com.chinamobile.bcbsp.util.Bytes.java Source code

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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 com.chinamobile.bcbsp.util;

import com.chinamobile.bcbsp.Constants;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.math.BigInteger;
import java.nio.ByteBuffer;
import java.util.Comparator;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.io.RawComparator;
import org.apache.hadoop.io.WritableComparator;
import org.apache.hadoop.io.WritableUtils;

/**
 * Bytes Utility class that handles byte arrays, conversions to/from other
 * types, comparisons, hash code generation, manufacturing keys for HashMaps or
 * HashSets, etc.
 */
public class Bytes {
    /** Size of boolean in bytes */
    public static final int SIZEOF_BOOLEAN = Byte.SIZE / Byte.SIZE;
    /** Size of byte in bytes */
    public static final int SIZEOF_BYTE = SIZEOF_BOOLEAN;
    /** Size of char in bytes */
    public static final int SIZEOF_CHAR = Character.SIZE / Byte.SIZE;
    /** Size of double in bytes */
    public static final int SIZEOF_DOUBLE = Double.SIZE / Byte.SIZE;
    /** Size of float in bytes */
    public static final int SIZEOF_FLOAT = Float.SIZE / Byte.SIZE;
    /** Size of int in bytes */
    public static final int SIZEOF_INT = Integer.SIZE / Byte.SIZE;
    /** Size of long in bytes */
    public static final int SIZEOF_LONG = Long.SIZE / Byte.SIZE;
    /** Size of short in bytes */
    public static final int SIZEOF_SHORT = Short.SIZE / Byte.SIZE;
    /**
     * Estimate of size cost to pay beyond payload in jvm for instance of byte [].
     * Estimate based on study of jhat and jprofiler numbers.
     */
    public static final int ESTIMATED_HEAP_TAX = 16;
    /** Define LOG for outputting log information */
    private static final Log LOG = LogFactory.getLog(Bytes.class);
    /** Pass this to TreeMaps where byte [] are keys. */
    private static Comparator<byte[]> BYTES_COMPARATOR = new ByteArrayComparator();
    /** Use comparing byte arrays, byte-by-byte */
    private static RawComparator<byte[]> BYTES_RAWCOMPARATOR = new ByteArrayComparator();

    /**
     * Byte array comparator class.
     */
    public static class ByteArrayComparator implements RawComparator<byte[]> {
        /**
         * Constructor
         */
        public ByteArrayComparator() {
            super();
        }

        /**
         * Compare two arrays.
         *
         * @param left Left operand
         * @param right Right operand
         * @return 0 if equal, < 0 if left is less than right, etc.
         */
        @Override
        public int compare(byte[] left, byte[] right) {
            return compareTo(left, right);
        }

        /**
         * Lexographically compare two arrays.
         *
         * @param b1
         *        left operand
         * @param b2
         *        right operand
         * @param s1
         *        Where to start comparing in the left buffer
         * @param s2
         *        Where to start comparing in the right buffer
         * @param l1
         *        How much to compare from the left buffer
         * @param l2
         *        How much to compare from the right buffer
         * @return 0 if equal, < 0 if left is less than right, etc.
         */
        @Override
        public int compare(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2) {
            return compareTo(b1, s1, l1, b2, s2, l2);
        }
    }

    /**
     * Read byte-array written with a WritableableUtils.vint prefix.
     *
     * @param in
     *        Input to read from.
     * @return byte array read off <code>in</code>
     * @throws IOException e
     */
    public static byte[] readByteArray(final DataInput in) throws IOException {
        int len = WritableUtils.readVInt(in);
        if (len < 0) {
            throw new NegativeArraySizeException(Integer.toString(len));
        }
        byte[] result = new byte[len];
        in.readFully(result, 0, len);
        return result;
    }

    /**
     * Read byte-array written with a WritableableUtils.vint prefix. IOException
     * is converted to a RuntimeException.
     *
     * @param in
     *        Input to read from.
     * @return byte array read off <code>in</code>
     * @throw Exception e
     */
    public static byte[] readByteArrayThrowsRuntime(final DataInput in) {
        try {
            return readByteArray(in);
        } catch (Exception e) {
            LOG.error("[readByteArrayThrowsRuntime]", e);
            throw new RuntimeException(e);
        }
    }

