[lttng-tools.git] / src / bin / lttng-sessiond / health.c

/*
 * Copyright (C) 2012 - David Goulet <dgoulet@efficios.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License, version 2 only, as
 * published by the Free Software Foundation.
 *
 * This program 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 General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 51
 * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#define _GNU_SOURCE
#include <assert.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#include <common/defaults.h>
#include <common/error.h>

#include "health.h"

static const struct timespec time_delta = {
	.tv_sec = DEFAULT_HEALTH_CHECK_DELTA_S,
	.tv_nsec = DEFAULT_HEALTH_CHECK_DELTA_NS,
};

/* Define TLS health state. */
DEFINE_URCU_TLS(struct health_state, health_state);

/*
 * It ensures that TLS memory used for the node and its container structure
 * don't get reclaimed after the TLS owner thread exits until we have finished
 * using it.
 */
static pthread_mutex_t health_mutex = PTHREAD_MUTEX_INITIALIZER;

static struct health_tls_state_list health_state_list = {
	.head = CDS_LIST_HEAD_INIT(health_state_list.head),
};

/*
 * This keeps track of the error state for unregistered thread. A thread
 * reporting a health error, normally unregisters and quits. This makes the TLS
 * health state not available to the health_check_state() call so on unregister
 * we update this global error array so we can keep track of which thread was
 * on error if the TLS health state has been removed.
 */
static enum health_flags global_error_state[HEALTH_NUM_TYPE];

/*
 * Lock health state global list mutex.
 */
static void state_lock(void)
{
	pthread_mutex_lock(&health_mutex);
}

/*
 * Unlock health state global list mutex.
 */
static void state_unlock(void)
{
	pthread_mutex_unlock(&health_mutex);
}

/*
 * Set time difference in res from time_a and time_b.
 */
static void time_diff(const struct timespec *time_a,
		const struct timespec *time_b, struct timespec *res)
{
	if (time_a->tv_nsec - time_b->tv_nsec < 0) {
		res->tv_sec = time_a->tv_sec - time_b->tv_sec - 1;
		res->tv_nsec = 1000000000L + time_a->tv_sec - time_b->tv_sec;
	} else {
		res->tv_sec = time_a->tv_sec - time_b->tv_sec;
		res->tv_nsec = time_a->tv_nsec - time_b->tv_nsec;
	}
}

/*
 * Return true if time_a - time_b > diff, else false.
 */
static int time_diff_gt(const struct timespec *time_a,
		const struct timespec *time_b, const struct timespec *diff)
{
	struct timespec res;

	time_diff(time_a, time_b, &res);
	time_diff(&res, diff, &res);

	if (res.tv_sec > 0) {
		return 1;
	} else if (res.tv_sec == 0 && res.tv_nsec > 0) {
		return 1;
	}

	return 0;
}

/*
 * Validate health state. Checks for the error flag or health conditions.
 *
 * Return 0 if health is bad or else 1.
 */
static int validate_state(struct health_state *state)
{
	int retval = 1, ret;
	unsigned long current, last;
	struct timespec current_time;

	assert(state);

	last = state->last;
	current = uatomic_read(&state->current);

	ret = clock_gettime(CLOCK_MONOTONIC, &current_time);
	if (ret < 0) {
		PERROR("Error reading time\n");
		/* error */
		retval = 0;
		goto end;
	}

	/*
	 * Thread is in bad health if flag HEALTH_ERROR is set. It is also in bad
	 * health if, after the delta delay has passed, its the progress counter
	 * has not moved and it has NOT been waiting for a poll() call.
	 */
	if (uatomic_read(&state->flags) & HEALTH_ERROR) {
		retval = 0;
		goto end;
	}

	/*
	 * Initial condition need to update the last counter and sample time, but
	 * should not check health in this initial case, because we don't know how
	 * much time has passed.
	 */
	if (state->last_time.tv_sec == 0 && state->last_time.tv_nsec == 0) {
		/* update last counter and last sample time */
		state->last = current;
		memcpy(&state->last_time, &current_time, sizeof(current_time));
	} else {
		if (time_diff_gt(&current_time, &state->last_time, &time_delta)) {
			if (current == last && !HEALTH_IS_IN_POLL(current)) {
				/* error */
				retval = 0;
			}
			/* update last counter and last sample time */
			state->last = current;
			memcpy(&state->last_time, &current_time, sizeof(current_time));

			/* On error, stop right now and notify caller. */
			if (retval == 0) {
				goto end;
			}
		}
	}

end:
	DBG("Health state current %lu, last %lu, ret %d",
			current, last, ret);
	return retval;
}

/*
 * Check health of a specific health type. Note that if a thread has not yet
 * initialize its health subsystem or has quit, it's considered in a good
 * state.
 *
 * Return 0 if health is bad or else 1.
 */
int health_check_state(enum health_type type)
{
	int retval = 1;
	struct health_state *state;

	assert(type < HEALTH_NUM_TYPE);

	state_lock();

	cds_list_for_each_entry(state, &health_state_list.head, node) {
		int ret;

		if (state->type != type) {
			continue;
		}

		ret = validate_state(state);
		if (!ret) {
			retval = 0;
			goto end;
		}
	}

	/* Check the global state since some state might not be visible anymore. */
	if (global_error_state[type] & HEALTH_ERROR) {
		retval = 0;
	}

end:
	state_unlock();

