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fd016ae3fb
Poll-loop is the core to implement main loop. It should be available in libopenvswitch. Signed-off-by: Xiao Liang <shaw.leon@gmail.com> Signed-off-by: Ben Pfaff <blp@ovn.org>
88 lines
2.1 KiB
C
88 lines
2.1 KiB
C
/*
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* Copyright (c) 2013 Nicira, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <config.h>
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#include "latch.h"
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#include <errno.h>
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#include <poll.h>
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#include <unistd.h>
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#include "openvswitch/poll-loop.h"
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#include "socket-util.h"
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/* Initializes 'latch' as initially unset. */
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void
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latch_init(struct latch *latch)
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{
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xpipe_nonblocking(latch->fds);
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}
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/* Destroys 'latch'. */
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void
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latch_destroy(struct latch *latch)
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{
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close(latch->fds[0]);
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close(latch->fds[1]);
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}
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/* Resets 'latch' to the unset state. Returns true if 'latch' was previously
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* set, false otherwise. */
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bool
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latch_poll(struct latch *latch)
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{
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char buffer[_POSIX_PIPE_BUF];
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return read(latch->fds[0], buffer, sizeof buffer) > 0;
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}
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/* Sets 'latch'.
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*
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* Calls are not additive: a single latch_poll() clears out any number of
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* latch_set(). */
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void
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latch_set(struct latch *latch)
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{
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ignore(write(latch->fds[1], "", 1));
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}
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/* Returns true if 'latch' is set, false otherwise. Does not reset 'latch'
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* to the unset state. */
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bool
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latch_is_set(const struct latch *latch)
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{
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struct pollfd pfd;
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int retval;
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pfd.fd = latch->fds[0];
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pfd.events = POLLIN;
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do {
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retval = poll(&pfd, 1, 0);
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} while (retval < 0 && errno == EINTR);
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return pfd.revents & POLLIN;
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}
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/* Causes the next poll_block() to wake up when 'latch' is set.
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*
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* ('where' is used in debug logging. Commonly one would use latch_wait() to
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* automatically provide the caller's source file and line number for
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* 'where'.) */
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void
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latch_wait_at(const struct latch *latch, const char *where)
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{
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poll_fd_wait_at(latch->fds[0], POLLIN, where);
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}
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