[lttng-ust.git] / libust / lttng-ust-comm.c

/*
 * lttng-ust-comm.c
 *
 * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
 * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; only
 * version 2.1 of the License.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#include <errno.h>
#include <pthread.h>
#include <semaphore.h>
#include <time.h>
#include <assert.h>
#include <urcu/uatomic.h>

#include <lttng-ust-comm.h>
#include <ust/usterr-signal-safe.h>
#include <ust/lttng-ust-abi.h>
#include <ust/tracepoint.h>

/*
 * Has lttng ust comm constructor been called ?
 */
static int initialized;

/*
 * communication thread mutex. Held when handling a command, also held
 * by fork() to deal with removal of threads, and by exit path.
 */
static pthread_mutex_t lttng_ust_comm_mutex = PTHREAD_MUTEX_INITIALIZER;

/* Should the ust comm thread quit ? */
static int lttng_ust_comm_should_quit;

/*
 * Wait for either of these before continuing to the main
 * program:
 * - the register_done message from sessiond daemon
 *   (will let the sessiond daemon enable sessions before main
 *   starts.)
 * - sessiond daemon is not reachable.
 * - timeout (ensuring applications are resilient to session
 *   daemon problems).
 */
static sem_t constructor_wait;
/*
 * Doing this for both the global and local sessiond.
 */
static int sem_count = { 2 };

/*
 * Info about socket and associated listener thread.
 */
struct sock_info {
	const char *name;
	char sock_path[PATH_MAX];
	int socket;
	pthread_t ust_listener;	/* listener thread */
	int root_handle;
	int constructor_sem_posted;;
};

/* Socket from app (connect) to session daemon (listen) for communication */
struct sock_info global_apps = {
	.name = "global",
	.sock_path = DEFAULT_GLOBAL_APPS_UNIX_SOCK,
	.socket = -1,
	.root_handle = -1,
};

/* TODO: allow global_apps_sock_path override */

struct sock_info local_apps = {
	.name = "local",
	.socket = -1,
	.root_handle = -1,
};

extern void ltt_ring_buffer_client_overwrite_init(void);
extern void ltt_ring_buffer_client_discard_init(void);
extern void ltt_ring_buffer_metadata_client_init(void);
extern void ltt_ring_buffer_client_overwrite_exit(void);
extern void ltt_ring_buffer_client_discard_exit(void);
extern void ltt_ring_buffer_metadata_client_exit(void);

static
int setup_local_apps_socket(void)
{
	const char *home_dir;

	home_dir = (const char *) getenv("HOME");
	if (!home_dir)
		return -ENOENT;
	snprintf(local_apps.sock_path, PATH_MAX,
		 DEFAULT_HOME_APPS_UNIX_SOCK, home_dir);
	return 0;
}

static
int register_app_to_sessiond(int socket)
{
	ssize_t ret;
	struct {
		uint32_t major;
		uint32_t minor;
		pid_t pid;
		uid_t uid;
	} reg_msg;

	reg_msg.major = LTTNG_UST_COMM_VERSION_MAJOR;
	reg_msg.minor = LTTNG_UST_COMM_VERSION_MINOR;
	reg_msg.pid = getpid();
	reg_msg.uid = getuid();

	ret = lttcomm_send_unix_sock(socket, &reg_msg, sizeof(reg_msg));
	if (ret >= 0 && ret != sizeof(reg_msg))
		return -EIO;
	return ret;
}

static
int send_reply(int sock, struct lttcomm_ust_reply *lur)
{
	ssize_t len;

	len = lttcomm_send_unix_sock(sock, lur, sizeof(*lur));
	switch (len) {
	case sizeof(*lur):
		DBG("message successfully sent");
		return 0;
	case -1:
		if (errno == ECONNRESET) {
			printf("remote end closed connection\n");
			return 0;
		}
		return -1;
	default:
		printf("incorrect message size: %zd\n", len);
		return -1;
	}
}

static
int handle_register_done(struct sock_info *sock_info)
{
	int ret;

	if (sock_info->constructor_sem_posted)
		return 0;
	sock_info->constructor_sem_posted = 1;
	ret = uatomic_add_return(&sem_count, -1);
	fprintf(stderr, "DEC ret %d\n", ret);
	if (ret == 0) {
		fprintf(stderr, "POST\n");
		ret = sem_post(&constructor_wait);
		assert(!ret);
	}
	return 0;
}

