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//
// Activity.h
//
// Library: Foundation
// Package: Threading
// Module: ActiveObjects
//
// Definition of the Activity template class.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier: BSL-1.0
//
#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.
{
try
{
stop();
wait();
}
catch (...)
{
poco_unexpected();
}
}
void start()
/// Starts the activity by acquiring a
/// thread for it from the default thread pool.
{
start(ThreadPool::defaultPool());
}
void start(ThreadPool& pool)
{
FastMutex::ScopedLock lock(_mutex);
if (!_running)
{
_done.reset();
_stopped = false;
_running = true;
try
{
pool.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
|
