[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 <sys/prctl.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;
	int prctl_ret;
	struct {
		uint32_t major;
		uint32_t minor;
		pid_t pid;
		pid_t ppid;
		uid_t uid;
		char name[16];	/* process name */
	} reg_msg;

	reg_msg.major = LTTNG_UST_COMM_VERSION_MAJOR;
	reg_msg.minor = LTTNG_UST_COMM_VERSION_MINOR;
	reg_msg.pid = getpid();
	reg_msg.ppid = getppid();
	reg_msg.uid = getuid();
	prctl_ret = prctl(PR_GET_NAME, (unsigned long) reg_msg.name, 0, 0, 0);
	if (prctl_ret) {
		ERR("Error executing prctl");
		return -errno;
	}

	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);
	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(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>
2629549e	24	#include <sys/prctl.h>
2691221a MD	25	#include <unistd.h>
2691221a MD	26	#include <errno.h>
d9e99d10	27	#include <pthread.h>
11ff9c7d MD	28	#include <semaphore.h>
11ff9c7d MD	29	#include <time.h>
1ea11eab	30	#include <assert.h>
95259bd0	31	#include <urcu/uatomic.h>
1ea11eab	32
edaa1431 MD	33	#include <lttng-ust-comm.h>
	34	#include <ust/usterr-signal-safe.h>
	35	#include <ust/lttng-ust-abi.h>
	36	#include <ust/tracepoint.h>
	37
	38	/*
	39	* Has lttng ust comm constructor been called ?
	40	*/
	41	static int initialized;
	42
1ea11eab MD	43	/*
	44	* communication thread mutex. Held when handling a command, also held
	45	* by fork() to deal with removal of threads, and by exit path.
	46	*/
	47	static pthread_mutex_t lttng_ust_comm_mutex = PTHREAD_MUTEX_INITIALIZER;
	48
	49	/* Should the ust comm thread quit ? */
	50	static int lttng_ust_comm_should_quit;
	51
11ff9c7d MD	52	/*
	53	* Wait for either of these before continuing to the main
	54	* program:
	55	* - the register_done message from sessiond daemon
	56	* (will let the sessiond daemon enable sessions before main
	57	* starts.)
	58	* - sessiond daemon is not reachable.
	59	* - timeout (ensuring applications are resilient to session
	60	* daemon problems).
	61	*/
	62	static sem_t constructor_wait;
950aab0c MD	63	/*
	64	* Doing this for both the global and local sessiond.
	65	*/
95259bd0	66	static int sem_count = { 2 };
11ff9c7d	67
1ea11eab MD	68	/*
	69	* Info about socket and associated listener thread.
	70	*/
	71	struct sock_info {
11ff9c7d	72	const char *name;
1ea11eab MD	73	char sock_path[PATH_MAX];
	74	int socket;
	75	pthread_t ust_listener; /* listener thread */
46050b1a	76	int root_handle;
edaa1431	77	int constructor_sem_posted;;
1ea11eab	78	};
2691221a MD	79
2691221a MD	80	/* Socket from app (connect) to session daemon (listen) for communication */
1ea11eab	81	struct sock_info global_apps = {
11ff9c7d	82	.name = "global",
1ea11eab MD	83	.sock_path = DEFAULT_GLOBAL_APPS_UNIX_SOCK,
1ea11eab MD	84	.socket = -1,
46050b1a	85	.root_handle = -1,
1ea11eab	86	};
2691221a MD	87
	88	/* TODO: allow global_apps_sock_path override */
	89
1ea11eab	90	struct sock_info local_apps = {
11ff9c7d	91	.name = "local",
1ea11eab	92	.socket = -1,
46050b1a	93	.root_handle = -1,
1ea11eab	94	};
2691221a	95
edaa1431 MD	96	extern void ltt_ring_buffer_client_overwrite_init(void);
	97	extern void ltt_ring_buffer_client_discard_init(void);