static
int handle_message(struct sock_info *sock_info,
		int sock, struct lttcomm_ust_msg *lum)
{
	int ret = 0;
	const struct objd_ops *ops;
	struct lttcomm_ust_reply lur;

	pthread_mutex_lock(&lttng_ust_comm_mutex);

	memset(&lur, 0, sizeof(lur));

	if (lttng_ust_comm_should_quit) {
		ret = -EPERM;
		goto end;
	}

	ops = objd_ops(lum->handle);
	if (!ops) {
		ret = -ENOENT;
		goto end;
	}

	switch (lum->cmd) {
	case LTTNG_UST_REGISTER_DONE:
		if (lum->handle == LTTNG_UST_ROOT_HANDLE)
			ret = handle_register_done(sock_info);
		else
			ret = -EINVAL;
		break;
	case LTTNG_UST_RELEASE:
		if (lum->handle == LTTNG_UST_ROOT_HANDLE)
			ret = -EPERM;
		else
			ret = objd_unref(lum->handle);
		break;
	default:
		if (ops->cmd)
			ret = ops->cmd(lum->handle, lum->cmd,
					(unsigned long) &lum->u);
		else
			ret = -ENOSYS;
		break;
	}

end:
	lur.handle = lum->handle;
	lur.cmd = lum->cmd;
	lur.ret_val = ret;
	if (ret >= 0) {
		lur.ret_code = LTTCOMM_OK;
	} else {
		lur.ret_code = LTTCOMM_SESSION_FAIL;
	}
	ret = send_reply(sock, &lur);

	pthread_mutex_unlock(&lttng_ust_comm_mutex);
	return ret;
}

static
void cleanup_sock_info(struct sock_info *sock_info)
{
	int ret;

	if (sock_info->socket != -1) {
		ret = close(sock_info->socket);
		if (ret) {
			ERR("Error closing local apps socket");
		}
		sock_info->socket = -1;
	}
	if (sock_info->root_handle != -1) {
		ret = objd_unref(sock_info->root_handle);
		if (ret) {
			ERR("Error unref root handle");
		}
		sock_info->root_handle = -1;
	}
}

/*
 * This thread does not allocate any resource, except within
 * handle_message, within mutex protection. This mutex protects against
 * fork and exit.
 * The other moment it allocates resources is at socket connexion, which
 * is also protected by the mutex.
 */
static
void *ust_listener_thread(void *arg)
{
	struct sock_info *sock_info = arg;
	int sock, ret;

	/* Restart trying to connect to the session daemon */
restart:
	pthread_mutex_lock(&lttng_ust_comm_mutex);

	if (lttng_ust_comm_should_quit) {
		pthread_mutex_unlock(&lttng_ust_comm_mutex);
		goto quit;
	}

	if (sock_info->socket != -1) {
		ret = close(sock_info->socket);
		if (ret) {
			ERR("Error closing %s apps socket", sock_info->name);
		}
		sock_info->socket = -1;
	}

	/* Check for sessiond availability with pipe TODO */

	/* Register */
	ret = lttcomm_connect_unix_sock(sock_info->sock_path);
	if (ret < 0) {
		ERR("Error connecting to %s apps socket", sock_info->name);
		/*
		 * If we cannot find the sessiond daemon, don't delay
		 * constructor execution.
		 */
		ret = handle_register_done(sock_info);
		assert(!ret);
		pthread_mutex_unlock(&lttng_ust_comm_mutex);
		sleep(5);
		goto restart;
	}

	sock_info->socket = sock = ret;

	/*
	 * Create only one root handle per listener thread for the whole
	 * process lifetime.
	 */
	if (sock_info->root_handle == -1) {
		ret = lttng_abi_create_root_handle();
		if (ret) {
			ERR("Error creating root handle");
			pthread_mutex_unlock(&lttng_ust_comm_mutex);
			goto quit;
		}
		sock_info->root_handle = ret;
	}

	ret = register_app_to_sessiond(sock);
	if (ret < 0) {
		ERR("Error registering to %s apps socket", sock_info->name);
		/*
		 * If we cannot register to the sessiond daemon, don't
		 * delay constructor execution.
		 */
		ret = handle_register_done(sock_info);
		assert(!ret);
		pthread_mutex_unlock(&lttng_ust_comm_mutex);
		sleep(5);
		goto restart;
	}
	pthread_mutex_unlock(&lttng_ust_comm_mutex);

	for (;;) {
		ssize_t len;
		struct lttcomm_ust_msg lum;

