ipc/chromium/src/base/lock_impl_win.cc@6474c204b198 (annotated)
ipc/chromium/src/base/lock_impl_win.cc
Wed, 31 Dec 2014 06:09:35 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Wed, 31 Dec 2014 06:09:35 +0100
- changeset 0
- 6474c204b198
- permissions
- -rw-r--r--
Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.
| michael@0 | 1 | // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved. |
| michael@0 | 2 | // Use of this source code is governed by a BSD-style license that can be |
| michael@0 | 3 | // found in the LICENSE file. |
| michael@0 | 4 | |
| michael@0 | 5 | #include "base/lock_impl.h" |
| michael@0 | 6 | #include "base/logging.h" |
| michael@0 | 7 | |
| michael@0 | 8 | // NOTE: Although windows critical sections support recursive locks, we do not |
| michael@0 | 9 | // allow this, and we will commonly fire a DCHECK() if a thread attempts to |
| michael@0 | 10 | // acquire the lock a second time (while already holding it). |
| michael@0 | 11 | |
| michael@0 | 12 | LockImpl::LockImpl() { |
| michael@0 | 13 | #ifndef NDEBUG |
| michael@0 | 14 | recursion_count_shadow_ = 0; |
| michael@0 | 15 | recursion_used_ = false; |
| michael@0 | 16 | owning_thread_id_ = 0; |
| michael@0 | 17 | #endif // NDEBUG |
| michael@0 | 18 | // The second parameter is the spin count, for short-held locks it avoid the |
| michael@0 | 19 | // contending thread from going to sleep which helps performance greatly. |
| michael@0 | 20 | ::InitializeCriticalSectionAndSpinCount(&os_lock_, 2000); |
| michael@0 | 21 | } |
| michael@0 | 22 | |
| michael@0 | 23 | LockImpl::~LockImpl() { |
| michael@0 | 24 | ::DeleteCriticalSection(&os_lock_); |
| michael@0 | 25 | } |
| michael@0 | 26 | |
| michael@0 | 27 | bool LockImpl::Try() { |
| michael@0 | 28 | if (::TryEnterCriticalSection(&os_lock_) != FALSE) { |
| michael@0 | 29 | #ifndef NDEBUG |
| michael@0 | 30 | // ONLY access data after locking. |
| michael@0 | 31 | owning_thread_id_ = PlatformThread::CurrentId(); |
| michael@0 | 32 | DCHECK_NE(owning_thread_id_, 0); |
| michael@0 | 33 | recursion_count_shadow_++; |
| michael@0 | 34 | if (2 == recursion_count_shadow_ && !recursion_used_) { |
| michael@0 | 35 | recursion_used_ = true; |
| michael@0 | 36 | DCHECK(false); // Catch accidental redundant lock acquisition. |
| michael@0 | 37 | } |
| michael@0 | 38 | #endif |
| michael@0 | 39 | return true; |
| michael@0 | 40 | } |
| michael@0 | 41 | return false; |
| michael@0 | 42 | } |
| michael@0 | 43 | |
| michael@0 | 44 | void LockImpl::Lock() { |
| michael@0 | 45 | ::EnterCriticalSection(&os_lock_); |
| michael@0 | 46 | #ifndef NDEBUG |
| michael@0 | 47 | // ONLY access data after locking. |
| michael@0 | 48 | owning_thread_id_ = PlatformThread::CurrentId(); |
| michael@0 | 49 | DCHECK_NE(owning_thread_id_, 0); |
| michael@0 | 50 | recursion_count_shadow_++; |
| michael@0 | 51 | if (2 == recursion_count_shadow_ && !recursion_used_) { |
| michael@0 | 52 | recursion_used_ = true; |
| michael@0 | 53 | DCHECK(false); // Catch accidental redundant lock acquisition. |
| michael@0 | 54 | } |
| michael@0 | 55 | #endif // NDEBUG |
| michael@0 | 56 | } |
| michael@0 | 57 | |
| michael@0 | 58 | void LockImpl::Unlock() { |
| michael@0 | 59 | #ifndef NDEBUG |
| michael@0 | 60 | --recursion_count_shadow_; // ONLY access while lock is still held. |
| michael@0 | 61 | DCHECK(0 <= recursion_count_shadow_); |
| michael@0 | 62 | owning_thread_id_ = 0; |
| michael@0 | 63 | #endif // NDEBUG |
| michael@0 | 64 | ::LeaveCriticalSection(&os_lock_); |
| michael@0 | 65 | } |
| michael@0 | 66 | |
| michael@0 | 67 | // In non-debug builds, this method is declared as an empty inline method. |
| michael@0 | 68 | #ifndef NDEBUG |
| michael@0 | 69 | void LockImpl::AssertAcquired() const { |
| michael@0 | 70 | DCHECK(recursion_count_shadow_ > 0); |
| michael@0 | 71 | DCHECK_EQ(owning_thread_id_, PlatformThread::CurrentId()); |
| michael@0 | 72 | } |
| michael@0 | 73 | #endif |
