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The OpenTripPlanner multimodal journey planning system

There is a newer version: 2.6.0

/* 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 . */

package org.opentripplanner.updater;

import org.opentripplanner.routing.graph.Graph;

/**
 * Interface for graph updaters. Objects that implement this interface should always be configured
 * via PreferencesConfigurable.configure after creating the object. GraphUpdaterConfigurator should
 * take care of that. Beware that updaters run in separate threads at the same time.
 * 
 * The only allowed way to make changes to the graph in an updater is by executing (anonymous)
 * GraphWriterRunnable objects via GraphUpdaterManager.execute.
 * 
 * Example implementations can be found in ExampleGraphUpdater and ExamplePollingGraphUpdater.
 */
public interface GraphUpdater extends JsonConfigurable {

    /**
     * Graph updaters must be aware of their manager to be able to execute GraphWriterRunnables.
     * GraphUpdaterConfigurator should take care of calling this function.
     */
    public void setGraphUpdaterManager(GraphUpdaterManager updaterManager);

    /**
     * Here the updater can be initialized. If it throws, the updater won't be started (i.e. the run
     * method won't be called). All updaters' setup methods will be run sequentially in a single-threaded manner
     * before updates begin, in order to avoid concurrent reads/writes.
     */
    public void setup(Graph graph) throws Exception;

    /**
     * This method will run in its own thread. It pulls or receives updates and applies them to the graph.
     * It must perform any writes to the graph by passing GraphWriterRunnables to GraphUpdaterManager.execute().
     * This queues up the write operations, ensuring that only one updater performs writes at a time.
     */
    public void run() throws Exception;

    /**
     * Here the updater can clean up after itself.
     */
    public void teardown();

}