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.update.processor;
  
  import java.io.IOException;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import org.apache.solr.update.AddUpdateCommand;
  import org.apache.solr.update.CommitUpdateCommand;
  import org.apache.solr.update.DeleteUpdateCommand;
  import org.apache.solr.update.MergeIndexesCommand;
  import org.apache.solr.update.RollbackUpdateCommand;
  
  
  /**
   * This is a good place for subclassed update handlers to process the document before it is 
   * indexed.  You may wish to add/remove fields or check if the requested user is allowed to 
   * update the given document...
   * 
   * Perhaps you continue adding an error message (without indexing the document)...
   * perhaps you throw an error and halt indexing (remove anything already indexed??)
   * 
   * By default, this just passes the request to the next processor in the chain.
   * 
   * @since solr 1.3
   */
  public abstract class UpdateRequestProcessor {
    protected final Logger log = LoggerFactory.getLogger(getClass());
  
    protected final UpdateRequestProcessor next;
  
    public UpdateRequestProcessor( UpdateRequestProcessor next) {
      this.next = next;
    }
  
    public void processAdd(AddUpdateCommand cmd) throws IOException {
      if (next != null) next.processAdd(cmd);
    }
  
    public void processDelete(DeleteUpdateCommand cmd) throws IOException {
      if (next != null) next.processDelete(cmd);
    }
  
    public void processMergeIndexes(MergeIndexesCommand cmd) throws IOException {
      if (next != null) next.processMergeIndexes(cmd);
    }
  
    public void processCommit(CommitUpdateCommand cmd) throws IOException
    {
      if (next != null) next.processCommit(cmd);
    }
  
    /**
     * @since Solr 1.4
     */
    public void processRollback(RollbackUpdateCommand cmd) throws IOException
    {
      if (next != null) next.processRollback(cmd);
    }
  
    public void finish() throws IOException {
      if (next != null) next.finish();    
    }
  }
  
  