JobSystemWithBarrier.h

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// Jolt Physics Library (https://github.com/jrouwe/JoltPhysics)
// SPDX-FileCopyrightText: 2023 Jorrit Rouwe
// SPDX-License-Identifier: MIT
 
#pragma once
 
#include <Jolt/Core/JobSystem.h>
#include <Jolt/Core/Semaphore.h>
 
JPH_NAMESPACE_BEGIN
 
class JPH_EXPORT JobSystemWithBarrier : public JobSystem
{
public:
    JPH_OVERRIDE_NEW_DELETE
 
    explicit                JobSystemWithBarrier(uint inMaxBarriers);
                            JobSystemWithBarrier() = default;
    virtual                 ~JobSystemWithBarrier() override;
 
    void                    Init(uint inMaxBarriers);
 
    // See JobSystem
    virtual Barrier *       CreateBarrier() override;
    virtual void            DestroyBarrier(Barrier *inBarrier) override;
    virtual void            WaitForJobs(Barrier *inBarrier) override;
 
private:
    class BarrierImpl : public Barrier
    {
    public:
        JPH_OVERRIDE_NEW_DELETE
 
                            BarrierImpl();
        virtual             ~BarrierImpl() override;
 
        // See Barrier
        virtual void        AddJob(const JobHandle &inJob) override;
        virtual void        AddJobs(const JobHandle *inHandles, uint inNumHandles) override;
 
        inline bool         IsEmpty() const                                 { return mJobReadIndex == mJobWriteIndex; }
 
        void                Wait();
 
        atomic<bool>        mInUse { false };
 
    protected:
        virtual void        OnJobFinished(Job *inJob) override;
 
        static constexpr uint cMaxJobs = 2048;
        static_assert(IsPowerOf2(cMaxJobs));                                // We do bit operations and require max jobs to be a power of 2
        atomic<Job *>       mJobs[cMaxJobs];                                
        alignas(JPH_CACHE_LINE_SIZE) atomic<uint> mJobReadIndex { 0 };      
        alignas(JPH_CACHE_LINE_SIZE) atomic<uint> mJobWriteIndex { 0 };     
        atomic<int>         mNumToAcquire { 0 };                            
        Semaphore           mSemaphore;                                     
    };
 
    uint                    mMaxBarriers = 0;                               
    BarrierImpl *           mBarriers = nullptr;                            
};
 
JPH_NAMESPACE_END