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51bb4dbb JG |
1 | /* |
2 | * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca> | |
3 | * Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
4 | * 2013 - Jérémie Galarneau <jeremie.galarneau@efficios.com> | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License, version 2 only, | |
8 | * as published by the Free Software Foundation. | |
9 | * | |
10 | * This program is distributed in the hope that it will be useful, | |
11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
13 | * GNU General Public License for more details. | |
14 | * | |
15 | * You should have received a copy of the GNU General Public License along | |
16 | * with this program; if not, write to the Free Software Foundation, Inc., | |
17 | * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. | |
18 | */ | |
19 | ||
20 | #include "lttng-sessiond.h" | |
21 | #include "utils.h" | |
22 | #include <common/utils.h> | |
6af972a2 JG |
23 | #include <pthread.h> |
24 | ||
25 | #define USEC_PER_SEC 1000000 | |
51bb4dbb JG |
26 | |
27 | /* | |
28 | * Quit pipe for all threads. This permits a single cancellation point | |
29 | * for all threads when receiving an event on the pipe. | |
30 | */ | |
31 | static int thread_quit_pipe[2] = { -1, -1 }; | |
32 | ||
33 | /* | |
34 | * Init thread quit pipe. | |
35 | * | |
36 | * Return -1 on error or 0 if all pipes are created. | |
37 | */ | |
38 | static int __init_thread_quit_pipe(int *a_pipe) | |
39 | { | |
40 | int ret, i; | |
41 | ||
42 | ret = pipe(a_pipe); | |
43 | if (ret < 0) { | |
44 | PERROR("thread quit pipe"); | |
45 | goto error; | |
46 | } | |
47 | ||
48 | for (i = 0; i < 2; i++) { | |
49 | ret = fcntl(a_pipe[i], F_SETFD, FD_CLOEXEC); | |
50 | if (ret < 0) { | |
51 | PERROR("fcntl"); | |
52 | goto error; | |
53 | } | |
54 | } | |
55 | ||
56 | error: | |
57 | return ret; | |
58 | } | |
59 | ||
60 | int sessiond_init_thread_quit_pipe(void) | |
61 | { | |
62 | return __init_thread_quit_pipe(thread_quit_pipe); | |
63 | } | |
64 | ||
65 | int sessiond_check_thread_quit_pipe(int fd, uint32_t events) | |
66 | { | |
67 | return (fd == thread_quit_pipe[0] && (events & LPOLLIN)); | |
68 | } | |
69 | ||
70 | /* | |
71 | * Wait for a notification on the quit pipe (with a timeout). | |
72 | * | |
6af972a2 JG |
73 | * A timeout value of -1U means no timeout. |
74 | * | |
51bb4dbb JG |
75 | * Returns 1 if the caller should quit, 0 if the timeout was reached, and |
76 | * -1 if an error was encountered. | |
77 | */ | |
78 | int sessiond_wait_for_quit_pipe(unsigned int timeout_us) | |
79 | { | |
80 | int ret; | |
81 | fd_set read_fds; | |
82 | struct timeval timeout; | |
83 | ||
84 | FD_ZERO(&read_fds); | |
85 | FD_SET(thread_quit_pipe[0], &read_fds); | |
86 | memset(&timeout, 0, sizeof(timeout)); | |
6af972a2 JG |
87 | timeout.tv_sec = timeout_us / USEC_PER_SEC; |
88 | timeout.tv_usec = timeout_us % USEC_PER_SEC; | |
51bb4dbb JG |
89 | |
90 | while (true) { | |
91 | ret = select(thread_quit_pipe[0] + 1, &read_fds, NULL, NULL, | |
6af972a2 | 92 | timeout_us != -1U ? &timeout : NULL); |
51bb4dbb JG |
93 | if (ret < 0 && errno == EINTR) { |
94 | /* Retry on interrupt. */ | |
95 | continue; | |
96 | } else { | |
97 | break; | |
98 | } | |
99 | } | |
100 | ||
101 | if (ret > 0) { | |
102 | /* Should quit. */ | |
103 | ret = 1; | |
104 | } else if (ret < 0 && errno != EINTR) { | |
105 | /* Unknown error. */ | |
106 | PERROR("Failed to select() thread quit pipe"); | |
107 | ret = -1; | |
108 | } else { | |
109 | /* Timeout reached. */ | |
110 | ret = 0; | |
111 | } | |
112 | ||
113 | return ret; | |
114 | } | |
115 | ||
116 | int sessiond_notify_quit_pipe(void) | |
117 | { | |
118 | return notify_thread_pipe(thread_quit_pipe[1]); | |
119 | } | |
120 | ||
121 | void sessiond_close_quit_pipe(void) | |
122 | { | |
123 | utils_close_pipe(thread_quit_pipe); | |
124 | } | |
125 | ||
126 | static | |
127 | int __sessiond_set_thread_pollset(struct lttng_poll_event *events, size_t size, | |
128 | int *a_pipe) | |
129 | { | |
130 | int ret; | |
131 | ||
132 | assert(events); | |
133 | ||
134 | ret = lttng_poll_create(events, size, LTTNG_CLOEXEC); | |
135 | if (ret < 0) { | |
136 | goto error; | |
137 | } | |
138 | ||
139 | /* Add quit pipe */ | |
140 | ret = lttng_poll_add(events, a_pipe[0], LPOLLIN | LPOLLERR); | |
141 | if (ret < 0) { | |
142 | goto error; | |
143 | } | |
144 | ||
145 | return 0; | |
146 | ||
147 | error: | |
148 | return ret; | |
149 | } | |
150 | ||
151 | /* | |
152 | * Create a poll set with O_CLOEXEC and add the thread quit pipe to the set. | |
153 | */ | |
154 | int sessiond_set_thread_pollset(struct lttng_poll_event *events, size_t size) | |
155 | { | |
156 | return __sessiond_set_thread_pollset(events, size, thread_quit_pipe); | |
157 | } |