taskqueue.h

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// Program Name: taskqueue.h
// Created     : Oct. 24, 2005
//
// Purpose     : Used to process delayed tasks
//                                                                            
// Copyright (c) 2005 David Blain <dblain@mythtv.org>
//                                          
// Licensed under the GPL v2 or later, see LICENSE for details
//
 
#ifndef TASKQUEUE_H
#define TASKQUEUE_H
 
// C++ headers
#include <chrono>
#include <map>
 
// Qt headers
#include <QMutex>
#include <QString>
 
// MythTV headers
#include "libmythbase/mthread.h"
#include "libmythbase/referencecounter.h"
 
#include "upnpexp.h"
 
class Task;
class TaskQueue;
 
// Typedefs
 
using TaskMap = std::multimap<std::chrono::microseconds, Task *>;
 
//
// Task Class Definition
// 
 
class Task : public ReferenceCounter
{
    protected:
        static long m_nTaskCount;
 
        long        m_nTaskId;
 
    protected:
 
        // Destructor protected to force use of Release Method
        ~Task() override = default;
 
    public:
 
               explicit Task(const QString &debugName); 
 
                long    Id() const { return( m_nTaskId ); }
 
        virtual void    Execute( TaskQueue *pQueue ) = 0;
        virtual QString Name   () = 0;
 
};
 
 
// TaskQueue Singleton
 
class UPNP_PUBLIC TaskQueue : public MThread
{
    private: 
 
        // Singleton instance used by all.
        static TaskQueue*        g_pTaskQueue;  
 
    protected:
 
        TaskMap     m_mapTasks;
        QMutex      m_mutex;
        bool        m_bTermRequested {false};
 
    protected:
 
        bool  IsTermRequested();
 
        void run() override; // MThread
 
    private:
 
        // ------------------------------------------------------------------
        // Private so the singleton pattern can be inforced.
        // ------------------------------------------------------------------
 
        TaskQueue();
 
    public:
 
        static TaskQueue* Instance();
        static void Shutdown();
 
        ~TaskQueue() override;
 
        void  RequestTerminate   ( );
 
        void  Clear              ( );
        void  AddTask            ( std::chrono::milliseconds msec , Task *pTask );
        void  AddTask            ( Task *pTask );
                                                          
        Task *GetNextExpiredTask ( std::chrono::microseconds tt, std::chrono::milliseconds nWithinMilliSecs = 50ms );
                                                                
    private:
        void  AddTaskAbsolute    ( std::chrono::microseconds tt, Task *pTask );
};
 
#endif // TASKQUEUE_H