webhcat/svr/src/main/java/org/apache/hcatalog/templeton/MaxByteArrayOutputStream.java

/**
 * 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.hcatalog.templeton;

import java.io.ByteArrayOutputStream;

/**
 * An output stream that will only accept the first N bytes of data.
 */
public class MaxByteArrayOutputStream extends ByteArrayOutputStream {
    /**
     * The max number of bytes stored.
     */
    private int maxBytes;

    /**
     * The number of bytes currently stored.
     */
    private int nBytes;

    /**
     * Create.
     */
    public MaxByteArrayOutputStream(int maxBytes) {
        this.maxBytes = maxBytes;
        nBytes = 0;
    }

    /**
     * Writes the specified byte to this byte array output stream.
     * Any bytes after the first maxBytes will be ignored.
     *
     * @param   b   the byte to be written.
     */
    public synchronized void write(int b) {
        if (nBytes < maxBytes) {
            ++nBytes;
            super.write(b);
        }
    }

    /**
     * Writes <code>len</code> bytes from the specified byte array
     * starting at offset <code>off</code> to this byte array output stream.
     * Any bytes after the first maxBytes will be ignored.
     *
     * @param   b     the data.
     * @param   off   the start offset in the data.
     * @param   len   the number of bytes to write.
     */
    public synchronized void write(byte b[], int off, int len) {
        int storable = Math.min(maxBytes - nBytes, len);
        if (storable > 0) {
            nBytes += storable;
            super.write(b, off, storable);
        }
    }


}