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

/*
 * 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 "lttng-relayd.hpp"
#include "viewer-stream.hpp"

#include <common/common.hpp>
#include <common/compat/string.hpp>
#include <common/index/index.hpp>
#include <common/urcu.hpp>
#include <common/utils.hpp>

#include <algorithm>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>

static void viewer_stream_release_composite_objects(struct relay_viewer_stream *vstream)
{
	if (vstream->stream_file.handle) {
		fs_handle_close(vstream->stream_file.handle);
		vstream->stream_file.handle = nullptr;
	}
	if (vstream->index_file) {
		lttng_index_file_put(vstream->index_file);
		vstream->index_file = nullptr;
	}
	if (vstream->stream) {
		stream_put(vstream->stream);
		vstream->stream = nullptr;
	}
	lttng_trace_chunk_put(vstream->stream_file.trace_chunk);
	vstream->stream_file.trace_chunk = nullptr;
}

static void viewer_stream_destroy(struct relay_viewer_stream *vstream)
{
	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 =
		lttng::utils::container_of(head, &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 = nullptr;

	ASSERT_LOCKED(stream->lock);

	vstream = zmalloc<relay_viewer_stream>();
	if (!vstream) {
		PERROR("relay viewer stream zmalloc");
		goto error;
	}
	if (trace_chunk) {
		const bool acquired_reference = lttng_trace_chunk_get(trace_chunk);

		LTTNG_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 == nullptr) {
		PERROR("relay viewer path_name alloc");
		goto error;
	}
	vstream->channel_name = lttng_strndup(stream->channel_name, LTTNG_VIEWER_NAME_MAX);
	if (vstream->channel_name == nullptr) {
		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 == nullptr) {
		vstream->index_file = nullptr;
	} else if (vstream->stream_file.trace_chunk) {
		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 = nullptr;
			} 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 && vstream->stream_file.trace_chunk) {
		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,
					     nullptr,
					     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) {
		/* Not using `put` since vstream is assumed to be published. */
		viewer_stream_release_composite_objects(vstream);
		viewer_stream_destroy(vstream);
	}
	return nullptr;
}

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);
	LTTNG_ASSERT(!ret);
}

static void viewer_stream_release(struct urcu_ref *ref)
{
	auto *vstream = lttng::utils::container_of(ref, &relay_viewer_stream::ref);

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

	const lttng::urcu::read_lock_guard read_lock;
	lttng_ht_lookup(viewer_streams_ht, &id, &iter);
	node = lttng_ht_iter_get_node<lttng_ht_node_u64>(&iter);
	if (!node) {
		DBG("Relay viewer stream %" PRIu64 " not found", id);
		goto end;
	}
	vstream = lttng::utils::container_of(node, &relay_viewer_stream::stream_n);
	if (!viewer_stream_get(vstream)) {
		vstream = nullptr;
	}
end:
	return vstream;
}

void viewer_stream_put(struct relay_viewer_stream *vstream)
{
	const lttng::urcu::read_lock_guard read_lock;
	urcu_ref_put(&vstream->ref, viewer_stream_release);
}

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

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;
	}

	/*
	 * Move the index sent seqcount forward if it was lagging behind
	 * the new tail of the tracefile array. If the current
	 * index_sent_seqcount is already further than the tracefile
	 * array tail position, keep its current position.
	 */
	vstream->index_sent_seqcount = std::max(seq_tail, vstream->index_sent_seqcount);
}

/*
 * 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 {
		const 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.
		 */
		LTTNG_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()
{
	if (!viewer_streams_ht) {
		return;
	}

