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// 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 name Chromium Embedded

// Framework 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 CEF_INCLUDE_BASE_CEF_THREAD_COLLISION_WARNER_H_

#define CEF_INCLUDE_BASE_CEF_THREAD_COLLISION_WARNER_H_

#pragma once

#if defined(BASE_THREADING_THREAD_COLLISION_WARNER_H_)

// Do nothing if the Chromium header has already been included.

// This can happen in cases where Chromium code is used directly by the

// client application. When using Chromium code directly always include

// the Chromium header first to avoid type conflicts.

#elif defined(USING_CHROMIUM_INCLUDES)

// When building CEF include the Chromium header directly.

#include "base/threading/thread_collision_warner.h"

#else // !USING_CHROMIUM_INCLUDES

// The following is substantially similar to the Chromium implementation.

// If the Chromium implementation diverges the below implementation should be

// updated to match.

#include <memory>

#include "include/base/cef_atomicops.h"

#include "include/base/cef_basictypes.h"

#include "include/base/cef_build.h"

#include "include/base/cef_macros.h"

// A helper class alongside macros to be used to verify assumptions about thread

// safety of a class.

// Example: Queue implementation non thread-safe but still usable if clients

// are synchronized somehow.

// In this case the macro DFAKE_SCOPED_LOCK has to be

// used, it checks that if a thread is inside the push/pop then

// noone else is still inside the pop/push

// class NonThreadSafeQueue {

// public:

// ...

// void push(int) { DFAKE_SCOPED_LOCK(push_pop_); ... }

// int pop() { DFAKE_SCOPED_LOCK(push_pop_); ... }

// ...

// private:

// DFAKE_MUTEX(push_pop_);

// };

// Example: Queue implementation non thread-safe but still usable if clients

// are synchronized somehow, it calls a method to "protect" from

// a "protected" method

// In this case the macro DFAKE_SCOPED_RECURSIVE_LOCK

// has to be used, it checks that if a thread is inside the push/pop

// then noone else is still inside the pop/push

// class NonThreadSafeQueue {

// public:

// void push(int) {

// DFAKE_SCOPED_LOCK(push_pop_);

// ...

// }

// int pop() {

// DFAKE_SCOPED_RECURSIVE_LOCK(push_pop_);

// bar();

// ...

// }

// void bar() { DFAKE_SCOPED_RECURSIVE_LOCK(push_pop_); ... }

// ...

// private:

// DFAKE_MUTEX(push_pop_);

// };

// Example: Queue implementation not usable even if clients are synchronized,

// so only one thread in the class life cycle can use the two members

// push/pop.

// In this case the macro DFAKE_SCOPED_LOCK_THREAD_LOCKED pins the

// specified

// critical section the first time a thread enters push or pop, from

// that time on only that thread is allowed to execute push or pop.

// class NonThreadSafeQueue {

// public:

// ...

// void push(int) { DFAKE_SCOPED_LOCK_THREAD_LOCKED(push_pop_); ... }

// int pop() { DFAKE_SCOPED_LOCK_THREAD_LOCKED(push_pop_); ... }

// ...

// private:

// DFAKE_MUTEX(push_pop_);

// };

// Example: Class that has to be contructed/destroyed on same thread, it has

// a "shareable" method (with external synchronization) and a not

// shareable method (even with external synchronization).

// In this case 3 Critical sections have to be defined

// class ExoticClass {

// public:

// ExoticClass() { DFAKE_SCOPED_LOCK_THREAD_LOCKED(ctor_dtor_); ... }

// ~ExoticClass() { DFAKE_SCOPED_LOCK_THREAD_LOCKED(ctor_dtor_); ... }

// void Shareable() { DFAKE_SCOPED_LOCK(shareable_section_); ... }

// void NotShareable() { DFAKE_SCOPED_LOCK_THREAD_LOCKED(ctor_dtor_); ... }

// ...

// private:

// DFAKE_MUTEX(ctor_dtor_);

// DFAKE_MUTEX(shareable_section_);

// };

#if !defined(NDEBUG)

// Defines a class member that acts like a mutex. It is used only as a

// verification tool.

#define DFAKE_MUTEX(obj) \

mutable base::ThreadCollisionWarner obj

// Asserts the call is never called simultaneously in two threads. Used at

// member function scope.

