Circuit.h

/******************************************************************************
DSPatch - The Refreshingly Simple C++ Dataflow Framework
Copyright (c) 2025, Marcus Tomlinson
 
BSD 2-Clause License
 
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
 
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   list of conditions and the following disclaimer.
 
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OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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******************************************************************************/
 
#pragma once
 
#include "Component.h"
 
#ifdef _WIN32
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#undef WIN32_LEAN_AND_MEAN
#endif
 
#include <algorithm>
#include <condition_variable>
#include <thread>
#include <unordered_set>
 
namespace DSPatch
{
 
 
class Circuit final
{
public:
    Circuit( const Circuit& ) = delete;
    Circuit& operator=( const Circuit& ) = delete;
 
    Circuit();
    ~Circuit();
 
    bool AddComponent( const Component::SPtr& component );
 
    bool RemoveComponent( const Component::SPtr& component );
    void RemoveAllComponents();
 
    int GetComponentCount() const;
 
    bool ConnectOutToIn( const Component::SPtr& fromComponent, int fromOutput, const Component::SPtr& toComponent, int toInput );
 
    bool DisconnectComponent( const Component::SPtr& component );
    void DisconnectAllComponents();
 
    void SetBufferCount( int bufferCount );
    int GetBufferCount() const;
 
    void SetThreadCount( int threadCount );
    int GetThreadCount() const;
 
    void Tick();
    void Sync();
 
    void StartAutoTick();
    void StopAutoTick();
    void PauseAutoTick();
    void ResumeAutoTick();
 
    void Optimize();
 
private:
    class AutoTickThread final
    {
    public:
        AutoTickThread( const AutoTickThread& ) = delete;
        AutoTickThread& operator=( const AutoTickThread& ) = delete;
 
        inline AutoTickThread() = default;
 
        inline ~AutoTickThread()
        {
            Stop();
        }
 
        inline void Start( DSPatch::Circuit* circuit )
        {
            if ( !_stopped )
            {
                Resume();
                return;
            }
 
            _circuit = circuit;
 
            _stop = false;
            _stopped = false;
            _pause = false;
 
            _thread = std::thread( &AutoTickThread::_Run, this );
        }
 
        inline void Stop()
        {
            _stop = true;
            _pause = true;
 
            if ( _thread.joinable() )
            {
                _thread.join();
            }
        }
 
        inline void Pause()
        {
            if ( !_stopped && ++pauseCount == 1 )
            {
                std::unique_lock<std::mutex> lock( _resumeMutex );
                _pause = true;
                _pauseCondt.wait( lock );  // wait for pause
            }
        }
 
        inline void Resume()
        {
            if ( _pause && --pauseCount == 0 )
            {
                _pause = false;
                _resumeCondt.notify_all();
                std::this_thread::yield();
            }
        }
 
    private:
        inline void _Run()
        {
            if ( _circuit )
            {
                while ( true )
                {
                    _circuit->Tick();
 
                    if ( _pause )
                    {
                        if ( _stop )
                        {
                            break;
                        }
 
                        std::unique_lock<std::mutex> lock( _resumeMutex );
 
                        _pauseCondt.notify_all();
                        _resumeCondt.wait( lock );  // wait for resume
                    }
                }
            }
 
            _stopped = true;
        }
 
        std::thread _thread;
        DSPatch::Circuit* _circuit = nullptr;
        int pauseCount = 0;
        bool _stop = false;
        bool _pause = false;
        bool _stopped = true;
        std::mutex _resumeMutex;
        std::condition_variable _resumeCondt, _pauseCondt;
    };
 
    class CircuitThread final
    {
    public:
        CircuitThread( const CircuitThread& ) = delete;
        CircuitThread& operator=( const CircuitThread& ) = delete;
 
        inline CircuitThread() = default;
 
        // cppcheck-suppress missingMemberCopy
        inline CircuitThread( CircuitThread&& )
        {
        }
 
        inline ~CircuitThread()
        {
            Stop();
        }
 
        inline void Start( std::vector<DSPatch::Component*>* components, int bufferNo, int bufferCount )
        {
            _components = components;
            _bufferNo = bufferNo;
            _loneBuffer = bufferCount <= 1;
 
            _stop = false;
            _gotSync = false;
 
            _thread = std::thread( &CircuitThread::_Run, this );
        }
 
        inline void Stop()
        {
            _stop = true;
 
