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//

// SocketReactor.h

//

// $Id: //poco/1.3/Net/include/Poco/Net/SocketReactor.h#2 $

//

// Library: Net

// Package: Reactor

// Module:  SocketReactor

//

// Definition of the SocketReactor class.

//

// Copyright (c) 2005-2006, Applied Informatics Software Engineering GmbH.

// and Contributors.

//

// Permission is hereby granted, free of charge, to any person or organization

// obtaining a copy of the software and accompanying documentation covered by

// this license (the "Software") to use, reproduce, display, distribute,

// execute, and transmit the Software, and to prepare derivative works of the

// Software, and to permit third-parties to whom the Software is furnished to

// do so, all subject to the following:

// 

// The copyright notices in the Software and this entire statement, including

// the above license grant, this restriction and the following disclaimer,

// must be included in all copies of the Software, in whole or in part, and

// all derivative works of the Software, unless such copies or derivative

// works are solely in the form of machine-executable object code generated by

// a source language processor.

// 

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT

// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE

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// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER

// DEALINGS IN THE SOFTWARE.

//

#ifndef Net_SocketReactor_INCLUDED

#define Net_SocketReactor_INCLUDED

#include "Poco/Net/Net.h"

#include "Poco/Net/Socket.h"

#include "Poco/Runnable.h"

#include "Poco/Timespan.h"

#include "Poco/Observer.h"

#include "Poco/AutoPtr.h"

#include <map>

namespace Poco {

namespace Net {

class Socket;

class SocketNotification;

class SocketNotifier;

class Net_API SocketReactor: public Poco::Runnable

        /// This class, which is part of the Reactor pattern,

        /// implements the "Initiation Dispatcher".

        ///

        /// The Reactor pattern has been described in the book

        /// "Pattern Languages of Program Design" by Jim Coplien

        /// and Douglas C. Schmidt (Addison Wesley, 1995).

        ///

        /// The Reactor design pattern handles service requests that

        /// are delivered concurrently to an application by one or more

        /// clients. Each service in an application may consist of several

        /// methods and is represented by a separate event handler. The event

        /// handler is responsible for servicing service-specific requests.

        /// The SocketReactor dispatches the event handlers.

        ///

        /// Event handlers (any class can be an event handler - there

        /// is no base class for event handlers) can be registered

        /// with the addEventHandler() method and deregistered with

        /// the removeEventHandler() method.

        /// 

        /// An event handler is always registered for a certain socket,

        /// which is given in the call to addEventHandler(). Any method

        /// of the event handler class can be registered to handle the

        /// event - the only requirement is that the method takes

        /// a pointer to an instance of SocketNotification (or a subclass of it)

        /// as argument.

        ///

        /// Once started, the SocketReactor waits for events

        /// on the registered sockets, using Socket::select().

        /// If an event is detected, the corresponding event handler

        /// is invoked. There are five event types (and corresponding

        /// notification classes) defined: ReadableNotification, WritableNotification,

        /// ErrorNotification, TimeoutNotification, IdleNotification and 

        /// ShutdownNotification.

        /// 

        /// The ReadableNotification will be dispatched if a socket becomes

        /// readable. The WritableNotification will be dispatched if a socket

        /// becomes writable. The ErrorNotification will be dispatched if

        /// there is an error condition on a socket.

        ///

        /// If the timeout expires and no event has occured, a

        /// TimeoutNotification will be dispatched to all event handlers

        /// registered for it. This is done in the onTimeout() method

        /// which can be overridden by subclasses to perform custom

        /// timeout processing.

        ///

        /// If there are no sockets for the SocketReactor to pass to

        /// Socket::select(), an IdleNotification will be dispatched to

        /// all event handlers registered for it. This is done in the

        /// onIdle() method which can be overridden by subclasses

        /// to perform custom idle processing. Since onIdle() will be

        /// called repeatedly in a loop, it is recommended to do a

        /// short sleep or yield in the event handler.

