Refactor: lttng_ustctl_flush_buffer is a duplicate of lttng_ustconsumer_flush_buffer
[lttng-tools.git] / src / common / health / health.c
1 /*
2 * Copyright (C) 2012 - David Goulet <dgoulet@efficios.com>
3 * Copyright (C) 2013 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
4 *
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License, version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This program is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
12 * more details.
13 *
14 * You should have received a copy of the GNU General Public License along with
15 * this program; if not, write to the Free Software Foundation, Inc., 51
16 * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
17 */
18
19 #define _LGPL_SOURCE
20 #include <assert.h>
21 #include <inttypes.h>
22 #include <stdio.h>
23 #include <stdlib.h>
24 #include <time.h>
25
26 #include <common/defaults.h>
27 #include <common/error.h>
28 #include <common/macros.h>
29 #include <common/sessiond-comm/inet.h>
30
31 #include <lttng/health-internal.h>
32
33 /*
34 * An application-specific error state for unregistered thread keeps
35 * track of thread errors. A thread reporting a health error, normally
36 * unregisters and quits. This makes the TLS health state not available
37 * to the health_check_state() call so on unregister we update this
38 * global error array so we can keep track of which thread was on error
39 * if the TLS health state has been removed.
40 */
41 struct health_app {
42 /* List of health state, for each application thread */
43 struct cds_list_head list;
44 /*
45 * This lock ensures that TLS memory used for the node and its
46 * container structure don't get reclaimed after the TLS owner
47 * thread exits until we have finished using it.
48 */
49 pthread_mutex_t lock;
50 int nr_types;
51 struct timespec time_delta;
52 /* Health flags containing thread type error state */
53 enum health_flags *flags;
54 };
55
56 /* Define TLS health state. */
57 DEFINE_URCU_TLS(struct health_state, health_state);
58
59 /*
60 * Initialize health check subsytem.
61 */
62 static
63 void health_init(struct health_app *ha)
64 {
65 /*
66 * Get the maximum value between the default delta value and the TCP
67 * timeout with a safety net of the default health check delta.
68 */
69 ha->time_delta.tv_sec = max_t(unsigned long,
70 lttcomm_inet_tcp_timeout + DEFAULT_HEALTH_CHECK_DELTA_S,
71 ha->time_delta.tv_sec);
72 DBG("Health check time delta in seconds set to %lu",
73 ha->time_delta.tv_sec);
74 }
75
76 struct health_app *health_app_create(int nr_types)
77 {
78 struct health_app *ha;
79
80 ha = zmalloc(sizeof(*ha));
81 if (!ha) {
82 return NULL;
83 }
84 ha->flags = zmalloc(sizeof(*ha->flags) * nr_types);
85 if (!ha->flags) {
86 goto error_flags;
87 }
88 CDS_INIT_LIST_HEAD(&ha->list);
89 pthread_mutex_init(&ha->lock, NULL);
90 ha->nr_types = nr_types;
91 ha->time_delta.tv_sec = DEFAULT_HEALTH_CHECK_DELTA_S;
92 ha->time_delta.tv_nsec = DEFAULT_HEALTH_CHECK_DELTA_NS;
93 health_init(ha);
94 return ha;
95
96 error_flags:
97 free(ha);
98 return NULL;
99 }
100
101 void health_app_destroy(struct health_app *ha)
102 {
103 free(ha->flags);
104 free(ha);
105 }
106
107 /*
108 * Lock health state global list mutex.
109 */
110 static void state_lock(struct health_app *ha)
111 {
112 pthread_mutex_lock(&ha->lock);
113 }
114
115 /*
116 * Unlock health state global list mutex.
117 */
118 static void state_unlock(struct health_app *ha)
119 {
120 pthread_mutex_unlock(&ha->lock);
121 }
122
123 /*
124 * Set time difference in res from time_a and time_b.
125 */
126 static void time_diff(const struct timespec *time_a,
127 const struct timespec *time_b, struct timespec *res)
128 {
129 if (time_a->tv_nsec - time_b->tv_nsec < 0) {
130 res->tv_sec = time_a->tv_sec - time_b->tv_sec - 1;
131 res->tv_nsec = 1000000000L + time_a->tv_sec - time_b->tv_sec;
132 } else {
133 res->tv_sec = time_a->tv_sec - time_b->tv_sec;
134 res->tv_nsec = time_a->tv_nsec - time_b->tv_nsec;
135 }
136 }
137
138 /*
139 * Return true if time_a - time_b > diff, else false.
