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.master.procedure;
019
020import org.apache.commons.lang3.builder.ToStringBuilder;
021import org.apache.commons.lang3.builder.ToStringStyle;
022import org.apache.hadoop.hbase.procedure2.LockStatus;
023import org.apache.hadoop.hbase.procedure2.Procedure;
024import org.apache.hadoop.hbase.procedure2.ProcedureDeque;
025import org.apache.hadoop.hbase.util.AvlUtil.AvlLinkedNode;
026import org.apache.yetus.audience.InterfaceAudience;
027
028@InterfaceAudience.Private
029abstract class Queue<TKey extends Comparable<TKey>> extends AvlLinkedNode<Queue<TKey>> {
030
031  /**
032   * @param proc must not be null
033   */
034  abstract boolean requireExclusiveLock(Procedure<?> proc);
035
036  private final TKey key;
037  private final int priority;
038  private final ProcedureDeque runnables = new ProcedureDeque();
039  // Reference to status of lock on entity this queue represents.
040  private final LockStatus lockStatus;
041
042  protected Queue(TKey key, LockStatus lockStatus) {
043    this(key, 1, lockStatus);
044  }
045
046  protected Queue(TKey key, int priority, LockStatus lockStatus) {
047    assert priority >= 1 : "priority must be greater than or equal to 1";
048    this.key = key;
049    this.priority = priority;
050    this.lockStatus = lockStatus;
051  }
052
053  protected TKey getKey() {
054    return key;
055  }
056
057  public int getPriority() {
058    return priority;
059  }
060
061  protected LockStatus getLockStatus() {
062    return lockStatus;
063  }
064
065  public boolean isAvailable() {
066    return !isEmpty();
067  }
068
069  // ======================================================================
070  // Functions to handle procedure queue
071  // ======================================================================
072  public void add(Procedure<?> proc, boolean addToFront) {
073    if (addToFront) {
074      runnables.addFirst(proc);
075    } else {
076      runnables.addLast(proc);
077    }
078  }
079
080  public Procedure<?> peek() {
081    return runnables.peek();
082  }
083
084  public Procedure<?> poll() {
085    return runnables.poll();
086  }
087
088  public boolean isEmpty() {
089    return runnables.isEmpty();
090  }
091
092  public int size() {
093    return runnables.size();
094  }
095
096  // ======================================================================
097  // Generic Helpers
098  // ======================================================================
099  public int compareKey(TKey cmpKey) {
100    return key.compareTo(cmpKey);
101  }
102
103  @Override
104  public int compareTo(Queue<TKey> other) {
105    return compareKey(other.key);
106  }
107
108  @Override
109  public String toString() {
110    return new ToStringBuilder(this, ToStringStyle.SHORT_PREFIX_STYLE).append("key", key)
111      .append("lockStatus", lockStatus.describeLockStatus()).append("size", size()).build();
112  }
113}