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71973b04 SH |
1 | /* |
2 | * Event loop with file descriptor polling | |
3 | * | |
4 | * Copyright 2012 IBM, Corp. | |
5 | * Copyright 2012 Red Hat, Inc. and/or its affiliates | |
6 | * | |
7 | * Authors: | |
8 | * Stefan Hajnoczi <stefanha@redhat.com> | |
9 | * | |
10 | * This work is licensed under the terms of the GNU GPL, version 2 or later. | |
11 | * See the COPYING file in the top-level directory. | |
12 | * | |
13 | */ | |
14 | ||
15 | #include <sys/epoll.h> | |
83c9f4ca | 16 | #include "event-poll.h" |
71973b04 SH |
17 | |
18 | /* Add an event notifier and its callback for polling */ | |
19 | void event_poll_add(EventPoll *poll, EventHandler *handler, | |
20 | EventNotifier *notifier, EventCallback *callback) | |
21 | { | |
22 | struct epoll_event event = { | |
23 | .events = EPOLLIN, | |
24 | .data.ptr = handler, | |
25 | }; | |
26 | handler->notifier = notifier; | |
27 | handler->callback = callback; | |
28 | if (epoll_ctl(poll->epoll_fd, EPOLL_CTL_ADD, | |
29 | event_notifier_get_fd(notifier), &event) != 0) { | |
30 | fprintf(stderr, "failed to add event handler to epoll: %m\n"); | |
31 | exit(1); | |
32 | } | |
33 | } | |
34 | ||
35 | /* Event callback for stopping event_poll() */ | |
36 | static void handle_stop(EventHandler *handler) | |
37 | { | |
38 | /* Do nothing */ | |
39 | } | |
40 | ||
41 | void event_poll_init(EventPoll *poll) | |
42 | { | |
43 | /* Create epoll file descriptor */ | |
44 | poll->epoll_fd = epoll_create1(EPOLL_CLOEXEC); | |
45 | if (poll->epoll_fd < 0) { | |
46 | fprintf(stderr, "epoll_create1 failed: %m\n"); | |
47 | exit(1); | |
48 | } | |
49 | ||
50 | /* Set up stop notifier */ | |
51 | if (event_notifier_init(&poll->stop_notifier, 0) < 0) { | |
52 | fprintf(stderr, "failed to init stop notifier\n"); | |
53 | exit(1); | |
54 | } | |
55 | event_poll_add(poll, &poll->stop_handler, | |
56 | &poll->stop_notifier, handle_stop); | |
57 | } | |
58 | ||
59 | void event_poll_cleanup(EventPoll *poll) | |
60 | { | |
61 | event_notifier_cleanup(&poll->stop_notifier); | |
62 | close(poll->epoll_fd); | |
63 | poll->epoll_fd = -1; | |
64 | } | |
65 | ||
66 | /* Block until the next event and invoke its callback */ | |
67 | void event_poll(EventPoll *poll) | |
68 | { | |
69 | EventHandler *handler; | |
70 | struct epoll_event event; | |
71 | int nevents; | |
72 | ||
73 | /* Wait for the next event. Only do one event per call to keep the | |
74 | * function simple, this could be changed later. */ | |
75 | do { | |
76 | nevents = epoll_wait(poll->epoll_fd, &event, 1, -1); | |
77 | } while (nevents < 0 && errno == EINTR); | |
78 | if (unlikely(nevents != 1)) { | |
79 | fprintf(stderr, "epoll_wait failed: %m\n"); | |
80 | exit(1); /* should never happen */ | |
81 | } | |
82 | ||
83 | /* Find out which event handler has become active */ | |
84 | handler = event.data.ptr; | |
85 | ||
86 | /* Clear the eventfd */ | |
87 | event_notifier_test_and_clear(handler->notifier); | |
88 | ||
89 | /* Handle the event */ | |
90 | handler->callback(handler); | |
91 | } | |
92 | ||
93 | /* Stop event_poll() | |
94 | * | |
95 | * This function can be used from another thread. | |
96 | */ | |
97 | void event_poll_notify(EventPoll *poll) | |
98 | { | |
99 | event_notifier_set(&poll->stop_notifier); | |
100 | } |