org.apache.hadoop.hbase.io.hfile.bucket.FileMmapEngine.java Source code

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Here is the source code for org.apache.hadoop.hbase.io.hfile.bucket.FileMmapEngine.java

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/**
 * 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.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.hbase.io.hfile.Cacheable;
import org.apache.hadoop.hbase.io.hfile.Cacheable.MemoryType;
import org.apache.hadoop.hbase.io.hfile.CacheableDeserializer;
import org.apache.hadoop.hbase.nio.ByteBuff;
import org.apache.hadoop.hbase.nio.SingleByteBuff;
import org.apache.hadoop.hbase.util.ByteBufferAllocator;
import org.apache.hadoop.hbase.util.ByteBufferArray;
import org.apache.hadoop.util.StringUtils;

/**
 * IO engine that stores data to a file on the local file system using memory mapping
 * mechanism
 */
@InterfaceAudience.Private
public class FileMmapEngine implements IOEngine {
    static final Log LOG = LogFactory.getLog(FileMmapEngine.class);

    private final String path;
    private long size;
    private ByteBufferArray bufferArray;
    private final FileChannel fileChannel;
    private RandomAccessFile raf = null;

    public FileMmapEngine(String filePath, long capacity) throws IOException {
        this.path = filePath;
        this.size = capacity;
        long fileSize = 0;
        try {
            raf = new RandomAccessFile(filePath, "rw");
            fileSize = roundUp(capacity, ByteBufferArray.DEFAULT_BUFFER_SIZE);
            raf.setLength(fileSize);
            fileChannel = raf.getChannel();
            LOG.info("Allocating " + StringUtils.byteDesc(fileSize) + ", on the path:" + filePath);
        } catch (java.io.FileNotFoundException fex) {
            LOG.error("Can't create bucket cache file " + filePath, fex);
            throw fex;
        } catch (IOException ioex) {
            LOG.error("Can't extend bucket cache file; insufficient space for " + StringUtils.byteDesc(fileSize),
                    ioex);
            shutdown();
            throw ioex;
        }
        ByteBufferAllocator allocator = new ByteBufferAllocator() {
            int pos = 0;

            @Override
            public ByteBuffer allocate(long size, boolean directByteBuffer) throws IOException {
                ByteBuffer buffer = null;
                if (directByteBuffer) {
                    buffer = fileChannel.map(java.nio.channels.FileChannel.MapMode.READ_WRITE, pos * size, size);
                } else {
                    throw new IllegalArgumentException("Only Direct Bytebuffers allowed with FileMMap engine");
                }
                pos++;
                return buffer;
            }
        };
        bufferArray = new ByteBufferArray(fileSize, true, allocator);
    }

    private long roundUp(long n, long to) {
        return ((n + to - 1) / to) * to;
    }

    @Override
    public String toString() {
        return "ioengine=" + this.getClass().getSimpleName() + ", path=" + this.path + ", size="
                + String.format("%,d", this.size);
    }

    /**
     * File IO engine is always able to support persistent storage for the cache
     * @return true
     */
    @Override
    public boolean isPersistent() {
        return true;
    }

    @Override
    public Cacheable read(long offset, int length, CacheableDeserializer<Cacheable> deserializer)
            throws IOException {
        byte[] dst = new byte[length];
        bufferArray.getMultiple(offset, length, dst);
        return deserializer.deserialize(new SingleByteBuff(ByteBuffer.wrap(dst)), true, MemoryType.EXCLUSIVE);
    }

    /**
     * Transfers data from the given byte buffer to file
     * @param srcBuffer the given byte buffer from which bytes are to be read
     * @param offset The offset in the file where 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());
    }

    @Override
    public void write(ByteBuff srcBuffer, long offset) throws IOException {
        // This singleByteBuff can be considered to be array backed
        assert srcBuffer.hasArray();
        bufferArray.putMultiple(offset, srcBuffer.remaining(), srcBuffer.array(), srcBuffer.arrayOffset());

    }

    /**
     * Sync the data to file after writing
     * @throws IOException
     */
    @Override
    public void sync() throws IOException {
        if (fileChannel != null) {
            fileChannel.force(true);
        }
    }

    /**
     * Close the file
     */
    @Override
    public void shutdown() {
        try {
            fileChannel.close();
        } catch (IOException ex) {
            LOG.error("Can't shutdown cleanly", ex);
        }
        try {
            raf.close();
        } catch (IOException ex) {
            LOG.error("Can't shutdown cleanly", ex);
        }
    }
}