IndexedGenerationCallable.java

/* 
 * Licensed under the Apache License, Version 2.0 (the "License");
 *
 * You may not use this file except in compliance with the License.
 *
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * Contributions from 2013-2017 where performed either by US government 
 * employees, or under US Veterans Health Administration contracts. 
 *
 * US Veterans Health Administration contributions by government employees
 * are work of the U.S. Government and are not subject to copyright
 * protection in the United States. Portions contributed by government 
 * employees are USGovWork (17USC §105). Not subject to copyright. 
 * 
 * Contribution by contractors to the US Veterans Health Administration
 * during this period are contractually contributed under the
 * Apache License, Version 2.0.
 *
 * See: https://www.usa.gov/government-works
 * 
 * Contributions prior to 2013:
 *
 * Copyright (C) International Health Terminology Standards Development Organisation.
 * Licensed under the Apache License, Version 2.0.
 *
 */



package sh.isaac.api.index;

//~--- JDK imports ------------------------------------------------------------

import java.util.concurrent.Callable;
import java.util.concurrent.CountDownLatch;

//~--- classes ----------------------------------------------------------------

/**
 * A
 * {@code Callable<Long>} object that will block until the indexer
 * has added the document to the index. The
 * {@code call()} method on the object will return the index generation
 * that contains the document, which can be used in search calls to make sure
 * that generation is available to the searcher.
 *
 * @author kec
 */
public class IndexedGenerationCallable
         implements Callable<Long> {
   /** The latch. */
   private final CountDownLatch latch = new CountDownLatch(1);

   /** The index generation. */
   private long indexGeneration;

   //~--- methods -------------------------------------------------------------

   /**
    * Call.
    *
    * @return the long
    * @throws Exception the exception
    */
   @Override
   public Long call()
            throws Exception {
      this.latch.await();
      return this.indexGeneration;
   }

   //~--- set methods ---------------------------------------------------------

   /**
    * Sets the index generation.
    *
    * @param indexGeneration the new index generation
    */
   public void setIndexGeneration(long indexGeneration) {
      this.indexGeneration = indexGeneration;
      this.latch.countDown();
   }
}