	for (auto *vstream :
	     lttng::urcu::lfht_iteration_adapter<relay_viewer_stream,
						 decltype(relay_viewer_stream::stream_n),
						 &relay_viewer_stream::stream_n>(
		     *viewer_streams_ht->ht)) {
		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);
	}
}
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 "lttng-relayd.hpp"
	12	#include "viewer-stream.hpp"
	13
	14	#include <common/common.hpp>
	15	#include <common/compat/string.hpp>
	16	#include <common/index/index.hpp>
	17	#include <common/urcu.hpp>
	18	#include <common/utils.hpp>
	19
	20	#include <algorithm>
	21	#include <fcntl.h>
	22	#include <sys/stat.h>
	23	#include <sys/types.h>
	24
	25	static void viewer_stream_release_composite_objects(struct relay_viewer_stream *vstream)
	26	{
	27	if (vstream->stream_file.handle) {
	28	fs_handle_close(vstream->stream_file.handle);
	29	vstream->stream_file.handle = nullptr;
	30	}
	31	if (vstream->index_file) {
	32	lttng_index_file_put(vstream->index_file);
	33	vstream->index_file = nullptr;
	34	}
	35	if (vstream->stream) {
	36	stream_put(vstream->stream);
	37	vstream->stream = nullptr;
	38	}
	39	lttng_trace_chunk_put(vstream->stream_file.trace_chunk);
	40	vstream->stream_file.trace_chunk = nullptr;
	41	}
	42
	43	static void viewer_stream_destroy(struct relay_viewer_stream *vstream)
	44	{
	45	free(vstream->path_name);
	46	free(vstream->channel_name);
	47	free(vstream);
	48	}
	49
	50	static void viewer_stream_destroy_rcu(struct rcu_head *head)
	51	{
	52	struct relay_viewer_stream *vstream =
	53	lttng::utils::container_of(head, &relay_viewer_stream::rcu_node);
	54
	55	viewer_stream_destroy(vstream);
	56	}
	57
	58	/* Relay stream's lock must be held by the caller. */
	59	struct relay_viewer_stream viewer_stream_create(struct relay_stream stream,
	60	struct lttng_trace_chunk *trace_chunk,
	61	enum lttng_viewer_seek seek_t)
	62	{
	63	struct relay_viewer_stream *vstream = nullptr;
	64
	65	ASSERT_LOCKED(stream->lock);
	66
	67	vstream = zmalloc<relay_viewer_stream>();
	68	if (!vstream) {
	69	PERROR("relay viewer stream zmalloc");
	70	goto error;
	71	}
	72	if (trace_chunk) {
	73	const bool acquired_reference = lttng_trace_chunk_get(trace_chunk);
	74
	75	LTTNG_ASSERT(acquired_reference);
	76	}
	77
	78	vstream->stream_file.trace_chunk = trace_chunk;
	79	vstream->path_name = lttng_strndup(stream->path_name, LTTNG_VIEWER_PATH_MAX);
	80	if (vstream->path_name == nullptr) {
	81	PERROR("relay viewer path_name alloc");
	82	goto error;
	83	}
	84	vstream->channel_name = lttng_strndup(stream->channel_name, LTTNG_VIEWER_NAME_MAX);
	85	if (vstream->channel_name == nullptr) {
	86	PERROR("relay viewer channel_name alloc");
	87	goto error;
	88	}
	89
	90	if (!stream_get(stream)) {
	91	ERR("Cannot get stream");
	92	goto error;
	93	}
	94	vstream->stream = stream;
	95
	96	if (stream->is_metadata && stream->trace->viewer_metadata_stream) {
	97	ERR("Cannot attach viewer metadata stream to trace (busy).");
	98	goto error;
	99	}
	100
	101	switch (seek_t) {
	102	case LTTNG_VIEWER_SEEK_BEGINNING:
	103	{
	104	uint64_t seq_tail = tracefile_array_get_seq_tail(stream->tfa);
	105
	106	if (seq_tail == -1ULL) {
	107	/*
	108	* Tail may not be initialized yet. Nonetheless, we know
	109	* we want to send the first index once it becomes
	110	* available.
	111	*/
	112	seq_tail = 0;
	113	}
	114	vstream->current_tracefile_id = tracefile_array_get_file_index_tail(stream->tfa);
	115	vstream->index_sent_seqcount = seq_tail;
	116	break;
	117	}
	118	case LTTNG_VIEWER_SEEK_LAST:
	119	vstream->current_tracefile_id =
	120	tracefile_array_get_read_file_index_head(stream->tfa);
	121	/*
	122	* We seek at the very end of each stream, awaiting for
	123	* a future packet to eventually come in.
	124	*
	125	* We don't need to check the head position for -1ULL since the
	126	* increment will set it to 0.
	127	*/
	128	vstream->index_sent_seqcount = tracefile_array_get_seq_head(stream->tfa) + 1;
	129	break;
	130	default:
	131	goto error;
	132	}
	133
	134	/*
