LCOV - app.info - ipc/chromium/src/base/thread_collision_warner.cc

LCOV - code coverage report
| Current view: | directory - ipc/chromium/src/base - thread_collision_warner.cc (source / functions) |  | Found | Hit | Coverage |
| Test: | app.info | Lines: | 25 | 0 | 0.0 %
| Date: | 2012-06-02 | Functions: | 5 | 0 | 0.0 %

           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/thread_collision_warner.h"
           6                 :
           7                 : #include "base/logging.h"
           8                 : #include "base/platform_thread.h"
           9                 :
          10                 : namespace base {
          11                 :
          12               0 : void DCheckAsserter::warn() {
          13               0 :   NOTREACHED() << "Thread Collision";
          14               0 : }
          15                 :
          16               0 : static subtle::Atomic32 CurrentThread() {
          17               0 :   const PlatformThreadId current_thread_id = PlatformThread::CurrentId();
          18                 :   // We need to get the thread id into an atomic data type. This might be a
          19                 :   // truncating conversion, but any loss-of-information just increases the
          20                 :   // chance of a fault negative, not a false positive.
          21                 :   const subtle::Atomic32 atomic_thread_id =
          22               0 :       static_cast<subtle::Atomic32>(current_thread_id);
          23                 :
          24               0 :   return atomic_thread_id;
          25                 : }
          26                 :
          27               0 : void ThreadCollisionWarner::EnterSelf() {
          28                 :   // If the active thread is 0 then I'll write the current thread ID
          29                 :   // if two or more threads arrive here only one will succeed to
          30                 :   // write on valid_thread_id_ the current thread ID.
          31               0 :   subtle::Atomic32 current_thread_id = CurrentThread();
          32                 :
          33                 :   int previous_value = subtle::NoBarrier_CompareAndSwap(&valid_thread_id_,
          34                 :                                                         0,
          35               0 :                                                         current_thread_id);
          36               0 :   if (previous_value != 0 && previous_value != current_thread_id) {
          37                 :     // gotcha! a thread is trying to use the same class and that is
          38                 :     // not current thread.
          39               0 :     asserter_->warn();
          40                 :   }
          41                 :
          42               0 :   subtle::NoBarrier_AtomicIncrement(&counter_, 1);
          43               0 : }
          44                 :
          45               0 : void ThreadCollisionWarner::Enter() {
          46               0 :   subtle::Atomic32 current_thread_id = CurrentThread();
          47                 :
          48               0 :   if (subtle::NoBarrier_CompareAndSwap(&valid_thread_id_,
          49                 :                                        0,
          50               0 :                                        current_thread_id) != 0) {
          51                 :     // gotcha! another thread is trying to use the same class.
          52               0 :     asserter_->warn();
          53                 :   }
          54                 :
          55               0 :   subtle::NoBarrier_AtomicIncrement(&counter_, 1);
          56               0 : }
          57                 :
          58               0 : void ThreadCollisionWarner::Leave() {
          59               0 :   if (subtle::Barrier_AtomicIncrement(&counter_, -1) == 0) {
          60               0 :     subtle::NoBarrier_Store(&valid_thread_id_, 0);
          61                 :   }
          62               0 : }
          63                 :
          64                 : }  // namespace base

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