topical media & game development
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lib-of-vs-libs-Poco-include-Poco-Activity.h / h



  //
  // Activity.h
  //
  // Id: //poco/1.3/Foundation/include/Poco/Activity.h#2 
  //
  // Library: Foundation
  // Package: Threading
  // Module:  ActiveObjects
  //
  // Definition of the Activity template class.
  //
  // Copyright (c) 2004-2006, 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
  // FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
  // ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  // DEALINGS IN THE SOFTWARE.
  //
  
  ifndef Foundation_Activity_INCLUDED
  define Foundation_Activity_INCLUDED
  
  include "Poco/Foundation.h"
  include "Poco/RunnableAdapter.h"
  include "Poco/ThreadPool.h"
  include "Poco/Event.h"
  include "Poco/Mutex.h"
  
  namespace Poco {
  
  template <class C>
  class Activity: public Runnable
This template class helps to implement active objects. An active object uses threads to decouple method execution from method invocation, or to perform tasks autonomously, without intervention of a caller. An activity is a (typically longer running) method that executes within its own task. Activities can be started automatically (upon object construction) or manually at a later time. Activities can also be stopped at any time. However, to make stopping an activity work, the method implementing the activity has to check periodically whether it has been requested to stop, and if so, return. Activities are stopped before the object they belong to is destroyed. Methods implementing activities cannot have arguments or return values. Activity objects are used as follows: class ActiveObject { public: ActiveObject(): _activity(this, &ActiveObject::runActivity) { ... } ... protected: void runActivity() { while (!_activity.isStopped()) { ... } } private: Activity<ActiveObject> _activity; }; { public: typedef RunnableAdapter<C> RunnableAdapterType; typedef typename RunnableAdapterType::Callback Callback; 

          Activity(C* pOwner, Callback method):
                  _pOwner(pOwner),
                  _runnable(*pOwner, method),
                  _stopped(true),
                  _running(false),
                  _done(false)
Creates the activity. Call start() to start it. { poco_check_ptr (pOwner); } ~Activity() Stops and destroys the activity. { stop(); wait(); } void start() Starts the activity by acquiring a thread for it from the default thread pool. { FastMutex::ScopedLock lock(_mutex); if (!_running) { _done.reset(); _stopped = false; _running = true; try { ThreadPool::defaultPool().start(*this); } catch (...) { _running = false; throw; } } } void stop() Requests to stop the activity. { FastMutex::ScopedLock lock(_mutex); 

                  _stopped = true;
          }
          
          void wait()
Waits for the activity to complete. { if (_running) { _done.wait(); } } 

          void wait(long milliseconds)
Waits the given interval for the activity to complete. An TimeoutException is thrown if the activity does not complete within the given interval. { if (_running) { _done.wait(milliseconds); } } bool isStopped() const Returns true if the activity has been requested to stop. { return _stopped; } bool isRunning() const Returns true if the activity is running. { return _running; } 

  protected:
          void run()
          {
                  try
                  {
                          _runnable.run();
                  }
                  catch (...)
                  {
                          _running = false;
                          _done.set();
                          throw;
                  }
                  _running = false;
                  _done.set();
          }
          
  private:
          Activity();
          Activity(const Activity&);
          Activity& operator = (const Activity&);
  
          C*                  _pOwner;
          RunnableAdapterType _runnable;
          volatile bool       _stopped;
          volatile bool       _running;
          Event               _done;
          FastMutex           _mutex;
  };
  
  } // namespace Poco
  
  endif // Foundation_Activity_INCLUDED
[] readme course(s) preface I 1 2 II 3 4 III 5 6 7 IV 8 9 10 V 11 12 afterthought(s) appendix reference(s) example(s) resource(s) _

(C) Æliens 04/09/2009

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