workerthreadbase.h

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/**********************************************************************
 * LeechCraft - modular cross-platform feature rich internet client.
 * Copyright (C) 2006-2014  Georg Rudoy
 *
 * Boost Software License - Version 1.0 - August 17th, 2003
 *
 * Permission is hereby granted, free of charge, to any person or organization
 * obtaining a copy of the software and accompanying documentation covered by
 * this license (the "Software") to use, reproduce, display, distribute,
 * execute, and transmit the Software, and to prepare derivative works of the
 * Software, and to permit third-parties to whom the Software is furnished to
 * do so, all subject to the following:
 *
 * The copyright notices in the Software and this entire statement, including
 * the above license grant, this restriction and the following disclaimer,
 * must be included in all copies of the Software, in whole or in part, and
 * all derivative works of the Software, unless such copies or derivative
 * works are solely in the form of machine-executable object code generated by
 * a source language processor.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
 * SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
 * FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 **********************************************************************/

#pragma once

#include <functional>
#include <atomic>
#include <QThread>
#include <QMutex>
#include <QMutexLocker>
#include <QFutureInterface>
#include <QFuture>
#include <QList>
#include <util/sll/oldcppkludges.h>
#include "futures.h"
#include "threadsconfig.h"

namespace LeechCraft
{
namespace Util
{
    class UTIL_THREADS_API WorkerThreadBase : public QThread
    {
        Q_OBJECT

        std::atomic_bool IsPaused_ { false };

        QMutex FunctionsMutex_;
        QList<std::function<void ()>> Functions_;
    public:
        using QThread::QThread;

        void SetPaused (bool);

        template<typename F>
        QFuture<std::result_of_t<F ()>> ScheduleImpl (F func)
        {
            QFutureInterface<std::result_of_t<F ()>> iface;
            iface.reportStarted ();

            auto reporting = [func, iface] () mutable
            {
                ReportFutureResult (iface, func);
            };

            {
                QMutexLocker locker { &FunctionsMutex_ };
                Functions_ << reporting;
            }

            emit rotateFuncs ();

            return iface.future ();
        }

        template<typename F, typename... Args>
        QFuture<std::result_of_t<F (Args...)>> ScheduleImpl (F f, Args&&... args)
        {
            return ScheduleImpl ([f, args...] () mutable { return Invoke (f, args...); });
        }

        virtual size_t GetQueueSize ();
    protected:
        void run () override final;

        virtual void Initialize () = 0;
        virtual void Cleanup () = 0;
    private:
        void RotateFuncs ();
    signals:
        void rotateFuncs ();
    };

    namespace detail
    {
        template<typename WorkerType>
        struct InitializerBase
        {
            virtual std::unique_ptr<WorkerType> Initialize () = 0;
        };

        template<typename WorkerType, typename... Args>
        struct Initializer : InitializerBase<WorkerType>
        {
            std::tuple<Args...> Args_;

            Initializer (std::tuple<Args...>&& tuple)
            : Args_ { std::move (tuple) }
            {
            }

            std::unique_ptr<WorkerType> Initialize () override
            {
                return CPP17::Apply ([] (auto&&... args) { return std::make_unique<WorkerType> (std::forward<Args> (args)...); }, Args_);
            }
        };

        template<typename WorkerType>
        struct Initializer<WorkerType> : InitializerBase<WorkerType>
        {
            std::unique_ptr<WorkerType> Initialize () override
            {
                return std::make_unique<WorkerType> ();
            }
        };
    }

    template<typename WorkerType>
    class WorkerThread : public WorkerThreadBase
    {
        std::atomic_bool IsAutoQuit_ { false };
    protected:
        using W = WorkerType;

        std::unique_ptr<WorkerType> Worker_;

        std::unique_ptr<detail::InitializerBase<WorkerType>> Initializer_;
    public:
        WorkerThread (QObject *parent = nullptr)
        : WorkerThreadBase { parent }
        , Initializer_ { std::make_unique<detail::Initializer<WorkerType>> () }
        {
        }

        template<typename... Args>
        WorkerThread (QObject *parent, const Args&... args)
        : WorkerThreadBase { parent }
        , Initializer_ { std::make_unique<detail::Initializer<WorkerType, std::decay_t<Args>...>> (std::tuple<std::decay_t<Args>...> { args... }) }
        {
        }

        template<
                typename Head,
                typename... Rest,
                typename = std::enable_if_t<
                        !std::is_base_of<QObject, std::remove_pointer_t<std::decay_t<Head>>>::value
                    >
            >
        WorkerThread (const Head& head, const Rest&... rest)
        : WorkerThread { static_cast<QObject*> (nullptr), head, rest... }
        {
        }

        ~WorkerThread ()
        {
            if (!IsAutoQuit_)
                return;

            quit ();
            wait (2000);

            if (isRunning ())
                qWarning () << Q_FUNC_INFO
                        << "thread is still running";
        }

        using WorkerThreadBase::ScheduleImpl;

        void SetAutoQuit (bool autoQuit)
        {
            IsAutoQuit_ = autoQuit;
        }

        template<typename F, typename... Args>
        QFuture<std::result_of_t<F (WorkerType*, Args...)>> ScheduleImpl (F f, Args&&... args)
        {
            const auto fWrapped = [f, this] (auto... args) mutable { return Invoke (f, Worker_.get (), args...); };
            return WorkerThreadBase::ScheduleImpl (fWrapped, std::forward<Args> (args)...);
        }
    protected:
        void Initialize () override
        {
            Worker_ = Initializer_->Initialize ();

            Initializer_.reset ();
        }

        void Cleanup () override
        {
            Worker_.reset ();
        }
    };
}
}