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/*
* Copyright (C) 2011 Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef ThreadRestrictionVerifier_h
#define ThreadRestrictionVerifier_h
#include <wtf/Assertions.h>
#include <wtf/Threading.h>
#include <wtf/ThreadingPrimitives.h>
#if HAVE(DISPATCH_H)
#include <dispatch/dispatch.h>
#endif
#ifndef NDEBUG
namespace WTF {
// Verifies that a class is used in a way that respects its lack of thread-safety.
// The default mode is to verify that the object will only be used on a single thread. The
// thread gets captured when setShared(true) is called.
// The mode may be changed by calling useMutexMode (or turnOffVerification).
class ThreadRestrictionVerifier {
public:
ThreadRestrictionVerifier()
: m_mode(SingleThreadVerificationMode)
, m_shared(false)
, m_owningThread(0)
, m_mutex(0)
#if HAVE(DISPATCH_H)
, m_owningQueue(0)
#endif
{
}
#if HAVE(DISPATCH_H)
~ThreadRestrictionVerifier()
{
if (m_owningQueue)
dispatch_release(m_owningQueue);
}
#endif
void setMutexMode(Mutex& mutex)
{
ASSERT(m_mode == SingleThreadVerificationMode || (m_mode == MutexVerificationMode && &mutex == m_mutex));
m_mode = MutexVerificationMode;
m_mutex = &mutex;
}
#if HAVE(DISPATCH_H)
void setDispatchQueueMode(dispatch_queue_t queue)
{
ASSERT(m_mode == SingleThreadVerificationMode);
m_mode = SingleDispatchQueueVerificationMode;
m_owningQueue = queue;
dispatch_retain(m_owningQueue);
}
#endif
void turnOffVerification()
{
ASSERT(m_mode == SingleThreadVerificationMode);
m_mode = NoVerificationMode;
}
// Indicates that the object may (or may not) be owned by more than one place.
void setShared(bool shared)
{
#if !ASSERT_DISABLED
bool previouslyShared = m_shared;
#endif
m_shared = shared;
if (!m_shared)
return;
switch (m_mode) {
case SingleThreadVerificationMode:
ASSERT(shared != previouslyShared);
// Capture the current thread to verify that subsequent ref/deref happen on this thread.
m_owningThread = currentThread();
return;
#if HAVE(DISPATCH_H)
case SingleDispatchQueueVerificationMode:
#endif
case MutexVerificationMode:
case NoVerificationMode:
return;
}
ASSERT_NOT_REACHED();
}
// Is it OK to use the object at this moment on the current thread?
bool isSafeToUse() const
{
if (!m_shared)
return true;
switch (m_mode) {
case SingleThreadVerificationMode:
return m_owningThread == currentThread();
case MutexVerificationMode:
if (!m_mutex->tryLock())
return true;
m_mutex->unlock();
return false;
#if HAVE(DISPATCH_H)
case SingleDispatchQueueVerificationMode:
return m_owningQueue == dispatch_get_current_queue();
#endif
case NoVerificationMode:
return true;
}
ASSERT_NOT_REACHED();
return true;
}
private:
enum VerificationMode {
SingleThreadVerificationMode,
MutexVerificationMode,
NoVerificationMode,
#if HAVE(DISPATCH_H)
SingleDispatchQueueVerificationMode,
#endif
};
VerificationMode m_mode;
bool m_shared;
// Used by SingleThreadVerificationMode
ThreadIdentifier m_owningThread;
// Used by MutexVerificationMode.
Mutex* m_mutex;
#if HAVE(DISPATCH_H)
// Used by SingleDispatchQueueVerificationMode.
dispatch_queue_t m_owningQueue;
#endif
};
}
#endif
#endif
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