OLD | NEW |
| (Empty) |
1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #include "net/disk_cache/blockfile/file_lock.h" | |
6 | |
7 #include "base/atomicops.h" | |
8 | |
9 namespace { | |
10 | |
11 void Barrier() { | |
12 #if !defined(COMPILER_MSVC) | |
13 // VS uses memory barrier semantics for volatiles. | |
14 base::subtle::MemoryBarrier(); | |
15 #endif | |
16 } | |
17 | |
18 } // namespace | |
19 | |
20 namespace disk_cache { | |
21 | |
22 FileLock::FileLock(BlockFileHeader* header) { | |
23 updating_ = &header->updating; | |
24 (*updating_)++; | |
25 Barrier(); | |
26 acquired_ = true; | |
27 } | |
28 | |
29 FileLock::~FileLock() { | |
30 Unlock(); | |
31 } | |
32 | |
33 void FileLock::Lock() { | |
34 if (acquired_) | |
35 return; | |
36 (*updating_)++; | |
37 Barrier(); | |
38 } | |
39 | |
40 void FileLock::Unlock() { | |
41 if (!acquired_) | |
42 return; | |
43 Barrier(); | |
44 (*updating_)--; | |
45 } | |
46 | |
47 } // namespace disk_cache | |
OLD | NEW |