		len = lttcomm_recv_unix_sock(sock, &lum, sizeof(lum));
		switch (len) {
		case 0:	/* orderly shutdown */
			DBG("%s ltt-sessiond has performed an orderly shutdown\n", sock_info->name);
			goto end;
		case sizeof(lum):
			DBG("message received\n");
			ret = handle_message(sock_info, sock, &lum);
			if (ret < 0) {
				ERR("Error handling message for %s socket", sock_info->name);
			}
			continue;
		case -1:
			if (errno == ECONNRESET) {
				ERR("%s remote end closed connection\n", sock_info->name);
				goto end;
			}
			goto end;
		default:
			ERR("incorrect message size (%s socket): %zd\n", sock_info->name, len);
			continue;
		}

	}
end:
	goto restart;	/* try to reconnect */
quit:
	return NULL;
}

/*
 * Return values: -1: don't wait. 0: wait forever. 1: timeout wait.
 */
static
int get_timeout(struct timespec *constructor_timeout)
{
	long constructor_delay_ms = LTTNG_UST_DEFAULT_CONSTRUCTOR_TIMEOUT_MS;
	char *str_delay;
	int ret;

	str_delay = getenv("UST_REGISTER_TIMEOUT");
	if (str_delay) {
		constructor_delay_ms = strtol(str_delay, NULL, 10);
	}

	switch (constructor_delay_ms) {
	case -1:/* fall-through */
	case 0:
		return constructor_delay_ms;
	default:
		break;
	}

	/*
	 * If we are unable to find the current time, don't wait.
	 */
	ret = clock_gettime(CLOCK_REALTIME, constructor_timeout);
	if (ret) {
		return -1;
	}
	constructor_timeout->tv_sec += constructor_delay_ms / 1000UL;
	constructor_timeout->tv_nsec +=
		(constructor_delay_ms % 1000UL) * 1000000UL;
	if (constructor_timeout->tv_nsec >= 1000000000UL) {
		constructor_timeout->tv_sec++;
		constructor_timeout->tv_nsec -= 1000000000UL;
	}
	return 1;
}

/*
 * sessiond monitoring thread: monitor presence of global and per-user
 * sessiond by polling the application common named pipe.
 */
/* TODO */

void __attribute__((constructor)) lttng_ust_init(void)
{
	struct timespec constructor_timeout;
	int timeout_mode;
	int ret;

	if (uatomic_xchg(&initialized, 1) == 1)
		return;

	/*
	 * We want precise control over the order in which we construct
	 * our sub-libraries vs starting to receive commands from
	 * sessiond (otherwise leading to errors when trying to create
	 * sessiond before the init functions are completed).
	 */
	init_usterr();
	init_tracepoint();
	ltt_ring_buffer_metadata_client_init();
	ltt_ring_buffer_client_overwrite_init();
	ltt_ring_buffer_client_discard_init();

	timeout_mode = get_timeout(&constructor_timeout);

	ret = sem_init(&constructor_wait, 0, 0);
	assert(!ret);

	ret = setup_local_apps_socket();
	if (ret) {
		ERR("Error setting up to local apps socket");
	}

	ret = pthread_create(&global_apps.ust_listener, NULL,
			ust_listener_thread, &global_apps);
	ret = pthread_create(&local_apps.ust_listener, NULL,
			ust_listener_thread, &local_apps);

	switch (timeout_mode) {
	case 1:	/* timeout wait */
		do {
			ret = sem_timedwait(&constructor_wait,
					&constructor_timeout);
		} while (ret < 0 && errno == EINTR);
		if (ret < 0 && errno == ETIMEDOUT) {
			ERR("Timed out waiting for ltt-sessiond");
		} else {
			assert(!ret);
		}
		break;
	case -1:/* wait forever */
		do {
			ret = sem_wait(&constructor_wait);
		} while (ret < 0 && errno == EINTR);
		assert(!ret);
		break;
	case 0:	/* no timeout */
		break;
	}
}

void __attribute__((destructor)) lttng_ust_exit(void)
{
	int ret;

	/*
	 * Using pthread_cancel here because:
	 * A) we don't want to hang application teardown.
	 * B) the thread is not allocating any resource.
	 */

	/*
	 * Require the communication thread to quit. Synchronize with
	 * mutexes to ensure it is not in a mutex critical section when
	 * pthread_cancel is later called.
	 */
	pthread_mutex_lock(&lttng_ust_comm_mutex);
	lttng_ust_comm_should_quit = 1;
	pthread_mutex_unlock(&lttng_ust_comm_mutex);