	98	extern void ltt_ring_buffer_metadata_client_init(void);
	99	extern void ltt_ring_buffer_client_overwrite_exit(void);
	100	extern void ltt_ring_buffer_client_discard_exit(void);
	101	extern void ltt_ring_buffer_metadata_client_exit(void);
	102
2691221a	103	static
9eb62b9c	104	int setup_local_apps_socket(void)
2691221a MD	105	{
2691221a MD	106	const char *home_dir;
2691221a MD	107
	108	home_dir = (const char *) getenv("HOME");
	109	if (!home_dir)
	110	return -ENOENT;
1ea11eab	111	snprintf(local_apps.sock_path, PATH_MAX,
2691221a	112	DEFAULT_HOME_APPS_UNIX_SOCK, home_dir);
2691221a MD	113	return 0;
	114	}
	115
	116	static
	117	int register_app_to_sessiond(int socket)
	118	{
	119	ssize_t ret;
2629549e	120	int prctl_ret;
2691221a	121	struct {
e44418f3 MD	122	uint32_t major;
e44418f3 MD	123	uint32_t minor;
2691221a	124	pid_t pid;
5c33bde8	125	pid_t ppid;
2691221a	126	uid_t uid;
2629549e	127	char name[16]; /* process name */
2691221a MD	128	} reg_msg;
2691221a MD	129
e44418f3 MD	130	reg_msg.major = LTTNG_UST_COMM_VERSION_MAJOR;
e44418f3 MD	131	reg_msg.minor = LTTNG_UST_COMM_VERSION_MINOR;
2691221a	132	reg_msg.pid = getpid();
5c33bde8	133	reg_msg.ppid = getppid();
2691221a	134	reg_msg.uid = getuid();
2629549e MD	135	prctl_ret = prctl(PR_GET_NAME, (unsigned long) reg_msg.name, 0, 0, 0);
	136	if (prctl_ret) {
	137	ERR("Error executing prctl");
	138	return -errno;
	139	}
2691221a MD	140
	141	ret = lttcomm_send_unix_sock(socket, &reg_msg, sizeof(reg_msg));
	142	if (ret >= 0 && ret != sizeof(reg_msg))
	143	return -EIO;
	144	return ret;
	145	}
	146
d9e99d10	147	static
d3a492d1	148	int send_reply(int sock, struct lttcomm_ust_reply *lur)
d9e99d10	149	{
9eb62b9c	150	ssize_t len;
d3a492d1	151
a4be8962	152	len = lttcomm_send_unix_sock(sock, lur, sizeof(*lur));
d3a492d1	153	switch (len) {
a4be8962	154	case sizeof(*lur):
d3a492d1 MD	155	DBG("message successfully sent");
	156	return 0;
	157	case -1:
	158	if (errno == ECONNRESET) {
	159	printf("remote end closed connection\n");
	160	return 0;
	161	}
	162	return -1;
	163	default:
	164	printf("incorrect message size: %zd\n", len);
	165	return -1;
	166	}
	167	}
	168
	169	static
edaa1431	170	int handle_register_done(struct sock_info *sock_info)
11ff9c7d MD	171	{
	172	int ret;
	173
edaa1431 MD	174	if (sock_info->constructor_sem_posted)
	175	return 0;
	176	sock_info->constructor_sem_posted = 1;
95259bd0 MD	177	ret = uatomic_add_return(&sem_count, -1);
	178	if (ret == 0) {
	179	ret = sem_post(&constructor_wait);
	180	assert(!ret);
	181	}
11ff9c7d MD	182	return 0;
	183	}
	184
	185	static
	186	int handle_message(struct sock_info *sock_info,
	187	int sock, struct lttcomm_ust_msg *lum)
d3a492d1	188	{
1ea11eab	189	int ret = 0;
46050b1a MD	190	const struct objd_ops *ops;
46050b1a MD	191	struct lttcomm_ust_reply lur;
1ea11eab MD	192
	193	pthread_mutex_lock(&lttng_ust_comm_mutex);
	194
46050b1a MD	195	memset(&lur, 0, sizeof(lur));
46050b1a MD	196
1ea11eab	197	if (lttng_ust_comm_should_quit) {
46050b1a	198	ret = -EPERM;
1ea11eab MD	199	goto end;
1ea11eab MD	200	}
9eb62b9c	201
46050b1a MD	202	ops = objd_ops(lum->handle);
	203	if (!ops) {
	204	ret = -ENOENT;
	205	goto end;
1ea11eab	206	}
46050b1a MD	207
46050b1a MD	208	switch (lum->cmd) {
