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/*
* Copyright (c) 2013 Nicira, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <config.h>
#include "latch.h"
#include <errno.h>
#include <poll.h>
#include <unistd.h>
#include "openvswitch/poll-loop.h"
#include "socket-util.h"
/* Initializes 'latch' as initially unset. */
void
latch_init(struct latch *latch)
{
xpipe_nonblocking(latch->fds);
}
/* Destroys 'latch'. */
void
latch_destroy(struct latch *latch)
{
close(latch->fds[0]);
close(latch->fds[1]);
}
/* Resets 'latch' to the unset state. Returns true if 'latch' was previously
* set, false otherwise. */
bool
latch_poll(struct latch *latch)
{
char latch_buffer[16];
bool result = false;
int ret;
do {
ret = read(latch->fds[0], &latch_buffer, sizeof latch_buffer);
result |= ret > 0;
/* Repeat as long as read() reads a full buffer. */
} while (ret == sizeof latch_buffer);
return result;
}
/* Sets 'latch'.
*
* Calls are not additive: a single latch_poll() clears out any number of
* latch_set(). */
void
latch_set(struct latch *latch)
{
ignore(write(latch->fds[1], "", 1));
}
/* Returns true if 'latch' is set, false otherwise. Does not reset 'latch'
* to the unset state. */
bool
latch_is_set(const struct latch *latch)
{
struct pollfd pfd;
int retval;
pfd.fd = latch->fds[0];
pfd.events = POLLIN;
do {
retval = poll(&pfd, 1, 0);
} while (retval < 0 && errno == EINTR);
return pfd.revents & POLLIN;
}
/* Causes the next poll_block() to wake up when 'latch' is set.
*
* ('where' is used in debug logging. Commonly one would use latch_wait() to
* automatically provide the caller's source file and line number for
* 'where'.) */
void
latch_wait_at(const struct latch *latch, const char *where)
{
poll_fd_wait_at(latch->fds[0], POLLIN, where);
}
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