#if 0
	ret = pthread_cancel(global_apps.ust_listener);
	if (ret) {
		ERR("Error cancelling global ust listener thread");
	}
#endif //0

	cleanup_sock_info(&global_apps);

	ret = pthread_cancel(local_apps.ust_listener);
	if (ret) {
		ERR("Error cancelling local ust listener thread");
	}

	cleanup_sock_info(&local_apps);

	lttng_ust_abi_exit();
	ltt_events_exit();
	ltt_ring_buffer_client_discard_exit();
	ltt_ring_buffer_client_overwrite_exit();
	ltt_ring_buffer_metadata_client_exit();
	exit_tracepoint();
}
Commit	Line	Data
2691221a MD	1	/*
	2	* lttng-ust-comm.c
	3	*
	4	* Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
	5	* Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	6	*
	7	* This library is free software; you can redistribute it and/or
	8	* modify it under the terms of the GNU Lesser General Public
	9	* License as published by the Free Software Foundation; only
	10	* version 2.1 of the License.
	11	*
	12	* This library is distributed in the hope that it will be useful,
	13	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	14	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	15	* Lesser General Public License for more details.
	16	*
	17	* You should have received a copy of the GNU Lesser General Public
	18	* License along with this library; if not, write to the Free Software
	19	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	20	*/
	21
	22	#include <sys/types.h>
	23	#include <sys/socket.h>
	24	#include <unistd.h>
	25	#include <errno.h>
d9e99d10	26	#include <pthread.h>
11ff9c7d MD	27	#include <semaphore.h>
11ff9c7d MD	28	#include <time.h>
1ea11eab	29	#include <assert.h>
95259bd0	30	#include <urcu/uatomic.h>
1ea11eab	31
edaa1431 MD	32	#include <lttng-ust-comm.h>
	33	#include <ust/usterr-signal-safe.h>
	34	#include <ust/lttng-ust-abi.h>
	35	#include <ust/tracepoint.h>
	36
	37	/*
	38	* Has lttng ust comm constructor been called ?
	39	*/
	40	static int initialized;
	41
1ea11eab MD	42	/*
	43	* communication thread mutex. Held when handling a command, also held
	44	* by fork() to deal with removal of threads, and by exit path.
	45	*/
	46	static pthread_mutex_t lttng_ust_comm_mutex = PTHREAD_MUTEX_INITIALIZER;
	47
	48	/* Should the ust comm thread quit ? */
	49	static int lttng_ust_comm_should_quit;
	50
11ff9c7d MD	51	/*
	52	* Wait for either of these before continuing to the main
	53	* program:
	54	* - the register_done message from sessiond daemon
	55	* (will let the sessiond daemon enable sessions before main
	56	* starts.)
	57	* - sessiond daemon is not reachable.
	58	* - timeout (ensuring applications are resilient to session
	59	* daemon problems).
	60	*/
	61	static sem_t constructor_wait;
950aab0c MD	62	/*
	63	* Doing this for both the global and local sessiond.
	64	*/
95259bd0	65	static int sem_count = { 2 };
11ff9c7d	66
1ea11eab MD	67	/*
	68	* Info about socket and associated listener thread.
	69	*/
	70	struct sock_info {
11ff9c7d	71	const char *name;
1ea11eab MD	72	char sock_path[PATH_MAX];
	73	int socket;
	74	pthread_t ust_listener; /* listener thread */
46050b1a	75	int root_handle;
edaa1431	76	int constructor_sem_posted;;
1ea11eab	77	};
2691221a MD	78
2691221a MD	79	/* Socket from app (connect) to session daemon (listen) for communication */
1ea11eab	80	struct sock_info global_apps = {
11ff9c7d	81	.name = "global",
