branch-0.23.1/hadoop-hdfs-project/hadoop-hdfs/src/ant/org/apache/hadoop/ant/condition/DfsBaseConditional.java

/**
 * 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.hadoop.ant.condition;

import org.apache.tools.ant.taskdefs.condition.Condition;

/**
 * This wrapper around {@link org.apache.hadoop.ant.DfsTask} implements the
 * Ant >1.5
 * {@link org.apache.tools.ant.taskdefs.condition.Condition Condition}
 * interface for HDFS tests. So one can test conditions like this:
 * {@code
 *   <condition property="precond">
 *     <and>
 *       <hadoop:exists file="fileA" />
 *       <hadoop:exists file="fileB" />
 *       <hadoop:sizezero file="fileB" />
 *     </and>
 *   </condition>
 * }
 * This will define the property precond if fileA exists and fileB has zero
 * length.
 */
public abstract class DfsBaseConditional extends org.apache.hadoop.ant.DfsTask
                       implements Condition {

  protected boolean result;
  String file;

  private void initArgs() {
    setCmd("test");
    setArgs("-"  +  getFlag() + "," + file);
  }

  public void setFile(String file) {
    this.file = file;
  }

  protected abstract char getFlag();

  protected int postCmd(int exit_code) {
    exit_code = super.postCmd(exit_code);
    result = exit_code == 0;
    return exit_code;
  }

  public boolean eval() {
    initArgs();
    execute();
    return result;
  }
}