            Resume();
 
            if ( _thread.joinable() )
            {
                _thread.join();
            }
        }
 
        inline void Sync()
        {
            std::unique_lock<std::mutex> lock( _syncMutex );
 
            if ( !_gotSync )  // if haven't already got sync
            {
                _syncCondt.wait( lock );  // wait for sync
            }
        }
 
        inline void Resume()
        {
            _gotSync = false;  // reset the sync flag
            _resumeCondt.notify_all();
            std::this_thread::yield();
        }
 
        inline void SyncAndResume()
        {
            Sync();
            Resume();
        }
 
    private:
        inline void _Run()
        {
#ifdef _WIN32
            SetThreadPriority( GetCurrentThread(), THREAD_PRIORITY_HIGHEST );
#else
            sched_param sch_params;
            sch_params.sched_priority = sched_get_priority_max( SCHED_RR );
            pthread_setschedparam( pthread_self(), SCHED_RR, &sch_params );
#endif
 
            if ( _components )
            {
                while ( true )
                {
                    {
                        std::unique_lock<std::mutex> lock( _syncMutex );
 
                        _gotSync = true;  // set the sync flag
                        _syncCondt.notify_all();
                        _resumeCondt.wait( lock );  // wait for resume
                    }
 
                    if ( _stop )
                    {
                        break;
                    }
 
                    // You might be thinking: Can't we have each thread start on a different component?
 
                    // Well no. In order to maintain synchronisation within the circuit, when a component
                    // wants to process its buffers in-order, it requires that every other in-order
                    // component in the system has not only processed its buffers in the same order, but
                    // has processed the same number of buffers too.
 
                    // E.g. 1,2,3 and 1,2,3. Not 1,2,3 and 2,3,1,2,3.
 
                    if ( _loneBuffer )
                    {
                        for ( auto component : *_components )
                        {
                            component->Tick();
                        }
                    }
                    else
                    {
                        for ( auto component : *_components )
                        {
                            component->Tick( _bufferNo );
                        }
                    }
                }
            }
        }
 
        std::thread _thread;
        std::vector<DSPatch::Component*>* _components = nullptr;
        int _bufferNo = 0;
        bool _loneBuffer = false;
        bool _stop = false;
        bool _gotSync = false;
        std::mutex _syncMutex;
        std::condition_variable _resumeCondt, _syncCondt;
    };
 
    class CircuitThreadParallel final
    {
    public:
        CircuitThreadParallel( const CircuitThreadParallel& ) = delete;
        CircuitThreadParallel& operator=( const CircuitThreadParallel& ) = delete;
 
        inline CircuitThreadParallel() = default;
 
        // cppcheck-suppress missingMemberCopy
        inline CircuitThreadParallel( CircuitThreadParallel&& )
        {
        }
 
        inline ~CircuitThreadParallel()
        {
            Stop();
        }
 
        inline void Start(
            std::vector<DSPatch::Component*>* components, int bufferNo, int bufferCount, int threadNo, int threadCount )
        {
            _components = components;
            _bufferNo = bufferNo;
            _loneBuffer = bufferCount <= 1;
            _threadNo = threadNo;
            _threadCount = threadCount;
 
            _stop = false;
            _gotSync = false;
 
            _thread = std::thread( &CircuitThreadParallel::_Run, this );
        }
 
        inline void Stop()
        {
            _stop = true;
 
            Resume();
 
            if ( _thread.joinable() )
            {
                _thread.join();
            }
        }
 
        inline void Sync()
        {
            std::unique_lock<std::mutex> lock( _syncMutex );
 
            if ( !_gotSync )  // if haven't already got sync
            {
                _syncCondt.wait( lock );  // wait for sync
            }
        }
 
        inline void Resume()
        {
            _gotSync = false;  // reset the sync flag
            _resumeCondt.notify_all();
            std::this_thread::yield();
        }
 
    private:
        inline void _Run()
        {
#ifdef _WIN32
            SetThreadPriority( GetCurrentThread(), THREAD_PRIORITY_HIGHEST );
#else
            sched_param sch_params;
            sch_params.sched_priority = sched_get_priority_max( SCHED_RR );
            pthread_setschedparam( pthread_self(), SCHED_RR, &sch_params );
#endif
 
            if ( _components )
            {
                while ( true )
                {
                    {
                        std::unique_lock<std::mutex> lock( _syncMutex );
 
                        _gotSync = true;  // set the sync flag
                        _syncCondt.notify_all();
                        _resumeCondt.wait( lock );  // wait for resume
                    }
 
                    if ( _stop )
                    {
                        break;
                    }
 
                    if ( _loneBuffer )
                    {
                        for ( auto it = _components->begin() + _threadNo; it < _components->end(); it += _threadCount )
                        {
                            ( *it )->TickParallel();
                        }
                    }
                    else
                    {
                        for ( auto it = _components->begin() + _threadNo; it < _components->end(); it += _threadCount )
                        {
                            ( *it )->TickParallel( _bufferNo );
                        }
                    }
                }
            }
        }
 
        std::thread _thread;
        std::vector<DSPatch::Component*>* _components = nullptr;
        int _bufferNo = 0;
        bool _loneBuffer = false;
        int _threadNo = 0;
        int _threadCount = 0;
        bool _stop = false;
        bool _gotSync = false;
        std::mutex _syncMutex;
        std::condition_variable _resumeCondt, _syncCondt;
    };
 
    void _Optimize();
 
    int _bufferCount = 0;
    int _threadCount = 0;
    int _currentBuffer = 0;
 
