mutex.h

Go to the documentation of this file.

/********************************************************************************************
* Twitch Broadcasting SDK
*
* This software is supplied under the terms of a license agreement with Twitch Interactive, Inc. and
* may not be copied or used except in accordance with the terms of that agreement
* Copyright (c) 2012-2016 Twitch Interactive, Inc.
*********************************************************************************************/

#pragma once

#include "twitchsdk/core/types/coretypes.h"
#include "twitchsdk/core/types/errortypes.h"

#include <memory>

#ifdef CreateMutex
    #undef CreateMutex
#endif

namespace ttv
{
    class IMutex;
    class IConditionMutex;
    class IMutexFactory;
    class AutoMutex;

    void SetMutexFactory(std::shared_ptr<IMutexFactory> factory);

    TTV_ErrorCode CreateMutex(std::shared_ptr<IMutex>& result);
    TTV_ErrorCode CreateConditionMutex(std::shared_ptr<IConditionMutex>& result);
}


class ttv::IMutex
{
public:
    virtual ~IMutex();

    virtual TTV_ErrorCode Lock() = 0;

    virtual TTV_ErrorCode TryLock() = 0;

    virtual TTV_ErrorCode Unlock() = 0;
};

/* Interface for a mutex with condition variable functionality.
 *
 * Wait() and WaitFor() must be called under lock (i.e. after Lock())
 * Signal() and Broadcast() in general should be called outside of lock to avoid pessimization.
 */
class ttv::IConditionMutex : public IMutex
{
public:
    virtual ~IConditionMutex();

    virtual TTV_ErrorCode Wait() = 0;

    virtual TTV_ErrorCode WaitFor(uint64_t timeoutMilliseconds) = 0;

    /* Notify one thread waiting to be notified (through Wait()/WaitFor()).
     * Nothing happens if there are no threads waiting.
     * @return
     *   - TTV_EC_SUCCESS: Successfully notified a waiting thread (or there were no waiting threads).
     */
    virtual TTV_ErrorCode Signal() = 0;

    /* Notify all threads waiting to be notified (through Wait()/WaitFor()).
     * Nothing happens if there are no threads waiting.
     * @return
     *   - TTV_EC_SUCCESS: Successfully notified all waiting threads (or there were no waiting threads).
     */
    virtual TTV_ErrorCode Broadcast() = 0;
};


class ttv::IMutexFactory
{
public:
    virtual ~IMutexFactory();

    virtual TTV_ErrorCode CreateMutex(std::shared_ptr<IMutex>& result) = 0;
    virtual TTV_ErrorCode CreateConditionMutex(std::shared_ptr<IConditionMutex>& result) = 0;
};


class ttv::AutoMutex
{
public:
    inline explicit AutoMutex(const std::shared_ptr<IMutex>& mutex)
    : mMutex(mutex)
    {
        assert(mutex != nullptr);
        mutex->Lock();
    }
    
    ~AutoMutex()
    {
        mMutex->Unlock();
    }

private:
    std::shared_ptr<IMutex> mMutex;
};