001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase.procedure2;
019
020import java.util.Collections;
021import java.util.List;
022import org.apache.yetus.audience.InterfaceAudience;
023import org.apache.yetus.audience.InterfaceStability;
024
025/**
026 * Simple scheduler for procedures
027 */
028@InterfaceAudience.Private
029@InterfaceStability.Evolving
030public class SimpleProcedureScheduler extends AbstractProcedureScheduler {
031  private final ProcedureDeque runnables = new ProcedureDeque();
032
033  @Override
034  protected void enqueue(final Procedure procedure, final boolean addFront) {
035    if (addFront) {
036      runnables.addFirst(procedure);
037    } else {
038      runnables.addLast(procedure);
039    }
040  }
041
042  @Override
043  protected Procedure dequeue() {
044    return runnables.poll();
045  }
046
047  @Override
048  public void clear() {
049    schedLock();
050    try {
051      runnables.clear();
052    } finally {
053      schedUnlock();
054    }
055  }
056
057  @Override
058  public void yield(final Procedure proc) {
059    addBack(proc);
060  }
061
062  @Override
063  public boolean queueHasRunnables() {
064    return runnables.size() > 0;
065  }
066
067  @Override
068  public int queueSize() {
069    return runnables.size();
070  }
071
072  @Override
073  public void completionCleanup(Procedure proc) {
074  }
075
076  @Override
077  public List<LockedResource> getLocks() {
078    return Collections.emptyList();
079  }
080
081  @Override
082  public LockedResource getLockResource(LockedResourceType resourceType, String resourceName) {
083    return null;
084  }
085}