workunit.cpp

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// The DAGFrameScheduler is a Multi-Threaded lock free and wait free scheduling library.
// © Copyright 2010 - 2016 BlackTopp Studios Inc.
/* This file is part of The DAGFrameScheduler.

    The DAGFrameScheduler is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    The DAGFrameScheduler 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 General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with The DAGFrameScheduler.  If not, see <http://www.gnu.org/licenses/>.
*/
/* The original authors have included a copy of the license specified above in the
   'doc' folder. See 'gpl.txt'
*/
/* We welcome the use of the DAGFrameScheduler to anyone, including companies who wish to
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   However there are some practical restrictions, so if your project involves
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   Joseph Toppi - toppij@gmail.com
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*/
#ifndef _workunit_cpp
#define _workunit_cpp

/// @file
/// @brief This file has the implementation of the @ref Mezzanine::Threading::DefaultWorkUnit.

#include "workunit.h"
#include "systemcalls.h"
#include "atomicoperations.h"
#include "doublebufferedresource.h"

#ifdef MEZZ_DEBUG
#include <cassert>
#endif

namespace Mezzanine
{
    namespace Threading
    {
        /////////////////////////////////////////////////////////////////////////////////////////////
        // The Simple Stuff

        DefaultWorkUnit::DefaultWorkUnit(const DefaultWorkUnit&)
            {}

        DefaultWorkUnit& DefaultWorkUnit::operator=(DefaultWorkUnit& Unused)
            { return Unused; }

        DefaultWorkUnit::DefaultWorkUnit() : CurrentRunningState(NotStarted)
            {}

        DefaultWorkUnit::~DefaultWorkUnit()
            {}

        /////////////////////////////////////////////////////////////////////////////////////////////
        // Work with the dependents as in what must not start until this finishes.

        Whole DefaultWorkUnit::GetDependentCount(FrameScheduler &SchedulerToCount)
            { return SchedulerToCount.GetDependentCountOf(this); }

        /////////////////////////////////////////////////////////////////////////////////////////////
        // Work with the dependencies as in what must finish before we can run this work unit.

        iWorkUnit* DefaultWorkUnit::GetDependency(Whole Index) const
            { return Dependencies.at(Index); }

        Whole DefaultWorkUnit::GetImmediateDependencyCount() const
            { return Dependencies.size(); }

        Whole DefaultWorkUnit::GetDependencyCount() const
        {
            Whole Results = Dependencies.size();
            for(std::vector<iWorkUnit*>::const_iterator Iter=Dependencies.begin(); Iter!=Dependencies.end(); ++Iter)
                { Results += (*Iter)->GetDependencyCount(); }
            return Results;

        }

        void DefaultWorkUnit::AddDependency(iWorkUnit* NewDependency)
            { Dependencies.push_back(NewDependency); }

        void DefaultWorkUnit::RemoveDependency(iWorkUnit* RemoveDependency)
        {
            Dependencies.erase(
                        std::remove(Dependencies.begin(),Dependencies.end(),RemoveDependency),
                        Dependencies.end()
                    );
        }

        void DefaultWorkUnit::ClearDependencies()
            { Dependencies.clear(); }

        bool DefaultWorkUnit::IsEveryDependencyComplete()
        {
            for (std::vector<iWorkUnit*>::iterator Iter = Dependencies.begin(); Iter!=Dependencies.end(); ++Iter)
            {
                if( Complete != (*Iter)->GetRunningState() )
                    { return false; }
            }
            return true;
        }

        /////////////////////////////////////////////////////////////////////////////////////////////
        // Work with the ownership and RunningState
        RunningState DefaultWorkUnit::TakeOwnerShip()
        {
            if(!IsEveryDependencyComplete())
                { return NotStarted; }

            if(NotStarted ==  AtomicCompareAndSwap32(&CurrentRunningState, NotStarted, Running) )
                { return Starting; } // This is the only place a starting should be generated, and it is never placed in CurrentRunningState

            return NotStarted;
        }

        RunningState DefaultWorkUnit::GetRunningState() const
            { return (RunningState)CurrentRunningState; } // This only works because we set all of in RunningState to be unsigned.

        void DefaultWorkUnit::PrepareForNextFrame()
            //{ while(CurrentRunningState!=AtomicCompareAndSwap(&CurrentRunningState,CurrentRunningState,NotStarted)); }
            { CurrentRunningState=NotStarted; }

        /////////////////////////////////////////////////////////////////////////////////////////////
        // Work with the performance log
        Whole DefaultWorkUnit::GetPerformance() const
            { return PerformanceLog.GetAverage(); }

        RollingAverage<Whole>& DefaultWorkUnit::GetPerformanceLog()
            { return PerformanceLog; }

        /////////////////////////////////////////////////////////////////////////////////////////////
        // Deciding when to and doing the work

        void DefaultWorkUnit::operator() (DefaultThreadSpecificStorage::Type& CurrentThreadStorage)
        {
            MaxInt Begin = Mezzanine::GetTimeStamp();

            std::ostream& Out = CurrentThreadStorage.GetUsableLogger();
            Out << "<WorkUnit id=\"" << std::hex << this << std::dec << "\">" << std::endl;
            #ifdef MEZZ_DEBUG
            Out << "<WorkUnitStart BeginTimeStamp=\"" << Begin << "\" ThreadID=\"" << Mezzanine::Threading::this_thread::get_id() << "\" />" << std::endl;
            #endif

            this->DoWork(CurrentThreadStorage);
            MaxInt End = Mezzanine::GetTimeStamp();
            this->GetPerformanceLog().Insert( Whole(End-Begin)); // A whole is usually a 32 bit type, which is fine unless a single workunit runs for 35 minutes.
            CurrentRunningState = Complete;

            #ifdef MEZZ_DEBUG
            Out << "<WorkUnitEnd EndTimeStamp=\"" << End << "\" Duration=\"" << (End-Begin) << "\" DurationStored=\"" << Whole(End-Begin) << "\" />" << std::endl;
            #endif
            Out << "</WorkUnit>" << std::endl;
        }

        WorkUnitKey DefaultWorkUnit::GetSortingKey(FrameScheduler& SchedulerToCount)
            { return WorkUnitKey( this->GetDependentCount(SchedulerToCount), GetPerformanceLog().GetAverage(), this); }

    }//Threading
}//Mezzanine

#endif