140 */
141 static int time_diff_gt(const struct timespec *time_a,
142 const struct timespec *time_b, const struct timespec *diff)
143 {
144 struct timespec res;
145
146 time_diff(time_a, time_b, &res);
147 time_diff(&res, diff, &res);
148
149 if (res.tv_sec > 0) {
150 return 1;
151 } else if (res.tv_sec == 0 && res.tv_nsec > 0) {
152 return 1;
153 }
154
155 return 0;
156 }
157
158 /*
159 * Validate health state. Checks for the error flag or health conditions.
160 *
161 * Return 0 if health is bad or else 1.
162 */
163 static int validate_state(struct health_app *ha, struct health_state *state)
164 {
165 int retval = 1, ret;
166 unsigned long current, last;
167 struct timespec current_time;
168
169 assert(state);
170
171 last = state->last;
172 current = uatomic_read(&state->current);
173
174 ret = lttng_clock_gettime(CLOCK_MONOTONIC, &current_time);
175 if (ret < 0) {
176 PERROR("Error reading time\n");
177 /* error */
178 retval = 0;
179 goto end;
180 }
181
182 /*
183 * Thread is in bad health if flag HEALTH_ERROR is set. It is also in bad
184 * health if, after the delta delay has passed, its the progress counter
185 * has not moved and it has NOT been waiting for a poll() call.
186 */
187 if (uatomic_read(&state->flags) & HEALTH_ERROR) {
188 retval = 0;
189 goto end;
190 }
191
192 /*
193 * Initial condition need to update the last counter and sample time, but
194 * should not check health in this initial case, because we don't know how
195 * much time has passed.
196 */
197 if (state->last_time.tv_sec == 0 && state->last_time.tv_nsec == 0) {
198 /* update last counter and last sample time */
199 state->last = current;
200 memcpy(&state->last_time, &current_time, sizeof(current_time));
201 } else {
202 if (time_diff_gt(&current_time, &state->last_time,
203 &ha->time_delta)) {
204 if (current == last && !HEALTH_IS_IN_POLL(current)) {
205 /* error */
206 retval = 0;
207 }
208 /* update last counter and last sample time */
209 state->last = current;
210 memcpy(&state->last_time, &current_time, sizeof(current_time));
211
212 /* On error, stop right now and notify caller. */
213 if (retval == 0) {
214 goto end;
215 }
216 }
217 }
218
219 end:
220 DBG("Health state current %lu, last %lu, ret %d",
221 current, last, ret);
222 return retval;
223 }
224
225 /*
226 * Check health of a specific health type. Note that if a thread has not yet
227 * initialize its health subsystem or has quit, it's considered in a good
228 * state.
229 *
230 * Return 0 if health is bad or else 1.
231 */
232 int health_check_state(struct health_app *ha, int type)
233 {
234 int retval = 1;
235 struct health_state *state;
236
237 assert(type < ha->nr_types);
238
239 state_lock(ha);
240
241 cds_list_for_each_entry(state, &ha->list, node) {
242 int ret;
243
244 if (state->type != type) {
245 continue;
246 }
247
248 ret = validate_state(ha, state);
249 if (!ret) {
250 retval = 0;
251 goto end;
252 }
253 }
254
255 /* Check the global state since some state might not be visible anymore. */
256 if (ha->flags[type] & HEALTH_ERROR) {
257 retval = 0;
258 }
259
260 end:
261 state_unlock(ha);
262
263 DBG("Health check for type %d is %s", (int) type,
264 (retval == 0) ? "BAD" : "GOOD");
265 return retval;
266 }
267
268 /*
269 * Init health state.
270 */
271 void health_register(struct health_app *ha, int type)
272 {
273 assert(type < ha->nr_types);
274
275 /* Init TLS state. */
276 uatomic_set(&URCU_TLS(health_state).last, 0);
277 uatomic_set(&URCU_TLS(health_state).last_time.tv_sec, 0);
278 uatomic_set(&URCU_TLS(health_state).last_time.tv_nsec, 0);
279 uatomic_set(&URCU_TLS(health_state).current, 0);
280 uatomic_set(&URCU_TLS(health_state).flags, 0);
281 uatomic_set(&URCU_TLS(health_state).type, type);
282
283 /* Add it to the global TLS state list. */
284 state_lock(ha);
285 cds_list_add(&URCU_TLS(health_state).node, &ha->list);
286 state_unlock(ha);
287 }
288
289 /*
290 * Remove node from global list.
291 */
292 void health_unregister(struct health_app *ha)
293 {
294 state_lock(ha);
295 /*
296 * On error, set the global_error_state since we are about to remove
297 * the node from the global list.
298 */
299 if (uatomic_read(&URCU_TLS(health_state).flags) & HEALTH_ERROR) {
300 uatomic_set(&ha->flags[URCU_TLS(health_state).type],
301 HEALTH_ERROR);
302 }
303 cds_list_del(&URCU_TLS(health_state).node);
304 state_unlock(ha);
305 }
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