[lttng-tools.git] / src / bin / lttng-relayd / viewer-stream.c

/*
 * Copyright (C) 2013 Julien Desfossez <jdesfossez@efficios.com>
 * Copyright (C) 2013 David Goulet <dgoulet@efficios.com>
 * Copyright (C) 2015 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * SPDX-License-Identifier: GPL-2.0-only
 *
 */

#define _LGPL_SOURCE
#include <common/common.h>
#include <common/index/index.h>
#include <common/compat/string.h>
#include <common/utils.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#include "lttng-relayd.h"
#include "viewer-stream.h"

static void viewer_stream_destroy(struct relay_viewer_stream *vstream)
{
	lttng_trace_chunk_put(vstream->stream_file.trace_chunk);
	free(vstream->path_name);
	free(vstream->channel_name);
	free(vstream);
}

static void viewer_stream_destroy_rcu(struct rcu_head *head)
{
	struct relay_viewer_stream *vstream =
		caa_container_of(head, struct relay_viewer_stream, rcu_node);

	viewer_stream_destroy(vstream);
}

/* Relay stream's lock must be held by the caller. */
struct relay_viewer_stream *viewer_stream_create(struct relay_stream *stream,
		struct lttng_trace_chunk *trace_chunk,
		enum lttng_viewer_seek seek_t)
{
	struct relay_viewer_stream *vstream = NULL;

	ASSERT_LOCKED(stream->lock);

	vstream = zmalloc(sizeof(*vstream));
	if (!vstream) {
		PERROR("relay viewer stream zmalloc");
		goto error;
	}

	if (trace_chunk) {
		const bool acquired_reference = lttng_trace_chunk_get(
				trace_chunk);

		assert(acquired_reference);
	}

	vstream->stream_file.trace_chunk = trace_chunk;
	vstream->path_name = lttng_strndup(stream->path_name, LTTNG_VIEWER_PATH_MAX);
	if (vstream->path_name == NULL) {
		PERROR("relay viewer path_name alloc");
		goto error;
	}
	vstream->channel_name = lttng_strndup(stream->channel_name,
			LTTNG_VIEWER_NAME_MAX);
	if (vstream->channel_name == NULL) {
		PERROR("relay viewer channel_name alloc");
		goto error;
	}

	if (!stream_get(stream)) {
		ERR("Cannot get stream");
		goto error;
	}
	vstream->stream = stream;

	if (stream->is_metadata && stream->trace->viewer_metadata_stream) {
		ERR("Cannot attach viewer metadata stream to trace (busy).");
		goto error;
	}

	switch (seek_t) {
	case LTTNG_VIEWER_SEEK_BEGINNING:
	{
		uint64_t seq_tail = tracefile_array_get_seq_tail(stream->tfa);

		if (seq_tail == -1ULL) {
			/*
			 * Tail may not be initialized yet. Nonetheless, we know
			 * we want to send the first index once it becomes
			 * available.
			 */
			seq_tail = 0;
		}
		vstream->current_tracefile_id =
			tracefile_array_get_file_index_tail(stream->tfa);
		vstream->index_sent_seqcount = seq_tail;
		break;
	}
	case LTTNG_VIEWER_SEEK_LAST:
		vstream->current_tracefile_id =
			tracefile_array_get_read_file_index_head(stream->tfa);
		/*
		 * We seek at the very end of each stream, awaiting for
		 * a future packet to eventually come in.
		 *
		 * We don't need to check the head position for -1ULL since the
		 * increment will set it to 0.
		 */
		vstream->index_sent_seqcount =
				tracefile_array_get_seq_head(stream->tfa) + 1;
		break;
	default:
		goto error;
	}

	/*
	 * If we never received an index for the current stream, delay
	 * the opening of the index, otherwise open it right now.
	 */
	if (stream->index_file == NULL) {
		vstream->index_file = NULL;
	} else {
		const uint32_t connection_major = stream->trace->session->major;
		const uint32_t connection_minor = stream->trace->session->minor;
		enum lttng_trace_chunk_status chunk_status;

		chunk_status = lttng_index_file_create_from_trace_chunk_read_only(
				vstream->stream_file.trace_chunk,
				stream->path_name,
				stream->channel_name, stream->tracefile_size,
				vstream->current_tracefile_id,
				lttng_to_index_major(connection_major,
						connection_minor),
				lttng_to_index_minor(connection_major,
						connection_minor),
				true, &vstream->index_file);
		if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
			if (chunk_status == LTTNG_TRACE_CHUNK_STATUS_NO_FILE) {
				vstream->index_file = NULL;
			} else {
				goto error;
			}
		}
	}