1ea11eab MD	82	.sock_path = DEFAULT_GLOBAL_APPS_UNIX_SOCK,
1ea11eab MD	83	.socket = -1,
46050b1a	84	.root_handle = -1,
1ea11eab	85	};
2691221a MD	86
	87	/* TODO: allow global_apps_sock_path override */
	88
1ea11eab	89	struct sock_info local_apps = {
11ff9c7d	90	.name = "local",
1ea11eab	91	.socket = -1,
46050b1a	92	.root_handle = -1,
1ea11eab	93	};
2691221a	94
edaa1431 MD	95	extern void ltt_ring_buffer_client_overwrite_init(void);
	96	extern void ltt_ring_buffer_client_discard_init(void);
	97	extern void ltt_ring_buffer_metadata_client_init(void);
	98	extern void ltt_ring_buffer_client_overwrite_exit(void);
	99	extern void ltt_ring_buffer_client_discard_exit(void);
	100	extern void ltt_ring_buffer_metadata_client_exit(void);
	101
2691221a	102	static
9eb62b9c	103	int setup_local_apps_socket(void)
2691221a MD	104	{
2691221a MD	105	const char *home_dir;
2691221a MD	106
	107	home_dir = (const char *) getenv("HOME");
	108	if (!home_dir)
	109	return -ENOENT;
1ea11eab	110	snprintf(local_apps.sock_path, PATH_MAX,
2691221a	111	DEFAULT_HOME_APPS_UNIX_SOCK, home_dir);
2691221a MD	112	return 0;
	113	}
	114
	115	static
	116	int register_app_to_sessiond(int socket)
	117	{
	118	ssize_t ret;
	119	struct {
e44418f3 MD	120	uint32_t major;
e44418f3 MD	121	uint32_t minor;
2691221a MD	122	pid_t pid;
	123	uid_t uid;
	124	} reg_msg;
	125
e44418f3 MD	126	reg_msg.major = LTTNG_UST_COMM_VERSION_MAJOR;
e44418f3 MD	127	reg_msg.minor = LTTNG_UST_COMM_VERSION_MINOR;
2691221a MD	128	reg_msg.pid = getpid();
	129	reg_msg.uid = getuid();
	130
	131	ret = lttcomm_send_unix_sock(socket, &reg_msg, sizeof(reg_msg));
	132	if (ret >= 0 && ret != sizeof(reg_msg))
	133	return -EIO;
	134	return ret;
	135	}
	136
d9e99d10	137	static
d3a492d1	138	int send_reply(int sock, struct lttcomm_ust_reply *lur)
d9e99d10	139	{
9eb62b9c	140	ssize_t len;
d3a492d1	141
a4be8962	142	len = lttcomm_send_unix_sock(sock, lur, sizeof(*lur));
d3a492d1	143	switch (len) {
a4be8962	144	case sizeof(*lur):
d3a492d1 MD	145	DBG("message successfully sent");
	146	return 0;
	147	case -1:
	148	if (errno == ECONNRESET) {
	149	printf("remote end closed connection\n");
	150	return 0;
	151	}
	152	return -1;
	153	default:
	154	printf("incorrect message size: %zd\n", len);
	155	return -1;
	156	}
	157	}
	158
	159	static
edaa1431	160	int handle_register_done(struct sock_info *sock_info)
11ff9c7d MD	161	{
	162	int ret;
	163
edaa1431 MD	164	if (sock_info->constructor_sem_posted)
	165	return 0;
	166	sock_info->constructor_sem_posted = 1;
95259bd0	167	ret = uatomic_add_return(&sem_count, -1);
edaa1431	168	fprintf(stderr, "DEC ret %d\n", ret);
95259bd0	169	if (ret == 0) {
edaa1431	170	fprintf(stderr, "POST\n");
95259bd0 MD	171	ret = sem_post(&constructor_wait);
	172	assert(!ret);
	173	}
11ff9c7d MD	174	return 0;
	175	}
	176
	177	static
	178	int handle_message(struct sock_info *sock_info,
	179	int sock, struct lttcomm_ust_msg *lum)
d3a492d1	180	{
1ea11eab	181	int ret = 0;
46050b1a MD	182	const struct objd_ops *ops;
46050b1a MD	183	struct lttcomm_ust_reply lur;
1ea11eab MD	184
	185	pthread_mutex_lock(&lttng_ust_comm_mutex);
	186
46050b1a MD	187	memset(&lur, 0, sizeof(lur));
46050b1a MD	188
1ea11eab	189	if (lttng_ust_comm_should_quit) {
46050b1a	190	ret = -EPERM;
1ea11eab MD	191	goto end;
1ea11eab MD	192	}
9eb62b9c	193
46050b1a MD	194	ops = objd_ops(lum->handle);
	195	if (!ops) {
