The Tor Browser: ipc/chromium/src/base/thread_collision

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

     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.

     5 #include "base/thread_collision_warner.h"

     7 #include "base/logging.h"

     8 #include "base/platform_thread.h"

    10 namespace base {

    12 void DCheckAsserter::warn() {

    13   NOTREACHED() << "Thread Collision";

    14 }

    16 static subtle::Atomic32 CurrentThread() {

    17   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       static_cast<subtle::Atomic32>(current_thread_id);

    24   return atomic_thread_id;

    25 }

    27 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   subtle::Atomic32 current_thread_id = CurrentThread();

    33   int previous_value = subtle::NoBarrier_CompareAndSwap(&valid_thread_id_,

    34                                                         0,

    35                                                         current_thread_id);

    36   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     asserter_->warn();

    40   }

    42   subtle::NoBarrier_AtomicIncrement(&counter_, 1);

    43 }

    45 void ThreadCollisionWarner::Enter() {

    46   subtle::Atomic32 current_thread_id = CurrentThread();

    48   if (subtle::NoBarrier_CompareAndSwap(&valid_thread_id_,

    49                                        0,

    50                                        current_thread_id) != 0) {

    51     // gotcha! another thread is trying to use the same class.

    52     asserter_->warn();

    53   }

    55   subtle::NoBarrier_AtomicIncrement(&counter_, 1);

    56 }

    58 void ThreadCollisionWarner::Leave() {

    59   if (subtle::Barrier_AtomicIncrement(&counter_, -1) == 0) {

    60     subtle::NoBarrier_Store(&valid_thread_id_, 0);

    61   }

    62 }

    64 }  // namespace base

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