hbase-server/src/main/java/org/apache/hadoop/hbase/wal/BoundedGroupingStrategy.java

   1 /**
   2  *
   3  * Licensed to the Apache Software Foundation (ASF) under one
   4  * or more contributor license agreements.  See the NOTICE file
   5  * distributed with this work for additional information
   6  * regarding copyright ownership.  The ASF licenses this file
   7  * to you under the Apache License, Version 2.0 (the
   8  * "License"); you may not use this file except in compliance
   9  * with the License.  You may obtain a copy of the License at
  10  *
  11  *     http://www.apache.org/licenses/LICENSE-2.0
  12  *
  13  * Unless required by applicable law or agreed to in writing, software
  14  * distributed under the License is distributed on an "AS IS" BASIS,
  15  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  16  * See the License for the specific language governing permissions and
  17  * limitations under the License.
  18  */
  19 package org.apache.hadoop.hbase.wal;
  20
  21 import static org.apache.hadoop.hbase.util.ConcurrentMapUtils.computeIfAbsent;
  22
  23 import java.util.concurrent.ConcurrentHashMap;
  24 import java.util.concurrent.atomic.AtomicInteger;
  25
  26 import org.apache.hadoop.conf.Configuration;
  27 import org.apache.yetus.audience.InterfaceAudience;
  28 import org.apache.hadoop.hbase.util.Bytes;
  29 import org.apache.hadoop.hbase.wal.RegionGroupingProvider.RegionGroupingStrategy;
  30
  31 /**
  32  * A WAL grouping strategy that limits the number of wal groups to
  33  * "hbase.wal.regiongrouping.numgroups".
  34  */
  35 @InterfaceAudience.Private
  36 public class BoundedGroupingStrategy implements RegionGroupingStrategy{
  37
  38   static final String NUM_REGION_GROUPS = "hbase.wal.regiongrouping.numgroups";
  39   static final int DEFAULT_NUM_REGION_GROUPS = 2;
  40
  41   private ConcurrentHashMap<String, String> groupNameCache = new ConcurrentHashMap<>();
  42   private AtomicInteger counter = new AtomicInteger(0);
  43   private String[] groupNames;
  44
  45   @Override
  46   public String group(byte[] identifier, byte[] namespace) {
  47     String idStr = Bytes.toString(identifier);
  48     return computeIfAbsent(groupNameCache, idStr,
  49       () -> groupNames[getAndIncrAtomicInteger(counter, groupNames.length)]);
  50   }
  51
  52   // Non-blocking incrementing & resetting of AtomicInteger.
  53   private int getAndIncrAtomicInteger(AtomicInteger atomicInt, int reset) {
  54     for (;;) {
  55       int current = atomicInt.get();
  56       int next = (current + 1);
  57       if (next == reset) {
  58         next = 0;
  59       }
  60       if (atomicInt.compareAndSet(current, next)) return current;
  61     }
  62   }
  63
  64   @Override
  65   public void init(Configuration config, String providerId) {
  66     int regionGroupNumber = config.getInt(NUM_REGION_GROUPS, DEFAULT_NUM_REGION_GROUPS);
  67     groupNames = new String[regionGroupNumber];
  68     for (int i = 0; i < regionGroupNumber; i++) {
  69       groupNames[i] = providerId + GROUP_NAME_DELIMITER + "regiongroup-" + i;
  70     }
  71   }
  72
  73 }