    /**
     * Write byte-array with a WritableableUtils.vint prefix.
     *
     * @param out
     *        output stream to be written to
     * @param b
     *        array to write
     * @throws IOException
     *         e
     */
    public static void writeByteArray(final DataOutput out, final byte[] b) throws IOException {
        if (b == null) {
            WritableUtils.writeVInt(out, 0);
        } else {
            writeByteArray(out, b, 0, b.length);
        }
    }

    /**
     * Write byte-array to out with a vint length prefix.
     *
     * @param out
     *        output stream
     * @param b
     *        array
     * @param offset
     *        offset into array
     * @param length
     *        length past offset
     * @throws IOException
     *         e
     */
    public static void writeByteArray(final DataOutput out, final byte[] b, final int offset, final int length)
            throws IOException {
        WritableUtils.writeVInt(out, length);
        out.write(b, offset, length);
    }

    /**
     * Write byte-array from src to tgt with a vint length prefix.
     *
     * @param tgt
     *        target array
     * @param tgtOffset
     *        offset into target array
     * @param src
     *        source array
     * @param srcOffset
     *        source offset
     * @param srcLength
     *        source length
     * @return New offset in src array.
     */
    public static int writeByteArray(final byte[] tgt, final int tgtOffset, final byte[] src, final int srcOffset,
            final int srcLength) {
        byte[] vint = vintToBytes(srcLength);
        System.arraycopy(vint, 0, tgt, tgtOffset, vint.length);
        int offset = tgtOffset + vint.length;
        System.arraycopy(src, srcOffset, tgt, offset, srcLength);
        return offset + srcLength;
    }

    /**
     * Put bytes at the specified byte array position.
     *
     * @param tgtBytes
     *        the byte array
     * @param tgtOffset
     *        position in the array
     * @param srcBytes
     *        array to write out
     * @param srcOffset
     *        source offset
     * @param srcLength
     *        source length
     * @return incremented offset
     */
    public static int putBytes(byte[] tgtBytes, int tgtOffset, byte[] srcBytes, int srcOffset, int srcLength) {
        System.arraycopy(srcBytes, srcOffset, tgtBytes, tgtOffset, srcLength);
        return tgtOffset + srcLength;
    }

    /**
     * Write a single byte out to the specified byte array position.
     *
     * @param bytes
     *        the byte array
     * @param offset
     *        position in the array
     * @param b
     *        byte to write out
     * @return incremented offset
     */
    public static int putByte(byte[] bytes, int offset, byte b) {
        bytes[offset] = b;
        return offset + 1;
    }

    /**
     * Returns a new byte array, copied from the passed ByteBuffer.
     *
     * @param bb
     *        A ByteBuffer
     * @return the byte array
     */
    public static byte[] toBytes(ByteBuffer bb) {
        int length = bb.limit();
        byte[] result = new byte[length];
        System.arraycopy(bb.array(), bb.arrayOffset(), result, 0, length);
        return result;
    }

    /**
     * @param b
     *        Presumed UTF-8 encoded byte array.
     * @return String made from <code>b</code>
     */
    public static String toString(final byte[] b) {
        if (b == null) {
            return null;
        }
        return toString(b, 0, b.length);
    }

    /**
     * Joins two byte arrays together using a separator.
     *
     * @param b1
     *        The first byte array.
     * @param sep
     *        The separator to use.
     * @param b2
     *        The second byte array.
     * @return String made from <code>b1, sep and b2</code> or null
     */
    public static String toString(final byte[] b1, String sep, final byte[] b2) {
        return toString(b1, 0, b1.length) + sep + toString(b2, 0, b2.length);
    }

    /**
     * This method will convert utf8 encoded bytes into a string. If an
     * UnsupportedEncodingException occurs, this method will eat it and return
     * null instead.
     *
     * @param b
     *        Presumed UTF-8 encoded byte array.
     * @param off
     *        offset into array
     * @param len
     *        length of utf-8 sequence
     * @return String made from <code>b</code> or null
     */
    public static String toString(final byte[] b, int off, int len) {
        if (b == null) {
            return null;
        }
        if (len == 0) {
            return "";
        }
        try {
            return new String(b, off, len, Constants.UTF8_ENCODING);
        } catch (UnsupportedEncodingException e) {
            LOG.error("UTF-8 not supported?", e);
            return null;
        }
    }

