ClickHouse/base/poco/Foundation/include/Poco/ActiveMethod.h

//
// ActiveMethod.h
//
// Library: Foundation
// Package: Threading
// Module:  ActiveObjects
//
// Definition of the ActiveMethod class.
//
// Copyright (c) 2004-2007, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#ifndef Foundation_ActiveMethod_INCLUDED
#define Foundation_ActiveMethod_INCLUDED


#include "Poco/Foundation.h"
#include "Poco/ActiveResult.h"
#include "Poco/ActiveRunnable.h"
#include "Poco/ActiveStarter.h"
#include "Poco/AutoPtr.h"


namespace Poco {


template <class ResultType, class ArgType, class OwnerType, class StarterType = ActiveStarter<OwnerType> >
class ActiveMethod
	/// An active method is a method that, when called, executes
	/// in its own thread. ActiveMethod's take exactly one
	/// argument and can return a value. To pass more than one
	/// argument to the method, use a struct.
	/// The following example shows how to add an ActiveMethod
	/// to a class:
	///
	///     class ActiveObject
	///     {
	///     public:
	///         ActiveObject():
	///             exampleActiveMethod(this, &ActiveObject::exampleActiveMethodImpl)
	///         {
	///         }
	///
	///         ActiveMethod<std::string, std::string, ActiveObject> exampleActiveMethod;
	///
	///     protected:
	///         std::string exampleActiveMethodImpl(const std::string& arg)
	///         {
	///             ...
	///         }
	///     };
	///
	/// And following is an example that shows how to invoke an ActiveMethod.
	///
	///     ActiveObject myActiveObject;
	///     ActiveResult<std::string> result = myActiveObject.exampleActiveMethod("foo");
	///     ...
	///     result.wait();
	///     std::cout << result.data() << std::endl;
	///
	/// The way an ActiveMethod is started can be changed by passing a StarterType
	/// template argument with a corresponding class. The default ActiveStarter
	/// starts the method in its own thread, obtained from a thread pool.
	///
	/// For an alternative implementation of StarterType, see ActiveDispatcher.
	///
	/// For methods that do not require an argument or a return value, the Void
	/// class can be used.
{
public:
	typedef ResultType (OwnerType::*Callback)(const ArgType&);
	typedef ActiveResult<ResultType> ActiveResultType;
	typedef ActiveRunnable<ResultType, ArgType, OwnerType> ActiveRunnableType;

	ActiveMethod(OwnerType* pOwner, Callback method):
		_pOwner(pOwner),
		_method(method)
		/// Creates an ActiveMethod object.
	{
		poco_check_ptr (pOwner);
	}
	
	ActiveResultType operator () (const ArgType& arg)
		/// Invokes the ActiveMethod.
	{
		ActiveResultType result(new ActiveResultHolder<ResultType>());
		ActiveRunnableBase::Ptr pRunnable(new ActiveRunnableType(_pOwner, _method, arg, result));
		StarterType::start(_pOwner, pRunnable);
		return result;
	}
		
	ActiveMethod(const ActiveMethod& other):
		_pOwner(other._pOwner),
		_method(other._method)
	{
	}

	ActiveMethod& operator = (const ActiveMethod& other)
	{
		ActiveMethod tmp(other);
		swap(tmp);
		return *this;
	}

	void swap(ActiveMethod& other)
	{
		std::swap(_pOwner, other._pOwner);
		std::swap(_method, other._method);
	}

private:
	ActiveMethod();

	OwnerType* _pOwner;
	Callback   _method;
};



template <class ResultType, class OwnerType, class StarterType>
class ActiveMethod <ResultType, void, OwnerType, StarterType>
	/// An active method is a method that, when called, executes
	/// in its own thread. ActiveMethod's take exactly one
	/// argument and can return a value. To pass more than one
	/// argument to the method, use a struct.
	/// The following example shows how to add an ActiveMethod
	/// to a class:
	///
	///     class ActiveObject
	///     {
	///     public:
	///         ActiveObject():
	///             exampleActiveMethod(this, &ActiveObject::exampleActiveMethodImpl)
	///         {
	///         }
	///
	///         ActiveMethod<std::string, std::string, ActiveObject> exampleActiveMethod;
	///
	///     protected:
	///         std::string exampleActiveMethodImpl(const std::string& arg)
	///         {
	///             ...
	///         }
	///     };
	///
	/// And following is an example that shows how to invoke an ActiveMethod.
	///
	///     ActiveObject myActiveObject;
	///     ActiveResult<std::string> result = myActiveObject.exampleActiveMethod("foo");
	///     ...
	///     result.wait();
	///     std::cout << result.data() << std::endl;
	///
	/// The way an ActiveMethod is started can be changed by passing a StarterType
	/// template argument with a corresponding class. The default ActiveStarter
	/// starts the method in its own thread, obtained from a thread pool.
	///
	/// For an alternative implementation of StarterType, see ActiveDispatcher.
	///
	/// For methods that do not require an argument or a return value, simply use void.
{
public:
	typedef ResultType (OwnerType::*Callback)(void);
	typedef ActiveResult<ResultType> ActiveResultType;
	typedef ActiveRunnable<ResultType, void, OwnerType> ActiveRunnableType;

	ActiveMethod(OwnerType* pOwner, Callback method):
		_pOwner(pOwner),
		_method(method)
		/// Creates an ActiveMethod object.
	{
		poco_check_ptr (pOwner);
	}
	
	ActiveResultType operator () (void)
		/// Invokes the ActiveMethod.
	{
		ActiveResultType result(new ActiveResultHolder<ResultType>());
		ActiveRunnableBase::Ptr pRunnable(new ActiveRunnableType(_pOwner, _method, result));
		StarterType::start(_pOwner, pRunnable);
		return result;
	}
		
	ActiveMethod(const ActiveMethod& other):
		_pOwner(other._pOwner),
		_method(other._method)
	{
	}

	ActiveMethod& operator = (const ActiveMethod& other)
	{
		ActiveMethod tmp(other);
		swap(tmp);
		return *this;
	}

	void swap(ActiveMethod& other)
	{
		std::swap(_pOwner, other._pOwner);
		std::swap(_method, other._method);
	}

private:
	ActiveMethod();

	OwnerType* _pOwner;
	Callback   _method;
};


} // namespace Poco


#endif // Foundation_ActiveMethod_INCLUDED