Poco::NotificationQueue

Poco::NotificationQueuePoco::PriorityNotificationQueue を紹介します。

メインスレッドで Poco::NotificationQueuePoco::PriorityNotificationQueue に enqueue して、3つのワーカースレッドで順次 dequeue するというサンプルです。
デザインパターンで言うと Worker Thread パターンになります。

NotificationQueueTest.cpp

・Foundation/samples/NotificationQueue とほとんど同じ処理だが、Poco::NotificationQueue
 Poco::PriorityNotificationQueue の両者を処理できるように Worker を template 化。
Poco::NotificationQueuePoco::PriorityNotificationQueue との enqueueNotification() の引数の数の
 違いを template の特殊化で対応。ついでに、非対応クラスを渡されてインスタンス化され、
 MyEnqueueNotification() が呼ばれたら、非対応な旨表示。

#include <Poco/Format.h>
#include <Poco/Notification.h>
#include <Poco/NotificationQueue.h>
#include <Poco/PriorityNotificationQueue.h>
#include <Poco/ThreadPool.h>
#include <Poco/Thread.h>
#include <Poco/Runnable.h>
#include <Poco/Random.h>
#include <Poco/AutoPtr.h>
 
#include <string>
#include <typeinfo>
 
#include "ScopedLogMessage.h"
#include "PrepareConsoleLogger.h"
 
const int kNumQueue		= 12;
const long kSleepMaxTime	= 200;
const long kSleepWaitTime	= 500;
 
class WorkNotification : public Poco::Notification
{
public:
	WorkNotification(int data):
		m_data(data)
	{
	}
 
	int data() const
	{
		return m_data;
	}
 
private:
	int	m_data;
};
 
template<class T>
class Worker : public Poco::Runnable
{
	typedef Poco::AutoPtr<WorkNotification> WorkNotificationPtr;
 
public:
	Worker(const std::string& name, T& queue, ScopedLogMessage& msg):
		m_name(name)
	,	m_queue(queue)
	,	m_msg(msg)
	{
		m_msg.Message(Poco::format("  %s created", m_name));
	}
 
	~Worker()
	{
		m_msg.Message(Poco::format("  %s deleted", m_name));
	}
 
	void run()
	{
		Poco::Random rnd;
		for(;;)
		{
			Poco::Notification::Ptr pNf(m_queue.waitDequeueNotification());
			if(pNf)
			{
				WorkNotificationPtr pWorkNf = pNf.cast<WorkNotification>();
				if(pWorkNf)
				{
					m_msg.Message(Poco::format("    %s got work notification %d", m_name, pWorkNf->data()));
					Poco::Thread::sleep(rnd.next(kSleepMaxTime));
				}
			}
			else break;
		}
	}
 
private:
	std::string		m_name;
	T&			m_queue;
	ScopedLogMessage&	m_msg;
};
 
template<class T>
class MyNotificationQueue : public T
{
public:
	MyNotificationQueue(ScopedLogMessage& msg) :
		m_msg(msg)
	,	m_numEnqueued(0)
	{
	}
 
	void MyEnqueueNotification(Poco::Notification::Ptr pNotification)
	{
		m_msg.Message(Poco::format("Class %s is not supported!", std::string(typeid(T).name())));
	}
 
private:
	ScopedLogMessage&	m_msg;
	int			m_numEnqueued;
};
 
template<>
void MyNotificationQueue<Poco::NotificationQueue>::MyEnqueueNotification(Poco::Notification::Ptr pNotification)
{
	enqueueNotification(pNotification);
	++m_numEnqueued;
}
 
template<>
void MyNotificationQueue<Poco::PriorityNotificationQueue>::MyEnqueueNotification(Poco::Notification::Ptr pNotification)
{
	enqueueNotification(pNotification, kNumQueue-m_numEnqueued);
	++m_numEnqueued;
}
 
template<class T>
void TestNotificationQueue(ScopedLogMessage& msg, const std::string& title)
{
	msg.Message(Poco::format("--- %s ---", title));
 