    /**
     * Write a printable representation of a byte array.
     *
     * @param b
     *        byte array
     * @return string
     * @see #toStringBinary(byte[], int, int)
     */
    public static String toStringBinary(final byte[] b) {
        return toStringBinary(b, 0, b.length);
    }

    /**
     * Write a printable representation of a byte array. Non-printable characters
     * are hex escaped in the format \\x%02X, eg: \x00 \x05 etc
     *
     * @param b
     *        array to write out
     * @param off
     *        offset to start at
     * @param len
     *        length to write
     * @return string output
     */
    public static String toStringBinary(final byte[] b, int off, int len) {
        StringBuilder result = new StringBuilder();
        try {
            String first = new String(b, off, len, "ISO-8859-1");
            for (int i = 0; i < first.length(); ++i) {
                int ch = first.charAt(i) & 0xFF;
                if ((ch >= '0' && ch <= '9') || (ch >= 'A' && ch <= 'Z') || (ch >= 'a' && ch <= 'z') || ch == ','
                        || ch == '_' || ch == '-' || ch == ':' || ch == ' ' || ch == '<' || ch == '>' || ch == '='
                        || ch == '/' || ch == '.') {
                    result.append(first.charAt(i));
                } else {
                    result.append(String.format("\\x%02X", ch));
                }
            }
        } catch (UnsupportedEncodingException e) {
            LOG.error("ISO-8859-1 not supported?", e);
        }
        return result.toString();
    }

    /**
     * To judge whether c hexadecimal number.
     *
     * @param c A char types of characters.
     * @return True if c is a hexadecimal number.
     */
    private static boolean isHexDigit(char c) {
        return (c >= 'A' && c <= 'F') || (c >= '0' && c <= '9');
    }

    /**
     * Takes a ASCII digit in the range A-F0-9 and returns the corresponding
     * integer/ordinal value.
     *
     * @param ch
     *        The hex digit.
     * @return The converted hex value as a byte.
     */
    public static byte toBinaryFromHex(byte ch) {
        if (ch >= 'A' && ch <= 'F') {
            return (byte) ((byte) 10 + (byte) (ch - 'A'));
        }
        return (byte) (ch - '0');
    }

    /**
     * Converts a string to a UTF-8 byte binary array.
     *
     * @param in String
     * @return The byte array
     */
    public static byte[] toBytesBinary(String in) {
        // this may be bigger than we need, but lets be safe.
        byte[] b = new byte[in.length()];
        int size = 0;
        for (int i = 0; i < in.length(); ++i) {
            char ch = in.charAt(i);
            if (ch == '\\') {
                // begin hex escape:
                char next = in.charAt(i + 1);
                if (next != 'x') {
                    // invalid escape sequence, ignore this one.
                    b[size++] = (byte) ch;
                    continue;
                }
                // ok, take next 2 hex digits.
                char hd1 = in.charAt(i + 2);
                char hd2 = in.charAt(i + 3);
                // they need to be A-F0-9:
                if (!isHexDigit(hd1) || !isHexDigit(hd2)) {
                    // bogus escape code, ignore:
                    continue;
                }
                // turn hex ASCII digit -> number
                byte d = (byte) ((toBinaryFromHex((byte) hd1) << 4) + toBinaryFromHex((byte) hd2));
                b[size++] = d;
                i += 3; // skip 3
            } else {
                b[size++] = (byte) ch;
            }
        }
        // resize:
        byte[] b2 = new byte[size];
        System.arraycopy(b, 0, b2, 0, size);
        return b2;
    }

    /**
     * Converts a string to a UTF-8 byte array.
     *
     * @param s
     *        string
     * @return the byte array
     */
    public static byte[] toBytes(String s) {
        try {
            return s.getBytes(Constants.UTF8_ENCODING);
        } catch (UnsupportedEncodingException e) {
            LOG.error("UTF-8 not supported?", e);
            return null;
        }
    }

