The Tor Browser: security/sandbox/chromium/base/synchronization/lock.h@7e26c7da4463 (annotated)

security/sandbox/chromium/base/synchronization/lock.h@7e26c7da4463 (annotated)

security/sandbox/chromium/base/synchronization/lock.h

Wed, 31 Dec 2014 06:55:50 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:55:50 +0100
changeset 2: 7e26c7da4463
permissions: -rw-r--r--

Added tag UPSTREAM_283F7C6 for changeset ca08bd8f51b2

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 #ifndef BASE_SYNCHRONIZATION_LOCK_H_
 #define BASE_SYNCHRONIZATION_LOCK_H_
 #include "base/base_export.h"
 #include "base/synchronization/lock_impl.h"
 #include "base/threading/platform_thread.h"
 namespace base {
 // A convenient wrapper for an OS specific critical section.  The only real
 // intelligence in this class is in debug mode for the support for the
 // AssertAcquired() method.
 class BASE_EXPORT Lock {
  public:
 #if defined(NDEBUG)             // Optimized wrapper implementation
   Lock() : lock_() {}
   ~Lock() {}
   void Acquire() { lock_.Lock(); }
   void Release() { lock_.Unlock(); }
   // If the lock is not held, take it and return true. If the lock is already
   // held by another thread, immediately return false. This must not be called
   // by a thread already holding the lock (what happens is undefined and an
   // assertion may fail).
   bool Try() { return lock_.Try(); }
   // Null implementation if not debug.
   void AssertAcquired() const {}
 #else
   Lock();
   ~Lock();
   // NOTE: Although windows critical sections support recursive locks, we do not
   // allow this, and we will commonly fire a DCHECK() if a thread attempts to
   // acquire the lock a second time (while already holding it).
   void Acquire() {
     lock_.Lock();
     CheckUnheldAndMark();
   }
   void Release() {
     CheckHeldAndUnmark();
     lock_.Unlock();
   }
   bool Try() {
     bool rv = lock_.Try();
     if (rv) {
       CheckUnheldAndMark();
     }
     return rv;
   }
   void AssertAcquired() const;
 #endif                          // NDEBUG
 #if defined(OS_POSIX)
   // The posix implementation of ConditionVariable needs to be able
   // to see our lock and tweak our debugging counters, as it releases
   // and acquires locks inside of pthread_cond_{timed,}wait.
   friend class ConditionVariable;
 #elif defined(OS_WIN)
   // The Windows Vista implementation of ConditionVariable needs the
   // native handle of the critical section.
   friend class WinVistaCondVar;
 #endif
  private:
 #if !defined(NDEBUG)
   // Members and routines taking care of locks assertions.
   // Note that this checks for recursive locks and allows them
   // if the variable is set.  This is allowed by the underlying implementation
   // on windows but not on Posix, so we're doing unneeded checks on Posix.
   // It's worth it to share the code.
   void CheckHeldAndUnmark();
   void CheckUnheldAndMark();
   // All private data is implicitly protected by lock_.
   // Be VERY careful to only access members under that lock.
   // Determines validity of owning_thread_id_.  Needed as we don't have
   // a null owning_thread_id_ value.
   bool owned_by_thread_;
   base::PlatformThreadId owning_thread_id_;
 #endif  // NDEBUG
   // Platform specific underlying lock implementation.
   internal::LockImpl lock_;
   DISALLOW_COPY_AND_ASSIGN(Lock);
 };
 // A helper class that acquires the given Lock while the AutoLock is in scope.
 class AutoLock {
  public:
   struct AlreadyAcquired {};
   explicit AutoLock(Lock& lock) : lock_(lock) {
     lock_.Acquire();
   }
   AutoLock(Lock& lock, const AlreadyAcquired&) : lock_(lock) {
     lock_.AssertAcquired();
   }
   ~AutoLock() {
     lock_.AssertAcquired();
     lock_.Release();
   }
  private:
   Lock& lock_;
   DISALLOW_COPY_AND_ASSIGN(AutoLock);
 };
 // AutoUnlock is a helper that will Release() the |lock| argument in the
 // constructor, and re-Acquire() it in the destructor.
 class AutoUnlock {
  public:
   explicit AutoUnlock(Lock& lock) : lock_(lock) {
     // We require our caller to have the lock.
     lock_.AssertAcquired();
     lock_.Release();
   }
   ~AutoUnlock() {
     lock_.Acquire();
   }
  private:
   Lock& lock_;
   DISALLOW_COPY_AND_ASSIGN(AutoUnlock);
 };
 }  // namespace base
 #endif  // BASE_SYNCHRONIZATION_LOCK_H_

The Tor Browser / annotate

security/sandbox/chromium/base/synchronization/lock.h@7e26c7da4463 (annotated)

security/sandbox/chromium/base/synchronization/lock.h