oz.hadoop.yarn.api.utils.ByteBufferUtils.java Source code

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Here is the source code for oz.hadoop.yarn.api.utils.ByteBufferUtils.java

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/*
 * Copyright 2014 the original author or authors.
 *
 * 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 oz.hadoop.yarn.api.utils;

import java.nio.ByteBuffer;

import org.apache.commons.collections.BufferOverflowException;

/**
 * An internal utility class that allows merging of the two ByteBuffers into one while 
 * expending the final buffer as necessary. 
 * 
 * @author Oleg Zhurakousky
 *
 */
public class ByteBufferUtils {

    private static int threshold = 1073741824; // 1GB

    /**
     * 
     * @param source
     * @param target
     * @return
     */
    public static ByteBuffer merge(ByteBuffer source, ByteBuffer target) {
        if (target.position() != 0) {
            target.flip();
        }
        int rPos = source.position() + target.limit();
        if (rPos <= source.capacity()) {
            source.put(target);
            return source;
        } else {
            int newLength = calculateNewLength(source, target);
            if (newLength > 0) {
                ByteBuffer b = ByteBuffer.allocate(newLength);
                source.flip();
                b.put(source);
                b.put(target);
                return b;
            } else {
                throw new BufferOverflowException(
                        "Buffer can no longer be expended. Maximum allowed size is " + threshold + " bytes.");
            }
        }
    }

    /**
     * 
     */
    private static int calculateNewLength(ByteBuffer source, ByteBuffer target) {
        long newLength = source.capacity() + (target.limit() - source.remaining());
        if (newLength <= threshold) {
            return (int) newLength;
        }
        return -1;
    }
}