108 lines
3.1 KiB
C++
108 lines
3.1 KiB
C++
/*
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* Copyright (C) 2009-2015 Max Kellermann <max.kellermann@gmail.com>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* - Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* - Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef THREAD_POSIX_COND_HXX
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#define THREAD_POSIX_COND_HXX
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#include "PosixMutex.hxx"
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#include <chrono>
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#include <sys/time.h>
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/**
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* Low-level wrapper for a pthread_cond_t.
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*/
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class PosixCond {
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pthread_cond_t cond;
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public:
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#ifdef __GLIBC__
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/* optimized constexpr constructor for pthread implementations
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that support it */
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constexpr PosixCond() noexcept:cond(PTHREAD_COND_INITIALIZER) {}
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#else
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/* slow fallback for pthread implementations that are not
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compatible with "constexpr" */
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PosixCond() noexcept {
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pthread_cond_init(&cond, nullptr);
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}
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~PosixCond() noexcept {
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pthread_cond_destroy(&cond);
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}
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#endif
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PosixCond(const PosixCond &other) = delete;
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PosixCond &operator=(const PosixCond &other) = delete;
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void signal() noexcept {
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pthread_cond_signal(&cond);
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}
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void broadcast() noexcept {
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pthread_cond_broadcast(&cond);
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}
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void wait(PosixMutex &mutex) noexcept {
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pthread_cond_wait(&cond, &mutex.mutex);
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}
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private:
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bool timed_wait(PosixMutex &mutex, unsigned timeout_ms) noexcept {
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struct timeval now;
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gettimeofday(&now, nullptr);
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struct timespec ts;
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ts.tv_sec = now.tv_sec + timeout_ms / 1000;
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ts.tv_nsec = (now.tv_usec + (timeout_ms % 1000) * 1000) * 1000;
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// Keep tv_nsec < 1E9 to prevent return of EINVAL
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if (ts.tv_nsec >= 1000000000) {
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ts.tv_nsec -= 1000000000;
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ts.tv_sec++;
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}
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return pthread_cond_timedwait(&cond, &mutex.mutex, &ts) == 0;
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}
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public:
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bool timed_wait(PosixMutex &mutex,
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std::chrono::steady_clock::duration timeout) noexcept {
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auto timeout_ms = std::chrono::duration_cast<std::chrono::milliseconds>(timeout).count();
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if (timeout_ms < 0)
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timeout_ms = 0;
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else if (timeout_ms > std::numeric_limits<unsigned>::max())
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timeout_ms = std::numeric_limits<unsigned>::max();
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return timed_wait(mutex, timeout_ms);
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}
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};
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#endif
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