From 338e83d9dc2aca8ced4358df7dae13e11a5c71a7 Mon Sep 17 00:00:00 2001
From: David Robillard <d@drobilla.net>
Date: Thu, 5 Apr 2012 00:15:54 +0000
Subject: Implement LV2 worker extension.

This is done by way of a generic Worker object/thread, which currently just
applies to one LV2 plugin, but the idea is to share one thread and set of
buffers among many plugins.  The same pattern may also be useful elsewhere in
Ardour.  The responding part gets a bit tricker when sharing a worker between
plugins, it's not a blocker, and I'm lazy, sooo here's this.

This commit also adds a new portable in-process semaphore to PBD.  The existing
one is pretty weird and uses a named semaphore on OSX for reasons unknown to
me.  Perhaps as a quick fix to avoid POSIX semaphores being utterly broken on
OSX?  It would probably be a good idea to replace that with this new one, which
uses Mach kernel semaphores on OSX which work well, though I am not sure how
pedantically real-time safe they are to signal.


git-svn-id: svn://localhost/ardour2/branches/3.0@11790 d708f5d6-7413-0410-9779-e7cbd77b26cf
---
 libs/ardour/worker.cc | 115 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 115 insertions(+)
 create mode 100644 libs/ardour/worker.cc

(limited to 'libs/ardour/worker.cc')

diff --git a/libs/ardour/worker.cc b/libs/ardour/worker.cc
new file mode 100644
index 0000000000..c108f653c4
--- /dev/null
+++ b/libs/ardour/worker.cc
@@ -0,0 +1,115 @@
+/*
+  Copyright (C) 2012 Paul Davis
+  Author: David Robillard
+
+  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; if not, write to the Free Software
+  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+#include <stdlib.h>
+
+#include "ardour/worker.h"
+#include "pbd/error.h"
+
+namespace ARDOUR {
+
+Worker::Worker(Workee* workee, uint32_t ring_size)
+	: _workee(workee)
+	, _thread(Glib::Thread::create(sigc::mem_fun(*this, &Worker::run), true))
+	, _requests(new RingBuffer<uint8_t>(ring_size))
+	, _responses(new RingBuffer<uint8_t>(ring_size))
+	, _response((uint8_t*)malloc(ring_size))
+	, _sem(0)
+	, _exit(false)
+{}
+
+Worker::~Worker()
+{
+	_exit = true;
+	_sem.post();
+	_thread->join();
+}
+
+bool
+Worker::schedule(uint32_t size, const void* data)
+{
+	if (_requests->write((const uint8_t*)&size, sizeof(size)) != sizeof(size)) {
+		return false;
+	}
+	if (_requests->write((const uint8_t*)data, size) != size) {
+		return false;  // FIXME: corruption
+	}
+	_sem.post();
+	return true;
+}
+
+bool
+Worker::respond(uint32_t size, const void* data)
+{
+	if (_responses->write((const uint8_t*)&size, sizeof(size)) != sizeof(size)) {
+		return false;
+	}
+	if (_responses->write((const uint8_t*)data, size) != size) {
+		return false;  // FIXME: corruption
+	}
+	return true;
+}
+
+void
+Worker::emit_responses()
+{
+	uint32_t read_space = _responses->read_space();
+	uint32_t size       = 0;
+	while (read_space > sizeof(size)) {
+		_responses->read((uint8_t*)&size, sizeof(size));
+		_responses->read(_response, size);
+		_workee->work_response(size, _response);
+		read_space -= sizeof(size) + size;
+	}
+}
+
+void
+Worker::run()
+{
+	void*  buf      = NULL;
+	size_t buf_size = 0;
+	while (true) {
+		_sem.wait();
+		if (_exit) {
+			return;
+		}
+
+		uint32_t size = 0;
+		if (_requests->read((uint8_t*)&size, sizeof(size)) < sizeof(size)) {
+			PBD::error << "Worker: Error reading size from request ring"
+			           << endmsg;
+			continue;
+		}
+
+		if (size > buf_size) {
+			buf = realloc(buf, size);
+			buf_size = size;
+		}
+
+		if (_requests->read((uint8_t*)buf, size) < size) {
+			PBD::error << "Worker: Error reading body from request ring"
+			           << endmsg;
+			continue;  // TODO: This is probably fatal
+		}
+
+		_workee->work(size, buf);
+	}
+}
+
+} // namespace ARDOUR
-- 
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