concurrentqueue.h

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/********************************************************************************************
* 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/mutex.h"
#include <queue>

namespace ttv
{
    template <typename TYPE> class ConcurrentQueue;
}

template <typename TYPE>
class ttv::ConcurrentQueue
{
public:
    ConcurrentQueue()
    {
        TTV_ErrorCode ec = ttv::CreateMutex(mMutex);
        assert(TTV_SUCCEEDED(ec) && mMutex != nullptr);
        UNUSED(ec);
    }

public:
    void clear()
    {
        AutoMutex lock(mMutex);
        while (!mQueue.empty())
        {
            mQueue.pop();
        }
    }

    bool empty() const
    {
        AutoMutex lock(mMutex);
        return mQueue.empty();
    }

    void push(const TYPE& item)
    {
        AutoMutex lock(mMutex);
        mQueue.emplace(item);
    }

    void push(TYPE&& item)
    {
        AutoMutex lock(mMutex);
        mQueue.emplace(std::forward<TYPE>(item));
    }

    bool try_pop(TYPE& result)
    {
        // NOTE: Reset the value before entering the lock to avoid resources potentially being
        // cleaned up while under the lock during assignment
        result = {};

        bool ret = false;

        AutoMutex lock(mMutex);
        if (!mQueue.empty())
        {
            result = std::move(mQueue.front());
            mQueue.pop();
            ret = true;
        }

        return ret;
    }

    size_t unsafe_size() const
    {
        return mQueue.size();
    }

private:
    std::queue<TYPE> mQueue;
    std::shared_ptr<IMutex> mMutex;
};