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a7333da7 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> | |
23 | ||
24 | /* | |
25 | * Quit pipe for all threads. This permits a single cancellation point | |
26 | * for all threads when receiving an event on the pipe. | |
27 | */ | |
28 | static int thread_quit_pipe[2] = { -1, -1 }; | |
29 | ||
30 | /* | |
31 | * Init thread quit pipe. | |
32 | * | |
33 | * Return -1 on error or 0 if all pipes are created. | |
34 | */ | |
35 | static int __init_thread_quit_pipe(int *a_pipe) | |
36 | { | |
37 | int ret, i; | |
38 | ||
39 | ret = pipe(a_pipe); | |
40 | if (ret < 0) { | |
41 | PERROR("thread quit pipe"); | |
42 | goto error; | |
43 | } | |
44 | ||
45 | for (i = 0; i < 2; i++) { | |
46 | ret = fcntl(a_pipe[i], F_SETFD, FD_CLOEXEC); | |
47 | if (ret < 0) { | |
48 | PERROR("fcntl"); | |
49 | goto error; | |
50 | } | |
51 | } | |
52 | ||
53 | error: | |
54 | return ret; | |
55 | } | |
56 | ||
57 | int sessiond_init_thread_quit_pipe(void) | |
58 | { | |
59 | return __init_thread_quit_pipe(thread_quit_pipe); | |
60 | } | |
61 | ||
62 | int sessiond_check_thread_quit_pipe(int fd, uint32_t events) | |
63 | { | |
64 | return (fd == thread_quit_pipe[0] && (events & LPOLLIN)); | |
65 | } | |
66 | ||
67 | /* | |
68 | * Wait for a notification on the quit pipe (with a timeout). | |
69 | * | |
70 | * Returns 1 if the caller should quit, 0 if the timeout was reached, and | |
71 | * -1 if an error was encountered. | |
72 | */ | |
73 | int sessiond_wait_for_quit_pipe(unsigned int timeout_us) | |
74 | { | |
75 | int ret; | |
76 | fd_set read_fds; | |
77 | struct timeval timeout; | |
78 | ||
79 | FD_ZERO(&read_fds); | |
80 | FD_SET(thread_quit_pipe[0], &read_fds); | |
81 | memset(&timeout, 0, sizeof(timeout)); | |
82 | timeout.tv_usec = timeout_us; | |
83 | ||
84 | while (true) { | |
85 | ret = select(thread_quit_pipe[0] + 1, &read_fds, NULL, NULL, | |
86 | &timeout); | |
87 | if (ret < 0 && errno == EINTR) { | |
88 | /* Retry on interrupt. */ | |
89 | continue; | |
90 | } else { | |
91 | break; | |
92 | } | |
93 | } | |
94 | ||
95 | if (ret > 0) { | |
96 | /* Should quit. */ | |
97 | ret = 1; | |
98 | } else if (ret < 0 && errno != EINTR) { | |
99 | /* Unknown error. */ | |
100 | PERROR("Failed to select() thread quit pipe"); | |
101 | ret = -1; | |
102 | } else { | |
103 | /* Timeout reached. */ | |
104 | ret = 0; | |
105 | } | |
106 | ||
107 | return ret; | |
108 | } | |
109 | ||
110 | int sessiond_notify_quit_pipe(void) | |
111 | { | |
112 | return notify_thread_pipe(thread_quit_pipe[1]); | |
113 | } | |
114 | ||
115 | void sessiond_close_quit_pipe(void) | |
116 | { | |
117 | utils_close_pipe(thread_quit_pipe); | |
118 | } | |
119 | ||
120 | static | |
121 | int __sessiond_set_thread_pollset(struct lttng_poll_event *events, size_t size, | |
122 | int *a_pipe) | |
123 | { | |
124 | int ret; | |
125 | ||
126 | assert(events); | |
127 | ||
128 | ret = lttng_poll_create(events, size, LTTNG_CLOEXEC); | |
129 | if (ret < 0) { | |
130 | goto error; | |
131 | } | |
132 | ||
133 | /* Add quit pipe */ | |
134 | ret = lttng_poll_add(events, a_pipe[0], LPOLLIN | LPOLLERR); | |
135 | if (ret < 0) { | |
136 | goto error; | |
137 | } | |
138 | ||
139 | return 0; | |
140 | ||
141 | error: | |
142 | return ret; | |
143 | } | |
144 | ||
145 | /* | |
146 | * Create a poll set with O_CLOEXEC and add the thread quit pipe to the set. | |
147 | */ | |
148 | int sessiond_set_thread_pollset(struct lttng_poll_event *events, size_t size) | |
149 | { | |
150 | return __sessiond_set_thread_pollset(events, size, thread_quit_pipe); | |
151 | } |