    /**
     * Convert a boolean to a byte array. True becomes -1 and false becomes 0.
     *
     * @param b
     *        value
     * @return <code>b</code> encoded in a byte array.
     */
    public static byte[] toBytes(final boolean b) {
        return new byte[] { b ? (byte) -1 : (byte) 0 };
    }

    /**
     * Reverses {@link #toBytes(boolean)}
     *
     * @param b
     *        array
     * @return True or false.
     */
    public static boolean toBoolean(final byte[] b) {
        if (b.length != 1) {
            throw new IllegalArgumentException("Array has wrong size: " + b.length);
        }
        return b[0] != (byte) 0;
    }

    /**
     * Convert a long value to a byte array using big-endian.
     *
     * @param val
     *        value to convert
     * @return the byte array
     */
    public static byte[] toBytes(long val) {
        byte[] b = new byte[8];
        for (int i = 7; i > 0; i--) {
            b[i] = (byte) val;
            val >>>= 8;
        }
        b[0] = (byte) val;
        return b;
    }

    /**
     * Converts a byte array to a long value. Reverses {@link #toBytes(long)}
     *
     * @param bytes
     *        array
     * @return the long value
     */
    public static long toLong(byte[] bytes) {
        return toLong(bytes, 0, SIZEOF_LONG);
    }

    /**
     * Converts a byte array to a long value. Assumes there will be
     * {@link #SIZEOF_LONG} bytes available.
     *
     * @param bytes
     *        bytes
     * @param offset
     *        offset
     * @return the long value
     */
    public static long toLong(byte[] bytes, int offset) {
        return toLong(bytes, offset, SIZEOF_LONG);
    }

    /**
     * Converts a byte array to a long value.
     *
     * @param bytes
     *        array of bytes
     * @param offset
     *        offset into array
     * @param length
     *        length of data (must be {@link #SIZEOF_LONG})
     * @return the long value
     * @throws IllegalArgumentException
     *         if length is not {@link #SIZEOF_LONG} or if there's not enough room
     *         in the array at the offset indicated.
     */
    public static long toLong(byte[] bytes, int offset, final int length) {
        if (length != SIZEOF_LONG || offset + length > bytes.length) {
            throw explainWrongLengthOrOffset(bytes, offset, length, SIZEOF_LONG);
        }
        long l = 0;
        for (int i = offset; i < offset + length; i++) {
            l <<= 8;
            l ^= bytes[i] & 0xFF;
        }
        return l;
    }

    /**
     * Explain the exception information.
     *
    * @param bytes
     *        array of bytes
     * @param offset
     *        offset into array
     * @param length
     *        length of data (must be {@link #SIZEOF_LONG})
     * @param expectedLength {@link #SIZEOF_**}
     * @return Exception information.
     */
    private static IllegalArgumentException explainWrongLengthOrOffset(final byte[] bytes, final int offset,
            final int length, final int expectedLength) {
        String reason;
        if (length != expectedLength) {
            reason = "Wrong length: " + length + ", expected " + expectedLength;
        } else {
            reason = "offset (" + offset + ") + length (" + length + ") exceed the" + " capacity of the array: "
                    + bytes.length;
        }
        return new IllegalArgumentException(reason);
    }

    /**
     * Put a long value out to the specified byte array position.
     *
     * @param bytes
     *        the byte array
     * @param offset
     *        position in the array
     * @param val
     *        long to write out
     * @return incremented offset
     * @throws IllegalArgumentException
     *         if the byte array given doesn't have enough room at the offset
     *         specified.
     */
    public static int putLong(byte[] bytes, int offset, long val) {
        if (bytes.length - offset < SIZEOF_LONG) {
            throw new IllegalArgumentException("Not enough room to put a long at" + " offset " + offset + " in a "
                    + bytes.length + " byte array");
        }
        for (int i = offset + 7; i > offset; i--) {
            bytes[i] = (byte) val;
            val >>>= 8;
        }
        bytes[offset] = (byte) val;
        return offset + SIZEOF_LONG;
    }

    /**
     * Presumes float encoded as IEEE 754 floating-point "single format"
     *
     * @param bytes
     *        byte array
     * @return Float made from passed byte array.
     */
    public static float toFloat(byte[] bytes) {
        return toFloat(bytes, 0);
    }