    AutoTickThread _autoTickThread;
 
    std::unordered_set<DSPatch::Component::SPtr> _componentsSet;
 
    std::vector<DSPatch::Component*> _components;
    std::vector<DSPatch::Component*> _componentsParallel;
 
    std::vector<CircuitThread> _circuitThreads;
    std::vector<std::vector<CircuitThreadParallel>> _circuitThreadsParallel;
 
    bool _circuitDirty = false;
};
 
inline Circuit::Circuit() = default;
 
inline Circuit::~Circuit()
{
    StopAutoTick();
    DisconnectAllComponents();
}
 
inline bool Circuit::AddComponent( const Component::SPtr& component )
{
    if ( !component || _componentsSet.find( component ) != _componentsSet.end() )
    {
        return false;
    }
 
    // components within the circuit need to have as many buffers as there are threads in the circuit
    component->SetBufferCount( _bufferCount, _currentBuffer );
 
    PauseAutoTick();
    _components.emplace_back( component.get() );
    _componentsParallel.emplace_back( component.get() );
    ResumeAutoTick();
 
    _componentsSet.emplace( component );
 
    return true;
}
 
inline bool Circuit::RemoveComponent( const Component::SPtr& component )
{
    if ( _componentsSet.find( component ) == _componentsSet.end() )
    {
        return false;
    }
 
    auto findFn = [&component]( auto comp ) { return comp == component.get(); };
 
    if ( auto it = std::find_if( _components.begin(), _components.end(), findFn ); it != _components.end() )
    {
        PauseAutoTick();
 
        DisconnectComponent( component );
 
        _components.erase( it );
 
        ResumeAutoTick();
 
        _componentsSet.erase( component );
 
        return true;
    }
 
    return false;
}
 
// cppcheck-suppress unusedFunction
inline void Circuit::RemoveAllComponents()
{
    PauseAutoTick();
 
    DisconnectAllComponents();
 
    _components.clear();
    _componentsParallel.clear();
 
    ResumeAutoTick();
 
    _componentsSet.clear();
}
 
inline int Circuit::GetComponentCount() const
{
    return (int)_components.size();
}
 
inline bool Circuit::ConnectOutToIn( const Component::SPtr& fromComponent,
                                     int fromOutput,
                                     const Component::SPtr& toComponent,
                                     int toInput )
{
    if ( _componentsSet.find( fromComponent ) == _componentsSet.end() ||
         _componentsSet.find( toComponent ) == _componentsSet.end() )
    {
        return false;
    }
 
    PauseAutoTick();
 
    bool result = toComponent->ConnectInput( fromComponent, fromOutput, toInput );
 
    _circuitDirty = result;
 
    ResumeAutoTick();
 
    return result;
}
 
inline bool Circuit::DisconnectComponent( const Component::SPtr& component )
{
    if ( _componentsSet.find( component ) == _componentsSet.end() )
    {
        return false;
    }
 
    PauseAutoTick();
 
    component->DisconnectAllInputs();
 
    // remove any connections this component has to other components
    for ( auto comp : _components )
    {
        comp->DisconnectInput( component );
    }
 
    _circuitDirty = true;
 
    ResumeAutoTick();
 
    return true;
}
 
inline void Circuit::DisconnectAllComponents()
{
    PauseAutoTick();
 
    for ( auto component : _components )
    {
        component->DisconnectAllInputs();
    }
 
    ResumeAutoTick();
}
 
inline void Circuit::SetBufferCount( int bufferCount )
{
    PauseAutoTick();
 
    _bufferCount = bufferCount;
 
    // stop all threads
    for ( auto& circuitThread : _circuitThreads )
    {
        circuitThread.Stop();
    }
 
    // resize thread array
    if ( _threadCount != 0 )
    {
        _circuitThreads.resize( 0 );
        SetThreadCount( _threadCount );
    }
    else
    {
        _circuitThreads.resize( _bufferCount );
 
        // initialise and start all threads
        for ( int i = 0; i < _bufferCount; ++i )
        {
            _circuitThreads[i].Start( &_components, i, _bufferCount );
        }
    }
 
    if ( _currentBuffer >= _bufferCount )
    {
        _currentBuffer = 0;
    }
 
    // set all components to the new buffer count
    for ( auto component : _components )
    {
        component->SetBufferCount( _bufferCount, _currentBuffer );
    }
 