	/*
	 * If we never received a data file for the current stream, delay the
	 * opening, otherwise open it right now.
	 */
	if (stream->file) {
		int ret;
		char file_path[LTTNG_PATH_MAX];
		enum lttng_trace_chunk_status status;

		ret = utils_stream_file_path(stream->path_name,
				stream->channel_name, stream->tracefile_size,
				vstream->current_tracefile_id, NULL, file_path,
				sizeof(file_path));
		if (ret < 0) {
			goto error;
		}

		status = lttng_trace_chunk_open_fs_handle(
				vstream->stream_file.trace_chunk, file_path,
				O_RDONLY, 0, &vstream->stream_file.handle,
				true);
		if (status != LTTNG_TRACE_CHUNK_STATUS_OK) {
			goto error;
		}
	}

	if (seek_t == LTTNG_VIEWER_SEEK_LAST && vstream->index_file) {
		off_t lseek_ret;

		lseek_ret = fs_handle_seek(
				vstream->index_file->file, 0, SEEK_END);
		if (lseek_ret < 0) {
			goto error;
		}
	}
	if (stream->is_metadata) {
		rcu_assign_pointer(stream->trace->viewer_metadata_stream,
				vstream);
	}

	vstream->last_seen_rotation_count = stream->completed_rotation_count;

	/* Globally visible after the add unique. */
	lttng_ht_node_init_u64(&vstream->stream_n, stream->stream_handle);
	urcu_ref_init(&vstream->ref);
	lttng_ht_add_unique_u64(viewer_streams_ht, &vstream->stream_n);

	return vstream;

error:
	if (vstream) {
		viewer_stream_destroy(vstream);
	}
	return NULL;
}

static void viewer_stream_unpublish(struct relay_viewer_stream *vstream)
{
	int ret;
	struct lttng_ht_iter iter;

	iter.iter.node = &vstream->stream_n.node;
	ret = lttng_ht_del(viewer_streams_ht, &iter);
	assert(!ret);
}

static void viewer_stream_release(struct urcu_ref *ref)
{
	struct relay_viewer_stream *vstream = caa_container_of(ref,
			struct relay_viewer_stream, ref);

	if (vstream->stream->is_metadata) {
		rcu_assign_pointer(vstream->stream->trace->viewer_metadata_stream, NULL);
	}

	viewer_stream_unpublish(vstream);

	if (vstream->stream_file.handle) {
		fs_handle_close(vstream->stream_file.handle);
		vstream->stream_file.handle = NULL;
	}
	if (vstream->index_file) {
		lttng_index_file_put(vstream->index_file);
		vstream->index_file = NULL;
	}
	if (vstream->stream) {
		stream_put(vstream->stream);
		vstream->stream = NULL;
	}
	lttng_trace_chunk_put(vstream->stream_file.trace_chunk);
	vstream->stream_file.trace_chunk = NULL;
	call_rcu(&vstream->rcu_node, viewer_stream_destroy_rcu);
}

/* Must be called with RCU read-side lock held. */
bool viewer_stream_get(struct relay_viewer_stream *vstream)
{
	return urcu_ref_get_unless_zero(&vstream->ref);
}

/*
 * Get viewer stream by id.
 *
 * Return viewer stream if found else NULL.
 */
struct relay_viewer_stream *viewer_stream_get_by_id(uint64_t id)
{
	struct lttng_ht_node_u64 *node;
	struct lttng_ht_iter iter;
	struct relay_viewer_stream *vstream = NULL;

	rcu_read_lock();
	lttng_ht_lookup(viewer_streams_ht, &id, &iter);
	node = lttng_ht_iter_get_node_u64(&iter);
	if (!node) {
		DBG("Relay viewer stream %" PRIu64 " not found", id);
		goto end;
	}
	vstream = caa_container_of(node, struct relay_viewer_stream, stream_n);
	if (!viewer_stream_get(vstream)) {
		vstream = NULL;
	}
end:
	rcu_read_unlock();
	return vstream;
}

void viewer_stream_put(struct relay_viewer_stream *vstream)
{
	rcu_read_lock();
	urcu_ref_put(&vstream->ref, viewer_stream_release);
	rcu_read_unlock();
}

