8a07e642607cb6cb401a57c845043ca63870f97e
[lttng-tools.git] / src / common / health / health.cpp
1 /*
2 * Copyright (C) 2012 David Goulet <dgoulet@efficios.com>
3 * Copyright (C) 2013 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
4 *
5 * SPDX-License-Identifier: GPL-2.0-only
6 *
7 */
8
9 #define _LGPL_SOURCE
10 #include <algorithm>
11 #include <inttypes.h>
12 #include <stdio.h>
13 #include <stdlib.h>
14 #include <time.h>
15
16 #include <common/defaults.h>
17 #include <common/error.h>
18 #include <common/macros.h>
19 #include <common/sessiond-comm/inet.h>
20
21 #include <lttng/health-internal.h>
22
23 /*
24 * An application-specific error state for unregistered thread keeps
25 * track of thread errors. A thread reporting a health error, normally
26 * unregisters and quits. This makes the TLS health state not available
27 * to the health_check_state() call so on unregister we update this
28 * global error array so we can keep track of which thread was on error
29 * if the TLS health state has been removed.
30 */
31 struct health_app {
32 /* List of health state, for each application thread */
33 struct cds_list_head list;
34 /*
35 * This lock ensures that TLS memory used for the node and its
36 * container structure don't get reclaimed after the TLS owner
37 * thread exits until we have finished using it.
38 */
39 pthread_mutex_t lock;
40 int nr_types;
41 struct timespec time_delta;
42 /* Health flags containing thread type error state */
43 enum health_flags *flags;
44 };
45
46 /* Define TLS health state. */
47 DEFINE_URCU_TLS(struct health_state, health_state);
48
49 /*
50 * Initialize health check subsytem.
51 */
52 static
53 void health_init(struct health_app *ha)
54 {
55 /*
56 * Get the maximum value between the default delta value and the TCP
57 * timeout with a safety net of the default health check delta.
58 */
59 ha->time_delta.tv_sec = std::max<unsigned long>(
60 lttcomm_inet_tcp_timeout + DEFAULT_HEALTH_CHECK_DELTA_S,
61 ha->time_delta.tv_sec);
62 DBG("Health check time delta in seconds set to %lu",
63 ha->time_delta.tv_sec);
64 }
65
66 struct health_app *health_app_create(int nr_types)
67 {
68 struct health_app *ha;
69
70 ha = (health_app *) zmalloc(sizeof(*ha));
71 if (!ha) {
72 return NULL;
73 }
74 ha->flags = (health_flags *) zmalloc(sizeof(*ha->flags) * nr_types);
75 if (!ha->flags) {
76 goto error_flags;
77 }
78 CDS_INIT_LIST_HEAD(&ha->list);
79 pthread_mutex_init(&ha->lock, NULL);
80 ha->nr_types = nr_types;
81 ha->time_delta.tv_sec = DEFAULT_HEALTH_CHECK_DELTA_S;
82 ha->time_delta.tv_nsec = DEFAULT_HEALTH_CHECK_DELTA_NS;
83 health_init(ha);
84 return ha;
85
86 error_flags:
87 free(ha);
88 return NULL;
89 }
90
91 void health_app_destroy(struct health_app *ha)
92 {
93 free(ha->flags);
94 free(ha);
95 }
96
97 /*
98 * Lock health state global list mutex.
99 */
100 static void state_lock(struct health_app *ha)
101 {
102 pthread_mutex_lock(&ha->lock);
103 }
104
105 /*
106 * Unlock health state global list mutex.
107 */
108 static void state_unlock(struct health_app *ha)
109 {
110 pthread_mutex_unlock(&ha->lock);
111 }
112
113 /*
114 * Set time difference in res from time_a and time_b.
115 */
116 static void time_diff(const struct timespec *time_a,
117 const struct timespec *time_b, struct timespec *res)
118 {
119 if (time_a->tv_nsec - time_b->tv_nsec < 0) {
120 res->tv_sec = time_a->tv_sec - time_b->tv_sec - 1;
121 res->tv_nsec = 1000000000L + time_a->tv_sec - time_b->tv_sec;
122 } else {
123 res->tv_sec = time_a->tv_sec - time_b->tv_sec;
124 res->tv_nsec = time_a->tv_nsec - time_b->tv_nsec;
125 }
126 }
127
128 /*
129 * Return true if time_a - time_b > diff, else false.
130 */
131 static int time_diff_gt(const struct timespec *time_a,
132 const struct timespec *time_b, const struct timespec *diff)
133 {
134 struct timespec res;
135
136 time_diff(time_a, time_b, &res);
137 time_diff(&res, diff, &res);
138
139 if (res.tv_sec > 0) {
140 return 1;
141 } else if (res.tv_sec == 0 && res.tv_nsec > 0) {
142 return 1;
143 }
144
145 return 0;
146 }
147
148 /*
149 * Validate health state. Checks for the error flag or health conditions.
