com.joyent.test.util.RandomInputStream.java Source code

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Here is the source code for com.joyent.test.util.RandomInputStream.java

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/*
 * Copyright (c) 2016-2017, Joyent, Inc. All rights reserved.
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */
package com.joyent.test.util;

import org.apache.commons.lang3.RandomUtils;

import java.io.IOException;
import java.io.InputStream;
import java.util.concurrent.atomic.AtomicLong;

/**
 * {@link InputStream} implementation that generates random data.
 *
 * @author <a href="https://github.com/dekobon">Elijah Zupancic</a>
 */
public class RandomInputStream extends InputStream {
    /**
     * End of file magic number.
     */
    private static final int EOF = -1;

    /**
     * Maximum number of bytes to generate.
     */
    private final long maximumBytes;

    /**
     * Current generated byte count.
     */
    private AtomicLong count = new AtomicLong(0L);

    /**
     * Creates a new instance.
     * @param maximumBytes maximum number of random bytes in stream
     */
    public RandomInputStream(final long maximumBytes) {
        this.maximumBytes = maximumBytes;
    }

    @Override
    public int read() throws IOException {
        if (count.getAndIncrement() >= maximumBytes) {
            return EOF;
        }

        return RandomUtils.nextInt(0, Integer.MAX_VALUE);
    }

    @Override
    public int read(final byte[] b, final int off, final int len) throws IOException {
        if (count.get() >= maximumBytes) {
            return EOF;
        }

        final int bytesToRead;

        if (maximumBytes - count.get() >= len) {
            bytesToRead = len;
        } else {
            bytesToRead = (int) (maximumBytes - count.get());
        }

        count.addAndGet(bytesToRead);

        final byte[] randomBytes = RandomUtils.nextBytes(bytesToRead);

        System.arraycopy(randomBytes, 0, b, off, bytesToRead);

        return bytesToRead;
    }
}