org.scache.network.buffer.FileSegmentManagedBuffer.java Source code

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Here is the source code for org.scache.network.buffer.FileSegmentManagedBuffer.java

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/*
 * 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.scache.network.buffer;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;

import com.google.common.base.Objects;
import com.google.common.io.ByteStreams;
import io.netty.channel.DefaultFileRegion;

import org.scache.network.util.JavaUtils;
import org.scache.network.util.LimitedInputStream;
import org.scache.network.util.TransportConf;

/**
 * A {@link ManagedBuffer} backed by a segment in a file.
 */
public final class FileSegmentManagedBuffer extends ManagedBuffer {
    private final TransportConf conf;
    private final File file;
    private final long offset;
    private final long length;

    public FileSegmentManagedBuffer(TransportConf conf, File file, long offset, long length) {
        this.conf = conf;
        this.file = file;
        this.offset = offset;
        this.length = length;
    }

    @Override
    public long size() {
        return length;
    }

    @Override
    public ByteBuffer nioByteBuffer() throws IOException {
        FileChannel channel = null;
        try {
            channel = new RandomAccessFile(file, "r").getChannel();
            // Just copy the buffer if it's sufficiently small, as memory mapping has a high overhead.
            if (length < conf.memoryMapBytes()) {
                ByteBuffer buf = ByteBuffer.allocate((int) length);
                channel.position(offset);
                while (buf.remaining() != 0) {
                    if (channel.read(buf) == -1) {
                        throw new IOException(String.format(
                                "Reached EOF before filling buffer\n" + "offset=%s\nfile=%s\nbuf.remaining=%s",
                                offset, file.getAbsoluteFile(), buf.remaining()));
                    }
                }
                buf.flip();
                return buf;
            } else {
                return channel.map(FileChannel.MapMode.READ_ONLY, offset, length);
            }
        } catch (IOException e) {
            try {
                if (channel != null) {
                    long size = channel.size();
                    throw new IOException("Error in reading " + this + " (actual file length " + size + ")", e);
                }
            } catch (IOException ignored) {
                // ignore
            }
            throw new IOException("Error in opening " + this, e);
        } finally {
            JavaUtils.closeQuietly(channel);
        }
    }

    @Override
    public InputStream createInputStream() throws IOException {
        FileInputStream is = null;
        try {
            is = new FileInputStream(file);
            ByteStreams.skipFully(is, offset);
            return new LimitedInputStream(is, length);
        } catch (IOException e) {
            try {
                if (is != null) {
                    long size = file.length();
                    throw new IOException("Error in reading " + this + " (actual file length " + size + ")", e);
                }
            } catch (IOException ignored) {
                // ignore
            } finally {
                JavaUtils.closeQuietly(is);
            }
            throw new IOException("Error in opening " + this, e);
        } catch (RuntimeException e) {
            JavaUtils.closeQuietly(is);
            throw e;
        }
    }

    @Override
    public ManagedBuffer retain() {
        return this;
    }

    @Override
    public ManagedBuffer release() {
        return this;
    }

    @Override
    public Object convertToNetty() throws IOException {
        if (conf.lazyFileDescriptor()) {
            return new DefaultFileRegion(file, offset, length);
        } else {
            FileChannel fileChannel = new FileInputStream(file).getChannel();
            return new DefaultFileRegion(fileChannel, offset, length);
        }
    }

    public File getFile() {
        return file;
    }

    public long getOffset() {
        return offset;
    }

    public long getLength() {
        return length;
    }

    @Override
    public String toString() {
        return Objects.toStringHelper(this).add("file", file).add("offset", offset).add("length", length)
                .toString();
    }
}