VILLASnode/common/include/villas/plugin.hpp

/** Loadable / plugin support.
 *
 * @file
 * @author Steffen Vogel <stvogel@eonerc.rwth-aachen.de>
 * @author Daniel Krebs <github@daniel-krebs.net>
 * @copyright 2014-2021, Institute for Automation of Complex Power Systems, EONERC
 * @license GNU General Public License (version 3)
 *
 * VILLAScommon
 *
 * 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/>.
 *********************************************************************************/

#pragma once

#include <iostream>
#include <list>
#include <string>
#include <jansson.h>
#include <spdlog/fmt/ostr.h>

#include <villas/log.hpp>
#include <villas/common.hpp>

namespace villas {
namespace plugin {

/* Forward declarations */
class Plugin;
class Registry;

extern Registry *registry;

template<typename T = Plugin>
using List = std::list<T *>;

class SubRegistry {

public:
	virtual
	List<> lookup() = 0;
};

class Registry {

protected:
	List<> plugins;
	List<SubRegistry> registries;

public:

	Logger getLogger()
	{
		return logging.get("plugin:registry");
	}

	void add(Plugin *p)
	{
		plugins.push_back(p);
	}

	void addSubRegistry(SubRegistry *sr)
	{
		registries.push_back(sr);
	}

	void remove(Plugin *p)
	{
		plugins.remove(p);
	}

	/// Get all plugins including sub-registries
	List<> lookup() {
		List<> all;

		all.insert(all.end(), plugins.begin(), plugins.end());

		for (auto r : registries) {
			auto p = r->lookup();

			all.insert(all.end(), p.begin(), p.end());
		}

		return all;
	}

	/// Get all plugins of specific type
	template<typename T = Plugin>
	List<T> lookup()
	{
		List<T> list;

		for (Plugin *p : lookup()) {
			T *t = dynamic_cast<T *>(p);
			if (t)
				list.push_back(t);
		}

		/* Sort alphabetically */
		list.sort([](const T *a, const T *b) {
			return a->getName() < b->getName();
		});

		return list;
	}

	/// Get all plugins of specific type and name
	template<typename T = Plugin>
	T * lookup(const std::string &name)
	{
		for (T *p : lookup<T>()) {
			if (p->getName() != name)
				continue;

			return p;
		}

		return nullptr;
	}

	template<typename T = Plugin>
	void dump();
};

class Plugin {

	friend plugin::Registry;

protected:
	Logger logger;

public:
	Plugin();

	virtual
	~Plugin();

	// copying a plugin doesn't make sense, so explicitly deny it
	Plugin(Plugin const&) = delete;
	void operator=(Plugin const&) = delete;

	virtual
	void dump();

	/// Get plugin name
	virtual
	std::string getName() const = 0;

	/// Get plugin type
	virtual
	std::string getType() const = 0;

	// Get plugin description
	virtual
	std::string getDescription() const = 0;

	virtual
	Logger getLogger()
	{
		if (!logger) {
			auto name = fmt::format("{}:{}", getType(), getName());
			logger = logging.get(name);
		}

		return logger;
	}

	/** Custom formatter for spdlog */
	template<typename OStream>
	friend OStream &operator<<(OStream &os, const class Plugin &p)
	{
		return os << p.getName();
	}
};

template<typename T = Plugin>
void
Registry::dump()
{
	getLogger()->info("Available plugins:");

	for (Plugin *p : plugins) {
		T *t = dynamic_cast<T *>(p);
		if (t)
			getLogger()->info(" - {}: {}", *p, p->getDescription());
	}
}

} /* namespace plugin */
} /* namespace villas */