ExampleGraphUpdater.java

/* This program is free software: you can redistribute it and/or
 modify it under the terms of the GNU Lesser General Public License
 as published by the Free Software Foundation, either version 3 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, see <http://www.gnu.org/licenses/>. */

package org.opentripplanner.updater.example;

import java.util.concurrent.ExecutionException;
import java.util.prefs.Preferences;

import com.fasterxml.jackson.databind.JsonNode;
import org.opentripplanner.routing.graph.Graph;
import org.opentripplanner.updater.GraphUpdater;
import org.opentripplanner.updater.GraphUpdaterManager;
import org.opentripplanner.updater.GraphWriterRunnable;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * This class shows an example of how to implement a graph updater. Besides implementing the methods
 * of the interface GraphUpdater, the updater also needs to be registered in the function
 * GraphUpdaterConfigurator.applyConfigurationToGraph.
 * 
 * This example is suited for streaming updaters. For polling updaters it is better to use the
 * abstract base class PollingGraphUpdater. The class ExamplePollingGraphUpdater shows an example of
 * this.
 * 
 * Usage example ('example' name is an example) in the file 'Graph.properties':
 * 
 * <pre>
 * example.type = example-updater
 * example.frequencySec = 60
 * example.url = https://api.updater.com/example-updater
 * </pre>
 * 
 * @see ExamplePollingGraphUpdater
 * @see GraphUpdaterConfigurator.applyConfigurationToGraph
 */
public class ExampleGraphUpdater implements GraphUpdater {

    private static Logger LOG = LoggerFactory.getLogger(ExampleGraphUpdater.class);

    private GraphUpdaterManager updaterManager;

    private Integer frequencySec;

    private String url;

    // Here the updater can be configured using the properties in the file 'Graph.properties'.
    @Override
    public void configure(Graph graph, JsonNode config) throws Exception {
        frequencySec = config.path("frequencySec").asInt(5);
        url = config.path("url").asText();
        LOG.info("Configured example updater: frequencySec={} and url={}", frequencySec, url);
    }

    // Here the updater gets to know its parent manager to execute GraphWriterRunnables.
    @Override
    public void setGraphUpdaterManager(GraphUpdaterManager updaterManager) {
        LOG.info("Example updater: updater manager is set");
        this.updaterManager = updaterManager;
    }

    // Here the updater can be initialized.
    @Override
    public void setup() {
        LOG.info("Setup example updater");
        
        // Execute anonymous graph writer runnable and wait for its termination
        try {
            updaterManager.executeBlocking(new GraphWriterRunnable() {
                @Override
                public void run(Graph graph) {
                    LOG.info("Anonymous graph writer {} runnable is run on the "
                            + "graph writer scheduler.", this.hashCode());
                    // Do some writing to the graph here
                }
            });
        } catch (InterruptedException e) {
        } catch (ExecutionException e) {
        }
    }

    // This is where the updater thread receives updates and applies them to the graph.
    // This method only runs once.
    @Override
    public void run() {
        LOG.info("Run example updater with hashcode: {}", this.hashCode());
        // Here the updater can connect to a server and register a callback function
        // to handle updates to the graph
    }

    // Here the updater can cleanup after itself.
    @Override
    public void teardown() {
        LOG.info("Teardown example updater");
    }

}