]>
Commit | Line | Data |
---|---|---|
aad84c8e BP |
1 | /* |
2 | * Copyright (c) 2013 Nicira, Inc. | |
3 | * | |
4 | * Licensed under the Apache License, Version 2.0 (the "License"); | |
5 | * you may not use this file except in compliance with the License. | |
6 | * You may obtain a copy of the License at: | |
7 | * | |
8 | * http://www.apache.org/licenses/LICENSE-2.0 | |
9 | * | |
10 | * Unless required by applicable law or agreed to in writing, software | |
11 | * distributed under the License is distributed on an "AS IS" BASIS, | |
12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
13 | * See the License for the specific language governing permissions and | |
14 | * limitations under the License. | |
15 | */ | |
16 | ||
17 | #include <config.h> | |
18 | ||
19 | #include "latch.h" | |
20 | #include <errno.h> | |
21 | #include <poll.h> | |
22 | #include <unistd.h> | |
23 | #include "poll-loop.h" | |
24 | #include "socket-util.h" | |
25 | ||
26 | /* Initializes 'latch' as initially unset. */ | |
27 | void | |
28 | latch_init(struct latch *latch) | |
29 | { | |
30 | xpipe_nonblocking(latch->fds); | |
31 | } | |
32 | ||
33 | /* Destroys 'latch'. */ | |
34 | void | |
35 | latch_destroy(struct latch *latch) | |
36 | { | |
37 | close(latch->fds[0]); | |
38 | close(latch->fds[1]); | |
39 | } | |
40 | ||
41 | /* Resets 'latch' to the unset state. Returns true if 'latch' was previously | |
42 | * set, false otherwise. */ | |
43 | bool | |
44 | latch_poll(struct latch *latch) | |
45 | { | |
46 | char buffer[_POSIX_PIPE_BUF]; | |
47 | ||
48 | return read(latch->fds[0], buffer, sizeof buffer) > 0; | |
49 | } | |
50 | ||
51 | /* Sets 'latch'. | |
52 | * | |
53 | * Calls are not additive: a single latch_poll() clears out any number of | |
54 | * latch_set(). */ | |
55 | void | |
56 | latch_set(struct latch *latch) | |
57 | { | |
58 | ignore(write(latch->fds[1], "", 1)); | |
59 | } | |
60 | ||
61 | /* Returns true if 'latch' is set, false otherwise. Does not reset 'latch' | |
62 | * to the unset state. */ | |
63 | bool | |
64 | latch_is_set(const struct latch *latch) | |
65 | { | |
66 | struct pollfd pfd; | |
67 | int retval; | |
68 | ||
69 | pfd.fd = latch->fds[0]; | |
70 | pfd.events = POLLIN; | |
71 | do { | |
72 | retval = poll(&pfd, 1, 0); | |
73 | } while (retval < 0 && errno == EINTR); | |
74 | ||
75 | return pfd.revents & POLLIN; | |
76 | } | |
77 | ||
5453ae20 BP |
78 | /* Causes the next poll_block() to wake up when 'latch' is set. |
79 | * | |
80 | * ('where' is used in debug logging. Commonly one would use latch_wait() to | |
81 | * automatically provide the caller's source file and line number for | |
82 | * 'where'.) */ | |
aad84c8e | 83 | void |
5453ae20 | 84 | latch_wait_at(const struct latch *latch, const char *where) |
aad84c8e | 85 | { |
1ca3348e | 86 | poll_fd_wait_at(latch->fds[0], POLLIN, where); |
aad84c8e | 87 | } |