CWE-ou-minkata/Sources/Plasma/CoreLib/hsThread.h

/*==LICENSE==*

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*==LICENSE==*/
#ifndef hsThread_Defined
#define hsThread_Defined

#include "HeadSpin.h"
#include <atomic>
#include <mutex>
#include <condition_variable>

typedef uint32_t hsMilliseconds;

#ifdef HS_BUILD_FOR_UNIX
    #include <pthread.h>
    #include <semaphore.h>
    //  We can't wait with a timeout with semas
    #define USE_SEMA
    // Linux kernel 2.4 w/ NTPL threading patch and O(1) scheduler
    // seems to have a problem in it's cond_t implementation that
    // causes a hang under heavy load. This is a workaround that
    // uses select() and pipes.
//  #define PSEUDO_EVENT
#endif

class hsThread 
{
public:
#if HS_BUILD_FOR_WIN32
    typedef uint32_t ThreadId;
#elif HS_BUILD_FOR_UNIX
    typedef pthread_t ThreadId;
#endif
private:
    bool        fQuit;
    uint32_t    fStackSize;
#if HS_BUILD_FOR_WIN32
    ThreadId    fThreadId;
    HANDLE      fThreadH;
    HANDLE      fQuitSemaH;
#elif HS_BUILD_FOR_UNIX
    ThreadId    fPThread;
    bool        fIsValid;
    pthread_mutex_t fMutex;
#endif
protected:
    bool        GetQuit() const { return fQuit; }
    void        SetQuit(bool value) { fQuit = value; }
public:
    hsThread(uint32_t stackSize = 0);
    virtual     ~hsThread();    // calls Stop()
#if HS_BUILD_FOR_WIN32
    ThreadId        GetThreadId() { return fThreadId; }
    static ThreadId GetMyThreadId();
#elif HS_BUILD_FOR_UNIX
    ThreadId            GetThreadId() { return fPThread; }
    static ThreadId     GetMyThreadId() { return pthread_self(); }
    pthread_mutex_t* GetStartupMutex() { return &fMutex;  }
#endif
                
    virtual hsError Run() = 0;      // override this to do your work
    virtual void    Start();        // initializes stuff and calls your Run() method
    virtual void    Stop();     // sets fQuit = true and the waits for the thread to stop
    virtual void    OnQuit() { }
                
    //  Static functions
    static void*    Alloc(size_t size); // does not call operator::new(), may return nil
    static void Free(void* p);      // does not call operator::delete()
    static void ThreadYield();
};

//////////////////////////////////////////////////////////////////////////////
class hsSemaphore
{
    std::mutex fMutex;
    std::condition_variable fCondition;
    unsigned fValue;

public:
    hsSemaphore(unsigned initial = 0) : fValue(initial) { }

    inline void Wait()
    {
        std::unique_lock<std::mutex> lock(fMutex);
        fCondition.wait(lock, [this]() { return fValue > 0; });
        --fValue;
    }

    template <class _Rep, class _Period>
    inline bool Wait(const std::chrono::duration<_Rep, _Period> &duration)
    {
        std::unique_lock<std::mutex> lock(fMutex);

        bool result = fCondition.wait_for(lock, duration, [this]() { return fValue > 0; });
        if (result)
            --fValue;

        return result;
    }

    inline void Signal()
    {
        std::unique_lock<std::mutex> lock(fMutex);
        ++fValue;
        fCondition.notify_one();
    }
};

//////////////////////////////////////////////////////////////////////////////
class hsGlobalSemaphore {
#if HS_BUILD_FOR_WIN32
    HANDLE  fSemaH;
#elif HS_BUILD_FOR_UNIX
#ifdef USE_SEMA
    sem_t*  fPSema;
    bool    fNamed;
#else
    pthread_mutex_t fPMutex;
    pthread_cond_t  fPCond;
    int32_t         fCounter;
#endif
#endif
public:
    hsGlobalSemaphore(int initialValue = 0, const char* name = nullptr);
    ~hsGlobalSemaphore();

#ifdef HS_BUILD_FOR_WIN32
    HANDLE GetHandle() const { return fSemaH; }
#endif

    bool Wait(hsMilliseconds timeToWait = kPosInfinity32);
    void Signal();
};

//////////////////////////////////////////////////////////////////////////////
class hsEvent
{
    std::mutex fMutex;
    std::condition_variable fCondition;

public:
    hsEvent() { }

    inline void Wait()
    {
        std::unique_lock<std::mutex> lock(fMutex);
        fCondition.wait(lock);
    }

    inline void Signal()
    {
        std::unique_lock<std::mutex> lock(fMutex);
        fCondition.notify_one();
    }
};

//////////////////////////////////////////////////////////////////////////////
class hsSleep
{
public:
    static void Sleep(uint32_t millis);
};

//////////////////////////////////////////////////////////////////////////////
// Allows multiple readers, locks out readers for writing.

class hsReaderWriterLock
{
public:
    hsReaderWriterLock() : fReaderCount(0), fWriterSem(1) { }

private:
    void LockForReading()
    {
        // Don't allow us to start reading if there's still an active writer
        std::lock_guard<std::mutex> lock(fReaderLock);

        fReaderCount++;
        if (fReaderCount == 1) {
            // Block writers from starting (wait is a misnomer here)
            fWriterSem.Wait();
        }
    }

    void UnlockForReading()
    {
        fReaderCount--;
        if (fReaderCount == 0)
            fWriterSem.Signal();
    }

    void LockForWriting()
    {
        // Blocks new readers from starting
        fReaderLock.lock();

        // Wait until all readers are done
        fWriterSem.Wait();
    }

    void UnlockForWriting()
    {
        fWriterSem.Signal();
        fReaderLock.unlock();
    }

    std::atomic<int>    fReaderCount;
    std::mutex          fReaderLock;
    hsSemaphore         fWriterSem;

    friend class hsLockForReading;
    friend class hsLockForWriting;
};

class hsLockForReading
{
    hsReaderWriterLock& fLock;

public:
    hsLockForReading(hsReaderWriterLock& lock) : fLock(lock)
    {
        fLock.LockForReading();
    }

    ~hsLockForReading()
    {
        fLock.UnlockForReading();
    }
};

class hsLockForWriting
{
    hsReaderWriterLock& fLock;

public:
    hsLockForWriting(hsReaderWriterLock& lock) : fLock(lock)
    {
        fLock.LockForWriting();
    }

    ~hsLockForWriting()
    {
        fLock.UnlockForWriting();
    }
};

#endif