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1 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2006-2009 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #ifndef BASE_LOCK_H_ | 5 #ifndef BASE_LOCK_H_ |
6 #define BASE_LOCK_H_ | 6 #define BASE_LOCK_H_ |
7 | 7 |
8 #include "base/lock_impl.h" | 8 #include "base/lock_impl.h" |
9 | 9 |
10 // A convenient wrapper for an OS specific critical section. | 10 // A convenient wrapper for an OS specific critical section. |
11 | 11 |
12 class Lock { | 12 class Lock { |
13 public: | 13 public: |
14 Lock() : lock_() {} | 14 Lock() : lock_() {} |
15 ~Lock() {} | 15 ~Lock() {} |
16 void Acquire() { lock_.Lock(); } | 16 void Acquire() { lock_.Lock(); } |
17 void Release() { lock_.Unlock(); } | 17 void Release() { lock_.Unlock(); } |
18 // If the lock is not held, take it and return true. If the lock is already | 18 // If the lock is not held, take it and return true. If the lock is already |
19 // held by another thread, immediately return false. | 19 // held by another thread, immediately return false. |
20 bool Try() { return lock_.Try(); } | 20 bool Try() { return lock_.Try(); } |
21 | 21 |
| 22 // In debug builds this method checks that the lock has been acquired by the |
| 23 // calling thread. If the lock has not been acquired, then the method |
| 24 // will DCHECK(). In non-debug builds, the LockImpl's implementation of |
| 25 // AssertAcquired() is an empty inline method. |
| 26 void AssertAcquired() { return lock_.AssertAcquired(); } |
| 27 |
22 // Return the underlying lock implementation. | 28 // Return the underlying lock implementation. |
23 // TODO(awalker): refactor lock and condition variables so that this is | 29 // TODO(awalker): refactor lock and condition variables so that this is |
24 // unnecessary. | 30 // unnecessary. |
25 LockImpl* lock_impl() { return &lock_; } | 31 LockImpl* lock_impl() { return &lock_; } |
26 | 32 |
27 private: | 33 private: |
28 LockImpl lock_; // Platform specific underlying lock implementation. | 34 LockImpl lock_; // Platform specific underlying lock implementation. |
29 | 35 |
30 DISALLOW_COPY_AND_ASSIGN(Lock); | 36 DISALLOW_COPY_AND_ASSIGN(Lock); |
31 }; | 37 }; |
32 | 38 |
33 // A helper class that acquires the given Lock while the AutoLock is in scope. | 39 // A helper class that acquires the given Lock while the AutoLock is in scope. |
34 class AutoLock { | 40 class AutoLock { |
35 public: | 41 public: |
36 explicit AutoLock(Lock& lock) : lock_(lock) { | 42 explicit AutoLock(Lock& lock) : lock_(lock) { |
37 lock_.Acquire(); | 43 lock_.Acquire(); |
38 } | 44 } |
39 | 45 |
40 ~AutoLock() { | 46 ~AutoLock() { |
| 47 lock_.AssertAcquired(); |
41 lock_.Release(); | 48 lock_.Release(); |
42 } | 49 } |
43 | 50 |
44 private: | 51 private: |
45 Lock& lock_; | 52 Lock& lock_; |
46 DISALLOW_COPY_AND_ASSIGN(AutoLock); | 53 DISALLOW_COPY_AND_ASSIGN(AutoLock); |
47 }; | 54 }; |
48 | 55 |
49 // AutoUnlock is a helper class for ConditionVariable that will Release() the | 56 // AutoUnlock is a helper that will Release() the |lock| argument in the |
50 // lock argument in the constructor, and re-Acquire() it in the destructor. | 57 // constructor, and re-Acquire() it in the destructor. |
51 class ConditionVariable; | |
52 class AutoUnlock { | 58 class AutoUnlock { |
53 private: // Everything is private, so only our friend can use us. | 59 public: |
54 friend class ConditionVariable; // The only user of this class. | 60 explicit AutoUnlock(Lock& lock) : lock_(lock) { |
55 | |
56 explicit AutoUnlock(Lock& lock) : lock_(&lock) { | |
57 // We require our caller to have the lock. | 61 // We require our caller to have the lock. |
58 lock_->Release(); | 62 lock_.AssertAcquired(); |
| 63 lock_.Release(); |
59 } | 64 } |
60 | 65 |
61 ~AutoUnlock() { | 66 ~AutoUnlock() { |
62 lock_->Acquire(); | 67 lock_.Acquire(); |
63 } | 68 } |
64 | 69 |
65 Lock* lock_; | 70 private: |
| 71 Lock& lock_; |
| 72 DISALLOW_COPY_AND_ASSIGN(AutoUnlock); |
66 }; | 73 }; |
67 | 74 |
68 #endif // BASE_LOCK_H_ | 75 #endif // BASE_LOCK_H_ |
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