src/main/java/net/onrc/onos/util/GraphDBConnection.java

package net.onrc.onos.util;

import java.util.Set;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.thinkaurelius.titan.core.TitanFactory;
import com.thinkaurelius.titan.core.TitanGraph;
import com.tinkerpop.blueprints.TransactionalGraph;
import com.tinkerpop.blueprints.Vertex;
import com.tinkerpop.blueprints.util.wrappers.event.EventTransactionalGraph;
import com.tinkerpop.frames.FramedGraph;

public class GraphDBConnection implements IDBConnection {
	public enum Transaction {
		COMMIT, ROLLBACK
	}

	public enum GenerateEvent {
		TRUE, FALSE
	}

	class TransactionHandle {
		protected TransactionalGraph tr;

		public void create() {
			tr = graph.newTransaction();
		}
	}

	protected static Logger log = LoggerFactory
			.getLogger(GraphDBConnection.class);
	private static GraphDBConnection singleton = new GraphDBConnection();
	private static TitanGraph graph;
	private static EventTransactionalGraph<TitanGraph> eg;
	private static String configFile;

	/*
	 * A private Constructor prevents any other class from instantiating.
	 */
	private GraphDBConnection() {
	}

	/* Static 'instance' method */
	public static synchronized GraphDBConnection getInstance(final String conf) {
		if (GraphDBConnection.configFile == null
				|| GraphDBConnection.configFile.isEmpty()) {
			GraphDBConnection.configFile = conf;
			log.debug("GraphDBConnection::Setting Config File {}",
					GraphDBConnection.configFile);
		}
		if (!GraphDBConnection.configFile.isEmpty()
				&& (graph == null || graph.isOpen() == Boolean.FALSE)) {
			graph = TitanFactory.open(GraphDBConnection.configFile);
			// FIXME: Creation on Indexes should be done only once
			Set<String> s = graph.getIndexedKeys(Vertex.class);
			if (!s.contains("dpid")) {
				graph.createKeyIndex("dpid", Vertex.class);
			}
			if (!s.contains("type")) {
				graph.createKeyIndex("type", Vertex.class);
			}
			if (!s.contains("dl_address")) {
				graph.createKeyIndex("dl_address", Vertex.class);
			}
			if (!s.contains("flow_id")) {
				graph.createKeyIndex("flow_id", Vertex.class);
			}
			if (!s.contains("flow_entry_id")) {
				graph.createKeyIndex("flow_entry_id", Vertex.class);
			}
			if (!s.contains("switch_state")) {
				graph.createKeyIndex("switch_state", Vertex.class);
			}
			graph.commit();
			eg = new EventTransactionalGraph<TitanGraph>(graph);
		}
		return singleton;
	}

	public FramedGraph<TitanGraph> getFramedGraph() {

		if (isValid()) {
			FramedGraph<TitanGraph> fg = new FramedGraph<TitanGraph>(graph);
			return fg;
		} else {
			log.error("new FramedGraph failed");
			return null;
		}
	}

	protected EventTransactionalGraph<TitanGraph> getEventGraph() {

		if (isValid()) {
			return eg;
		} else {
			return null;
		}
	}

	public void addEventListener(final LocalGraphChangedListener listener) {
		EventTransactionalGraph<TitanGraph> eg = this.getEventGraph();
		eg.addListener(listener);
		log.debug("Registered listener {}", listener.getClass());
	}

	public Boolean isValid() {

		return (graph != null || graph.isOpen());
	}

	public void startTx() {

	}

	public void endTx(Transaction tx) {
		try {
			switch (tx) {
			case COMMIT:
				graph.commit();
			case ROLLBACK:
				graph.rollback();
			}
		} catch (Exception e) {
			// TODO Auto-generated catch block
			log.error("{}", e.toString());
		}
	}

	public void endTx(TransactionHandle tr, Transaction tx) {
		switch (tx) {
		case COMMIT:
			if (tr != null && tr.tr != null) {
				tr.tr.commit();
			} else {
				graph.commit();
			}
		case ROLLBACK:
			if (tr != null && tr.tr != null) {
				tr.tr.rollback();
			} else {
				graph.rollback();
			}
		}
	}

	public void endTx(Transaction tx, GenerateEvent fire) {

		try {
			if (fire.equals(GenerateEvent.TRUE)) {
				switch (tx) {
				case COMMIT:
					eg.commit();
				case ROLLBACK:
					eg.rollback();
				}
			} else {
				endTx(tx);
			}
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	public void close() {
		endTx(Transaction.COMMIT);
	}
}