mirror of
https://github.com/openvswitch/ovs
synced 2025-08-22 18:07:40 +00:00
066a84f89a
1. Make latch behave as described and documented - clear all outstanding latch writes when invoking latch_poll(). 2. Decrease the size of the latch buffer. Less stack usage, less cache thrashing. Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com> Signed-off-by: Ben Pfaff <blp@ovn.org>
96 lines
2.3 KiB
C
96 lines
2.3 KiB
C
/*
|
|
* 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);
|
|
}
|