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[lttng-tools.git] / src / bin / lttng-sessiond / notify-apps.cpp
1 /*
2 * Copyright (C) 2013 David Goulet <dgoulet@efficios.com>
3 *
4 * SPDX-License-Identifier: GPL-2.0-only
5 *
6 */
7
8 #define _LGPL_SOURCE
9
10 #include <common/common.hpp>
11 #include <common/utils.hpp>
12
13 #include "fd-limit.hpp"
14 #include "lttng-sessiond.hpp"
15 #include "notify-apps.hpp"
16 #include "health-sessiond.hpp"
17 #include "testpoint.hpp"
18 #include "utils.hpp"
19 #include "thread.hpp"
20
21 namespace {
22 struct thread_notifiers {
23 struct lttng_pipe *quit_pipe;
24 int apps_cmd_notify_pipe_read_fd;
25 };
26 } /* namespace */
27
28 /*
29 * This thread manage application notify communication.
30 */
31 static void *thread_application_notification(void *data)
32 {
33 int i, ret, pollfd, err = -1;
34 ssize_t size_ret;
35 uint32_t revents, nb_fd;
36 struct lttng_poll_event events;
37 struct thread_notifiers *notifiers = (thread_notifiers *) data;
38 const int quit_pipe_read_fd = lttng_pipe_get_readfd(notifiers->quit_pipe);
39
40 DBG("[ust-thread] Manage application notify command");
41
42 rcu_register_thread();
43 rcu_thread_online();
44
45 health_register(the_health_sessiond,
46 HEALTH_SESSIOND_TYPE_APP_MANAGE_NOTIFY);
47
48 if (testpoint(sessiond_thread_app_manage_notify)) {
49 goto error_testpoint;
50 }
51
52 health_code_update();
53
54 ret = lttng_poll_create(&events, 2, LTTNG_CLOEXEC);
55 if (ret < 0) {
56 goto error_poll_create;
57 }
58
59 /* Add notify pipe to the pollset. */
60 ret = lttng_poll_add(&events, notifiers->apps_cmd_notify_pipe_read_fd,
61 LPOLLIN | LPOLLERR | LPOLLHUP | LPOLLRDHUP);
62 if (ret < 0) {
63 goto error;
64 }
65
66 ret = lttng_poll_add(&events, quit_pipe_read_fd,
67 LPOLLIN | LPOLLERR);
68 if (ret < 0) {
69 goto error;
70 }
71
72 health_code_update();
73
74 while (1) {
75 DBG3("[ust-thread] Manage notify polling");
76
77 /* Inifinite blocking call, waiting for transmission */
78 restart:
79 health_poll_entry();
80 ret = lttng_poll_wait(&events, -1);
81 DBG3("[ust-thread] Manage notify return from poll on %d fds",
82 LTTNG_POLL_GETNB(&events));
83 health_poll_exit();
84 if (ret < 0) {
85 /*
86 * Restart interrupted system call.
87 */
88 if (errno == EINTR) {
89 goto restart;
90 }
91 goto error;
92 }
93
94 nb_fd = ret;
95
96 for (i = 0; i < nb_fd; i++) {
97 health_code_update();
98
99 /* Fetch once the poll data */
100 revents = LTTNG_POLL_GETEV(&events, i);
101 pollfd = LTTNG_POLL_GETFD(&events, i);
102
103 /* Thread quit pipe has been closed. Killing thread. */
104 if (pollfd == quit_pipe_read_fd) {
105 err = 0;
106 goto exit;
107 } else if (pollfd == notifiers->apps_cmd_notify_pipe_read_fd) {
108 /* Inspect the apps cmd pipe */
109 int sock;
110
111 if (revents & LPOLLIN) {
112 /* Get socket from dispatch thread. */
113 size_ret = lttng_read(notifiers->apps_cmd_notify_pipe_read_fd,
114 &sock, sizeof(sock));
115 if (size_ret < sizeof(sock)) {
116 PERROR("read apps notify pipe");
117 goto error;
118 }
119 health_code_update();
120
121 ret = lttng_poll_add(&events, sock,
122 LPOLLIN | LPOLLERR | LPOLLHUP | LPOLLRDHUP);
123 if (ret < 0) {
124 /*
125 * It's possible we've reached the max poll fd allowed.