11ff9c7d MD	209	case LTTNG_UST_REGISTER_DONE:
11ff9c7d MD	210	if (lum->handle == LTTNG_UST_ROOT_HANDLE)
edaa1431	211	ret = handle_register_done(sock_info);
11ff9c7d MD	212	else
	213	ret = -EINVAL;
	214	break;
46050b1a MD	215	case LTTNG_UST_RELEASE:
	216	if (lum->handle == LTTNG_UST_ROOT_HANDLE)
	217	ret = -EPERM;
	218	else
	219	ret = objd_unref(lum->handle);
d9e99d10 MD	220	break;
d9e99d10 MD	221	default:
46050b1a MD	222	if (ops->cmd)
	223	ret = ops->cmd(lum->handle, lum->cmd,
	224	(unsigned long) &lum->u);
	225	else
	226	ret = -ENOSYS;
	227	break;
d9e99d10	228	}
46050b1a	229
1ea11eab	230	end:
46050b1a MD	231	lur.handle = lum->handle;
	232	lur.cmd = lum->cmd;
	233	lur.ret_val = ret;
	234	if (ret >= 0) {
	235	lur.ret_code = LTTCOMM_OK;
	236	} else {
	237	lur.ret_code = LTTCOMM_SESSION_FAIL;
	238	}
	239	ret = send_reply(sock, &lur);
	240
1ea11eab MD	241	pthread_mutex_unlock(&lttng_ust_comm_mutex);
1ea11eab MD	242	return ret;
d9e99d10 MD	243	}
d9e99d10 MD	244
46050b1a MD	245	static
	246	void cleanup_sock_info(struct sock_info *sock_info)
	247	{
	248	int ret;
	249
	250	if (sock_info->socket != -1) {
	251	ret = close(sock_info->socket);
	252	if (ret) {
	253	ERR("Error closing local apps socket");
	254	}
	255	sock_info->socket = -1;
	256	}
	257	if (sock_info->root_handle != -1) {
	258	ret = objd_unref(sock_info->root_handle);
	259	if (ret) {
	260	ERR("Error unref root handle");
	261	}
	262	sock_info->root_handle = -1;
	263	}
	264	}
	265
1ea11eab MD	266	/*
	267	* This thread does not allocate any resource, except within
	268	* handle_message, within mutex protection. This mutex protects against
	269	* fork and exit.
	270	* The other moment it allocates resources is at socket connexion, which
	271	* is also protected by the mutex.
	272	*/
d9e99d10 MD	273	static
	274	void ust_listener_thread(void arg)
	275	{
1ea11eab MD	276	struct sock_info *sock_info = arg;
1ea11eab MD	277	int sock, ret;
d9e99d10	278
9eb62b9c MD	279	/* Restart trying to connect to the session daemon */
9eb62b9c MD	280	restart:
1ea11eab MD	281	pthread_mutex_lock(&lttng_ust_comm_mutex);
	282
	283	if (lttng_ust_comm_should_quit) {
	284	pthread_mutex_unlock(&lttng_ust_comm_mutex);
	285	goto quit;
	286	}
9eb62b9c	287
1ea11eab MD	288	if (sock_info->socket != -1) {
	289	ret = close(sock_info->socket);
	290	if (ret) {
11ff9c7d	291	ERR("Error closing %s apps socket", sock_info->name);
1ea11eab MD	292	}
	293	sock_info->socket = -1;
	294	}
46050b1a	295
9eb62b9c MD	296	/* Check for sessiond availability with pipe TODO */
	297
	298	/* Register */
1ea11eab	299	ret = lttcomm_connect_unix_sock(sock_info->sock_path);
9eb62b9c	300	if (ret < 0) {
11ff9c7d MD	301	ERR("Error connecting to %s apps socket", sock_info->name);
	302	/*
	303	* If we cannot find the sessiond daemon, don't delay
	304	* constructor execution.
	305	*/
edaa1431	306	ret = handle_register_done(sock_info);
11ff9c7d	307	assert(!ret);
1ea11eab	308	pthread_mutex_unlock(&lttng_ust_comm_mutex);
4eef2998	309	sleep(5);
1ea11eab	310	goto restart;
46050b1a MD	311	}
	312
	313	sock_info->socket = sock = ret;
	314
	315	/*
	316	* Create only one root handle per listener thread for the whole
	317	* process lifetime.
