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88 lines
3.3 KiB
C++
88 lines
3.3 KiB
C++
// Copyright (c) 2014 Marshall A. Greenblatt. Portions copyright (c) 2011
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// Google 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 are
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// 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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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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// * Neither the name of Google Inc. nor the name Chromium Embedded
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// Framework nor the names of its contributors may be used to endorse
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// or promote products derived from this software without specific prior
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// written permission.
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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 FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY 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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#ifndef CEF_INCLUDE_BASE_CEF_ATOMIC_FLAG_H_
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#define CEF_INCLUDE_BASE_CEF_ATOMIC_FLAG_H_
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#pragma once
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#if defined(USING_CHROMIUM_INCLUDES)
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// When building CEF include the Chromium header directly.
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#include "base/synchronization/atomic_flag.h"
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#else // !USING_CHROMIUM_INCLUDES
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// The following is substantially similar to the Chromium implementation.
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// If the Chromium implementation diverges the below implementation should be
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// updated to match.
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#include <stdint.h>
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#include <atomic>
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#include "include/base/cef_macros.h"
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#include "include/base/cef_thread_checker.h"
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namespace base {
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// A flag that can safely be set from one thread and read from other threads.
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//
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// This class IS NOT intended for synchronization between threads.
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class AtomicFlag {
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public:
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AtomicFlag();
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~AtomicFlag();
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// Set the flag. Must always be called from the same thread.
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void Set();
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// Returns true iff the flag was set. If this returns true, the current thread
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// is guaranteed to be synchronized with all memory operations on the thread
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// which invoked Set() up until at least the first call to Set() on it.
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bool IsSet() const {
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// Inline here: this has a measurable performance impact on base::WeakPtr.
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return flag_.load(std::memory_order_acquire) != 0;
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}
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// Resets the flag. Be careful when using this: callers might not expect
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// IsSet() to return false after returning true once.
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void UnsafeResetForTesting();
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private:
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std::atomic<uint_fast8_t> flag_{0};
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base::ThreadChecker set_thread_checker_;
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DISALLOW_COPY_AND_ASSIGN(AtomicFlag);
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};
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} // namespace base
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#endif // !USING_CHROMIUM_INCLUDES
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#endif // CEF_INCLUDE_BASE_CEF_ATOMIC_FLAG_H_
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