DebugSubstep.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "Misc/Build.h"
 
#ifndef CHAOS_DEBUG_SUBSTEP
#define CHAOS_DEBUG_SUBSTEP !(UE_BUILD_SHIPPING || UE_BUILD_TEST)
#endif
 
#if CHAOS_DEBUG_SUBSTEP
 
#include "HAL/CriticalSection.h"
#include "HAL/ThreadSafeBool.h"
#include "Containers/Queue.h"
 
class FEvent;
 
namespace Chaos
{
    class FDebugSubstep final
    {
        friend class FDebugSolverTask;
        friend class FDebugSolverTasks;
 
    public:
        FDebugSubstep();
        CHAOS_API ~FDebugSubstep();
 
        bool IsEnabled() const { return bIsEnabled; }
 
        FORCEINLINE void Add(const TCHAR* Label = nullptr) const { Add(false, Label); }
 
        CHAOS_API void Enable(bool bEnable);
 
        CHAOS_API void ProgressToSubstep();
 
        CHAOS_API void ProgressToStep();
 
    private:
        FDebugSubstep(const FDebugSubstep&) = delete;
        FDebugSubstep& operator=(const FDebugSubstep&) = delete;
 
        CHAOS_API void Initialize();
 
        CHAOS_API void Release();
 
        FORCEINLINE bool IsInitialized() const { return !!ProgressEvent && !!SubstepEvent; }
 
        /*
         * Disable and wait for the completion of the debug thread.
         * Not thread safe. Must be called from within the physics thread or with the physics thread locked.
         * Once shutdown, the debug thread can still be restarted when SyncAdvance is called.
         */
        CHAOS_API void Shutdown();
 
        CHAOS_API void AssumeThisThread();
 
        CHAOS_API bool SyncAdvance(bool bIsSolverEnabled);
 
        CHAOS_API void Add(bool bInStep, const TCHAR* Label) const;
 
        CHAOS_API void Start();
 
        CHAOS_API void Stop();
 
        CHAOS_API void Substep(bool bShouldStep);
 
    private:
        enum class ECommand { Enable, Disable, ProgressToSubstep, ProgressToStep };
 
        FThreadSafeBool bIsEnabled;    // Status of the debugging thread. Can find itself in a race condition while the Add() method is ran outside of the debug thread, hence the FThreadSafeBool.
        TQueue<ECommand, EQueueMode::Mpsc> CommandQueue;  // Command queue, thread safe, Multiple-producers single-consumer (MPSC) model.
        FEvent* ProgressEvent;         // Progress synchronization event.
        FEvent* SubstepEvent;          // Substep synchronization event.
        uint32 ThreadId;               // Thread id used to check that the debug substep code is still running within the debug thread.
        mutable bool bWaitForStep;     // Boolean used to flag the completion of a step. Set within the a const function, hence the mutable.
        bool bShouldEnable;            // Whether an enable command has been requested. The debugging thread might not be ready yet (e.g. disabled solver), this will ensure it still enable the debug substepping once it is ready.
    };
}
 
#else  // #if CHAOS_DEBUG_SUBSTEP
 
#include "HAL/Platform.h"
 
namespace Chaos
{
    class FDebugSubstep final
    {
    public:
        FDebugSubstep() {}
        ~FDebugSubstep() {}
 
        bool IsEnabled() const { return false; }
 
        void Add(const TCHAR* /*Label*/ = nullptr) {}
 
        void Enable(bool /*bEnable*/) {}
 
        void ProgressToSubstep() {}
        void ProgressToStep() {}
 
    private:
        FDebugSubstep(const FDebugSubstep&) = delete;
        FDebugSubstep& operator=(const FDebugSubstep&) = delete;
    };
}
 
#endif  // #if CHAOS_DEBUG_SUBSTEP #else