126 * Let's close the socket but continue normal execution.
127 */
128 ret = close(sock);
129 if (ret) {
130 PERROR("close notify socket %d", sock);
131 }
132 lttng_fd_put(LTTNG_FD_APPS, 1);
133 continue;
134 }
135 DBG3("UST thread notify added sock %d to pollset", sock);
136 } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
137 ERR("Apps notify command pipe error");
138 goto error;
139 } else {
140 ERR("Unexpected poll events %u for sock %d", revents, pollfd);
141 goto error;
142 }
143 } else {
144 /*
145 * At this point, we know that a registered application
146 * triggered the event.
147 */
148 if (revents & (LPOLLIN | LPOLLPRI)) {
149 ret = ust_app_recv_notify(pollfd);
150 if (ret < 0) {
151 /* Removing from the poll set */
152 ret = lttng_poll_del(&events, pollfd);
153 if (ret < 0) {
154 goto error;
155 }
156
157 /* The socket is closed after a grace period here. */
158 ust_app_notify_sock_unregister(pollfd);
159 }
160 } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
161 /* Removing from the poll set */
162 ret = lttng_poll_del(&events, pollfd);
163 if (ret < 0) {
164 goto error;
165 }
166
167 /* The socket is closed after a grace period here. */
168 ust_app_notify_sock_unregister(pollfd);
169 } else {
170 ERR("Unexpected poll events %u for sock %d", revents, pollfd);
171 goto error;
172 }
173 health_code_update();
174 }
175 }
176 }
177
178 exit:
179 error:
180 lttng_poll_clean(&events);
181 error_poll_create:
182 error_testpoint:
183
184 DBG("Application notify communication apps thread cleanup complete");
185 if (err) {
186 health_error();
187 ERR("Health error occurred in %s", __func__);
188 }
189 health_unregister(the_health_sessiond);
190 rcu_thread_offline();
191 rcu_unregister_thread();
192 return NULL;
193 }
194
195 static bool shutdown_application_notification_thread(void *data)
196 {
197 struct thread_notifiers *notifiers = (thread_notifiers *) data;
198 const int write_fd = lttng_pipe_get_writefd(notifiers->quit_pipe);
199
200 return notify_thread_pipe(write_fd) == 1;
201 }
202
203 static void cleanup_application_notification_thread(void *data)
204 {
205 struct thread_notifiers *notifiers = (thread_notifiers *) data;
206
207 lttng_pipe_destroy(notifiers->quit_pipe);
208 free(notifiers);
209 }
210
211 bool launch_application_notification_thread(int apps_cmd_notify_pipe_read_fd)
212 {
213 struct lttng_thread *thread;
214 struct thread_notifiers *notifiers;
215 struct lttng_pipe *quit_pipe;
216
217 notifiers = zmalloc<thread_notifiers>();
218 if (!notifiers) {
219 goto error_alloc;
220 }
221 notifiers->apps_cmd_notify_pipe_read_fd = apps_cmd_notify_pipe_read_fd;
222
223 quit_pipe = lttng_pipe_open(FD_CLOEXEC);
224 if (!quit_pipe) {
225 goto error;
226 }
227 notifiers->quit_pipe = quit_pipe;
228
229 thread = lttng_thread_create("Application notification",
230 thread_application_notification,
231 shutdown_application_notification_thread,
232 cleanup_application_notification_thread,
233 notifiers);
234 if (!thread) {
235 goto error;
236 }
237 lttng_thread_put(thread);
238 return true;
239 error:
240 cleanup_application_notification_thread(notifiers);
241 error_alloc:
242 return false;
243 }
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