content: /*
   * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
   * (the "License"). You may not use this work except in compliance with the License, which is
   * available at www.apache.org/licenses/LICENSE-2.0
   *
   * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
   * either express or implied, as more fully set forth in the License.
   *
   * See the NOTICE file distributed with this work for information regarding copyright ownership.
   */
  
  package alluxio.master.metastore.rocks;
  
  import alluxio.exception.runtime.AlluxioRuntimeException;
  
  import java.util.concurrent.Callable;
  
  /**
   * This is a handle used to manage the write lock(exclusive lock) on RocksStore.
   * The exclusive lock is acquired when ref count is zero, and the StopServing flag ensures
   * no new r/w will come in, so the ref count will stay zero throughout the period.
   *
   * One exception is when the exclusive lock is forced (ignoring uncompleted r/w operations),
   * when the reader comes back the exclusive lock is already held. At this moment when the late
   * reader comes back, it should not update the ref count anymore. See Javadoc on
   * {@link RocksSharedLockHandle#close()} for how that is handled.
   */
  public class RocksExclusiveLockHandle implements AutoCloseable {
    private final Callable<Void> mCloseAction;
  
    /**
     * The constructor.
     * @param closeAction the action called on close
     */
    public RocksExclusiveLockHandle(Callable<Void> closeAction) {
      mCloseAction = closeAction;
    }
  
    @Override
    public void close() {
      try {
        mCloseAction.call();
      } catch (Exception e) {
        // From the current usage in RocksStore, this is unreachable
        throw AlluxioRuntimeException.from(e);
      }
    }
  }
  