	DBG("Health check for type %d is %s", (int) type,
			(retval == 0) ? "BAD" : "GOOD");
	return retval;
}

/*
 * Init health state.
 */
void health_register(enum health_type type)
{
	assert(type < HEALTH_NUM_TYPE);

	/* Init TLS state. */
	uatomic_set(&URCU_TLS(health_state).last, 0);
	uatomic_set(&URCU_TLS(health_state).last_time.tv_sec, 0);
	uatomic_set(&URCU_TLS(health_state).last_time.tv_nsec, 0);
	uatomic_set(&URCU_TLS(health_state).current, 0);
	uatomic_set(&URCU_TLS(health_state).flags, 0);
	uatomic_set(&URCU_TLS(health_state).type, type);

	/* Add it to the global TLS state list. */
	state_lock();
	cds_list_add(&URCU_TLS(health_state).node, &health_state_list.head);
	state_unlock();
}

/*
 * Remove node from global list.
 */
void health_unregister(void)
{
	state_lock();
	/*
	 * On error, set the global_error_state since we are about to remove
	 * the node from the global list.
	 */
	if (uatomic_read(&URCU_TLS(health_state).flags) & HEALTH_ERROR) {
		uatomic_set(&global_error_state[URCU_TLS(health_state).type],
				HEALTH_ERROR);
	}
	cds_list_del(&URCU_TLS(health_state).node);
	state_unlock();
}
Commit	Line	Data
	1	/*
	2	* Copyright (C) 2012 - David Goulet <dgoulet@efficios.com>
	3	*
	4	* This program is free software; you can redistribute it and/or modify it
	5	* under the terms of the GNU General Public License, version 2 only, as
	6	* published by the Free Software Foundation.
	7	*
	8	* This program is distributed in the hope that it will be useful, but WITHOUT
	9	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	10	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
	11	* more details.
	12	*
	13	* You should have received a copy of the GNU General Public License along with
	14	* this program; if not, write to the Free Software Foundation, Inc., 51
	15	* Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
	16	*/
	17
	18	#define _GNU_SOURCE
	19	#include <assert.h>
	20	#include <inttypes.h>
	21	#include <stdio.h>
	22	#include <stdlib.h>
	23	#include <time.h>
	24
	25	#include <common/defaults.h>
	26	#include <common/error.h>
	27
	28	#include "health.h"
	29
	30	static const struct timespec time_delta = {
	31	.tv_sec = DEFAULT_HEALTH_CHECK_DELTA_S,
	32	.tv_nsec = DEFAULT_HEALTH_CHECK_DELTA_NS,
	33	};
	34
	35	/* Define TLS health state. */
	36	DEFINE_URCU_TLS(struct health_state, health_state);
	37
	38	/*
	39	* It ensures that TLS memory used for the node and its container structure
	40	* don't get reclaimed after the TLS owner thread exits until we have finished
	41	* using it.
	42	*/
	43	static pthread_mutex_t health_mutex = PTHREAD_MUTEX_INITIALIZER;
	44
	45	static struct health_tls_state_list health_state_list = {
	46	.head = CDS_LIST_HEAD_INIT(health_state_list.head),
	47	};
	48
	49	/*
	50	* This keeps track of the error state for unregistered thread. A thread
	51	* reporting a health error, normally unregisters and quits. This makes the TLS
	52	* health state not available to the health_check_state() call so on unregister
	53	* we update this global error array so we can keep track of which thread was
	54	* on error if the TLS health state has been removed.
	55	*/
	56	static enum health_flags global_error_state[HEALTH_NUM_TYPE];
	57
	58	/*
	59	* Lock health state global list mutex.
	60	*/
	61	static void state_lock(void)
	62	{
	63	pthread_mutex_lock(&health_mutex);
	64	}
	65
	66	/*
	67	* Unlock health state global list mutex.
	68	*/
	69	static void state_unlock(void)
	70	{
	71	pthread_mutex_unlock(&health_mutex);
	72	}
	73
	74	/*
	75	* Set time difference in res from time_a and time_b.
	76	*/
	77	static void time_diff(const struct timespec *time_a,
	78	const struct timespec time_b, struct timespec res)
	79	{
	80	if (time_a->tv_nsec - time_b->tv_nsec < 0) {
	81	res->tv_sec = time_a->tv_sec - time_b->tv_sec - 1;
	82	res->tv_nsec = 1000000000L + time_a->tv_sec - time_b->tv_sec;
	83	} else {
	84	res->tv_sec = time_a->tv_sec - time_b->tv_sec;
	85	res->tv_nsec = time_a->tv_nsec - time_b->tv_nsec;
	86	}
	87	}
	88
	89	/*
	90	* Return true if time_a - time_b > diff, else false.
	91	*/
	92	static int time_diff_gt(const struct timespec *time_a,
	93	const struct timespec time_b, const struct timespec diff)
	94	{
	95	struct timespec res;
	96
	97	time_diff(time_a, time_b, &res);
