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| 1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2011 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_SYNCHRONIZATION_LOCK_H_ | 5 #ifndef BASE_SYNCHRONIZATION_LOCK_H_ |
| 6 #define BASE_SYNCHRONIZATION_LOCK_H_ | 6 #define BASE_SYNCHRONIZATION_LOCK_H_ |
| 7 | 7 |
| 8 #include "base/base_export.h" | 8 #include "base/base_export.h" |
| 9 #include "base/synchronization/lock_impl.h" | 9 #include "base/synchronization/lock_impl.h" |
| 10 #include "base/threading/platform_thread.h" | 10 #include "base/threading/platform_thread.h" |
| 11 | 11 |
| 12 namespace base { | 12 namespace base { |
| 13 | 13 |
| 14 // A convenient wrapper for an OS specific critical section. The only real | 14 // A convenient wrapper for an OS specific critical section. The only real |
| 15 // intelligence in this class is in debug mode for the support for the | 15 // intelligence in this class is in debug mode for the support for the |
| 16 // AssertAcquired() method. | 16 // AssertAcquired() method. |
| 17 class BASE_EXPORT Lock { | 17 class BASE_EXPORT Lock { |
| 18 public: | 18 public: |
| 19 #if defined(NDEBUG) // Optimized wrapper implementation | |
| 20 Lock() : lock_() {} | |
| 21 ~Lock() {} | |
| 22 void Acquire() { lock_.Lock(); } | |
| 23 void Release() { lock_.Unlock(); } | |
| 24 | |
| 25 // If the lock is not held, take it and return true. If the lock is already | |
| 26 // held by another thread, immediately return false. This must not be called | |
| 27 // by a thread already holding the lock (what happens is undefined and an | |
| 28 // assertion may fail). | |
| 29 bool Try() { return lock_.Try(); } | |
| 30 | |
| 31 // Null implementation if not debug. | |
| 32 void AssertAcquired() const {} | |
| 33 #else | |
| 34 Lock(); | 19 Lock(); |
| 35 ~Lock() {} | 20 ~Lock() {} |
| 36 | 21 |
| 37 // NOTE: Although windows critical sections support recursive locks, we do not | 22 // NOTE: Although windows critical sections support recursive locks, we do not |
| 38 // allow this, and we will commonly fire a DCHECK() if a thread attempts to | 23 // allow this, and we will commonly fire a DCHECK() if a thread attempts to |
| 39 // acquire the lock a second time (while already holding it). | 24 // acquire the lock a second time (while already holding it). |
| 40 void Acquire() { | 25 void Acquire() { |
| 41 lock_.Lock(); | 26 lock_.Lock(); |
| 42 CheckUnheldAndMark(); | 27 CheckUnheldAndMark(); |
| 43 } | 28 } |
| 44 void Release() { | 29 void Release() { |
| 45 CheckHeldAndUnmark(); | 30 CheckHeldAndUnmark(); |
| 46 lock_.Unlock(); | 31 lock_.Unlock(); |
| 47 } | 32 } |
| 48 | 33 |
| 49 bool Try() { | 34 bool Try() { |
| 50 bool rv = lock_.Try(); | 35 bool rv = lock_.Try(); |
| 51 if (rv) { | 36 if (rv) { |
| 52 CheckUnheldAndMark(); | 37 CheckUnheldAndMark(); |
| 53 } | 38 } |
| 54 return rv; | 39 return rv; |
| 55 } | 40 } |
| 56 | 41 |
| 57 void AssertAcquired() const; | 42 void AssertAcquired() const; |
| 58 #endif // NDEBUG | |
| 59 | 43 |
| 60 #if defined(OS_POSIX) | 44 #if defined(OS_POSIX) |
| 61 // The posix implementation of ConditionVariable needs to be able | 45 // The posix implementation of ConditionVariable needs to be able |
| 62 // to see our lock and tweak our debugging counters, as it releases | 46 // to see our lock and tweak our debugging counters, as it releases |
| 63 // and acquires locks inside of pthread_cond_{timed,}wait. | 47 // and acquires locks inside of pthread_cond_{timed,}wait. |
| 64 friend class ConditionVariable; | 48 friend class ConditionVariable; |
| 65 #elif defined(OS_WIN) | 49 #elif defined(OS_WIN) |
| 66 // The Windows Vista implementation of ConditionVariable needs the | 50 // The Windows Vista implementation of ConditionVariable needs the |
| 67 // native handle of the critical section. | 51 // native handle of the critical section. |
| 68 friend class WinVistaCondVar; | 52 friend class WinVistaCondVar; |
| 69 #endif | 53 #endif |
| 70 | 54 |
| 71 private: | 55 private: |
| 72 #if !defined(NDEBUG) | |
| 73 // Members and routines taking care of locks assertions. | 56 // Members and routines taking care of locks assertions. |
| 74 // Note that this checks for recursive locks and allows them | 57 // Note that this checks for recursive locks and allows them |
| 75 // if the variable is set. This is allowed by the underlying implementation | 58 // if the variable is set. This is allowed by the underlying implementation |
| 76 // on windows but not on Posix, so we're doing unneeded checks on Posix. | 59 // on windows but not on Posix, so we're doing unneeded checks on Posix. |
| 77 // It's worth it to share the code. | 60 // It's worth it to share the code. |
| 78 void CheckHeldAndUnmark(); | 61 void CheckHeldAndUnmark(); |
| 79 void CheckUnheldAndMark(); | 62 void CheckUnheldAndMark(); |
| 80 | 63 |
| 81 // All private data is implicitly protected by lock_. | 64 // All private data is implicitly protected by lock_. |
| 82 // Be VERY careful to only access members under that lock. | 65 // Be VERY careful to only access members under that lock. |
| 83 | 66 |
| 84 // Determines validity of owning_thread_id_. Needed as we don't have | 67 // Determines validity of owning_thread_id_. Needed as we don't have |
| 85 // a null owning_thread_id_ value. | 68 // a null owning_thread_id_ value. |
| 86 bool owned_by_thread_; | 69 bool owned_by_thread_; |
| 87 base::PlatformThreadId owning_thread_id_; | 70 base::PlatformThreadId owning_thread_id_; |
| 88 #endif // NDEBUG | |
| 89 | 71 |
| 90 // Platform specific underlying lock implementation. | 72 // Platform specific underlying lock implementation. |
| 91 internal::LockImpl lock_; | 73 internal::LockImpl lock_; |
| 92 | 74 |
| 93 DISALLOW_COPY_AND_ASSIGN(Lock); | 75 DISALLOW_COPY_AND_ASSIGN(Lock); |
| 94 }; | 76 }; |
| 95 | 77 |
| 96 // A helper class that acquires the given Lock while the AutoLock is in scope. | 78 // A helper class that acquires the given Lock while the AutoLock is in scope. |
| 97 class AutoLock { | 79 class AutoLock { |
| 98 public: | 80 public: |
| (...skipping 26 matching lines...) Expand all Loading... |
| 125 } | 107 } |
| 126 | 108 |
| 127 private: | 109 private: |
| 128 Lock& lock_; | 110 Lock& lock_; |
| 129 DISALLOW_COPY_AND_ASSIGN(AutoUnlock); | 111 DISALLOW_COPY_AND_ASSIGN(AutoUnlock); |
| 130 }; | 112 }; |
| 131 | 113 |
| 132 } // namespace base | 114 } // namespace base |
| 133 | 115 |
| 134 #endif // BASE_SYNCHRONIZATION_LOCK_H_ | 116 #endif // BASE_SYNCHRONIZATION_LOCK_H_ |
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