PDG_EventQueue.h

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/*
 * PROPRIETARY INFORMATION.  This software is proprietary to
 * Side Effects Software Inc., and is not to be reproduced,
 * transmitted, or disclosed in any way without written permission.
 *
 * COMMENTS:
 */

#ifndef __PDG_EventQueue_h__
#define __PDG_EventQueue_h__

#include "PDG_API.h"
#include "PDG_Event.h"

#include <UT/UT_Set.h>
#include <UT/UT_ConcurrentQueue.h>
#include <UT/UT_ConcurrentSet.h>
#include <UT/UT_Thread.h>
#include <UT/UT_RWLock.h>
#include <UT/UT_Map.h>

#include <SYS/SYS_AtomicInt.h>

#include <utility>

class PDG_EventEmitter;
class PDG_EventHandler;

class PDG_API PDG_EventQueue
{
public:
    using EventInfo = std::pair<const PDG_EventEmitter*, PDG_Event>;

    PDG_EventQueue();
    ~PDG_EventQueue();

    void term();

    void queueEvent(
        const PDG_EventEmitter* emitter,
        const PDG_Event& event);

    void waitAllEvents();

    void registerEmitter(PDG_EventEmitter* emitter);
    void deregisterEmitter(PDG_EventEmitter* emitter);

    void pause() { myPauseRequests.add(1); }
    void resume() { myPauseRequests.add(-1); }

    class ScopedPause
    {
    public:
        ScopedPause(PDG_EventQueue* queue)
            : myQueue(queue)
        {
            queue->pause();
        }

        ~ScopedPause()
        {
            myQueue->resume();
        }

    private:
        PDG_EventQueue* myQueue = nullptr;
    };

private:
#if PDG_EVENT_QUEUE_DEBUG
    UT_Map<PDG_EventType, UT_StringHolder> myEventStrings;
#endif
    
    static void* run(void* param);

    bool myTerminate = false;
    bool myWaitingEvents = false;
    UT_Thread* myThread = nullptr;

    UT_RWLock myEmittersLock;
    UT_ConcurrentSet<PDG_EventEmitter*> myEmitters;
    UT_ConcurrentQueue<EventInfo> myEvents;

    SYS_AtomicInt32 myPauseRequests;

    static constexpr int theSleepTime = 10;
};

#endif