ThreadManager.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreTypes.h"
#include "CoreGlobals.h"
#include "Containers/Map.h"
#include "HAL/CriticalSection.h"
 
#ifndef PLATFORM_SUPPORTS_ALL_THREAD_BACKTRACES
    #define PLATFORM_SUPPORTS_ALL_THREAD_BACKTRACES (PLATFORM_WINDOWS || PLATFORM_MAC)
#endif
 
class FRunnableThread;
 
/**
 * Manages runnables and runnable threads.
 */
class FThreadManager
{
    /** Critical section for ThreadList */
    FCriticalSection ThreadsCritical;
 
    using FThreads = TMap<uint32, FRunnableThread*, TInlineSetAllocator<256>>;
    /** List of thread objects to be ticked. */
    FThreads Threads;
 
public:
 
    /**
    * Used internally to add a new thread object.
    *
    * @param Thread thread object.
    * @see RemoveThread
    */
    void AddThread(uint32 ThreadId, FRunnableThread* Thread);
 
    /**
    * Used internally to remove thread object.
    *
    * @param Thread thread object to be removed.
    * @see AddThread
    */
    void RemoveThread(FRunnableThread* Thread);
 
    /** Get the number of registered threads */
    int32 NumThreads() const { return Threads.Num(); }
 
    /** Ticks all fake threads and their runnable objects. */
    void Tick();
 
    /** Returns the name of a thread given its TLS id */
    inline static const FString& GetThreadName(uint32 ThreadId)
    {
        static FString GameThreadName(TEXT("GameThread"));
        static FString RenderThreadName(TEXT("RenderThread"));
        PRAGMA_DISABLE_DEPRECATION_WARNINGS
        if (ThreadId == GGameThreadId)
        {
            return GameThreadName;
        }
        else if (ThreadId == GRenderThreadId)
        {
            return RenderThreadName;
        }
        PRAGMA_ENABLE_DEPRECATION_WARNINGS
        return Get().GetThreadNameInternal(ThreadId);
    }
 
#if PLATFORM_SUPPORTS_ALL_THREAD_BACKTRACES
    struct FThreadStackBackTrace
    {
        uint32 ThreadId;
        FString ThreadName;
        TArray<uint64, TInlineAllocator<100>> ProgramCounters;
    };
 
    void GetAllThreadStackBackTraces(TArray<FThreadStackBackTrace>& StackTraces);
#endif
 
    /**
     * Enumerate each thread.
     *
     */
    void ForEachThread(TFunction<void(uint32 ThreadId, FRunnableThread* Thread)> Func);
 
    /**
     * Access to the singleton object.
     *
     * @return Thread manager object.
     */
    static FThreadManager& Get();
 
private:
 
    friend class FForkProcessHelper;
 
    /** Returns a list of registered forkable threads  */
    TArray<FRunnableThread*> GetForkableThreads();
 
    /** Returns internal name of a the thread given its TLS id */
    const FString& GetThreadNameInternal(uint32 ThreadId);
};