/**
* Copyright The Apache Software Foundation
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with this
* work for additional information regarding copyright ownership. The ASF
* licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*/
package org.apache.hadoop.hbase.io.hfile.bucket;
import java.io.IOException;
import java.nio.ByteBuffer;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.hbase.util.ByteBufferArray;
/**
* IO engine that stores data in memory using an array of ByteBuffers
* {@link ByteBufferArray}
*/
@InterfaceAudience.Private
public class ByteBufferIOEngine implements IOEngine {
private ByteBufferArray bufferArray;
private final long capacity;
private final boolean direct;
/**
* Construct the ByteBufferIOEngine with the given capacity
* @param capacity
* @param direct true if allocate direct buffer
* @throws IOException
*/
public ByteBufferIOEngine(long capacity, boolean direct)
throws IOException {
this.capacity = capacity;
this.direct = direct;
bufferArray = new ByteBufferArray(capacity, direct);
}
@Override
public String toString() {
return "ioengine=" + this.getClass().getSimpleName() + ", capacity=" +
String.format("%,d", this.capacity) + ", direct=" + this.direct;
}
/**
* Memory IO engine is always unable to support persistent storage for the
* cache
* @return false
*/
@Override
public boolean isPersistent() {
return false;
}
/**
* Transfers data from the buffer array to the given byte buffer
* @param dstBuffer the given byte buffer into which bytes are to be written
* @param offset The offset in the ByteBufferArray of the first byte to be
* read
* @return number of bytes read
* @throws IOException
*/
@Override
public int read(ByteBuffer dstBuffer, long offset) throws IOException {
assert dstBuffer.hasArray();
return bufferArray.getMultiple(offset, dstBuffer.remaining(), dstBuffer.array(),
dstBuffer.arrayOffset());
}
/**
* Transfers data from the given byte buffer to the buffer array
* @param srcBuffer the given byte buffer from which bytes are to be read
* @param offset The offset in the ByteBufferArray of the first byte to be
* written
* @throws IOException
*/
@Override
public void write(ByteBuffer srcBuffer, long offset) throws IOException {
assert srcBuffer.hasArray();
bufferArray.putMultiple(offset, srcBuffer.remaining(), srcBuffer.array(),
srcBuffer.arrayOffset());
}
/**
* No operation for the sync in the memory IO engine
*/
@Override
public void sync() {
// Nothing to do.
}
/**
* No operation for the shutdown in the memory IO engine
*/
@Override
public void shutdown() {
// Nothing to do.
}
}