	318	*/
	319	if (sock_info->root_handle == -1) {
	320	ret = lttng_abi_create_root_handle();
	321	if (ret) {
	322	ERR("Error creating root handle");
	323	pthread_mutex_unlock(&lttng_ust_comm_mutex);
	324	goto quit;
	325	}
	326	sock_info->root_handle = ret;
9eb62b9c	327	}
1ea11eab	328
9eb62b9c MD	329	ret = register_app_to_sessiond(sock);
9eb62b9c MD	330	if (ret < 0) {
11ff9c7d MD	331	ERR("Error registering to %s apps socket", sock_info->name);
	332	/*
	333	* If we cannot register to the sessiond daemon, don't
	334	* delay constructor execution.
	335	*/
edaa1431	336	ret = handle_register_done(sock_info);
11ff9c7d	337	assert(!ret);
46050b1a	338	pthread_mutex_unlock(&lttng_ust_comm_mutex);
9eb62b9c MD	339	sleep(5);
	340	goto restart;
	341	}
46050b1a MD	342	pthread_mutex_unlock(&lttng_ust_comm_mutex);
46050b1a MD	343
d9e99d10 MD	344	for (;;) {
d9e99d10 MD	345	ssize_t len;
e7723462	346	struct lttcomm_ust_msg lum;
d9e99d10	347
e7723462	348	len = lttcomm_recv_unix_sock(sock, &lum, sizeof(lum));
d9e99d10 MD	349	switch (len) {
d9e99d10 MD	350	case 0: /* orderly shutdown */
11ff9c7d	351	DBG("%s ltt-sessiond has performed an orderly shutdown\n", sock_info->name);
d9e99d10	352	goto end;
e7723462	353	case sizeof(lum):
d9e99d10	354	DBG("message received\n");
11ff9c7d	355	ret = handle_message(sock_info, sock, &lum);
2a80c9d8	356	if (ret < 0) {
11ff9c7d	357	ERR("Error handling message for %s socket", sock_info->name);
d9e99d10 MD	358	}
	359	continue;
	360	case -1:
	361	if (errno == ECONNRESET) {
11ff9c7d	362	ERR("%s remote end closed connection\n", sock_info->name);
d9e99d10 MD	363	goto end;
	364	}
	365	goto end;
	366	default:
11ff9c7d	367	ERR("incorrect message size (%s socket): %zd\n", sock_info->name, len);
d9e99d10 MD	368	continue;
	369	}
	370
	371	}
	372	end:
9eb62b9c	373	goto restart; /* try to reconnect */
1ea11eab	374	quit:
d9e99d10 MD	375	return NULL;
	376	}
	377
cf12a773 MD	378	/*
	379	* Return values: -1: don't wait. 0: wait forever. 1: timeout wait.
	380	*/
11ff9c7d MD	381	static
	382	int get_timeout(struct timespec *constructor_timeout)
	383	{
cf12a773 MD	384	long constructor_delay_ms = LTTNG_UST_DEFAULT_CONSTRUCTOR_TIMEOUT_MS;
cf12a773 MD	385	char *str_delay;
11ff9c7d MD	386	int ret;
11ff9c7d MD	387
cf12a773 MD	388	str_delay = getenv("UST_REGISTER_TIMEOUT");
	389	if (str_delay) {
	390	constructor_delay_ms = strtol(str_delay, NULL, 10);
	391	}
	392
	393	switch (constructor_delay_ms) {
	394	case -1:/* fall-through */
	395	case 0:
	396	return constructor_delay_ms;
	397	default:
	398	break;
	399	}
	400
	401	/*
	402	* If we are unable to find the current time, don't wait.
	403	*/
	404	ret = clock_gettime(CLOCK_REALTIME, constructor_timeout);
	405	if (ret) {
	406	return -1;
	407	}
95259bd0 MD	408	constructor_timeout->tv_sec += constructor_delay_ms / 1000UL;
	409	constructor_timeout->tv_nsec +=
	410	(constructor_delay_ms % 1000UL) * 1000000UL;
11ff9c7d MD	411	if (constructor_timeout->tv_nsec >= 1000000000UL) {
	412	constructor_timeout->tv_sec++;
	413	constructor_timeout->tv_nsec -= 1000000000UL;
	414	}
cf12a773	415	return 1;
11ff9c7d	416	}
d9e99d10	417
2691221a MD	418	/*
	419	* sessiond monitoring thread: monitor presence of global and per-user
	420	* sessiond by polling the application common named pipe.