void viewer_stream_close_files(struct relay_viewer_stream *vstream)
{
	if (vstream->index_file) {
		lttng_index_file_put(vstream->index_file);
		vstream->index_file = NULL;
	}
	if (vstream->stream_file.handle) {
	        fs_handle_close(vstream->stream_file.handle);
		vstream->stream_file.handle = NULL;
	}
}

void viewer_stream_sync_tracefile_array_tail(struct relay_viewer_stream *vstream)
{
	const struct relay_stream *stream = vstream->stream;
	uint64_t seq_tail;

	vstream->current_tracefile_id = tracefile_array_get_file_index_tail(stream->tfa);
	seq_tail = tracefile_array_get_seq_tail(stream->tfa);
	if (seq_tail == -1ULL) {
		seq_tail = 0;
	}
	vstream->index_sent_seqcount = seq_tail;
}

/*
 * Rotate a stream to the next tracefile.
 *
 * Must be called with the rstream lock held.
 * Returns 0 on success, 1 on EOF.
 */
int viewer_stream_rotate(struct relay_viewer_stream *vstream)
{
	int ret;
	uint64_t new_id;
	const struct relay_stream *stream = vstream->stream;

	/* Detect the last tracefile to open. */
	if (stream->index_received_seqcount
			== vstream->index_sent_seqcount
			&& stream->trace->session->connection_closed) {
		ret = 1;
		goto end;
	}

	if (stream->tracefile_count == 0) {
		/* Ignore rotation, there is none to do. */
		ret = 0;
		goto end;
	}

	/*
	 * Try to move to the next file.
	 */
	new_id = (vstream->current_tracefile_id + 1)
			% stream->tracefile_count;
	if (tracefile_array_seq_in_file(stream->tfa, new_id,
			vstream->index_sent_seqcount)) {
		vstream->current_tracefile_id = new_id;
	} else {
		uint64_t seq_tail = tracefile_array_get_seq_tail(stream->tfa);

		/*
		 * This can only be reached on overwrite, which implies there
		 * has been data written at some point, which will have set the
		 * tail.
		 */
		assert(seq_tail != -1ULL);
		/*
		 * We need to resync because we lag behind tail.
		 */
		vstream->current_tracefile_id =
			tracefile_array_get_file_index_tail(stream->tfa);
		vstream->index_sent_seqcount = seq_tail;
	}
	viewer_stream_close_files(vstream);
	ret = 0;
end:
	return ret;
}

void print_viewer_streams(void)
{
	struct lttng_ht_iter iter;
	struct relay_viewer_stream *vstream;

