http://lucene.apache.org/lucene-parent/lucene-core: Apache Lucene Java Core (The Apache Software Foundation) 
/*
 * 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.lucene.store;


import java.io.Closeable;
import java.io.IOException;


An interprocess mutex lock.

Typical use might look like:
  try (final Lock lock = directory.obtainLock("my.lock")) {
    // ... code to execute while locked ...
  }



See Also:
  • obtainLock.obtainLock(String)
@lucene.internal
/** An interprocess mutex lock.
 * <p>Typical use might look like:<pre class="prettyprint">
 *   try (final Lock lock = directory.obtainLock("my.lock")) {
 *     // ... code to execute while locked ...
 *   }
 * </pre>
 *
 * @see Directory#obtainLock(String)
 *
 * @lucene.internal
 */
public abstract class Lock implements Closeable {

  
Releases exclusive access.


Note that exceptions thrown from close may require
human intervention, as it may mean the lock was no
longer valid, or that fs permissions prevent removal
of the lock file, or other reasons.


{@inheritDoc} 

Throws:
/** 
   * Releases exclusive access.
   * <p>
   * Note that exceptions thrown from close may require
   * human intervention, as it may mean the lock was no
   * longer valid, or that fs permissions prevent removal
   * of the lock file, or other reasons.
   * <p>
   * {@inheritDoc} 
   * @throws LockReleaseFailedException optional specific exception) if 
   *         the lock could not be properly released.
   */
  public abstract void close() throws IOException;
  
  
Best effort check that this lock is still valid. Locks
could become invalidated externally for a number of reasons,
for example if a user deletes the lock file manually or
when a network filesystem is in use. 

Throws:
  • IOException – if the lock is no longer valid.
/** 
   * Best effort check that this lock is still valid. Locks
   * could become invalidated externally for a number of reasons,
   * for example if a user deletes the lock file manually or
   * when a network filesystem is in use. 
   * @throws IOException if the lock is no longer valid.
   */
  public abstract void ensureValid() throws IOException;
}