	196	ret = -ENOENT;
	197	goto end;
1ea11eab	198	}
46050b1a MD	199
46050b1a MD	200	switch (lum->cmd) {
11ff9c7d MD	201	case LTTNG_UST_REGISTER_DONE:
11ff9c7d MD	202	if (lum->handle == LTTNG_UST_ROOT_HANDLE)
edaa1431	203	ret = handle_register_done(sock_info);
11ff9c7d MD	204	else
	205	ret = -EINVAL;
	206	break;
46050b1a MD	207	case LTTNG_UST_RELEASE:
	208	if (lum->handle == LTTNG_UST_ROOT_HANDLE)
	209	ret = -EPERM;
	210	else
	211	ret = objd_unref(lum->handle);
d9e99d10 MD	212	break;
d9e99d10 MD	213	default:
46050b1a MD	214	if (ops->cmd)
	215	ret = ops->cmd(lum->handle, lum->cmd,
	216	(unsigned long) &lum->u);
	217	else
	218	ret = -ENOSYS;
	219	break;
d9e99d10	220	}
46050b1a	221
1ea11eab	222	end:
46050b1a MD	223	lur.handle = lum->handle;
	224	lur.cmd = lum->cmd;
	225	lur.ret_val = ret;
	226	if (ret >= 0) {
	227	lur.ret_code = LTTCOMM_OK;
	228	} else {
	229	lur.ret_code = LTTCOMM_SESSION_FAIL;
	230	}
	231	ret = send_reply(sock, &lur);
	232
1ea11eab MD	233	pthread_mutex_unlock(&lttng_ust_comm_mutex);
1ea11eab MD	234	return ret;
d9e99d10 MD	235	}
d9e99d10 MD	236
46050b1a MD	237	static
	238	void cleanup_sock_info(struct sock_info *sock_info)
	239	{
	240	int ret;
	241
	242	if (sock_info->socket != -1) {
	243	ret = close(sock_info->socket);
	244	if (ret) {
	245	ERR("Error closing local apps socket");
	246	}
	247	sock_info->socket = -1;
	248	}
	249	if (sock_info->root_handle != -1) {
	250	ret = objd_unref(sock_info->root_handle);
	251	if (ret) {
	252	ERR("Error unref root handle");
	253	}
	254	sock_info->root_handle = -1;
	255	}
	256	}
	257
1ea11eab MD	258	/*
	259	* This thread does not allocate any resource, except within
	260	* handle_message, within mutex protection. This mutex protects against
	261	* fork and exit.
	262	* The other moment it allocates resources is at socket connexion, which
	263	* is also protected by the mutex.
	264	*/
d9e99d10 MD	265	static
	266	void ust_listener_thread(void arg)
	267	{
1ea11eab MD	268	struct sock_info *sock_info = arg;
1ea11eab MD	269	int sock, ret;
d9e99d10	270
9eb62b9c MD	271	/* Restart trying to connect to the session daemon */
9eb62b9c MD	272	restart:
1ea11eab MD	273	pthread_mutex_lock(&lttng_ust_comm_mutex);
	274
	275	if (lttng_ust_comm_should_quit) {
	276	pthread_mutex_unlock(&lttng_ust_comm_mutex);
	277	goto quit;
	278	}
9eb62b9c	279
1ea11eab MD	280	if (sock_info->socket != -1) {
	281	ret = close(sock_info->socket);
	282	if (ret) {
11ff9c7d	283	ERR("Error closing %s apps socket", sock_info->name);
1ea11eab MD	284	}
	285	sock_info->socket = -1;
	286	}
46050b1a	287
9eb62b9c MD	288	/* Check for sessiond availability with pipe TODO */
	289
	290	/* Register */
1ea11eab	291	ret = lttcomm_connect_unix_sock(sock_info->sock_path);
9eb62b9c	292	if (ret < 0) {
11ff9c7d MD	293	ERR("Error connecting to %s apps socket", sock_info->name);
	294	/*
	295	* If we cannot find the sessiond daemon, don't delay
	296	* constructor execution.
	297	*/
edaa1431	298	ret = handle_register_done(sock_info);
11ff9c7d	299	assert(!ret);
1ea11eab	300	pthread_mutex_unlock(&lttng_ust_comm_mutex);
4eef2998	301	sleep(5);
1ea11eab	302	goto restart;
46050b1a MD	303	}
	304
	305	sock_info->socket = sock = ret;
	306
	307	/*
	308	* Create only one root handle per listener thread for the whole
	309	* process lifetime.
	310	*/
	311	if (sock_info->root_handle == -1) {
