/**

 * Relational pipes

 * Copyright © 2020 František Kučera (Frantovo.cz, GlobalCode.info)

 *

 * 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, version 3 of the License.

 *

 * 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 "streamlet-common.h"

#include <unistd.h>

/**

 * This streamlet is useful only for debugging or study purposes.

 * 

 * It provides two attributes:

 *  - pid_streamlet: getpid()

 *  - pid_worker: getppid()

 *	

 * Can be used for studying how the parallelism works:

 *  - Each instance of streamlet (each --streamlet pid) will have different pid_streamlet.

 *  - Each worker (their number = X in --parallelism X) will have different pid_worker.

 * 

 * So we can check how evenly the work has been distributed across processes (e.g. do some GROUP BY in SQL).

 */

class PidStreamlet : public Streamlet {

	std::vector<AttributeMetadata> getOutputAttributesMetadata() override {

		std::vector<AttributeMetadata> oam;

		int i = 0;

		oam.push_back({getAlias(i++, L"pid_streamlet"), INTEGER});

		oam.push_back({getAlias(i++, L"pid_worker"), INTEGER});

		return oam;

	}

	std::vector<OutputAttribute> getOutputAttributes() override {

		std::vector<OutputAttribute> oa;

		oa.push_back({std::to_wstring(getpid()), false});

		oa.push_back({std::to_wstring(getppid()), false});

		return oa;

	}

};

STREAMLET_RUN(PidStreamlet)