op-pedal/src/Worker.cpp

// Copyright (c) 2022 Robin Davies
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of
// this software and associated documentation files (the "Software"), to deal in
// the Software without restriction, including without limitation the rights to
// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
// the Software, and to permit persons to whom the Software is furnished to do so,
// subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// 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 AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
// COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
// IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
// CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

/*
  Borrows heavily from worker.c by David Robillard.

  Copyright 2007-2012 David Robillard <http://drobilla.net>

  Permission to use, copy, modify, and/or distribute this software for any
  purpose with or without fee is hereby granted, provided that the above
  copyright notice and this permission notice appear in all copies.

  THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/

#include "Worker.hpp"
#include <mutex>
#include <lv2/lv2plug.in/ns/ext/worker/worker.h>
#include "Lv2Log.hpp"
#include <iostream>
#include <unistd.h> // for nice()

using namespace pipedal;

const int RING_BUFFER_SIZE = 16 * 1024;

Worker::Worker(LilvInstance *lilvInstance_, const LV2_Worker_Interface *workerInterface_)
    : lilvInstance(lilvInstance_),
      requestRingBuffer(RING_BUFFER_SIZE),
      responseRingBuffer(RING_BUFFER_SIZE),
      workerInterface(workerInterface_)
{

    responseBuffer = (char *)malloc(RING_BUFFER_SIZE);

    StartWorkerThread();
}

Worker::~Worker()
{
    StopWorkerThread();
    sem_destroy(&requestSemaphore);
    free(responseBuffer);
}

LV2_Worker_Status Worker::worker_respond_fn(LV2_Worker_Respond_Handle handle, uint32_t size, const void *data)
{
    Worker *this_ = (Worker *)handle;
    return this_->WorkerResponse(size, data);
}

LV2_Worker_Status Worker::WorkerResponse(uint32_t size, const void *data)
{
    if (responseRingBuffer.writeSpace() < sizeof(size)+size)
    {
        return LV2_WORKER_ERR_NO_SPACE;
    }
    if (!responseRingBuffer.write(sizeof(size), (uint8_t *)&size))
    {
        return LV2_WORKER_ERR_NO_SPACE;
    }
    if (!responseRingBuffer.write(size, (uint8_t *)data))
    {
        return LV2_WORKER_ERR_NO_SPACE;
    }
    return LV2_WORKER_SUCCESS;
}

void Worker::EmitResponses()
{
    while (true)
    {
        uint32_t available = responseRingBuffer.readSpace();
        uint32_t size = 0;
        if (available <= sizeof(size)) // i.e. we need a size AND a response.
            break;

        responseRingBuffer.read(sizeof(size), (uint8_t *)&size);
        responseRingBuffer.read(size, (uint8_t *)responseBuffer);

        workerInterface->work_response(lilvInstance->lv2_handle, size, responseBuffer);
    }
}
void Worker::ThreadProc()
{
    // run nice +1 (priority -1 on Windows)
    errno = 0;
    nice(1);
    if (errno != 0)
    {
        std::cout << "Warning: Unable to run Lv2 schedule thread at nice +1" << std::endl;
    }

    try
    {
        while (true)
        {
            if (!requestRingBuffer.readWait())
            {
                return;
            }
            uint32_t size;
            while (requestRingBuffer.readSpace() > sizeof(size))
            {
                if (!requestRingBuffer.read(sizeof(size), (uint8_t *)&size))
                {
                    throw PiPedalStateException("Working ringbuffer read failed.");
                }
                void *data = malloc(size);
                if (!requestRingBuffer.read(size, (uint8_t *)data))
                {
                    throw PiPedalStateException("Working ringbuffer read failed.");
                }
                workerInterface->work(lilvInstance->lv2_handle, worker_respond_fn, (LV2_Handle)this, size, data);
                free(data);
            }
        }
    }
    catch (const std::exception &e)
    {
        Lv2Log::error("Lv2 Worker thread proc exited abnormally. (%s)", e.what());
    }
}

void Worker::StopWorkerThread()
{
    if (pThread)
    {
        auto pThread = this->pThread;
        this->pThread = nullptr;
        exiting = true;
        requestRingBuffer.close();
        pThread->join();
        delete pThread;
    }
}
void Worker::StartWorkerThread()
{
    auto fn = [this]()
    { this->ThreadProc(); };
    this->pThread = new std::thread(fn);
}

LV2_Worker_Status Worker::ScheduleWork(
    uint32_t size,
    const void *data)
{
    if (!exiting)
    {
        size_t space = requestRingBuffer.writeSpace();
        if (space < sizeof(size) + size)
        {
            return LV2_WORKER_ERR_NO_SPACE;
        }
        if (!requestRingBuffer.write(sizeof(size), (uint8_t *)&size))
        {
            Lv2Log::debug("Not enough space in Worker ring buffer. Request failed.");
            return LV2_WORKER_ERR_NO_SPACE;
        }
        if (!requestRingBuffer.write(size, (uint8_t *)data))
        {
            // probably not going to survive. :-(
            Lv2Log::error("Not enough space in Worker ring buffer. Request ring buffer probably lost sync.");
            return LV2_WORKER_ERR_NO_SPACE;
        }
    }
    return LV2_WORKER_ERR_NO_SPACE;
}