Swiften/EventLoop/SingleThreadedEventLoop.h

/*
 * Copyright (c) 2010 Soren Dreijer
 * Licensed under the simplified BSD license.
 * See Documentation/Licenses/BSD-simplified.txt for more information.
 */

#pragma once

#include <vector>
#include <boost/thread/mutex.hpp>
#include <boost/thread/condition_variable.hpp>

#include "Swiften/EventLoop/EventLoop.h"

// DESCRIPTION:
//
// All interaction with Swiften should happen on the same thread, such as the main GUI thread,
// since the library isn't thread-safe.
// For applications that don't have a main loop, such as WPF and MFC applications, we need a
// different approach to process events from Swiften.
//
// The SingleThreadedEventLoop class implements an event loop that can be used from such applications.
//
// USAGE:
//  
// Spawn a new thread in the desired framework and call SingleThreadedEventLoop::waitForEvents(). The method 
// blocks until a new event has arrived at which time it'll return, or until the wait is canceled
// at which time it throws EventLoopCanceledException. 
//
// When a new event has arrived and SingleThreadedEventLoop::waitForEvents() returns, the caller should then
// call SingleThreadedEventLoop::handleEvents() on the main GUI thread. For WPF applications, for instance, 
// the Dispatcher class can be used to execute the call on the GUI thread.
//

namespace Swift {
  class SingleThreadedEventLoop : public EventLoop {
    public:
      class EventLoopCanceledException : public std::exception { };

    public:
      SingleThreadedEventLoop();
      ~SingleThreadedEventLoop();

      // Blocks while waiting for new events and returns when new events are available.
      // Throws EventLoopCanceledException when the wait is canceled.
      void waitForEvents();
      void handleEvents();
      void stop();      

      virtual void post(const Event& event);
      
    private:
      bool shouldShutDown_;
      std::vector<Event> events_;
      boost::mutex eventsMutex_;
      boost::condition_variable eventsAvailable_;
  };
}