mirror of
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114 lines
3.1 KiB
C++
114 lines
3.1 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "mozilla/RWLock.h"
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#ifdef XP_WIN
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# include <windows.h>
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static_assert(sizeof(SRWLOCK) <= sizeof(void*), "SRWLOCK is too big!");
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# define NativeHandle(m) (reinterpret_cast<SRWLOCK*>(&m))
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#else
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# define NativeHandle(m) (&m)
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#endif
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namespace mozilla {
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RWLock::RWLock(const char* aName)
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: BlockingResourceBase(aName, eMutex)
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#ifdef DEBUG
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,
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mOwningThread(nullptr)
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#endif
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{
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#ifdef XP_WIN
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InitializeSRWLock(NativeHandle(mRWLock));
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#else
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MOZ_RELEASE_ASSERT(pthread_rwlock_init(NativeHandle(mRWLock), nullptr) == 0,
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"pthread_rwlock_init failed");
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#endif
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}
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#ifdef DEBUG
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bool RWLock::LockedForWritingByCurrentThread() {
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return mOwningThread == PR_GetCurrentThread();
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}
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#endif
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#ifndef XP_WIN
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RWLock::~RWLock() {
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MOZ_RELEASE_ASSERT(pthread_rwlock_destroy(NativeHandle(mRWLock)) == 0,
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"pthread_rwlock_destroy failed");
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}
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#endif
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bool RWLock::TryReadLockInternal() {
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#ifdef XP_WIN
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return TryAcquireSRWLockShared(NativeHandle(mRWLock));
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#else
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int rv = pthread_rwlock_tryrdlock(NativeHandle(mRWLock));
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// We allow EDEADLK here because it has been observed returned on macos when
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// the write lock is held by the current thread.
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MOZ_RELEASE_ASSERT(rv == 0 || rv == EBUSY || rv == EDEADLK,
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"pthread_rwlock_tryrdlock failed");
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return rv == 0;
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#endif
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}
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void RWLock::ReadLockInternal() {
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#ifdef XP_WIN
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AcquireSRWLockShared(NativeHandle(mRWLock));
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#else
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MOZ_RELEASE_ASSERT(pthread_rwlock_rdlock(NativeHandle(mRWLock)) == 0,
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"pthread_rwlock_rdlock failed");
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#endif
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}
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void RWLock::ReadUnlockInternal() {
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#ifdef XP_WIN
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ReleaseSRWLockShared(NativeHandle(mRWLock));
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#else
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MOZ_RELEASE_ASSERT(pthread_rwlock_unlock(NativeHandle(mRWLock)) == 0,
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"pthread_rwlock_unlock failed");
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#endif
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}
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bool RWLock::TryWriteLockInternal() {
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#ifdef XP_WIN
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return TryAcquireSRWLockExclusive(NativeHandle(mRWLock));
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#else
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int rv = pthread_rwlock_trywrlock(NativeHandle(mRWLock));
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// We allow EDEADLK here because it has been observed returned on macos when
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// the write lock is held by the current thread.
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MOZ_RELEASE_ASSERT(rv == 0 || rv == EBUSY || rv == EDEADLK,
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"pthread_rwlock_trywrlock failed");
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return rv == 0;
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#endif
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}
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void RWLock::WriteLockInternal() {
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#ifdef XP_WIN
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AcquireSRWLockExclusive(NativeHandle(mRWLock));
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#else
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MOZ_RELEASE_ASSERT(pthread_rwlock_wrlock(NativeHandle(mRWLock)) == 0,
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"pthread_rwlock_wrlock failed");
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#endif
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}
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void RWLock::WriteUnlockInternal() {
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#ifdef XP_WIN
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ReleaseSRWLockExclusive(NativeHandle(mRWLock));
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#else
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MOZ_RELEASE_ASSERT(pthread_rwlock_unlock(NativeHandle(mRWLock)) == 0,
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"pthread_rwlock_unlock failed");
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#endif
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}
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} // namespace mozilla
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#undef NativeHandle
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