asyncqueue.hpp

/*
    Copyright (C) 2014  Intel Corporation

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
*/

#include <glib.h>

#include <abstractpropertytype.h>
#include "listplusplus.h"

#include <mutex>
#include <condition_variable>
#include <unordered_set>
#include <vector>

namespace amb
{

template <typename T, class Pred = std::equal_to<T> >
class Queue
{
public:
    Queue(bool unique = false, bool blocking = false)
        :mUnique(unique), mBlocking(blocking)
    {

    }

    virtual ~Queue()
    {

    }

    int count()
    {
        std::lock_guard<std::mutex> lock(mutex);

        return mQueue.size();
    }

    T pop()
    {
        std::unique_lock<std::mutex> lock(mutex);

        if(mBlocking)
        {
            if(!mQueue.size())
            {
                cond.wait(lock);
            }
        }

        if(!mQueue.size())
            throw std::runtime_error("nothing in queue");

        auto itr = mQueue.begin();

        T item = *itr;

        mQueue.erase(itr);

        return item;
    }

    virtual void append(T item)
    {
        {
            std::lock_guard<std::mutex> lock(mutex);
            if(contains(mQueue, item))
            {
                mQueue.erase(std::find(mQueue.begin(), mQueue.end(), item));
            }
            mQueue.push_back(item);
        }

        if(mBlocking)
        {
            cond.notify_all();
        }
    }

    void remove(T item)
    {
        std::lock_guard<std::mutex> lock(mutex);
        removeOne(&mQueue, item);
    }

private:
    bool mBlocking;
    bool mUnique;
    std::mutex mutex;
    std::condition_variable cond;
    std::vector<T> mQueue;
};

template <typename T, class Pred = std::equal_to<T> >
struct AsyncQueueSource{
    GSource source;
    Queue<T, Pred>* queue;
    int minQueueSize;
};

template <typename T, class Pred = std::equal_to<T> >
class AsyncQueueWatcher
{
public:
    typedef function<void (Queue<T, Pred> *)> AsyncQueueWatcherCallback;
    AsyncQueueWatcher(Queue<T, Pred> * queue, AsyncQueueWatcherCallback cb, int queueSize = 0, AbstractPropertyType::Priority priority = AbstractPropertyType::Normal)
        : callback(cb), mMaxQueueSize(queueSize)
    {

        static GSourceFuncs funcs = {prepare, check, dispatch, finalize};
        GSource* source = (GSource *) g_source_new(&funcs, sizeof(AsyncQueueSource<T, Pred>));

        AsyncQueueSource<T, Pred>* watch = (AsyncQueueSource<T, Pred>*)source;
        watch->queue = queue;
        watch->minQueueSize = queueSize;

        gint p = G_PRIORITY_DEFAULT;

        if(priority == AbstractPropertyType::Normal)
            p = G_PRIORITY_DEFAULT;
        else if(priority == AbstractPropertyType::High)
            p = G_PRIORITY_HIGH;
        else if(priority == AbstractPropertyType::Low)
            p = G_PRIORITY_LOW;

        g_source_set_priority(source, p);
        g_source_set_callback(source, nullptr, this, nullptr);

        g_source_attach(source, nullptr);
        g_source_unref(source);
    }

    AsyncQueueWatcherCallback callback;


protected:
    AsyncQueueWatcher(){}

    int mMaxQueueSize;

private:

    static gboolean prepare(GSource *source, gint *timeout)
    {
        AsyncQueueSource<T, Pred>* s = (AsyncQueueSource<T, Pred>*)source;
        *timeout = -1;

        if (!s)
            return false;

        return s->queue->count() > s->minQueueSize;
    }

    static gboolean check(GSource *source)
    {
        AsyncQueueSource<T, Pred>* s = (AsyncQueueSource<T, Pred>*)source;

        if (!s)
            return false;

        return s->queue->count() > s->minQueueSize;
    }

    static gboolean dispatch(GSource *source, GSourceFunc callback, gpointer userData)
    {
        AsyncQueueSource<T, Pred>* s = (AsyncQueueSource<T, Pred>*)source;

        if (!s)
            return false;

        AsyncQueueWatcher<T, Pred>* watcher = static_cast<AsyncQueueWatcher<T, Pred>*>(userData);

        watcher->callback(s->queue);
        return true;
    }

    static void finalize(GSource* source)
    {

    }
};
}  // namespace amb