	if (!viewer_streams_ht) {
		return;
	}

	rcu_read_lock();
	cds_lfht_for_each_entry(viewer_streams_ht->ht, &iter.iter, vstream,
			stream_n.node) {
		if (!viewer_stream_get(vstream)) {
			continue;
		}
		DBG("vstream %p refcount %ld stream %" PRIu64 " trace %" PRIu64
			" session %" PRIu64,
			vstream,
			vstream->ref.refcount,
			vstream->stream->stream_handle,
			vstream->stream->trace->id,
			vstream->stream->trace->session->id);
		viewer_stream_put(vstream);
	}
	rcu_read_unlock();
}
Commit	Line	Data
	1	/*
	2	* Copyright (C) 2013 Julien Desfossez <jdesfossez@efficios.com>
	3	* Copyright (C) 2013 David Goulet <dgoulet@efficios.com>
	4	* Copyright (C) 2015 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	5	*
	6	* SPDX-License-Identifier: GPL-2.0-only
	7	*
	8	*/
	9
	10	#define _LGPL_SOURCE
	11	#include <common/common.h>
	12	#include <common/index/index.h>
	13	#include <common/compat/string.h>
	14	#include <common/utils.h>
	15	#include <sys/types.h>
	16	#include <sys/stat.h>
	17	#include <fcntl.h>
	18
	19	#include "lttng-relayd.h"
	20	#include "viewer-stream.h"
	21
	22	static void viewer_stream_destroy(struct relay_viewer_stream *vstream)
	23	{
	24	lttng_trace_chunk_put(vstream->stream_file.trace_chunk);
	25	free(vstream->path_name);
	26	free(vstream->channel_name);
	27	free(vstream);
	28	}
	29
	30	static void viewer_stream_destroy_rcu(struct rcu_head *head)
	31	{
	32	struct relay_viewer_stream *vstream =
	33	caa_container_of(head, struct relay_viewer_stream, rcu_node);
	34
	35	viewer_stream_destroy(vstream);
	36	}
	37
	38	/* Relay stream's lock must be held by the caller. */
	39	struct relay_viewer_stream viewer_stream_create(struct relay_stream stream,
	40	struct lttng_trace_chunk *trace_chunk,
	41	enum lttng_viewer_seek seek_t)
	42	{
	43	struct relay_viewer_stream *vstream = NULL;
	44
	45	ASSERT_LOCKED(stream->lock);
	46
	47	vstream = zmalloc(sizeof(*vstream));
	48	if (!vstream) {
	49	PERROR("relay viewer stream zmalloc");
	50	goto error;
	51	}
	52
	53	if (trace_chunk) {
	54	const bool acquired_reference = lttng_trace_chunk_get(
	55	trace_chunk);
	56
	57	assert(acquired_reference);
	58	}
	59
	60	vstream->stream_file.trace_chunk = trace_chunk;
	61	vstream->path_name = lttng_strndup(stream->path_name, LTTNG_VIEWER_PATH_MAX);
	62	if (vstream->path_name == NULL) {
	63	PERROR("relay viewer path_name alloc");
	64	goto error;
	65	}
	66	vstream->channel_name = lttng_strndup(stream->channel_name,
	67	LTTNG_VIEWER_NAME_MAX);
	68	if (vstream->channel_name == NULL) {
	69	PERROR("relay viewer channel_name alloc");
	70	goto error;
	71	}
	72
	73	if (!stream_get(stream)) {
	74	ERR("Cannot get stream");
	75	goto error;
	76	}
	77	vstream->stream = stream;
	78
	79	if (stream->is_metadata && stream->trace->viewer_metadata_stream) {
	80	ERR("Cannot attach viewer metadata stream to trace (busy).");
	81	goto error;
	82	}
	83
	84	switch (seek_t) {
	85	case LTTNG_VIEWER_SEEK_BEGINNING:
	86	{
	87	uint64_t seq_tail = tracefile_array_get_seq_tail(stream->tfa);
	88
	89	if (seq_tail == -1ULL) {
	90	/*
	91	* Tail may not be initialized yet. Nonetheless, we know
	92	* we want to send the first index once it becomes
	93	* available.
	94	*/
	95	seq_tail = 0;
	96	}
	97	vstream->current_tracefile_id =
	98	tracefile_array_get_file_index_tail(stream->tfa);
	99	vstream->index_sent_seqcount = seq_tail;
	100	break;
	101	}
	102	case LTTNG_VIEWER_SEEK_LAST:
	103	vstream->current_tracefile_id =
	104	tracefile_array_get_read_file_index_head(stream->tfa);
	105	/*
	106	* We seek at the very end of each stream, awaiting for
	107	* a future packet to eventually come in.
	108	*
	109	* We don't need to check the head position for -1ULL since the
	110	* increment will set it to 0.
	111	*/
	112	vstream->index_sent_seqcount =
	113	tracefile_array_get_seq_head(stream->tfa) + 1;
	114	break;
	115	default:
	116	goto error;
	117	}
	118
	119	/*
	120	* If we never received an index for the current stream, delay
