CircuitThread.h

/******************************************************************************
DSPatch - The Refreshingly Simple C++ Dataflow Framework
Copyright (c) 2025, Marcus Tomlinson
 
BSD 2-Clause License
 
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#pragma once
 
#include <dspatch/Component.h>
 
#ifdef _WIN32
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#undef WIN32_LEAN_AND_MEAN
#endif
 
#include <condition_variable>
#include <thread>
 
namespace DSPatch
{
namespace internal
{
 
 
class CircuitThread final
{
public:
    NONCOPYABLE( CircuitThread );
 
    inline CircuitThread() = default;
 
    // cppcheck-suppress missingMemberCopy
    inline CircuitThread( CircuitThread&& )
    {
    }
 
    inline ~CircuitThread()
    {
        Stop();
    }
 
    inline void Start( std::vector<DSPatch::Component*>* components, int bufferNo )
    {
        _components = components;
        _bufferNo = bufferNo;
 
        _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();
    }
 
    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 ( !_stop )
            {
                {
                    std::unique_lock<std::mutex> lock( _syncMutex );
 
                    _gotSync = true;  // set the sync flag
                    _syncCondt.notify_all();
                    _resumeCondt.wait( lock );  // wait for resume
                }
 
                // cppcheck-suppress knownConditionTrueFalse
                if ( !_stop )
                {
                    // You might be thinking: Can't we have each thread start on a different component?
 
                    // Well no. Because bufferNo == bufferNo, 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.
 
                    for ( auto component : *_components )
                    {
                        component->TickSeries( _bufferNo );
                    }
                }
            }
        }
    }
 
    std::thread _thread;
    std::vector<DSPatch::Component*>* _components = nullptr;
    int _bufferNo = 0;
    bool _stop = false;
    bool _gotSync = false;
    std::mutex _syncMutex;
    std::condition_variable _resumeCondt, _syncCondt;
};
 
}  // namespace internal
}  // namespace DSPatch