voldemort.common.nio.ByteBufferBackedInputStream.java Source code

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Here is the source code for voldemort.common.nio.ByteBufferBackedInputStream.java

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/*
 * Copyright 2009 Mustard Grain, Inc
 * 
 * Licensed 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 voldemort.common.nio;

import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;

import org.apache.commons.lang.mutable.MutableLong;

import voldemort.annotations.concurrency.NotThreadsafe;

/**
 * ByteBufferBackedInputStream allows a ByteBuffer to be the source of data for
 * InputStream-based callers.
 * <p/>
 * This class is used to interface with callers using "classic" java.io.* APIs.
 * For code that manages the ByteBufferBackedInputStream, there are accessor
 * methods for the underlying buffer should it need to expand and contract on
 * reuse.
 * 
 */

@NotThreadsafe
public class ByteBufferBackedInputStream extends InputStream {

    private ByteBuffer buffer;

    /**
     * Reference to a size tracking object, that tracks the size of the buffer
     * in bytes
     */
    private MutableLong sizeTracker;

    public ByteBufferBackedInputStream(ByteBuffer buffer) {
        this.buffer = buffer;
        this.sizeTracker = null;
    }

    public ByteBufferBackedInputStream(ByteBuffer buffer, MutableLong sizeTracker) {
        this.buffer = buffer;
        this.sizeTracker = sizeTracker;
        if (buffer != null)
            this.sizeTracker.add(buffer.capacity());
    }

    public ByteBuffer getBuffer() {
        return buffer;
    }

    public void setBuffer(ByteBuffer newBuffer) {
        // update the size tracker with the new buffer size
        if ((sizeTracker != null && this.buffer != null && newBuffer != null)) {
            sizeTracker.add(newBuffer.capacity());
            sizeTracker.subtract(this.buffer.capacity());
        }
        this.buffer = newBuffer;
    }

    @Override
    public int read() throws IOException {
        if (!buffer.hasRemaining())
            return -1;

        return buffer.get() & 0xff;
    }

    @Override
    public int read(byte[] bytes, int off, int len) throws IOException {
        if (!buffer.hasRemaining())
            return -1;

        len = Math.min(len, buffer.remaining());
        buffer.get(bytes, off, len);
        return len;
    }

    public void close() {
        if (sizeTracker != null && this.buffer != null) {
            sizeTracker.subtract(this.buffer.capacity());
        }
    }
}