	121	* the opening of the index, otherwise open it right now.
	122	*/
	123	if (stream->index_file == NULL) {
	124	vstream->index_file = NULL;
	125	} else {
	126	const uint32_t connection_major = stream->trace->session->major;
	127	const uint32_t connection_minor = stream->trace->session->minor;
	128	enum lttng_trace_chunk_status chunk_status;
	129
	130	chunk_status = lttng_index_file_create_from_trace_chunk_read_only(
	131	vstream->stream_file.trace_chunk,
	132	stream->path_name,
	133	stream->channel_name, stream->tracefile_size,
	134	vstream->current_tracefile_id,
	135	lttng_to_index_major(connection_major,
	136	connection_minor),
	137	lttng_to_index_minor(connection_major,
	138	connection_minor),
	139	true, &vstream->index_file);
	140	if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
	141	if (chunk_status == LTTNG_TRACE_CHUNK_STATUS_NO_FILE) {
	142	vstream->index_file = NULL;
	143	} else {
	144	goto error;
	145	}
	146	}
	147	}
	148
	149	/*
	150	* If we never received a data file for the current stream, delay the
	151	* opening, otherwise open it right now.
	152	*/
	153	if (stream->file) {
	154	int ret;
	155	char file_path[LTTNG_PATH_MAX];
	156	enum lttng_trace_chunk_status status;
	157
	158	ret = utils_stream_file_path(stream->path_name,
	159	stream->channel_name, stream->tracefile_size,
	160	vstream->current_tracefile_id, NULL, file_path,
	161	sizeof(file_path));
	162	if (ret < 0) {
	163	goto error;
	164	}
	165
	166	status = lttng_trace_chunk_open_fs_handle(
	167	vstream->stream_file.trace_chunk, file_path,
	168	O_RDONLY, 0, &vstream->stream_file.handle,
	169	true);
	170	if (status != LTTNG_TRACE_CHUNK_STATUS_OK) {
	171	goto error;
	172	}
	173	}
	174
	175	if (seek_t == LTTNG_VIEWER_SEEK_LAST && vstream->index_file) {
	176	off_t lseek_ret;
	177
	178	lseek_ret = fs_handle_seek(
	179	vstream->index_file->file, 0, SEEK_END);
	180	if (lseek_ret < 0) {
	181	goto error;
	182	}
	183	}
	184	if (stream->is_metadata) {
	185	rcu_assign_pointer(stream->trace->viewer_metadata_stream,
	186	vstream);
	187	}
	188
	189	vstream->last_seen_rotation_count = stream->completed_rotation_count;
	190
	191	/* Globally visible after the add unique. */
	192	lttng_ht_node_init_u64(&vstream->stream_n, stream->stream_handle);
	193	urcu_ref_init(&vstream->ref);
	194	lttng_ht_add_unique_u64(viewer_streams_ht, &vstream->stream_n);
	195
	196	return vstream;
	197
	198	error:
	199	if (vstream) {
	200	viewer_stream_destroy(vstream);
	201	}
	202	return NULL;
	203	}
	204
	205	static void viewer_stream_unpublish(struct relay_viewer_stream *vstream)
	206	{
	207	int ret;
	208	struct lttng_ht_iter iter;
	209
	210	iter.iter.node = &vstream->stream_n.node;
	211	ret = lttng_ht_del(viewer_streams_ht, &iter);
	212	assert(!ret);
	213	}
	214
	215	static void viewer_stream_release(struct urcu_ref *ref)
	216	{
	217	struct relay_viewer_stream *vstream = caa_container_of(ref,
	218	struct relay_viewer_stream, ref);
	219
	220	if (vstream->stream->is_metadata) {
	221	rcu_assign_pointer(vstream->stream->trace->viewer_metadata_stream, NULL);
	222	}
	223
	224	viewer_stream_unpublish(vstream);
	225
	226	if (vstream->stream_file.handle) {
	227	fs_handle_close(vstream->stream_file.handle);
	228	vstream->stream_file.handle = NULL;
	229	}
	230	if (vstream->index_file) {
	231	lttng_index_file_put(vstream->index_file);
	232	vstream->index_file = NULL;
	233	}
	234	if (vstream->stream) {
	235	stream_put(vstream->stream);
	236	vstream->stream = NULL;
	237	}
	238	lttng_trace_chunk_put(vstream->stream_file.trace_chunk);
	239	vstream->stream_file.trace_chunk = NULL;
	240	call_rcu(&vstream->rcu_node, viewer_stream_destroy_rcu);
	241	}
	242
	243	/* Must be called with RCU read-side lock held. */
	244	bool viewer_stream_get(struct relay_viewer_stream *vstream)
	245	{
	246	return urcu_ref_get_unless_zero(&vstream->ref);
	247	}
	248
	249	/*
	250	* Get viewer stream by id.