150 *
151 * Return 0 if health is bad or else 1.
152 */
153 static int validate_state(struct health_app *ha, struct health_state *state)
154 {
155 int retval = 1, ret;
156 unsigned long current, last;
157 struct timespec current_time;
158
159 LTTNG_ASSERT(state);
160
161 last = state->last;
162 current = uatomic_read(&state->current);
163
164 ret = lttng_clock_gettime(CLOCK_MONOTONIC, &current_time);
165 if (ret < 0) {
166 PERROR("Error reading time\n");
167 /* error */
168 retval = 0;
169 goto end;
170 }
171
172 /*
173 * Thread is in bad health if flag HEALTH_ERROR is set. It is also in bad
174 * health if, after the delta delay has passed, its the progress counter
175 * has not moved and it has NOT been waiting for a poll() call.
176 */
177 if (uatomic_read(&state->flags) & HEALTH_ERROR) {
178 retval = 0;
179 goto end;
180 }
181
182 /*
183 * Initial condition need to update the last counter and sample time, but
184 * should not check health in this initial case, because we don't know how
185 * much time has passed.
186 */
187 if (state->last_time.tv_sec == 0 && state->last_time.tv_nsec == 0) {
188 /* update last counter and last sample time */
189 state->last = current;
190 memcpy(&state->last_time, &current_time, sizeof(current_time));
191 } else {
192 if (time_diff_gt(&current_time, &state->last_time,
193 &ha->time_delta)) {
194 if (current == last && !HEALTH_IS_IN_POLL(current)) {
195 /* error */
196 retval = 0;
197 }
198 /* update last counter and last sample time */
199 state->last = current;
200 memcpy(&state->last_time, &current_time, sizeof(current_time));
201
202 /* On error, stop right now and notify caller. */
203 if (retval == 0) {
204 goto end;
205 }
206 }
207 }
208
209 end:
210 DBG("Health state current %lu, last %lu, ret %d",
211 current, last, ret);
212 return retval;
213 }
214
215 /*
216 * Check health of a specific health type. Note that if a thread has not yet
217 * initialize its health subsystem or has quit, it's considered in a good
218 * state.
219 *
220 * Return 0 if health is bad or else 1.
221 */
222 int health_check_state(struct health_app *ha, int type)
223 {
224 int retval = 1;
225 struct health_state *state;
226
227 LTTNG_ASSERT(type < ha->nr_types);
228
229 state_lock(ha);
230
231 cds_list_for_each_entry(state, &ha->list, node) {
232 int ret;
233
234 if (state->type != type) {
235 continue;
236 }
237
238 ret = validate_state(ha, state);
239 if (!ret) {
240 retval = 0;
241 goto end;
242 }
243 }
244
245 /* Check the global state since some state might not be visible anymore. */
246 if (ha->flags[type] & HEALTH_ERROR) {
247 retval = 0;
248 }
249
250 end:
251 state_unlock(ha);
252
253 DBG("Health check for type %d is %s", (int) type,
254 (retval == 0) ? "BAD" : "GOOD");
255 return retval;
256 }
257
258 /*
259 * Init health state.
260 */
261 void health_register(struct health_app *ha, int type)
262 {
263 LTTNG_ASSERT(type < ha->nr_types);
264
265 /* Init TLS state. */
266 uatomic_set(&URCU_TLS(health_state).last, 0);
267 uatomic_set(&URCU_TLS(health_state).last_time.tv_sec, 0);
268 uatomic_set(&URCU_TLS(health_state).last_time.tv_nsec, 0);
269 uatomic_set(&URCU_TLS(health_state).current, 0);
270 uatomic_set(&URCU_TLS(health_state).flags, (health_flags) 0);
271 uatomic_set(&URCU_TLS(health_state).type, type);
272
273 /* Add it to the global TLS state list. */
274 state_lock(ha);
275 cds_list_add(&URCU_TLS(health_state).node, &ha->list);
276 state_unlock(ha);
277 }
278
279 /*
280 * Remove node from global list.
281 */
282 void health_unregister(struct health_app *ha)
283 {
284 state_lock(ha);
285 /*
286 * On error, set the global_error_state since we are about to remove
287 * the node from the global list.
288 */
289 if (uatomic_read(&URCU_TLS(health_state).flags) & HEALTH_ERROR) {
290 uatomic_set(&ha->flags[URCU_TLS(health_state).type],
291 HEALTH_ERROR);
292 }
293 cds_list_del(&URCU_TLS(health_state).node);
294 state_unlock(ha);
295 }
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