+	assert(channel->type != CONSUMER_CHANNEL_TYPE_METADATA);
+
+	rcu_read_lock();
+	pthread_mutex_lock(&channel->lock);
+	cds_list_for_each_entry(stream, &channel->streams.head, send_node) {
+		health_code_update();
+		pthread_mutex_lock(&stream->lock);
+
+		ret = consumer_flush_buffer(stream, 1);
+		if (ret < 0) {
+			ERR("Failed to flush stream %" PRIu64 " during channel clear",
+					stream->key);
+			ret = LTTCOMM_CONSUMERD_FATAL;
+			goto error_unlock;
+		}
+
+		ret = consumer_clear_buffer(stream);
+		if (ret < 0) {
+			ERR("Failed to clear stream %" PRIu64 " during channel clear",
+					stream->key);
+			ret = LTTCOMM_CONSUMERD_FATAL;
+			goto error_unlock;
+		}
+		pthread_mutex_unlock(&stream->lock);
+	}
+	pthread_mutex_unlock(&channel->lock);
+	rcu_read_unlock();
+	return 0;
+
+error_unlock:
+	pthread_mutex_unlock(&stream->lock);
+	pthread_mutex_unlock(&channel->lock);
+	rcu_read_unlock();
+	return ret;
+}
+
+int lttng_consumer_clear_channel(struct lttng_consumer_channel *channel)
+{
+	int ret;
+
+	DBG("Consumer clear channel %" PRIu64, channel->key);
+
+	if (!channel->monitor) {
+		/* Snapshot mode */
+		if (channel->type == CONSUMER_CHANNEL_TYPE_METADATA) {
+			/*
+			 * Nothing to do for the metadata channel/stream.
+			 * Snapshot mechanism already take care of the metadata
+			 * handling/generation.
+			 */
+			goto end;
+		}
+		ret = clear_unmonitored_channel(channel);
+		if (ret) {
+			goto error;
+		}
+	} else {
+		/* TODO:
+		 * Normal channel and relayd bound clear operation not supported
+		 * for now
+		 */
+		ret = LTTCOMM_CONSUMERD_FATAL;
+		goto error;
+	}
+
+end:
+	ret = LTTCOMM_CONSUMERD_SUCCESS;
+error:
+	return ret;
+}
diff --git a/src/common/consumer/consumer.h b/src/common/consumer/consumer.h
index 17e5b55a6..c4ea005b1 100644
--- a/src/common/consumer/consumer.h
+++ b/src/common/consumer/consumer.h
@@ -755,5 +755,6 @@ int consumer_add_metadata_stream(struct lttng_consumer_stream *stream);
 void consumer_del_stream_for_metadata(struct lttng_consumer_stream *stream);
 int consumer_create_index_file(struct lttng_consumer_stream *stream);
 void lttng_consumer_cleanup_relayd(struct consumer_relayd_sock_pair *relayd);
+int lttng_consumer_clear_channel(struct lttng_consumer_channel *channel);
 
 #endif /* LIB_CONSUMER_H */