VILLASnode/lib/nodes/loopback.cpp

/** Node-type for loopback connections.
 *
 * @author Steffen Vogel <svogel2@eonerc.rwth-aachen.de>
 * @copyright 2014-2022, Institute for Automation of Complex Power Systems, EONERC
 * @license GNU General Public License (version 3)
 *
 * VILLASnode
 *
 * 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 3 of the License, or
 * 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, see <http://www.gnu.org/licenses/>.
 *********************************************************************************/

#include <cstring>

#include <villas/node/config.hpp>
#include <villas/node_compat.hpp>
#include <villas/nodes/loopback.hpp>
#include <villas/exceptions.hpp>
#include <villas/node/memory.hpp>
#include <villas/utils.hpp>

using namespace villas;
using namespace villas::node;
using namespace villas::utils;

LoopbackNode::LoopbackNode(const std::string &name) :
	Node(name),
	queuelen(DEFAULT_QUEUE_LENGTH),
	mode(QueueSignalledMode::AUTO)
{
	queue.queue.state = State::DESTROYED;
}

LoopbackNode::~LoopbackNode()
{
	int ret __attribute__((unused));

	ret = queue_signalled_destroy(&queue);
}

int LoopbackNode::prepare()
{
	assert(state == State::CHECKED);

	int ret = queue_signalled_init(&queue, queuelen, &memory::mmap, mode);
	if (ret)
		throw RuntimeError("Failed to initialize queue");

	return Node::prepare();
}

int LoopbackNode::stop()
{
	int ret;

	ret = queue_signalled_close(&queue);
	if (ret)
		return ret;

	return 0;
}

int LoopbackNode::_read(struct Sample * smps[], unsigned cnt)
{
	int avail;

	struct Sample *cpys[cnt];

	avail = queue_signalled_pull_many(&queue, (void **) cpys, cnt);

	sample_copy_many(smps, cpys, avail);
	sample_decref_many(cpys, avail);

	return avail;
}

int LoopbackNode::_write(struct Sample * smps[], unsigned cnt)
{
	sample_incref_many(smps, cnt);

	int pushed = queue_signalled_push_many(&queue, (void **) smps, cnt);
	if (pushed < 0) {
		sample_decref_many(smps, cnt);
		return pushed;
	}

	/* Released unpushed samples */
	if ((unsigned) pushed < cnt) {
		sample_decref_many(smps + pushed, cnt - pushed);
		logger->warn("Queue overrun");
	}

	return pushed;
}

std::vector<int> LoopbackNode::getPollFDs()
{
	return { queue_signalled_fd(&queue) };
}

const std::string & LoopbackNode::getDetails()
{
	if (details.empty()) {
		details = fmt::format("queuelen={}", queuelen);
	}

	return details;
}

int LoopbackNode::parse(json_t *json)
{
	const char *mode_str = nullptr;

	json_error_t err;
	int ret;

	ret = json_unpack_ex(json, &err, 0, "{ s?: i, s?: s }",
		"queuelen", queuelen,
		"mode", &mode_str
	);
	if (ret)
		throw ConfigError(json, err, "node-config-node-loopback");

	if (mode_str) {
		if (!strcmp(mode_str, "auto"))
			mode = QueueSignalledMode::AUTO;
#ifdef HAVE_EVENTFD
		else if (!strcmp(mode_str, "eventfd"))
			mode = QueueSignalledMode::EVENTFD;
#endif
		else if (!strcmp(mode_str, "pthread"))
			mode = QueueSignalledMode::PTHREAD;
		else if (!strcmp(mode_str, "polling"))
			mode = QueueSignalledMode::POLLING;
		else
			throw ConfigError(json, "node-config-node-loopback-mode", "Unknown mode '{}'", mode_str);
	}

	return 0;
}

static char n[] = "loopback";
static char d[] = "loopback node-type";
static NodePlugin<LoopbackNode, n, d, (int) NodeFactory::Flags::SUPPORTS_POLL |
                                      (int) NodeFactory::Flags::SUPPORTS_READ |
				      (int) NodeFactory::Flags::SUPPORTS_WRITE> nf;