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

//
// ActiveDispatcher.h
//
// Library: Foundation
// Package: Threading
// Module:  ActiveObjects
//
// Definition of the ActiveDispatcher class.
//
// Copyright (c) 2006-2007, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#ifndef Foundation_ActiveDispatcher_INCLUDED
#define Foundation_ActiveDispatcher_INCLUDED


#include "Poco/ActiveRunnable.h"
#include "Poco/ActiveStarter.h"
#include "Poco/Foundation.h"
#include "Poco/NotificationQueue.h"
#include "Poco/Runnable.h"
#include "Poco/Thread.h"


namespace Poco
{


class Foundation_API ActiveDispatcher : protected Runnable
/// This class is used to implement an active object
/// with strictly serialized method execution.
///
/// An active object, which is an ordinary object
/// containing ActiveMethod members, executes all
/// active methods in their own thread.
/// This behavior does not fit the "classic"
/// definition of an active object, which serializes
/// the execution of active methods (in other words,
/// only one active method can be running at any given
/// time).
///
/// Using this class as a base class, the serializing
/// behavior for active objects can be implemented.
///
/// The following example shows how this is done:
///
///     class ActiveObject: public ActiveDispatcher
///     {
///     public:
///         ActiveObject():
///             exampleActiveMethod(this, &ActiveObject::exampleActiveMethodImpl)
///         {
///         }
///
///         ActiveMethod<std::string, std::string, ActiveObject, ActiveStarter<ActiveDispatcher> > exampleActiveMethod;
///
///     protected:
///         std::string exampleActiveMethodImpl(const std::string& arg)
///         {
///             ...
///         }
///     };
///
/// The only things different from the example in
/// ActiveMethod is that the ActiveObject in this case
/// inherits from ActiveDispatcher, and that the ActiveMethod
/// template for exampleActiveMethod has an additional parameter,
/// specifying the specialized ActiveStarter for ActiveDispatcher.
{
public:
    ActiveDispatcher();
    /// Creates the ActiveDispatcher.

    ActiveDispatcher(Thread::Priority prio);
    /// Creates the ActiveDispatcher and sets
    /// the priority of its thread.

    virtual ~ActiveDispatcher();
    /// Destroys the ActiveDispatcher.

    void start(ActiveRunnableBase::Ptr pRunnable);
    /// Adds the Runnable to the dispatch queue.

    void cancel();
    /// Cancels all queued methods.

protected:
    void run();
    void stop();

private:
    Thread _thread;
    NotificationQueue _queue;
};


template <>
class ActiveStarter<ActiveDispatcher>
/// A specialization of ActiveStarter
/// for ActiveDispatcher.
{
public:
    static void start(ActiveDispatcher * pOwner, ActiveRunnableBase::Ptr pRunnable) { pOwner->start(pRunnable); }
};


} // namespace Poco


#endif // Foundation_ActiveDispatcher_INCLUDED