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/*
* Copyright (C) 2009-2010 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
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* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
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* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef CrossThreadTask_h
#define CrossThreadTask_h
#include "core/dom/ExecutionContext.h"
#include "core/dom/ExecutionContextTask.h"
#include "platform/ThreadSafeFunctional.h"
#include <type_traits>
namespace blink {
// createCrossThreadTask(...) is ExecutionContextTask version of
// threadSafeBind().
// Using WTF::bind() directly is not thread-safe due to temporary objects, see
// https://crbug.com/390851 for details.
//
// Example:
// void func1(int, const String&);
// createCrossThreadTask(func1, 42, str);
// func1(42, str2) will be called, where |str2| is a deep copy of
// |str| (created by str.isolatedCopy()).
//
// Don't (if you pass the task across threads):
// bind(func1, 42, str);
// bind(func1, 42, str.isolatedCopy());
//
// For functions:
// void functionEC(MP1, ..., MPn, ExecutionContext*);
// void function(MP1, ..., MPn);
// class C {
// void memberEC(MP1, ..., MPn, ExecutionContext*);
// void member(MP1, ..., MPn);
// };
// We create tasks represented by std::unique_ptr<ExecutionContextTask>:
// createCrossThreadTask(functionEC, const P1& p1, ..., const Pn& pn);
// createCrossThreadTask(memberEC, C* ptr, const P1& p1, ..., const Pn& pn);
// createCrossThreadTask(function, const P1& p1, ..., const Pn& pn);
// createCrossThreadTask(member, C* ptr, const P1& p1, ..., const Pn& pn);
// (|ptr| can also be WeakPtr<C> or other pointer-like types)
// and then the following are called on the target thread:
// functionEC(p1, ..., pn, context);
// ptr->memberEC(p1, ..., pn, context);
// function(p1, ..., pn);
// ptr->member(p1, ..., pn);
//
// ExecutionContext:
// |context| is supplied by the target thread.
//
// Deep copies by threadSafeBind():
// |ptr|, |p1|, ..., |pn| are processed by threadSafeBind() and thus
// CrossThreadCopier.
// You don't have to call manually e.g. isolatedCopy().
// To pass things that cannot be copied by CrossThreadCopier
// (e.g. pointers), use AllowCrossThreadAccess() explicitly.
// RETTYPE, PS, and MPS are added as template parameters to circumvent MSVC 18.00.21005.1 (VS 2013) issues.
template<typename FunctionType, typename... P,
typename RETTYPE = std::unique_ptr<ExecutionContextTask>, size_t PS = sizeof...(P), size_t MPS = WTF::FunctionWrapper<FunctionType>::numberOfArguments>
typename std::enable_if<PS + 1 == MPS, RETTYPE>::type createCrossThreadTask(FunctionType function, P&&... parameters)
{
return internal::createCallClosureTask(threadSafeBind(function, std::forward<P>(parameters)...));
}
template<typename FunctionType, typename... P,
typename RETTYPE = std::unique_ptr<ExecutionContextTask>, size_t PS = sizeof...(P), size_t MPS = WTF::FunctionWrapper<FunctionType>::numberOfArguments>
typename std::enable_if<PS == MPS, RETTYPE>::type createCrossThreadTask(FunctionType function, P&&... parameters)
{
return internal::createCallClosureTask(threadSafeBind(function, std::forward<P>(parameters)...));
}
} // namespace blink
#endif // CrossThreadTask_h