1 /** 2 * Copyright The Apache Software Foundation 3 * 4 * Licensed to the Apache Software Foundation (ASF) under one or more 5 * contributor license agreements. See the NOTICE file distributed with this 6 * work for additional information regarding copyright ownership. The ASF 7 * licenses this file to you under the Apache License, Version 2.0 (the 8 * "License"); you may not use this file except in compliance with the License. 9 * 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, WITHOUT 15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 16 * License for the specific language governing permissions and limitations 17 * under the License. 18 */ 19 package org.apache.hadoop.hbase.io.hfile.bucket; 20 21 import java.io.IOException; 22 import java.nio.ByteBuffer; 23 24 import org.apache.hadoop.classification.InterfaceAudience; 25 import org.apache.hadoop.hbase.util.ByteBufferArray; 26 27 /** 28 * IO engine that stores data on the memory using an array of ByteBuffers 29 * {@link ByteBufferArray} 30 */ 31 @InterfaceAudience.Private 32 public class ByteBufferIOEngine implements IOEngine { 33 34 private ByteBufferArray bufferArray; 35 private final long capacity; 36 private final boolean direct; 37 38 /** 39 * Construct the ByteBufferIOEngine with the given capacity 40 * @param capacity 41 * @param direct true if allocate direct buffer 42 * @throws IOException 43 */ 44 public ByteBufferIOEngine(long capacity, boolean direct) 45 throws IOException { 46 this.capacity = capacity; 47 this.direct = direct; 48 bufferArray = new ByteBufferArray(capacity, direct); 49 } 50 51 @Override 52 public String toString() { 53 return "ioengine=" + this.getClass().getSimpleName() + ", capacity=" + 54 String.format("%,d", this.capacity) + ", direct=" + this.direct; 55 } 56 57 /** 58 * Memory IO engine is always unable to support persistent storage for the 59 * cache 60 * @return false 61 */ 62 @Override 63 public boolean isPersistent() { 64 return false; 65 } 66 67 /** 68 * Transfers data from the buffer array to the given byte buffer 69 * @param dstBuffer the given byte buffer into which bytes are to be written 70 * @param offset The offset in the ByteBufferArray of the first byte to be 71 * read 72 * @return number of bytes read 73 * @throws IOException 74 */ 75 @Override 76 public int read(ByteBuffer dstBuffer, long offset) throws IOException { 77 assert dstBuffer.hasArray(); 78 return bufferArray.getMultiple(offset, dstBuffer.remaining(), dstBuffer.array(), 79 dstBuffer.arrayOffset()); 80 } 81 82 /** 83 * Transfers data from the given byte buffer to the buffer array 84 * @param srcBuffer the given byte buffer from which bytes are to be read 85 * @param offset The offset in the ByteBufferArray of the first byte to be 86 * written 87 * @throws IOException 88 */ 89 @Override 90 public void write(ByteBuffer srcBuffer, long offset) throws IOException { 91 assert srcBuffer.hasArray(); 92 bufferArray.putMultiple(offset, srcBuffer.remaining(), srcBuffer.array(), 93 srcBuffer.arrayOffset()); 94 } 95 96 /** 97 * No operation for the sync in the memory IO engine 98 */ 99 @Override 100 public void sync() { 101 102 } 103 104 /** 105 * No operation for the shutdown in the memory IO engine 106 */ 107 @Override 108 public void shutdown() { 109 110 } 111 }