	421	*/
	422	/* TODO */
	423
edaa1431	424	void __attribute__((constructor)) lttng_ust_init(void)
2691221a	425	{
11ff9c7d	426	struct timespec constructor_timeout;
cf12a773	427	int timeout_mode;
2691221a MD	428	int ret;
2691221a MD	429
edaa1431 MD	430	if (uatomic_xchg(&initialized, 1) == 1)
	431	return;
	432
	433	/*
	434	* We want precise control over the order in which we construct
	435	* our sub-libraries vs starting to receive commands from
	436	* sessiond (otherwise leading to errors when trying to create
	437	* sessiond before the init functions are completed).
	438	*/
2691221a	439	init_usterr();
edaa1431 MD	440	init_tracepoint();
	441	ltt_ring_buffer_metadata_client_init();
	442	ltt_ring_buffer_client_overwrite_init();
	443	ltt_ring_buffer_client_discard_init();
2691221a	444
cf12a773	445	timeout_mode = get_timeout(&constructor_timeout);
11ff9c7d	446
95259bd0	447	ret = sem_init(&constructor_wait, 0, 0);
11ff9c7d MD	448	assert(!ret);
11ff9c7d MD	449
9eb62b9c	450	ret = setup_local_apps_socket();
2691221a	451	if (ret) {
9eb62b9c	452	ERR("Error setting up to local apps socket");
2691221a	453	}
11ff9c7d	454
1ea11eab MD	455	ret = pthread_create(&global_apps.ust_listener, NULL,
1ea11eab MD	456	ust_listener_thread, &global_apps);
1ea11eab MD	457	ret = pthread_create(&local_apps.ust_listener, NULL,
1ea11eab MD	458	ust_listener_thread, &local_apps);
11ff9c7d	459
cf12a773 MD	460	switch (timeout_mode) {
cf12a773 MD	461	case 1: /* timeout wait */
95259bd0 MD	462	do {
	463	ret = sem_timedwait(&constructor_wait,
	464	&constructor_timeout);
	465	} while (ret < 0 && errno == EINTR);
cf12a773 MD	466	if (ret < 0 && errno == ETIMEDOUT) {
	467	ERR("Timed out waiting for ltt-sessiond");
	468	} else {
	469	assert(!ret);
	470	}
	471	break;
7b766b16	472	case -1:/* wait forever */
95259bd0 MD	473	do {
	474	ret = sem_wait(&constructor_wait);
	475	} while (ret < 0 && errno == EINTR);
11ff9c7d	476	assert(!ret);
cf12a773	477	break;
7b766b16	478	case 0: /* no timeout */
cf12a773	479	break;
11ff9c7d	480	}
2691221a MD	481	}
2691221a MD	482
edaa1431	483	void __attribute__((destructor)) lttng_ust_exit(void)
2691221a MD	484	{
	485	int ret;
	486
9eb62b9c MD	487	/*
	488	* Using pthread_cancel here because:
	489	* A) we don't want to hang application teardown.
	490	* B) the thread is not allocating any resource.
	491	*/
1ea11eab MD	492
	493	/*
	494	* Require the communication thread to quit. Synchronize with
	495	* mutexes to ensure it is not in a mutex critical section when
	496	* pthread_cancel is later called.
	497	*/
	498	pthread_mutex_lock(&lttng_ust_comm_mutex);
	499	lttng_ust_comm_should_quit = 1;
	500	pthread_mutex_unlock(&lttng_ust_comm_mutex);
	501
	502	#if 0
	503	ret = pthread_cancel(global_apps.ust_listener);
9eb62b9c MD	504	if (ret) {
9eb62b9c MD	505	ERR("Error cancelling global ust listener thread");
2691221a	506	}
1ea11eab	507	#endif //0
46050b1a MD	508
46050b1a MD	509	cleanup_sock_info(&global_apps);
1ea11eab MD	510
1ea11eab MD	511	ret = pthread_cancel(local_apps.ust_listener);
9eb62b9c MD	512	if (ret) {
9eb62b9c MD	513	ERR("Error cancelling local ust listener thread");
2691221a	514	}
1ea11eab	515
46050b1a	516	cleanup_sock_info(&local_apps);
1ea11eab	517
b35d179d	518	lttng_ust_abi_exit();
1ea11eab	519	ltt_events_exit();
edaa1431 MD	520	ltt_ring_buffer_client_discard_exit();
	521	ltt_ring_buffer_client_overwrite_exit();
	522	ltt_ring_buffer_metadata_client_exit();
	523	exit_tracepoint();
2691221a	524	}