Implement Lv2 Worker (LMMS#6484)

include/AudioEngine.h

@@ -197,6 +197,7 @@ class LMMS_EXPORT AudioEngine : public QObject
 
 	// audio-device-stuff
 
+	bool renderOnly() const { return m_renderOnly; }
 	// Returns the current audio device's name. This is not necessarily
 	// the user's preferred audio device, in case you were thinking that.
 	inline const QString & audioDevName() const

include/LmmsSemaphore.h

@@ -0,0 +1,93 @@
+/*
+ * Semaphore.h - Semaphore declaration
+ *
+ * Copyright (c) 2022-2022 Johannes Lorenz <jlsf2013$users.sourceforge.net, $=@>
+ *
+ * This file is part of LMMS - https://lmms.io
+ *
+ * This program 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 2 of the License, or (at your option) any later version.
+ *
+ * This program 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 this program (see COPYING); if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301 USA.
+ *
+ */
+
+/*
+ * This code has been copied and adapted from https://github.com/drobilla/jalv
+ * File src/zix/sem.h
+ */
+
+#ifndef LMMS_SEMAPHORE_H
+#define LMMS_SEMAPHORE_H
+
+#include "lmmsconfig.h"
+
+#ifdef LMMS_BUILD_APPLE
+#    include <mach/mach.h>
+#elif defined(LMMS_BUILD_WIN32)
+#    include <windows.h>
+#else
+#    include <semaphore.h>
+#endif
+
+#include <system_error>
+
+namespace lmms {
+
+/**
+   A counting semaphore.
+
+   This is an integer that is always positive, and has two main operations:
+   increment (post) and decrement (wait).  If a decrement can not be performed
+   (i.e. the value is 0) the caller will be blocked until another thread posts
+   and the operation can succeed.
+
+   Semaphores can be created with any starting value, but typically this will
+   be 0 so the semaphore can be used as a simple signal where each post
+   corresponds to one wait.
+
+   Semaphores are very efficient (much moreso than a mutex/cond pair).  In
+   particular, at least on Linux, post is async-signal-safe, which means it
+   does not block and will not be interrupted.  If you need to signal from
+   a realtime thread, this is the most appropriate primitive to use.
+
+   @note Likely outdated with C++20's std::counting_semaphore
+		 (though we have to check that this will be RT conforming on all platforms)
+*/
+class Semaphore
+{
+public:
+	Semaphore(unsigned initial);
+	Semaphore(const Semaphore&) = delete;
+	Semaphore& operator=(const Semaphore&) = delete;
+	Semaphore(Semaphore&&) = delete;
+	Semaphore& operator=(Semaphore&&) = delete;
+	~Semaphore();
+
+	void post();
+	void wait();
+	bool tryWait();
+
+private:
+#ifdef LMMS_BUILD_APPLE
+	semaphore_t m_sem;
+#elif defined(LMMS_BUILD_WIN32)
+	HANDLE m_sem;
+#else
+	sem_t m_sem;
+#endif
+};
+
+} // namespace lmms
+
+#endif // LMMS_SEMAPHORE_H

include/LocklessRingBuffer.h

@@ -51,13 +51,14 @@ class LocklessRingBuffer
 	std::size_t capacity() const {return m_buffer.maximum_eventual_write_space();}
 	std::size_t free() const {return m_buffer.write_space();}
 	void wakeAll() {m_notifier.wakeAll();}
-	std::size_t write(const sampleFrame *src, std::size_t cnt, bool notify = false)
+	std::size_t write(const T *src, std::size_t cnt, bool notify = false)
 	{
 		std::size_t written = LocklessRingBuffer<T>::m_buffer.write(src, cnt);
 		// Let all waiting readers know new data are available.
 		if (notify) {LocklessRingBuffer<T>::m_notifier.wakeAll();}
 		return written;
 	}
+	void mlock() { m_buffer.mlock(); }
 
 protected:
 	ringbuffer_t<T> m_buffer;

include/Lv2Proc.h

@@ -1,7 +1,7 @@
 /*
  * Lv2Proc.h - Lv2 processor class
  *
- * Copyright (c) 2019-2020 Johannes Lorenz <jlsf2013$users.sourceforge.net, $=@>
+ * Copyright (c) 2019-2022 Johannes Lorenz <jlsf2013$users.sourceforge.net, $=@>
  *
  * This file is part of LMMS - https://lmms.io
  *
@@ -31,11 +31,14 @@
 