	135	* If we never received an index for the current stream, delay
	136	* the opening of the index, otherwise open it right now.
	137	*/
	138	if (stream->index_file == nullptr) {
	139	vstream->index_file = nullptr;
	140	} else if (vstream->stream_file.trace_chunk) {
	141	const uint32_t connection_major = stream->trace->session->major;
	142	const uint32_t connection_minor = stream->trace->session->minor;
	143	enum lttng_trace_chunk_status chunk_status;
	144
	145	chunk_status = lttng_index_file_create_from_trace_chunk_read_only(
	146	vstream->stream_file.trace_chunk,
	147	stream->path_name,
	148	stream->channel_name,
	149	stream->tracefile_size,
	150	vstream->current_tracefile_id,
	151	lttng_to_index_major(connection_major, connection_minor),
	152	lttng_to_index_minor(connection_major, connection_minor),
	153	true,
	154	&vstream->index_file);
	155	if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
	156	if (chunk_status == LTTNG_TRACE_CHUNK_STATUS_NO_FILE) {
	157	vstream->index_file = nullptr;
	158	} else {
	159	goto error;
	160	}
	161	}
	162	}
	163
	164	/*
	165	* If we never received a data file for the current stream, delay the
	166	* opening, otherwise open it right now.
	167	*/
	168	if (stream->file && vstream->stream_file.trace_chunk) {
	169	int ret;
	170	char file_path[LTTNG_PATH_MAX];
	171	enum lttng_trace_chunk_status status;
	172
	173	ret = utils_stream_file_path(stream->path_name,
	174	stream->channel_name,
	175	stream->tracefile_size,
	176	vstream->current_tracefile_id,
	177	nullptr,
	178	file_path,
	179	sizeof(file_path));
	180	if (ret < 0) {
	181	goto error;
	182	}
	183
	184	status = lttng_trace_chunk_open_fs_handle(vstream->stream_file.trace_chunk,
	185	file_path,
	186	O_RDONLY,
	187	0,
	188	&vstream->stream_file.handle,
	189	true);
	190	if (status != LTTNG_TRACE_CHUNK_STATUS_OK) {
	191	goto error;
	192	}
	193	}
	194
	195	if (seek_t == LTTNG_VIEWER_SEEK_LAST && vstream->index_file) {
	196	off_t lseek_ret;
	197
	198	lseek_ret = fs_handle_seek(vstream->index_file->file, 0, SEEK_END);
	199	if (lseek_ret < 0) {
	200	goto error;
	201	}
	202	}
	203	if (stream->is_metadata) {
	204	rcu_assign_pointer(stream->trace->viewer_metadata_stream, vstream);
	205	}
	206
	207	vstream->last_seen_rotation_count = stream->completed_rotation_count;
	208
	209	/* Globally visible after the add unique. */
	210	lttng_ht_node_init_u64(&vstream->stream_n, stream->stream_handle);
	211	urcu_ref_init(&vstream->ref);
	212	lttng_ht_add_unique_u64(viewer_streams_ht, &vstream->stream_n);
	213	return vstream;
	214
	215	error:
	216	if (vstream) {
	217	/* Not using `put` since vstream is assumed to be published. */
	218	viewer_stream_release_composite_objects(vstream);
	219	viewer_stream_destroy(vstream);
	220	}
	221	return nullptr;
	222	}
	223
	224	static void viewer_stream_unpublish(struct relay_viewer_stream *vstream)
	225	{
	226	int ret;
	227	struct lttng_ht_iter iter;
	228
	229	iter.iter.node = &vstream->stream_n.node;
	230	ret = lttng_ht_del(viewer_streams_ht, &iter);
	231	LTTNG_ASSERT(!ret);
	232	}
	233
	234	static void viewer_stream_release(struct urcu_ref *ref)
	235	{
	236	auto *vstream = lttng::utils::container_of(ref, &relay_viewer_stream::ref);
	237
	238	if (vstream->stream->is_metadata) {
	239	rcu_assign_pointer(vstream->stream->trace->viewer_metadata_stream, NULL);
	240	}
	241	viewer_stream_unpublish(vstream);
	242	viewer_stream_release_composite_objects(vstream);
	243	call_rcu(&vstream->rcu_node, viewer_stream_destroy_rcu);
	244	}
	245
	246	/* Must be called with RCU read-side lock held. */
	247	bool viewer_stream_get(struct relay_viewer_stream *vstream)
	248	{
	249	return urcu_ref_get_unless_zero(&vstream->ref);
	250	}
	251
	252	/*
	253	* Get viewer stream by id.
	254	*
	255	* Return viewer stream if found else NULL.
	256	*/
	257	struct relay_viewer_stream *viewer_stream_get_by_id(uint64_t id)
	258	{
	259	struct lttng_ht_node_u64 *node;
	260	struct lttng_ht_iter iter;
	261	struct relay_viewer_stream *vstream = nullptr;