	98	time_diff(&res, diff, &res);
	99
	100	if (res.tv_sec > 0) {
	101	return 1;
	102	} else if (res.tv_sec == 0 && res.tv_nsec > 0) {
	103	return 1;
	104	}
	105
	106	return 0;
	107	}
	108
	109	/*
	110	* Validate health state. Checks for the error flag or health conditions.
	111	*
	112	* Return 0 if health is bad or else 1.
	113	*/
	114	static int validate_state(struct health_state *state)
	115	{
	116	int retval = 1, ret;
	117	unsigned long current, last;
	118	struct timespec current_time;
	119
	120	assert(state);
	121
	122	last = state->last;
	123	current = uatomic_read(&state->current);
	124
	125	ret = clock_gettime(CLOCK_MONOTONIC, &current_time);
	126	if (ret < 0) {
	127	PERROR("Error reading time\n");
	128	/* error */
	129	retval = 0;
	130	goto end;
	131	}
	132
	133	/*
	134	* Thread is in bad health if flag HEALTH_ERROR is set. It is also in bad
	135	* health if, after the delta delay has passed, its the progress counter
	136	* has not moved and it has NOT been waiting for a poll() call.
	137	*/
	138	if (uatomic_read(&state->flags) & HEALTH_ERROR) {
	139	retval = 0;
	140	goto end;
	141	}
	142
	143	/*
	144	* Initial condition need to update the last counter and sample time, but
	145	* should not check health in this initial case, because we don't know how
	146	* much time has passed.
	147	*/
	148	if (state->last_time.tv_sec == 0 && state->last_time.tv_nsec == 0) {
	149	/* update last counter and last sample time */
	150	state->last = current;
	151	memcpy(&state->last_time, &current_time, sizeof(current_time));
	152	} else {
	153	if (time_diff_gt(&current_time, &state->last_time, &time_delta)) {
	154	if (current == last && !HEALTH_IS_IN_POLL(current)) {
	155	/* error */
	156	retval = 0;
	157	}
	158	/* update last counter and last sample time */
	159	state->last = current;
	160	memcpy(&state->last_time, &current_time, sizeof(current_time));
	161
	162	/* On error, stop right now and notify caller. */
	163	if (retval == 0) {
	164	goto end;
	165	}
	166	}
	167	}
	168
	169	end:
	170	DBG("Health state current %lu, last %lu, ret %d",
	171	current, last, ret);
	172	return retval;
	173	}
	174
	175	/*
	176	* Check health of a specific health type. Note that if a thread has not yet
	177	* initialize its health subsystem or has quit, it's considered in a good
	178	* state.
	179	*
	180	* Return 0 if health is bad or else 1.
	181	*/
	182	int health_check_state(enum health_type type)
	183	{
	184	int retval = 1;
	185	struct health_state *state;
	186
	187	assert(type < HEALTH_NUM_TYPE);
	188
	189	state_lock();
	190
	191	cds_list_for_each_entry(state, &health_state_list.head, node) {
	192	int ret;
	193
	194	if (state->type != type) {
	195	continue;
	196	}
	197
	198	ret = validate_state(state);
	199	if (!ret) {
	200	retval = 0;
	201	goto end;
	202	}
	203	}
	204
	205	/* Check the global state since some state might not be visible anymore. */
	206	if (global_error_state[type] & HEALTH_ERROR) {
	207	retval = 0;
	208	}
	209
	210	end:
	211	state_unlock();
	212
	213	DBG("Health check for type %d is %s", (int) type,
	214	(retval == 0) ? "BAD" : "GOOD");
	215	return retval;
	216	}
	217
	218	/*
	219	* Init health state.
	220	*/
	221	void health_register(enum health_type type)
	222	{
	223	assert(type < HEALTH_NUM_TYPE);
	224
	225	/* Init TLS state. */
	226	uatomic_set(&URCU_TLS(health_state).last, 0);
	227	uatomic_set(&URCU_TLS(health_state).last_time.tv_sec, 0);
	228	uatomic_set(&URCU_TLS(health_state).last_time.tv_nsec, 0);
	229	uatomic_set(&URCU_TLS(health_state).current, 0);
	230	uatomic_set(&URCU_TLS(health_state).flags, 0);
	231	uatomic_set(&URCU_TLS(health_state).type, type);
	232
	233	/* Add it to the global TLS state list. */
	234	state_lock();
	235	cds_list_add(&URCU_TLS(health_state).node, &health_state_list.head);
	236	state_unlock();
	237	}
	238
	239	/*
	240	* Remove node from global list.
	241	*/
	242	void health_unregister(void)
	243	{
	244	state_lock();
	245	/*
	246	* On error, set the global_error_state since we are about to remove
	247	* the node from the global list.
	248	*/
	249	if (uatomic_read(&URCU_TLS(health_state).flags) & HEALTH_ERROR) {
	250	uatomic_set(&global_error_state[URCU_TLS(health_state).type],
	251	HEALTH_ERROR);
	252	}
	253	cds_list_del(&URCU_TLS(health_state).node);
	254	state_unlock();
	255	}