	MyNotificationQueue<T> queue(msg);
 
	Worker< MyNotificationQueue<T> > worker1("Worker 1", queue, msg);
	Worker< MyNotificationQueue<T> > worker2("Worker 2", queue, msg);
	Worker< MyNotificationQueue<T> > worker3("Worker 3", queue, msg);
 
	for(int i=0; i<kNumQueue; ++i)
	{
		queue.MyEnqueueNotification(new WorkNotification(i));
	}
 
	Poco::ThreadPool::defaultPool().start(worker1);
	Poco::ThreadPool::defaultPool().start(worker2);
	Poco::ThreadPool::defaultPool().start(worker3);
 
	while(!queue.empty())
	{
		Poco::Thread::sleep(kSleepMaxTime);
	}
	Poco::Thread::sleep(kSleepWaitTime);
 
	queue.wakeUpAll();
	Poco::ThreadPool::defaultPool().joinAll();
}
 
int main(int /*argc*/, char** /*argv*/)
{
	PrepareConsoleLogger logger(Poco::Logger::ROOT, Poco::Message::PRIO_INFORMATION);
 
	ScopedLogMessage msg("NotificationQueueTest ", "start", "end");
 
	TestNotificationQueue<Poco::NotificationQueue>(msg, "Poco::NotificationQueue");
	TestNotificationQueue<Poco::PriorityNotificationQueue>(msg, "Poco::PriorityNotificationQueue");
 
	return 0;
}

Results of execution

Poco::NotificationQueue の場合は、queue に積んだ順に処理される。
Poco::PriorityNotificationQueue の場合は、queue に積んだ順ではなく、priority 値の小さい順に
 処理される。
・どの Worker(どの thread)で処理されるかは、実行する度に変化。

[0] NotificationQueueTest start
[0] --- Poco::NotificationQueue ---
[0]   Worker 1 created
[0]   Worker 2 created
[0]   Worker 3 created
[2]     Worker 2 got work notification 0
[1]     Worker 1 got work notification 1
[3]     Worker 3 got work notification 2
[2]     Worker 2 got work notification 3
[1]     Worker 1 got work notification 4
[3]     Worker 3 got work notification 5
[2]     Worker 2 got work notification 6
[1]     Worker 1 got work notification 7
[3]     Worker 3 got work notification 8
[2]     Worker 2 got work notification 9
[1]     Worker 1 got work notification 10
[3]     Worker 3 got work notification 11
[0]   Worker 3 deleted
[0]   Worker 2 deleted
[0]   Worker 1 deleted
[0] --- Poco::PriorityNotificationQueue ---
[0]   Worker 1 created
[0]   Worker 2 created
[0]   Worker 3 created
[3]     Worker 3 got work notification 11
[1]     Worker 1 got work notification 10
[2]     Worker 2 got work notification 9
[3]     Worker 3 got work notification 8
[1]     Worker 1 got work notification 7
[2]     Worker 2 got work notification 6
[3]     Worker 3 got work notification 5
[1]     Worker 1 got work notification 4
[2]     Worker 2 got work notification 3
[3]     Worker 3 got work notification 2
[1]     Worker 1 got work notification 1
[2]     Worker 2 got work notification 0
[0]   Worker 3 deleted
[0]   Worker 2 deleted
[0]   Worker 1 deleted
[0] NotificationQueueTest end

Downloads

ここをクリックすると、makefile や VC++ プロジェクトなど一式がダウンロードできます。
(2013.05.31 updated)
・2010年6月8日からのダウンロード数:814

Subversion

・フリーの Subversion ホスティングサービス Assemblaで、ソースコードを管理しています。

Reference

POCO::Foundationでデザインパターン – マルチスレッド編 –
http://pocoproject.org にある NotificationsEvents のプレセンテーション。(PDF)

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