tests: use --background for session daemon
[lttng-tools.git] / src / bin / lttng-sessiond / ust-thread.c
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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#define _GNU_SOURCE
18#include <assert.h>
19
20#include <common/common.h>
21#include <common/utils.h>
22
23#include "fd-limit.h"
24#include "lttng-sessiond.h"
25#include "ust-thread.h"
8782cc74 26#include "health-sessiond.h"
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27
28/*
29 * This thread manage application notify communication.
30 */
31void *ust_thread_manage_notify(void *data)
32{
380e8d6f 33 int i, ret, pollfd, err = -1;
6cd525e8 34 ssize_t size_ret;
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35 uint32_t revents, nb_fd;
36 struct lttng_poll_event events;
37
38 DBG("[ust-thread] Manage application notify command");
39
40 rcu_register_thread();
41 rcu_thread_online();
42
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43 health_register(health_sessiond,
44 HEALTH_SESSIOND_TYPE_APP_MANAGE_NOTIFY);
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45
46 health_code_update();
47
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48 ret = sessiond_set_thread_pollset(&events, 2);
49 if (ret < 0) {
50 goto error_poll_create;
51 }
52
53 /* Add notify pipe to the pollset. */
54 ret = lttng_poll_add(&events, apps_cmd_notify_pipe[0], LPOLLIN | LPOLLERR);
55 if (ret < 0) {
56 goto error;
57 }
58
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59 health_code_update();
60
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61 while (1) {
62 DBG3("[ust-thread] Manage notify polling on %d fds",
63 LTTNG_POLL_GETNB(&events));
64
65 /* Inifinite blocking call, waiting for transmission */
66restart:
380e8d6f 67 health_poll_entry();
d0b96690 68 ret = lttng_poll_wait(&events, -1);
380e8d6f 69 health_poll_exit();
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70 if (ret < 0) {
71 /*
72 * Restart interrupted system call.
73 */
74 if (errno == EINTR) {
75 goto restart;
76 }
77 goto error;
78 }
79
80 nb_fd = ret;
81
82 for (i = 0; i < nb_fd; i++) {
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83 health_code_update();
84
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85 /* Fetch once the poll data */
86 revents = LTTNG_POLL_GETEV(&events, i);
87 pollfd = LTTNG_POLL_GETFD(&events, i);
88
89 /* Thread quit pipe has been closed. Killing thread. */
90 ret = sessiond_check_thread_quit_pipe(pollfd, revents);
91 if (ret) {
380e8d6f 92 err = 0;
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93 goto exit;
94 }
95
96 /* Inspect the apps cmd pipe */
97 if (pollfd == apps_cmd_notify_pipe[0]) {
98 int sock;
99
100 if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
101 ERR("Apps notify command pipe error");
102 goto error;
103 } else if (!(revents & LPOLLIN)) {
104 /* No POLLIN and not a catched error, stop the thread. */
105 ERR("Notify command pipe failed. revent: %u", revents);
106 goto error;
107 }
108
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109 /* Get socket from dispatch thread. */
110 size_ret = lttng_read(apps_cmd_notify_pipe[0],
111 &sock, sizeof(sock));
112 if (size_ret < sizeof(sock)) {
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113 PERROR("read apps notify pipe");
114 goto error;
115 }
380e8d6f 116 health_code_update();
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117
118 ret = lttng_poll_add(&events, sock,
119 LPOLLIN | LPOLLERR | LPOLLHUP | LPOLLRDHUP);
120 if (ret < 0) {
121 /*
122 * It's possible we've reached the max poll fd allowed.
123 * Let's close the socket but continue normal execution.
124 */
125 ret = close(sock);
126 if (ret) {
127 PERROR("close notify socket %d", sock);
128 }
129 lttng_fd_put(LTTNG_FD_APPS, 1);
130 continue;
131 }
132 DBG3("UST thread notify added sock %d to pollset", sock);
133 } else {
134 /*
135 * At this point, we know that a registered application
136 * triggered the event.
137 */
138 if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
139 /* Removing from the poll set */
140 ret = lttng_poll_del(&events, pollfd);
141 if (ret < 0) {
142 goto error;
143 }
144
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145 /* The socket is closed after a grace period here. */
146 ust_app_notify_sock_unregister(pollfd);
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147 } else if (revents & (LPOLLIN | LPOLLPRI)) {
148 ret = ust_app_recv_notify(pollfd);
149 if (ret < 0) {
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150 /*
151 * If the notification failed either the application is
152 * dead or an internal error happened. In both cases,
153 * we can only continue here. If the application is
154 * dead, an unregistration will follow or else the
155 * application will notice that we are not responding
156 * on that socket and will close it.
157 */
158 continue;
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159 }
160 } else {
161 ERR("Unknown poll events %u for sock %d", revents, pollfd);
162 continue;
163 }
380e8d6f 164 health_code_update();
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165 }
166 }
167 }
168
169exit:
170error:
171 lttng_poll_clean(&events);
172error_poll_create:
173 utils_close_pipe(apps_cmd_notify_pipe);
174 apps_cmd_notify_pipe[0] = apps_cmd_notify_pipe[1] = -1;
175 DBG("Application notify communication apps thread cleanup complete");
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176 if (err) {
177 health_error();
178 ERR("Health error occurred in %s", __func__);
179 }
8782cc74 180 health_unregister(health_sessiond);
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181 rcu_thread_offline();
182 rcu_unregister_thread();
183 return NULL;
184}
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