1 /** 2 * Licensed to the Apache Software Foundation (ASF) under one 3 * or more contributor license agreements. See the NOTICE file 4 * distributed with this work for additional information 5 * regarding copyright ownership. The ASF licenses this file 6 * to you under the Apache License, Version 2.0 (the 7 * "License"); you may not use this file except in compliance 8 * with the License. You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 package org.apache.hadoop.hdfs.shortcircuit; 19 20 import org.apache.hadoop.classification.InterfaceAudience; 21 22 import java.io.Closeable; 23 import java.nio.MappedByteBuffer; 24 25 import org.apache.commons.logging.Log; 26 import org.apache.commons.logging.LogFactory; 27 28 /** 29 * A reference to a memory-mapped region used by an HDFS client. 30 */ 31 @InterfaceAudience.Private 32 public class ClientMmap implements Closeable { 33 static final Log LOG = LogFactory.getLog(ClientMmap.class); 34 35 /** 36 * A reference to the block replica which this mmap relates to. 37 */ 38 private ShortCircuitReplica replica; 39 40 /** 41 * The java ByteBuffer object. 42 */ 43 private final MappedByteBuffer map; 44 45 /** 46 * Whether or not this ClientMmap anchors the replica into memory while 47 * it exists. Closing an anchored ClientMmap unanchors the replica. 48 */ 49 private final boolean anchored; 50 ClientMmap(ShortCircuitReplica replica, MappedByteBuffer map, boolean anchored)51 ClientMmap(ShortCircuitReplica replica, MappedByteBuffer map, 52 boolean anchored) { 53 this.replica = replica; 54 this.map = map; 55 this.anchored = anchored; 56 } 57 58 /** 59 * Close the ClientMmap object. 60 */ 61 @Override close()62 public void close() { 63 if (replica != null) { 64 if (anchored) { 65 replica.removeNoChecksumAnchor(); 66 } 67 replica.unref(); 68 } 69 replica = null; 70 } 71 getMappedByteBuffer()72 public MappedByteBuffer getMappedByteBuffer() { 73 return map; 74 } 75 }