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.regionserver;
20
21 import com.google.common.hash.Hashing;
22
23 import java.util.concurrent.atomic.AtomicInteger;
24 import java.util.concurrent.atomic.AtomicLong;
25
26 import org.apache.hadoop.hbase.ServerName;
27 import org.apache.hadoop.hbase.classification.InterfaceAudience;
28 import org.apache.hadoop.hbase.util.Bytes;
29
30 /**
31 * Generate a new style scanner id to prevent collision with previous started server or other RSs.
32 * We have 64 bits to use.
33 * The first 32 bits are MurmurHash32 of ServerName string "host,port,ts".
34 * The ServerName contains both host, port, and start timestamp so it can prevent collision.
35 * The lowest 32bit is generated by atomic int.
36 */
37 @InterfaceAudience.Private
38 public class ScannerIdGenerator {
39
40 private final long serverNameHash;
41 private final AtomicInteger scannerIdGen = new AtomicInteger(0);
42
43 public ScannerIdGenerator(ServerName serverName) {
44 this.serverNameHash = (long)Hashing.murmur3_32().hashString(serverName.toString()).asInt() << 32;
45 }
46
47 public long generateNewScannerId() {
48 return (scannerIdGen.incrementAndGet() & 0x00000000FFFFFFFFL) | serverNameHash;
49 }
50
51 }