    ResumeAutoTick();
}
 
inline int Circuit::GetBufferCount() const
{
    return _bufferCount;
}
 
inline void Circuit::SetThreadCount( int threadCount )
{
    PauseAutoTick();
 
    if ( _threadCount == 0 && threadCount != 0 )
    {
        _circuitDirty = true;
    }
 
    _threadCount = threadCount;
 
    // stop all threads
    for ( auto& circuitThreads : _circuitThreadsParallel )
    {
        for ( auto& circuitThread : circuitThreads )
        {
            circuitThread.Stop();
        }
    }
 
    // resize thread array
    if ( _threadCount == 0 )
    {
        _circuitThreadsParallel.resize( 0 );
        SetBufferCount( _bufferCount );
    }
    else
    {
        _circuitThreadsParallel.resize( _bufferCount == 0 ? 1 : _bufferCount );
        for ( auto& circuitThread : _circuitThreadsParallel )
        {
            circuitThread.resize( _threadCount );
        }
 
        // initialise and start all threads
        int i = 0;
        for ( auto& circuitThreads : _circuitThreadsParallel )
        {
            int j = 0;
            for ( auto& circuitThread : circuitThreads )
            {
                circuitThread.Start( &_componentsParallel, i, _bufferCount, j++, _threadCount );
            }
            ++i;
        }
    }
 
    ResumeAutoTick();
}
 
// cppcheck-suppress unusedFunction
inline int Circuit::GetThreadCount() const
{
    return _threadCount;
}
 
inline void Circuit::Tick()
{
    if ( _circuitDirty )
    {
        _Optimize();
    }
 
    // process in multiple threads if this circuit has threads
    // =======================================================
    if ( _threadCount != 0 )
    {
        auto& circuitThreads = _circuitThreadsParallel[_currentBuffer];
 
        for ( auto& circuitThread : circuitThreads )
        {
            circuitThread.Sync();
        }
        for ( auto& circuitThread : circuitThreads )
        {
            circuitThread.Resume();
        }
    }
    // process in a single thread if this circuit has no threads
    // =========================================================
    else if ( _bufferCount == 0 )
    {
        // tick all internal components
        for ( auto component : _components )
        {
            component->Tick();
        }
 
        return;
    }
    else
    {
        _circuitThreads[_currentBuffer].SyncAndResume();  // sync and resume thread x
    }
 
    if ( _bufferCount != 0 && ++_currentBuffer == _bufferCount )
    {
        _currentBuffer = 0;
    }
}
 
inline void Circuit::Sync()
{
    // sync all threads
    for ( auto& circuitThread : _circuitThreads )
    {
        circuitThread.Sync();
    }
    for ( auto& circuitThreads : _circuitThreadsParallel )
    {
        for ( auto& circuitThread : circuitThreads )
        {
            circuitThread.Sync();
        }
    }
}
 
inline void Circuit::StartAutoTick()
{
    _autoTickThread.Start( this );
}
 
inline void Circuit::StopAutoTick()
{
    _autoTickThread.Stop();
    Sync();
}
 
inline void Circuit::PauseAutoTick()
{
    _autoTickThread.Pause();
    Sync();
}
 
inline void Circuit::ResumeAutoTick()
{
    _autoTickThread.Resume();
}
 
inline void Circuit::Optimize()
{
    if ( _circuitDirty )
    {
        PauseAutoTick();
        _Optimize();
        ResumeAutoTick();
    }
}
 
inline void Circuit::_Optimize()
{
    // scan for optimal series order -> update _components
    std::vector<DSPatch::Component*> orderedComponents;
    orderedComponents.reserve( _components.size() );
 
    for ( auto component : _components )
    {
        component->Scan( orderedComponents );
    }
    for ( auto component : _components )
    {
        component->EndScan();
    }
 
    _components = std::move( orderedComponents );
 
    // scan for optimal parallel order -> update _componentsParallel
    if ( _threadCount != 0 )
    {
        std::vector<std::vector<DSPatch::Component*>> componentsMap;
        componentsMap.reserve( _components.size() );
 
        int scanPosition;
        for ( auto component : _components )
        {
            component->ScanParallel( componentsMap, scanPosition );
        }
        for ( auto component : _components )
        {
            component->EndScan();
        }
 
        _componentsParallel.clear();
        _componentsParallel.reserve( _components.size() );
        for ( auto& componentsMapEntry : componentsMap )
        {
            _componentsParallel.insert( _componentsParallel.end(), componentsMapEntry.begin(), componentsMapEntry.end() );
        }
    }
 
    // clear _circuitDirty flag
    _circuitDirty = false;
}
 
}  // namespace DSPatch