Launch the application notification thread using lttng_thread
[lttng-tools.git] / src / bin / lttng-sessiond / ust-thread.c
1 /*
2 * Copyright (C) 2013 - 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 _LGPL_SOURCE
19 #include <assert.h>
20
21 #include <common/common.h>
22 #include <common/utils.h>
23
24 #include "fd-limit.h"
25 #include "lttng-sessiond.h"
26 #include "ust-thread.h"
27 #include "health-sessiond.h"
28 #include "testpoint.h"
29 #include "utils.h"
30 #include "thread.h"
31
32 struct thread_notifiers {
33 struct lttng_pipe *quit_pipe;
34 int apps_cmd_notify_pipe_read_fd;
35 };
36
37 /*
38 * This thread manage application notify communication.
39 */
40 static void *thread_application_notification(void *data)
41 {
42 int i, ret, pollfd, err = -1;
43 ssize_t size_ret;
44 uint32_t revents, nb_fd;
45 struct lttng_poll_event events;
46 struct thread_notifiers *notifiers = data;
47 const int quit_pipe_read_fd = lttng_pipe_get_readfd(notifiers->quit_pipe);
48
49 DBG("[ust-thread] Manage application notify command");
50
51 rcu_register_thread();
52 rcu_thread_online();
53
54 health_register(health_sessiond,
55 HEALTH_SESSIOND_TYPE_APP_MANAGE_NOTIFY);
56
57 if (testpoint(sessiond_thread_app_manage_notify)) {
58 goto error_testpoint;
59 }
60
61 health_code_update();
62
63 ret = lttng_poll_create(&events, 2, LTTNG_CLOEXEC);
64 if (ret < 0) {
65 goto error_poll_create;
66 }
67
68 /* Add notify pipe to the pollset. */
69 ret = lttng_poll_add(&events, notifiers->apps_cmd_notify_pipe_read_fd,
70 LPOLLIN | LPOLLERR | LPOLLHUP | LPOLLRDHUP);
71 if (ret < 0) {
72 goto error;
73 }
74
75 ret = lttng_poll_add(&events, quit_pipe_read_fd,
76 LPOLLIN | LPOLLERR);
77 if (ret < 0) {
78 goto error;
79 }
80
81 health_code_update();
82
83 while (1) {
84 DBG3("[ust-thread] Manage notify polling");
85
86 /* Inifinite blocking call, waiting for transmission */
87 restart:
88 health_poll_entry();
89 ret = lttng_poll_wait(&events, -1);
90 DBG3("[ust-thread] Manage notify return from poll on %d fds",
91 LTTNG_POLL_GETNB(&events));
92 health_poll_exit();
93 if (ret < 0) {
94 /*
95 * Restart interrupted system call.
96 */
97 if (errno == EINTR) {
98 goto restart;
99 }
100 goto error;
101 }
102
103 nb_fd = ret;
104
105 for (i = 0; i < nb_fd; i++) {
106 health_code_update();
107
108 /* Fetch once the poll data */
109 revents = LTTNG_POLL_GETEV(&events, i);
110 pollfd = LTTNG_POLL_GETFD(&events, i);
111
112 if (!revents) {
113 /* No activity for this FD (poll implementation). */
114 continue;
115 }
116
117 /* Thread quit pipe has been closed. Killing thread. */
118 if (pollfd == quit_pipe_read_fd) {
119 err = 0;
120 goto exit;
121 } else if (pollfd == notifiers->apps_cmd_notify_pipe_read_fd) {
122 /* Inspect the apps cmd pipe */
123 int sock;
124
125 if (revents & LPOLLIN) {
126 /* Get socket from dispatch thread. */
127 size_ret = lttng_read(notifiers->apps_cmd_notify_pipe_read_fd,
128 &sock, sizeof(sock));
129 if (size_ret < sizeof(sock)) {
130 PERROR("read apps notify pipe");
131 goto error;
132 }
133 health_code_update();
134
135 ret = lttng_poll_add(&events, sock,
136 LPOLLIN | LPOLLERR | LPOLLHUP | LPOLLRDHUP);
137 if (ret < 0) {
138 /*
139 * It's possible we've reached the max poll fd allowed.
140 * Let's close the socket but continue normal execution.
141 */
142 ret = close(sock);
143 if (ret) {
144 PERROR("close notify socket %d", sock);
145 }
146 lttng_fd_put(LTTNG_FD_APPS, 1);
147 continue;
148 }
149 DBG3("UST thread notify added sock %d to pollset", sock);
150 } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
151 ERR("Apps notify command pipe error");
152 goto error;
153 } else {
154 ERR("Unexpected poll events %u for sock %d", revents, pollfd);
155 goto error;
156 }
157 } else {
158 /*
159 * At this point, we know that a registered application
160 * triggered the event.
161 */
162 if (revents & (LPOLLIN | LPOLLPRI)) {
163 ret = ust_app_recv_notify(pollfd);
164 if (ret < 0) {
165 /* Removing from the poll set */
166 ret = lttng_poll_del(&events, pollfd);
167 if (ret < 0) {
168 goto error;
169 }
170
171 /* The socket is closed after a grace period here. */
172 ust_app_notify_sock_unregister(pollfd);
173 }
174 } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
175 /* Removing from the poll set */
176 ret = lttng_poll_del(&events, pollfd);
177 if (ret < 0) {
178 goto error;
179 }
180
181 /* The socket is closed after a grace period here. */
182 ust_app_notify_sock_unregister(pollfd);
183 } else {
184 ERR("Unexpected poll events %u for sock %d", revents, pollfd);
185 goto error;
186 }
187 health_code_update();
188 }
189 }
190 }
191
192 exit:
193 error:
194 lttng_poll_clean(&events);
195 error_poll_create:
196 error_testpoint:
197
198 DBG("Application notify communication apps thread cleanup complete");
199 if (err) {
200 health_error();
201 ERR("Health error occurred in %s", __func__);
202 }
203 health_unregister(health_sessiond);
204 rcu_thread_offline();
205 rcu_unregister_thread();
206 return NULL;
207 }
208
209 static bool shutdown_application_notification_thread(void *data)
210 {
211 struct thread_notifiers *notifiers = data;
212 const int write_fd = lttng_pipe_get_writefd(notifiers->quit_pipe);
213
214 return notify_thread_pipe(write_fd) == 1;
215 }
216
217 static void cleanup_application_notification_thread(void *data)
218 {
219 struct thread_notifiers *notifiers = data;
220
221 lttng_pipe_destroy(notifiers->quit_pipe);
222 free(notifiers);
223 }
224
225 bool launch_application_notification_thread(int apps_cmd_notify_pipe_read_fd)
226 {
227 struct lttng_thread *thread;
228 struct thread_notifiers *notifiers;
229 struct lttng_pipe *quit_pipe;
230
231 notifiers = zmalloc(sizeof(*notifiers));
232 if (!notifiers) {
233 goto error;
234 }
235 notifiers->apps_cmd_notify_pipe_read_fd = apps_cmd_notify_pipe_read_fd;
236
237 quit_pipe = lttng_pipe_open(FD_CLOEXEC);
238 if (!quit_pipe) {
239 goto error;
240 }
241 notifiers->quit_pipe = quit_pipe;
242
243 thread = lttng_thread_create("Application notification",
244 thread_application_notification,
245 shutdown_application_notification_thread,
246 cleanup_application_notification_thread,
247 notifiers);
248 if (!thread) {
249 goto error;
250 }
251 lttng_thread_put(thread);
252 return true;
253 error:
254 cleanup_application_notification_thread(notifiers);
255 return false;
256 }
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