	312	ret = lttng_abi_create_root_handle();
	313	if (ret) {
	314	ERR("Error creating root handle");
	315	pthread_mutex_unlock(&lttng_ust_comm_mutex);
	316	goto quit;
	317	}
	318	sock_info->root_handle = ret;
9eb62b9c	319	}
1ea11eab	320
9eb62b9c MD	321	ret = register_app_to_sessiond(sock);
9eb62b9c MD	322	if (ret < 0) {
11ff9c7d MD	323	ERR("Error registering to %s apps socket", sock_info->name);
	324	/*
	325	* If we cannot register to the sessiond daemon, don't
	326	* delay constructor execution.
	327	*/
edaa1431	328	ret = handle_register_done(sock_info);
11ff9c7d	329	assert(!ret);
46050b1a	330	pthread_mutex_unlock(&lttng_ust_comm_mutex);
9eb62b9c MD	331	sleep(5);
	332	goto restart;
	333	}
46050b1a MD	334	pthread_mutex_unlock(&lttng_ust_comm_mutex);
46050b1a MD	335
d9e99d10 MD	336	for (;;) {
d9e99d10 MD	337	ssize_t len;
e7723462	338	struct lttcomm_ust_msg lum;
d9e99d10	339
e7723462	340	len = lttcomm_recv_unix_sock(sock, &lum, sizeof(lum));
d9e99d10 MD	341	switch (len) {
d9e99d10 MD	342	case 0: /* orderly shutdown */
11ff9c7d	343	DBG("%s ltt-sessiond has performed an orderly shutdown\n", sock_info->name);
d9e99d10	344	goto end;
e7723462	345	case sizeof(lum):
d9e99d10	346	DBG("message received\n");
11ff9c7d	347	ret = handle_message(sock_info, sock, &lum);
2a80c9d8	348	if (ret < 0) {
11ff9c7d	349	ERR("Error handling message for %s socket", sock_info->name);
d9e99d10 MD	350	}
	351	continue;
	352	case -1:
	353	if (errno == ECONNRESET) {
11ff9c7d	354	ERR("%s remote end closed connection\n", sock_info->name);
d9e99d10 MD	355	goto end;
	356	}
	357	goto end;
	358	default:
11ff9c7d	359	ERR("incorrect message size (%s socket): %zd\n", sock_info->name, len);
d9e99d10 MD	360	continue;
	361	}
	362
	363	}
	364	end:
9eb62b9c	365	goto restart; /* try to reconnect */
1ea11eab	366	quit:
d9e99d10 MD	367	return NULL;
	368	}
	369
cf12a773 MD	370	/*
	371	* Return values: -1: don't wait. 0: wait forever. 1: timeout wait.
	372	*/
11ff9c7d MD	373	static
	374	int get_timeout(struct timespec *constructor_timeout)
	375	{
cf12a773 MD	376	long constructor_delay_ms = LTTNG_UST_DEFAULT_CONSTRUCTOR_TIMEOUT_MS;
cf12a773 MD	377	char *str_delay;
11ff9c7d MD	378	int ret;
11ff9c7d MD	379
cf12a773 MD	380	str_delay = getenv("UST_REGISTER_TIMEOUT");
	381	if (str_delay) {
	382	constructor_delay_ms = strtol(str_delay, NULL, 10);
	383	}
	384
	385	switch (constructor_delay_ms) {
	386	case -1:/* fall-through */
	387	case 0:
	388	return constructor_delay_ms;
	389	default:
	390	break;
	391	}
	392
	393	/*
	394	* If we are unable to find the current time, don't wait.
	395	*/
	396	ret = clock_gettime(CLOCK_REALTIME, constructor_timeout);
	397	if (ret) {
	398	return -1;
	399	}
95259bd0 MD	400	constructor_timeout->tv_sec += constructor_delay_ms / 1000UL;
	401	constructor_timeout->tv_nsec +=
	402	(constructor_delay_ms % 1000UL) * 1000000UL;
11ff9c7d MD	403	if (constructor_timeout->tv_nsec >= 1000000000UL) {
	404	constructor_timeout->tv_sec++;
	405	constructor_timeout->tv_nsec -= 1000000000UL;
	406	}
cf12a773	407	return 1;
11ff9c7d	408	}
d9e99d10	409
2691221a MD	410	/*
	411	* sessiond monitoring thread: monitor presence of global and per-user
	412	* sessiond by polling the application common named pipe.
	413	*/
	414	/* TODO */
	415
edaa1431	416	void __attribute__((constructor)) lttng_ust_init(void)
2691221a	417	{
