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comparison: ipc/chromium/src/base/lock_impl_win.cc
ipc/chromium/src/base/lock_impl_win.cc
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| 1 // Copyright (c) 2006-2008 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 "base/lock_impl.h" | |
| 6 #include "base/logging.h" | |
| 7 | |
| 8 // NOTE: Although windows critical sections support recursive locks, we do not | |
| 9 // allow this, and we will commonly fire a DCHECK() if a thread attempts to | |
| 10 // acquire the lock a second time (while already holding it). | |
| 11 | |
| 12 LockImpl::LockImpl() { | |
| 13 #ifndef NDEBUG | |
| 14 recursion_count_shadow_ = 0; | |
| 15 recursion_used_ = false; | |
| 16 owning_thread_id_ = 0; | |
| 17 #endif // NDEBUG | |
| 18 // The second parameter is the spin count, for short-held locks it avoid the | |
| 19 // contending thread from going to sleep which helps performance greatly. | |
| 20 ::InitializeCriticalSectionAndSpinCount(&os_lock_, 2000); | |
| 21 } | |
| 22 | |
| 23 LockImpl::~LockImpl() { | |
| 24 ::DeleteCriticalSection(&os_lock_); | |
| 25 } | |
| 26 | |
| 27 bool LockImpl::Try() { | |
| 28 if (::TryEnterCriticalSection(&os_lock_) != FALSE) { | |
| 29 #ifndef NDEBUG | |
| 30 // ONLY access data after locking. | |
| 31 owning_thread_id_ = PlatformThread::CurrentId(); | |
| 32 DCHECK_NE(owning_thread_id_, 0); | |
| 33 recursion_count_shadow_++; | |
| 34 if (2 == recursion_count_shadow_ && !recursion_used_) { | |
| 35 recursion_used_ = true; | |
| 36 DCHECK(false); // Catch accidental redundant lock acquisition. | |
| 37 } | |
| 38 #endif | |
| 39 return true; | |
| 40 } | |
| 41 return false; | |
| 42 } | |
| 43 | |
| 44 void LockImpl::Lock() { | |
| 45 ::EnterCriticalSection(&os_lock_); | |
| 46 #ifndef NDEBUG | |
| 47 // ONLY access data after locking. | |
| 48 owning_thread_id_ = PlatformThread::CurrentId(); | |
| 49 DCHECK_NE(owning_thread_id_, 0); | |
| 50 recursion_count_shadow_++; | |
| 51 if (2 == recursion_count_shadow_ && !recursion_used_) { | |
| 52 recursion_used_ = true; | |
| 53 DCHECK(false); // Catch accidental redundant lock acquisition. | |
| 54 } | |
| 55 #endif // NDEBUG | |
| 56 } | |
| 57 | |
| 58 void LockImpl::Unlock() { | |
| 59 #ifndef NDEBUG | |
| 60 --recursion_count_shadow_; // ONLY access while lock is still held. | |
| 61 DCHECK(0 <= recursion_count_shadow_); | |
| 62 owning_thread_id_ = 0; | |
| 63 #endif // NDEBUG | |
| 64 ::LeaveCriticalSection(&os_lock_); | |
| 65 } | |
| 66 | |
| 67 // In non-debug builds, this method is declared as an empty inline method. | |
| 68 #ifndef NDEBUG | |
| 69 void LockImpl::AssertAcquired() const { | |
| 70 DCHECK(recursion_count_shadow_ > 0); | |
| 71 DCHECK_EQ(owning_thread_id_, PlatformThread::CurrentId()); | |
| 72 } | |
| 73 #endif |
