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.commons.lang3.builder.ToStringBuilder;
023import org.apache.commons.lang3.builder.ToStringStyle;
024import org.apache.yetus.audience.InterfaceAudience;
025import org.apache.yetus.audience.InterfaceStability;
026
027/**
028 * Simple scheduler for procedures
029 */
030@InterfaceAudience.Private
031@InterfaceStability.Evolving
032public class SimpleProcedureScheduler extends AbstractProcedureScheduler {
033  private final ProcedureDeque runnables = new ProcedureDeque();
034
035  @Override
036  protected void enqueue(final Procedure procedure, final boolean addFront) {
037    if (addFront) {
038      runnables.addFirst(procedure);
039    } else {
040      runnables.addLast(procedure);
041    }
042  }
043
044  @Override
045  protected Procedure dequeue() {
046    return runnables.poll();
047  }
048
049  @Override
050  public void clear() {
051    schedLock();
052    try {
053      runnables.clear();
054    } finally {
055      schedUnlock();
056    }
057  }
058
059  @Override
060  public void yield(final Procedure proc) {
061    addBack(proc);
062  }
063
064  @Override
065  public boolean queueHasRunnables() {
066    return runnables.size() > 0;
067  }
068
069  @Override
070  public int queueSize() {
071    return runnables.size();
072  }
073
074  @Override
075  public void completionCleanup(Procedure proc) {
076  }
077
078  @Override
079  public List<LockedResource> getLocks() {
080    return Collections.emptyList();
081  }
082
083  @Override
084  public LockedResource getLockResource(LockedResourceType resourceType, String resourceName) {
085    return null;
086  }
087
088  @Override
089  public String toString() {
090    return new ToStringBuilder(this, ToStringStyle.SHORT_PREFIX_STYLE).appendSuper(super.toString())
091      .append("runnables", runnables).build();
092  }
093}