content: /**
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You 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.
   */
  
  package org.apache.solr.core;
  
  import org.apache.solr.search.SolrIndexSearcher;
  import org.apache.solr.util.plugin.NamedListInitializedPlugin;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * @version $Id: SolrEventListener.java 1052938 2010-12-26 20:21:48Z rmuir $
   */
  public interface SolrEventListener extends NamedListInitializedPlugin{
    static final Logger log = LoggerFactory.getLogger(SolrCore.class);
  
  
    public void postCommit();
  
    /** The searchers passed here are only guaranteed to be valid for the duration
     * of this method call, so care should be taken not to spawn threads or asynchronous
     * tasks with references to these searchers.
     * <p/>
     * Implementations should add the {@link org.apache.solr.common.params.EventParams#EVENT} parameter and set it to a value of either:
     * <ul>
     * <li>{@link org.apache.solr.common.params.EventParams#FIRST_SEARCHER} - First Searcher event</li>
     * <li>{@link org.apache.solr.common.params.EventParams#NEW_SEARCHER} - New Searcher event</li>
     * </ul>
     *
     * Sample:
     * <pre>
      if (currentSearcher != null) {
        nlst.add(CommonParams.EVENT, CommonParams.NEW_SEARCHER);
      } else {
        nlst.add(CommonParams.EVENT, CommonParams.FIRST_SEARCHER);
      }
     *
     * </pre>
     *
     * @see org.apache.solr.core.AbstractSolrEventListener#addEventParms(org.apache.solr.search.SolrIndexSearcher, org.apache.solr.common.util.NamedList) 
     *
     * @param newSearcher The new {@link org.apache.solr.search.SolrIndexSearcher} to use
     * @param currentSearcher The existing {@link org.apache.solr.search.SolrIndexSearcher}.  null if this is a firstSearcher event.
     *
     */
    public void newSearcher(SolrIndexSearcher newSearcher, SolrIndexSearcher currentSearcher);
  
  }
  