        ///

        /// Finally, when the SocketReactor is about to shut down (as a result 

        /// of stop() being called), it dispatches a ShutdownNotification

        /// to all event handlers. This is done in the onShutdown() method

        /// which can be overridded by subclasses to perform custom

        /// shutdown processing.

        ///

        /// The SocketReactor is implemented so that it can 

        /// run in its own thread. It is also possible to run

        /// multiple SocketReactors in parallel, as long as

        /// they work on different sockets.

        ///

        /// It is safe to call addEventHandler() and removeEventHandler()

        /// from another thread while the SocketReactor is running. Also,

        /// it is safe to call addEventHandler() and removeEventHandler()

        /// from event handlers.

{

public:

        SocketReactor();

                /// Creates the SocketReactor.

        SocketReactor(const Poco::Timespan& timeout);

                /// Creates the SocketReactor, using the given timeout.

        virtual ~SocketReactor();

                /// Destroys the SocketReactor.

        void run();

                /// Runs the SocketReactor. The reactor will run

                /// until stop() is called (in a separate thread).

        void stop();

                /// Stops the SocketReactor.

                ///

                /// The reactor will be stopped when the next event

                /// (including a timeout event) occurs.

        void setTimeout(const Poco::Timespan& timeout);

                /// Sets the timeout. 

                ///

                /// If no other event occurs for the given timeout 

                /// interval, a timeout event is sent to all event listeners.

                ///

                /// The default timeout is 250 milliseconds;

                ///

                /// The timeout is passed to the Socket::select()

                /// method.

        const Poco::Timespan& getTimeout() const;

                /// Returns the timeout.

        void addEventHandler(const Socket& socket, const Poco::AbstractObserver& observer);

                /// Registers an event handler with the SocketReactor.

                ///

                /// Usage:

                ///     Poco::Observer<MyEventHandler, SocketNotification> obs(*this, &MyEventHandler::handleMyEvent);

                ///     reactor.addEventHandler(obs);

        void removeEventHandler(const Socket& socket, const Poco::AbstractObserver& observer);

                /// Unregisters an event handler with the SocketReactor.

                ///

                /// Usage:

                ///     Poco::Observer<MyEventHandler, SocketNotification> obs(*this, &MyEventHandler::handleMyEvent);

                ///     reactor.removeEventHandler(obs);

protected:

        virtual void onTimeout();

                /// Called if the timeout expires and no other events are available.

                ///

                /// Can be overridden by subclasses. The default implementation

                /// dispatches the TimeoutNotification and thus should be called by overriding

                /// implementations.

        virtual void onIdle();

                /// Called if no sockets are available to call select() on.

                ///

                /// Can be overridden by subclasses. The default implementation

                /// dispatches the IdleNotification and thus should be called by overriding

                /// implementations.

        virtual void onShutdown();

                /// Called when the SocketReactor is about to terminate.

                ///

                /// Can be overridden by subclasses. The default implementation

                /// dispatches the ShutdownNotification and thus should be called by overriding

                /// implementations.

        void dispatch(const Socket& socket, SocketNotification* pNotification);

                /// Dispatches the given notification to all observers

                /// registered for the given socket.

        void dispatch(SocketNotification* pNotification);

                /// Dispatches the given notification to all observers.

private:

        typedef Poco::AutoPtr<SocketNotifier>     NotifierPtr;

        typedef Poco::AutoPtr<SocketNotification> NotificationPtr;

        typedef std::map<Socket, NotifierPtr>     EventHandlerMap;

        void dispatch(NotifierPtr& pNotifier, SocketNotification* pNotification);

        enum

        {

                DEFAULT_TIMEOUT = 250000

        };

        bool            _stop;

        Poco::Timespan  _timeout;

        EventHandlerMap _handlers;

        NotificationPtr _pReadableNotification;

        NotificationPtr _pWritableNotification;

        NotificationPtr _pErrorNotification;

        NotificationPtr _pTimeoutNotification;

        NotificationPtr _pIdleNotification;

        NotificationPtr _pShutdownNotification;

        Poco::FastMutex _mutex;

        friend class SocketNotifier;

};

} } // namespace Poco::Net

#endif // Net_SocketReactor_INCLUDED