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git.proxmox.com Git - mirror_ovs.git/blob - lib/latch.c
2 * Copyright (c) 2013 Nicira, Inc.
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:
8 * http://www.apache.org/licenses/LICENSE-2.0
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.
23 #include "poll-loop.h"
24 #include "socket-util.h"
26 /* Initializes 'latch' as initially unset. */
28 latch_init(struct latch
*latch
)
30 xpipe_nonblocking(latch
->fds
);
33 /* Destroys 'latch'. */
35 latch_destroy(struct latch
*latch
)
41 /* Resets 'latch' to the unset state. Returns true if 'latch' was previously
42 * set, false otherwise. */
44 latch_poll(struct latch
*latch
)
46 char buffer
[_POSIX_PIPE_BUF
];
48 return read(latch
->fds
[0], buffer
, sizeof buffer
) > 0;
53 * Calls are not additive: a single latch_poll() clears out any number of
56 latch_set(struct latch
*latch
)
58 ignore(write(latch
->fds
[1], "", 1));
61 /* Returns true if 'latch' is set, false otherwise. Does not reset 'latch'
62 * to the unset state. */
64 latch_is_set(const struct latch
*latch
)
69 pfd
.fd
= latch
->fds
[0];
72 retval
= poll(&pfd
, 1, 0);
73 } while (retval
< 0 && errno
== EINTR
);
75 return pfd
.revents
& POLLIN
;
78 /* Causes the next poll_block() to wake up when 'latch' is set. */
80 (latch_wait
)(const struct latch
*latch
, const char *where
)
82 (poll_fd_wait
)(latch
->fds
[0], POLLIN
, where
);