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79 lines
2.0 KiB
C
79 lines
2.0 KiB
C
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// Copyright (c) 2011 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_SYNCHRONIZATION_LOCK_IMPL_H_
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#define BASE_SYNCHRONIZATION_LOCK_IMPL_H_
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#include "base/base_export.h"
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#include "base/logging.h"
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#include "base/macros.h"
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#include "build/build_config.h"
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#if defined(OS_WIN)
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#include <windows.h>
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#elif defined(OS_POSIX)
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#include <errno.h>
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#include <pthread.h>
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#endif
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namespace base {
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namespace internal {
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// This class implements the underlying platform-specific spin-lock mechanism
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// used for the Lock class. Most users should not use LockImpl directly, but
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// should instead use Lock.
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class BASE_EXPORT LockImpl {
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public:
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#if defined(OS_WIN)
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using NativeHandle = SRWLOCK;
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#elif defined(OS_POSIX)
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using NativeHandle = pthread_mutex_t;
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#endif
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LockImpl();
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~LockImpl();
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// If the lock is not held, take it and return true. If the lock is already
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// held by something else, immediately return false.
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bool Try();
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// Take the lock, blocking until it is available if necessary.
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void Lock();
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// Release the lock. This must only be called by the lock's holder: after
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// a successful call to Try, or a call to Lock.
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inline void Unlock();
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// Return the native underlying lock.
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// TODO(awalker): refactor lock and condition variables so that this is
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// unnecessary.
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NativeHandle* native_handle() { return &native_handle_; }
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#if defined(OS_POSIX)
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// Whether this lock will attempt to use priority inheritance.
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static bool PriorityInheritanceAvailable();
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#endif
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private:
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NativeHandle native_handle_;
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DISALLOW_COPY_AND_ASSIGN(LockImpl);
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};
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#if defined(OS_WIN)
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void LockImpl::Unlock() {
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::ReleaseSRWLockExclusive(&native_handle_);
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}
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#elif defined(OS_POSIX)
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void LockImpl::Unlock() {
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int rv = pthread_mutex_unlock(&native_handle_);
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DCHECK_EQ(rv, 0) << ". " << strerror(rv);
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}
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#endif
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} // namespace internal
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} // namespace base
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#endif // BASE_SYNCHRONIZATION_LOCK_IMPL_H_
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