11ff9c7d	418	struct timespec constructor_timeout;
cf12a773	419	int timeout_mode;
2691221a MD	420	int ret;
2691221a MD	421
edaa1431 MD	422	if (uatomic_xchg(&initialized, 1) == 1)
	423	return;
	424
	425	/*
	426	* We want precise control over the order in which we construct
	427	* our sub-libraries vs starting to receive commands from
	428	* sessiond (otherwise leading to errors when trying to create
	429	* sessiond before the init functions are completed).
	430	*/
2691221a	431	init_usterr();
edaa1431 MD	432	init_tracepoint();
	433	ltt_ring_buffer_metadata_client_init();
	434	ltt_ring_buffer_client_overwrite_init();
	435	ltt_ring_buffer_client_discard_init();
2691221a	436
cf12a773	437	timeout_mode = get_timeout(&constructor_timeout);
11ff9c7d	438
95259bd0	439	ret = sem_init(&constructor_wait, 0, 0);
11ff9c7d MD	440	assert(!ret);
11ff9c7d MD	441
9eb62b9c	442	ret = setup_local_apps_socket();
2691221a	443	if (ret) {
9eb62b9c	444	ERR("Error setting up to local apps socket");
2691221a	445	}
11ff9c7d	446
1ea11eab MD	447	ret = pthread_create(&global_apps.ust_listener, NULL,
1ea11eab MD	448	ust_listener_thread, &global_apps);
1ea11eab MD	449	ret = pthread_create(&local_apps.ust_listener, NULL,
1ea11eab MD	450	ust_listener_thread, &local_apps);
11ff9c7d	451
cf12a773 MD	452	switch (timeout_mode) {
cf12a773 MD	453	case 1: /* timeout wait */
95259bd0 MD	454	do {
	455	ret = sem_timedwait(&constructor_wait,
	456	&constructor_timeout);
	457	} while (ret < 0 && errno == EINTR);
cf12a773 MD	458	if (ret < 0 && errno == ETIMEDOUT) {
	459	ERR("Timed out waiting for ltt-sessiond");
	460	} else {
	461	assert(!ret);
	462	}
	463	break;
7b766b16	464	case -1:/* wait forever */
95259bd0 MD	465	do {
	466	ret = sem_wait(&constructor_wait);
	467	} while (ret < 0 && errno == EINTR);
11ff9c7d	468	assert(!ret);
cf12a773	469	break;
7b766b16	470	case 0: /* no timeout */
cf12a773	471	break;
11ff9c7d	472	}
2691221a MD	473	}
2691221a MD	474
edaa1431	475	void __attribute__((destructor)) lttng_ust_exit(void)
2691221a MD	476	{
	477	int ret;
	478
9eb62b9c MD	479	/*
	480	* Using pthread_cancel here because:
	481	* A) we don't want to hang application teardown.
	482	* B) the thread is not allocating any resource.
	483	*/
1ea11eab MD	484
	485	/*
	486	* Require the communication thread to quit. Synchronize with
	487	* mutexes to ensure it is not in a mutex critical section when
	488	* pthread_cancel is later called.
	489	*/
	490	pthread_mutex_lock(&lttng_ust_comm_mutex);
	491	lttng_ust_comm_should_quit = 1;
	492	pthread_mutex_unlock(&lttng_ust_comm_mutex);
	493
	494	#if 0
	495	ret = pthread_cancel(global_apps.ust_listener);
9eb62b9c MD	496	if (ret) {
9eb62b9c MD	497	ERR("Error cancelling global ust listener thread");
2691221a	498	}
1ea11eab	499	#endif //0
46050b1a MD	500
46050b1a MD	501	cleanup_sock_info(&global_apps);
1ea11eab MD	502
1ea11eab MD	503	ret = pthread_cancel(local_apps.ust_listener);
9eb62b9c MD	504	if (ret) {
9eb62b9c MD	505	ERR("Error cancelling local ust listener thread");
2691221a	506	}
1ea11eab	507
46050b1a	508	cleanup_sock_info(&local_apps);
1ea11eab	509
b35d179d	510	lttng_ust_abi_exit();
1ea11eab	511	ltt_events_exit();
edaa1431 MD	512	ltt_ring_buffer_client_discard_exit();
	513	ltt_ring_buffer_client_overwrite_exit();
	514	ltt_ring_buffer_metadata_client_exit();
	515	exit_tracepoint();
2691221a	516	}