    /**
     * Presumes float encoded as IEEE 754 floating-point "single format"
     *
     * @param bytes
     *        array to convert
     * @param offset
     *        offset into array
     * @return Float made from passed byte array.
     */
    public static float toFloat(byte[] bytes, int offset) {
        return Float.intBitsToFloat(toInt(bytes, offset, SIZEOF_INT));
    }

    /**
     * Put an float value out to the specified byte array position.
     *
     * @param bytes
     *        byte array
     * @param offset
     *        offset to write to
     * @param f
     *        float value
     * @return New offset in <code>bytes</code>
     */
    public static int putFloat(byte[] bytes, int offset, float f) {
        return putInt(bytes, offset, Float.floatToRawIntBits(f));
    }

    /**
     * Converts a byte array to a byte value.
     *
     * @param f
     *        float value
     * @return the float represented as byte []
     */
    public static byte[] toBytes(final float f) {
        // Encode it as int
        return Bytes.toBytes(Float.floatToRawIntBits(f));
    }

    /**
     * Converts a byte array to a double value.
     *
     * @param bytes
     *        byte array
     * @return Return double made from passed bytes.
     */
    public static double toDouble(final byte[] bytes) {
        return toDouble(bytes, 0);
    }

    /**
     * Converts a byte array to a double value.
     *
     * @param bytes
     *        byte array
     * @param offset
     *        offset where double is
     * @return Return double made from passed bytes.
     */
    public static double toDouble(final byte[] bytes, final int offset) {
        return Double.longBitsToDouble(toLong(bytes, offset, SIZEOF_LONG));
    }

    /**
     * Put an double value out to the specified byte array position.
     *
     * @param bytes
     *        byte array
     * @param offset
     *        offset to write to
     * @param d
     *        value
     * @return New offset into array <code>bytes</code>
     */
    public static int putDouble(byte[] bytes, int offset, double d) {
        return putLong(bytes, offset, Double.doubleToLongBits(d));
    }

    /**
     * Serialize a double as the IEEE 754 double format output. The resultant
     * array will be 8 bytes long.
     *
     * @param d
     *        value
     * @return the double represented as byte []
     */
    public static byte[] toBytes(final double d) {
        // Encode it as a long
        return Bytes.toBytes(Double.doubleToRawLongBits(d));
    }

    /**
     * Convert an int value to a byte array
     *
     * @param val
     *        value
     * @return the byte array
     */
    public static byte[] toBytes(int val) {
        byte[] b = new byte[4];
        for (int i = 3; i > 0; i--) {
            b[i] = (byte) val;
            val >>>= 8;
        }
        b[0] = (byte) val;
        return b;
    }

    /**
     * Converts a byte array to an int value
     *
     * @param bytes
     *        byte array
     * @return the int value
     */
    public static int toInt(byte[] bytes) {
        return toInt(bytes, 0, SIZEOF_INT);
    }

    /**
     * Converts a byte array to an int value
     *
     * @param bytes
     *        byte array
     * @param offset
     *        offset into array
     * @return the int value
     */
    public static int toInt(byte[] bytes, int offset) {
        return toInt(bytes, offset, SIZEOF_INT);
    }

    /**
     * Converts a byte array to an int value
     *
     * @param bytes
     *        byte array
     * @param offset
     *        offset into array
     * @param length
     *        length of int (has to be {@link #SIZEOF_INT})
     * @return the int value
     * @throws IllegalArgumentException
     *         if length is not {@link #SIZEOF_INT} or if there's not enough room
     *         in the array at the offset indicated.
     */
    public static int toInt(byte[] bytes, int offset, final int length) {
        if (length != SIZEOF_INT || offset + length > bytes.length) {
            throw explainWrongLengthOrOffset(bytes, offset, length, SIZEOF_INT);
        }
        int n = 0;
        for (int i = offset; i < (offset + length); i++) {
            n <<= 8;
            n ^= bytes[i] & 0xFF;
        }
        return n;
    }

