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48 lines
819 B
C++
48 lines
819 B
C++
// Copyright (c) 2012 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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#include "net/disk_cache/blockfile/file_lock.h"
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#include "base/atomicops.h"
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namespace {
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void Barrier() {
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#if !defined(COMPILER_MSVC)
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// VS uses memory barrier semantics for volatiles.
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base::subtle::MemoryBarrier();
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#endif
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}
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} // namespace
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namespace disk_cache {
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FileLock::FileLock(BlockFileHeader* header) {
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updating_ = &header->updating;
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(*updating_)++;
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Barrier();
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acquired_ = true;
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}
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FileLock::~FileLock() {
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Unlock();
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}
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void FileLock::Lock() {
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if (acquired_)
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return;
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(*updating_)++;
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Barrier();
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}
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void FileLock::Unlock() {
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if (!acquired_)
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return;
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Barrier();
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(*updating_)--;
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}
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} // namespace disk_cache
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