#define DFAKE_SCOPED_LOCK(obj) \

base::ThreadCollisionWarner::ScopedCheck s_check_##obj(&obj)

// Asserts the call is never called simultaneously in two threads. Used at

// member function scope. Same as DFAKE_SCOPED_LOCK but allows recursive locks.

#define DFAKE_SCOPED_RECURSIVE_LOCK(obj) \

base::ThreadCollisionWarner::ScopedRecursiveCheck sr_check_##obj(&obj)

// Asserts the code is always executed in the same thread.

#define DFAKE_SCOPED_LOCK_THREAD_LOCKED(obj) \

base::ThreadCollisionWarner::Check check_##obj(&obj)

#else

#define DFAKE_MUTEX(obj) typedef void InternalFakeMutexType##obj

#define DFAKE_SCOPED_LOCK(obj) ((void)0)

#define DFAKE_SCOPED_RECURSIVE_LOCK(obj) ((void)0)

#define DFAKE_SCOPED_LOCK_THREAD_LOCKED(obj) ((void)0)

#endif

namespace base {

// The class ThreadCollisionWarner uses an Asserter to notify the collision

// AsserterBase is the interfaces and DCheckAsserter is the default asserter

// used. During the unit tests is used another class that doesn't "DCHECK"

// in case of collision (check thread_collision_warner_unittests.cc)

struct AsserterBase {

virtual ~AsserterBase() {}

virtual void warn() = 0;

};

struct DCheckAsserter : public AsserterBase {

virtual ~DCheckAsserter() {}

virtual void warn() OVERRIDE;

};

class ThreadCollisionWarner {

public:

// The parameter asserter is there only for test purpose

explicit ThreadCollisionWarner(AsserterBase* asserter = new DCheckAsserter())

: valid_thread_id_(0),

counter_(0),

asserter_(asserter) {}

~ThreadCollisionWarner() {

delete asserter_;

}

// This class is meant to be used through the macro

// DFAKE_SCOPED_LOCK_THREAD_LOCKED

// it doesn't leave the critical section, as opposed to ScopedCheck,

// because the critical section being pinned is allowed to be used only

// from one thread

class Check {

public:

explicit Check(ThreadCollisionWarner* warner)

: warner_(warner) {

warner_->EnterSelf();

}

~Check() {}

private:

ThreadCollisionWarner* warner_;

DISALLOW_COPY_AND_ASSIGN(Check);

};

// This class is meant to be used through the macro

// DFAKE_SCOPED_LOCK

class ScopedCheck {

public:

explicit ScopedCheck(ThreadCollisionWarner* warner)

: warner_(warner) {

warner_->Enter();

}

~ScopedCheck() {

warner_->Leave();

}

private:

ThreadCollisionWarner* warner_;

DISALLOW_COPY_AND_ASSIGN(ScopedCheck);

};

// This class is meant to be used through the macro

// DFAKE_SCOPED_RECURSIVE_LOCK

class ScopedRecursiveCheck {

public:

explicit ScopedRecursiveCheck(ThreadCollisionWarner* warner)

: warner_(warner) {

warner_->EnterSelf();

}

~ScopedRecursiveCheck() {

warner_->Leave();

}

private:

ThreadCollisionWarner* warner_;

DISALLOW_COPY_AND_ASSIGN(ScopedRecursiveCheck);

};

private:

// This method stores the current thread identifier and does a DCHECK

// if a another thread has already done it, it is safe if same thread

// calls this multiple time (recursion allowed).

void EnterSelf();

// Same as EnterSelf but recursion is not allowed.

void Enter();

// Removes the thread_id stored in order to allow other threads to

// call EnterSelf or Enter.

void Leave();

// This stores the thread id that is inside the critical section, if the

// value is 0 then no thread is inside.

volatile subtle::Atomic32 valid_thread_id_;

// Counter to trace how many time a critical section was "pinned"

// (when allowed) in order to unpin it when counter_ reaches 0.

volatile subtle::Atomic32 counter_;

// Here only for class unit tests purpose, during the test I need to not

// DCHECK but notify the collision with something else.

AsserterBase* asserter_;

DISALLOW_COPY_AND_ASSIGN(ThreadCollisionWarner);

};

} // namespace base

#endif // !USING_CHROMIUM_INCLUDES

#endif // CEF_INCLUDE_BASE_CEF_THREAD_COLLISION_WARNER_H_

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