	251	*
	252	* Return viewer stream if found else NULL.
	253	*/
	254	struct relay_viewer_stream *viewer_stream_get_by_id(uint64_t id)
	255	{
	256	struct lttng_ht_node_u64 *node;
	257	struct lttng_ht_iter iter;
	258	struct relay_viewer_stream *vstream = NULL;
	259
	260	rcu_read_lock();
	261	lttng_ht_lookup(viewer_streams_ht, &id, &iter);
	262	node = lttng_ht_iter_get_node_u64(&iter);
	263	if (!node) {
	264	DBG("Relay viewer stream %" PRIu64 " not found", id);
	265	goto end;
	266	}
	267	vstream = caa_container_of(node, struct relay_viewer_stream, stream_n);
	268	if (!viewer_stream_get(vstream)) {
	269	vstream = NULL;
	270	}
	271	end:
	272	rcu_read_unlock();
	273	return vstream;
	274	}
	275
	276	void viewer_stream_put(struct relay_viewer_stream *vstream)
	277	{
	278	rcu_read_lock();
	279	urcu_ref_put(&vstream->ref, viewer_stream_release);
	280	rcu_read_unlock();
	281	}
	282
	283	void viewer_stream_close_files(struct relay_viewer_stream *vstream)
	284	{
	285	if (vstream->index_file) {
	286	lttng_index_file_put(vstream->index_file);
	287	vstream->index_file = NULL;
	288	}
	289	if (vstream->stream_file.handle) {
	290	fs_handle_close(vstream->stream_file.handle);
	291	vstream->stream_file.handle = NULL;
	292	}
	293	}
	294
	295	void viewer_stream_sync_tracefile_array_tail(struct relay_viewer_stream *vstream)
	296	{
	297	const struct relay_stream *stream = vstream->stream;
	298	uint64_t seq_tail;
	299
	300	vstream->current_tracefile_id = tracefile_array_get_file_index_tail(stream->tfa);
	301	seq_tail = tracefile_array_get_seq_tail(stream->tfa);
	302	if (seq_tail == -1ULL) {
	303	seq_tail = 0;
	304	}
	305	vstream->index_sent_seqcount = seq_tail;
	306	}
	307
	308	/*
	309	* Rotate a stream to the next tracefile.
	310	*
	311	* Must be called with the rstream lock held.
	312	* Returns 0 on success, 1 on EOF.
	313	*/
	314	int viewer_stream_rotate(struct relay_viewer_stream *vstream)
	315	{
	316	int ret;
	317	uint64_t new_id;
	318	const struct relay_stream *stream = vstream->stream;
	319
	320	/* Detect the last tracefile to open. */
	321	if (stream->index_received_seqcount
	322	== vstream->index_sent_seqcount
	323	&& stream->trace->session->connection_closed) {
	324	ret = 1;
	325	goto end;
	326	}
	327
	328	if (stream->tracefile_count == 0) {
	329	/* Ignore rotation, there is none to do. */
	330	ret = 0;
	331	goto end;
	332	}
	333
	334	/*
	335	* Try to move to the next file.
	336	*/
	337	new_id = (vstream->current_tracefile_id + 1)
	338	% stream->tracefile_count;
	339	if (tracefile_array_seq_in_file(stream->tfa, new_id,
	340	vstream->index_sent_seqcount)) {
	341	vstream->current_tracefile_id = new_id;
	342	} else {
	343	uint64_t seq_tail = tracefile_array_get_seq_tail(stream->tfa);
	344
	345	/*
	346	* This can only be reached on overwrite, which implies there
	347	* has been data written at some point, which will have set the
	348	* tail.
	349	*/
	350	assert(seq_tail != -1ULL);
	351	/*
	352	* We need to resync because we lag behind tail.
	353	*/
	354	vstream->current_tracefile_id =
	355	tracefile_array_get_file_index_tail(stream->tfa);
	356	vstream->index_sent_seqcount = seq_tail;
	357	}
	358	viewer_stream_close_files(vstream);
	359	ret = 0;
	360	end:
	361	return ret;
	362	}
	363
	364	void print_viewer_streams(void)
	365	{
	366	struct lttng_ht_iter iter;
	367	struct relay_viewer_stream *vstream;
	368
	369	if (!viewer_streams_ht) {
	370	return;
	371	}
	372
	373	rcu_read_lock();
	374	cds_lfht_for_each_entry(viewer_streams_ht->ht, &iter.iter, vstream,
	375	stream_n.node) {
	376	if (!viewer_stream_get(vstream)) {
	377	continue;
	378	}
	379	DBG("vstream %p refcount %ld stream %" PRIu64 " trace %" PRIu64
	380	" session %" PRIu64,
	381	vstream,
	382	vstream->ref.refcount,
	383	vstream->stream->stream_handle,
	384	vstream->stream->trace->id,
	385	vstream->stream->trace->session->id);
	386	viewer_stream_put(vstream);
	387	}
	388	rcu_read_unlock();
	389	}