 #include <lilv/lilv.h>
 #include <memory>
+#include <optional>
 
+#include "LinkedModelGroups.h"
+#include "LmmsSemaphore.h"
 #include "Lv2Basics.h"
 #include "Lv2Features.h"
 #include "Lv2Options.h"
-#include "LinkedModelGroups.h"
+#include "Lv2Worker.h"
 #include "Plugin.h"
 #include "../src/3rdparty/ringbuffer/include/ringbuffer/ringbuffer.h"
 #include "TimePos.h"
@@ -174,8 +177,14 @@ class Lv2Proc : public LinkedModelGroup
 	const LilvPlugin* m_plugin;
 	LilvInstance* m_instance;
 	Lv2Features m_features;
+
+	// options
 	Lv2Options m_options;
 
+	// worker
+	std::optional<Lv2Worker> m_worker;
+	Semaphore m_workLock; // this must be shared by different workers
+
 	// full list of ports
 	std::vector<std::unique_ptr<Lv2Ports::PortBase>> m_ports;
 	// quick reference to specific, unique ports

include/Lv2Worker.h

@@ -0,0 +1,93 @@
+/*
+ * Lv2Worker.h - Lv2Worker class
+ *
+ * Copyright (c) 2022-2022 Johannes Lorenz <jlsf2013$users.sourceforge.net, $=@>
+ *
+ * This file is part of LMMS - https://lmms.io
+ *
+ * This program 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 2 of the License, or (at your option) any later version.
+ *
+ * This program 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 this program (see COPYING); if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301 USA.
+ *
+ */
+
+#ifndef LV2WORKER_H
+#define LV2WORKER_H
+
+#include "lmmsconfig.h"
+
+#ifdef LMMS_HAVE_LV2
+
+#include <lilv/lilv.h>
+#include <lv2/lv2plug.in/ns/ext/worker/worker.h>
+#include <thread>
+#include <vector>
+
+#include "LocklessRingBuffer.h"
+#include "LmmsSemaphore.h"
+
+namespace lmms
+{
+
+/**
+	Worker container
+*/
+class Lv2Worker
+{
+public:
+	// CTOR/DTOR/feature access
+	Lv2Worker(const LV2_Worker_Interface* iface, Semaphore* common_work_lock, bool threaded);
+	~Lv2Worker();
+	void setHandle(LV2_Handle handle) { m_handle = handle; }
+	LV2_Worker_Schedule* feature() { return &m_scheduleFeature; }
+
+	// public API
+	void emitResponses();
+	void notifyPluginThatRunFinished()
+	{
+		if(m_iface->end_run) { m_iface->end_run(m_scheduleFeature.handle); }
+	}
+
+	// to be called only by static functions
+	LV2_Worker_Status scheduleWork(uint32_t size, const void* data);
+	LV2_Worker_Status respond(uint32_t size, const void* data);
+
+private:
+	// functions
+	void workerFunc();
+	std::size_t bufferSize() const;  //!< size of internal buffers
+
+	// parameters
+	const LV2_Worker_Interface* m_iface;
+	bool m_threaded;
+	LV2_Handle m_handle;
+	LV2_Worker_Schedule m_scheduleFeature;
+
+	// threading/synchronization
+	std::thread m_thread;
+	std::vector<char> m_response;  //!< buffer where single requests from m_requests are unpacked
+	LocklessRingBuffer<char> m_requests, m_responses;  //!< ringbuffer to queue multiple requests
+	LocklessRingBufferReader<char> m_requestsReader, m_responsesReader;
+	std::atomic<bool> m_exit = false;  //!< Whether the worker function should keep looping
+	Semaphore m_sem;
+	Semaphore* m_workLock;
+};
+
+
+} // namespace lmms
+
+#endif // LMMS_HAVE_LV2
+
+#endif // LV2WORKER_H
+

src/core/CMakeLists.txt

@@ -70,6 +70,7 @@ set(LMMS_SRCS
 	core/SamplePlayHandle.cpp
 	core/SampleRecordHandle.cpp
 	core/Scale.cpp
+	core/LmmsSemaphore.cpp
 	core/SerializingObject.cpp
 	core/Song.cpp
 	core/TempoSyncKnobModel.cpp
@@ -112,6 +113,7 @@ set(LMMS_SRCS
 	core/lv2/Lv2SubPluginFeatures.cpp
 	core/lv2/Lv2UridCache.cpp
 	core/lv2/Lv2UridMap.cpp
+	core/lv2/Lv2Worker.cpp
 
 	core/midi/MidiAlsaRaw.cpp
 	core/midi/MidiAlsaSeq.cpp