	262
	263	const lttng::urcu::read_lock_guard read_lock;
	264	lttng_ht_lookup(viewer_streams_ht, &id, &iter);
	265	node = lttng_ht_iter_get_node<lttng_ht_node_u64>(&iter);
	266	if (!node) {
	267	DBG("Relay viewer stream %" PRIu64 " not found", id);
	268	goto end;
	269	}
	270	vstream = lttng::utils::container_of(node, &relay_viewer_stream::stream_n);
	271	if (!viewer_stream_get(vstream)) {
	272	vstream = nullptr;
	273	}
	274	end:
	275	return vstream;
	276	}
	277
	278	void viewer_stream_put(struct relay_viewer_stream *vstream)
	279	{
	280	const lttng::urcu::read_lock_guard read_lock;
	281	urcu_ref_put(&vstream->ref, viewer_stream_release);
	282	}
	283
	284	void viewer_stream_close_files(struct relay_viewer_stream *vstream)
	285	{
	286	if (vstream->index_file) {
	287	lttng_index_file_put(vstream->index_file);
	288	vstream->index_file = nullptr;
	289	}
	290	if (vstream->stream_file.handle) {
	291	fs_handle_close(vstream->stream_file.handle);
	292	vstream->stream_file.handle = nullptr;
	293	}
	294	}
	295
	296	void viewer_stream_sync_tracefile_array_tail(struct relay_viewer_stream *vstream)
	297	{
	298	const struct relay_stream *stream = vstream->stream;
	299	uint64_t seq_tail;
	300
	301	vstream->current_tracefile_id = tracefile_array_get_file_index_tail(stream->tfa);
	302	seq_tail = tracefile_array_get_seq_tail(stream->tfa);
	303	if (seq_tail == -1ULL) {
	304	seq_tail = 0;
	305	}
	306
	307	/*
	308	* Move the index sent seqcount forward if it was lagging behind
	309	* the new tail of the tracefile array. If the current
	310	* index_sent_seqcount is already further than the tracefile
	311	* array tail position, keep its current position.
	312	*/
	313	vstream->index_sent_seqcount = std::max(seq_tail, vstream->index_sent_seqcount);
	314	}
	315
	316	/*
	317	* Rotate a stream to the next tracefile.
	318	*
	319	* Must be called with the rstream lock held.
	320	* Returns 0 on success, 1 on EOF.
	321	*/
	322	int viewer_stream_rotate(struct relay_viewer_stream *vstream)
	323	{
	324	int ret;
	325	uint64_t new_id;
	326	const struct relay_stream *stream = vstream->stream;
	327
	328	/* Detect the last tracefile to open. */
	329	if (stream->index_received_seqcount == vstream->index_sent_seqcount &&
	330	stream->trace->session->connection_closed) {
	331	ret = 1;
	332	goto end;
	333	}
	334
	335	if (stream->tracefile_count == 0) {
	336	/* Ignore rotation, there is none to do. */
	337	ret = 0;
	338	goto end;
	339	}
	340
	341	/*
	342	* Try to move to the next file.
	343	*/
	344	new_id = (vstream->current_tracefile_id + 1) % stream->tracefile_count;
	345	if (tracefile_array_seq_in_file(stream->tfa, new_id, vstream->index_sent_seqcount)) {
	346	vstream->current_tracefile_id = new_id;
	347	} else {
	348	const uint64_t seq_tail = tracefile_array_get_seq_tail(stream->tfa);
	349
	350	/*
	351	* This can only be reached on overwrite, which implies there
	352	* has been data written at some point, which will have set the
	353	* tail.
	354	*/
	355	LTTNG_ASSERT(seq_tail != -1ULL);
	356	/*
	357	* We need to resync because we lag behind tail.
	358	*/
	359	vstream->current_tracefile_id = tracefile_array_get_file_index_tail(stream->tfa);
	360	vstream->index_sent_seqcount = seq_tail;
	361	}
	362	viewer_stream_close_files(vstream);
	363	ret = 0;
	364	end:
	365	return ret;
	366	}
	367
	368	void print_viewer_streams()
	369	{
	370	if (!viewer_streams_ht) {
	371	return;
	372	}
	373
	374	for (auto *vstream :
	375	lttng::urcu::lfht_iteration_adapter<relay_viewer_stream,
	376	decltype(relay_viewer_stream::stream_n),
	377	&relay_viewer_stream::stream_n>(
	378	*viewer_streams_ht->ht)) {
	379	if (!viewer_stream_get(vstream)) {
	380	continue;
	381	}
	382
	383	DBG("vstream %p refcount %ld stream %" PRIu64 " trace %" PRIu64 " session %" PRIu64,
	384	vstream,
	385	vstream->ref.refcount,
	386	vstream->stream->stream_handle,
	387	vstream->stream->trace->id,
	388	vstream->stream->trace->session->id);
	389	viewer_stream_put(vstream);
	390	}
	391	}