[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 <ust/lttng-ust-abi.h>
#include <lttng-ust-comm.h>
#include <ust/usterr-signal-safe.h>
#include <pthread.h>
#include <semaphore.h>
#include <time.h>
#include <assert.h>
#include <urcu/uatomic.h>

/*
 * 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;
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;
};

/* 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,
};

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(void)
{
	int ret;

	ret = uatomic_add_return(&sem_count, -1);
	if (ret == 0) {
		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();
		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();
		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();
		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_comm_init(void)
{
	struct timespec constructor_timeout;
	int timeout_mode;
	int ret;

	init_usterr();

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