98 lines
3.6 KiB
C++
98 lines
3.6 KiB
C++
/*
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* Copyright (C) 2015-2017 Apple Inc. All rights reserved.
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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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* 1. 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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* 2. 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 distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "config.h"
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#include <wtf/Lock.h>
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#include <wtf/LockAlgorithmInlines.h>
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#include <wtf/StackShotProfiler.h>
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#if OS(WINDOWS)
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#include <windows.h>
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#else
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#include <unistd.h>
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#endif
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namespace WTF {
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static constexpr bool profileLockContention = false;
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void Lock::lockSlow()
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{
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if (profileLockContention)
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STACK_SHOT_PROFILE(4, 2, 5);
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// Heap allocations are forbidden on certain threads (e.g. audio rendering thread) for performance reasons so we need to
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// explicitly allow the following allocation(s). In some rare cases, the lockSlow() algorithm may cause allocations.
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DisableMallocRestrictionsForCurrentThreadScope disableMallocRestrictions;
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DefaultLockAlgorithm::lockSlow(m_byte);
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}
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void Lock::unlockSlow()
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{
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// Heap allocations are forbidden on certain threads (e.g. audio rendering thread) for performance reasons so we need to
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// explicitly allow the following allocation(s). In some rare cases, the unlockSlow() algorithm may cause allocations.
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DisableMallocRestrictionsForCurrentThreadScope disableMallocRestrictions;
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DefaultLockAlgorithm::unlockSlow(m_byte, DefaultLockAlgorithm::Unfair);
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}
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void Lock::unlockFairlySlow()
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{
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// Heap allocations are forbidden on certain threads (e.g. audio rendering thread) for performance reasons so we need to
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// explicitly allow the following allocation(s). In some rare cases, the unlockSlow() algorithm may cause allocations.
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DisableMallocRestrictionsForCurrentThreadScope disableMallocRestrictions;
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DefaultLockAlgorithm::unlockSlow(m_byte, DefaultLockAlgorithm::Fair);
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}
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void Lock::safepointSlow()
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{
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DefaultLockAlgorithm::safepointSlow(m_byte);
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}
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bool Lock::tryLockWithTimeout(Seconds timeout)
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{
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// This function may be called from a signal handler (e.g. via visit()). Hence,
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// it should only use APIs that are safe to call from signal handlers. This is
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// why we use unistd.h's sleep() instead of its alternatives.
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// We'll be doing sleep(1) between tries below. Hence, sleepPerRetry is 1.
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unsigned maxRetries = (timeout < Seconds::infinity()) ? timeout.value() : std::numeric_limits<unsigned>::max();
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unsigned tryCount = 0;
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while (!tryLock() && tryCount++ <= maxRetries) {
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#if OS(WINDOWS)
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Sleep(1000);
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#else
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::sleep(1);
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#endif
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}
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return isHeld();
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}
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} // namespace WTF
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