    /**
     * Put an int value out to the specified byte array position.
     *
     * @param bytes
     *        the byte array
     * @param offset
     *        position in the array
     * @param val
     *        int to write out
     * @return incremented offset
     * @throws IllegalArgumentException
     *         if the byte array given doesn't have enough room at the offset
     *         specified.
     */
    public static int putInt(byte[] bytes, int offset, int val) {
        if (bytes.length - offset < SIZEOF_INT) {
            throw new IllegalArgumentException("Not enough room to put an int at" + " offset " + offset + " in a "
                    + bytes.length + " byte array");
        }
        for (int i = offset + 3; i > offset; i--) {
            bytes[i] = (byte) val;
            val >>>= 8;
        }
        bytes[offset] = (byte) val;
        return offset + SIZEOF_INT;
    }

    /**
     * Convert a short value to a byte array of {@link #SIZEOF_SHORT} bytes long.
     *
     * @param val
     *        value
     * @return the byte array
     */
    public static byte[] toBytes(short val) {
        byte[] b = new byte[SIZEOF_SHORT];
        b[1] = (byte) val;
        val >>= 8;
        b[0] = (byte) val;
        return b;
    }

    /**
     * Converts a byte array to a short value
     *
     * @param bytes
     *        byte array
     * @return the short value
     */
    public static short toShort(byte[] bytes) {
        return toShort(bytes, 0, SIZEOF_SHORT);
    }

    /**
     * Converts a byte array to a short value
     *
     * @param bytes
     *        byte array
     * @param offset
     *        offset into array
     * @return the short value
     */
    public static short toShort(byte[] bytes, int offset) {
        return toShort(bytes, offset, SIZEOF_SHORT);
    }

    /**
     * Converts a byte array to a short value
     *
     * @param bytes
     *        byte array
     * @param offset
     *        offset into array
     * @param length
     *        length, has to be {@link #SIZEOF_SHORT}
     * @return the short value
     * @throws IllegalArgumentException
     *         if length is not {@link #SIZEOF_SHORT} or if there's not enough
     *         room in the array at the offset indicated.
     */
    public static short toShort(byte[] bytes, int offset, final int length) {
        if (length != SIZEOF_SHORT || offset + length > bytes.length) {
            throw explainWrongLengthOrOffset(bytes, offset, length, SIZEOF_SHORT);
        }
        short n = 0;
        n ^= bytes[offset] & 0xFF;
        n <<= 8;
        n ^= bytes[offset + 1] & 0xFF;
        return n;
    }

    /**
     * Put a short value out to the specified byte array position.
     *
     * @param bytes
     *        the byte array
     * @param offset
     *        position in the array
     * @param val
     *        short to write out
     * @return incremented offset
     * @throws IllegalArgumentException
     *         if the byte array given doesn't have enough room at the offset
     *         specified.
     */
    public static int putShort(byte[] bytes, int offset, short val) {
        if (bytes.length - offset < SIZEOF_SHORT) {
            throw new IllegalArgumentException("Not enough room to put a short at" + " offset " + offset + " in a "
                    + bytes.length + " byte array");
        }
        bytes[offset + 1] = (byte) val;
        val >>= 8;
        bytes[offset] = (byte) val;
        return offset + SIZEOF_SHORT;
    }

    /**
     * Converts a long to a byte array.
     *
     * @param vint
     *        Integer to make a vint of.
     * @return Vint as bytes array.
     */
    public static byte[] vintToBytes(final long vint) {
        long i = vint;
        int size = WritableUtils.getVIntSize(i);
        byte[] result = new byte[size];
        int offset = 0;
        if (i >= -112 && i <= 127) {
            result[offset] = (byte) i;
            return result;
        }
        int len = -112;
        if (i < 0) {
            i ^= -1L; // take one's complement'
            len = -120;
        }
        long tmp = i;
        while (tmp != 0) {
            tmp = tmp >> 8;
            len--;
        }
        result[offset++] = (byte) len;
        len = (len < -120) ? -(len + 120) : -(len + 112);
        for (int idx = len; idx != 0; idx--) {
            int shiftbits = (idx - 1) * 8;
            long mask = 0xFFL << shiftbits;
            result[offset++] = (byte) ((i & mask) >> shiftbits);
        }
        return result;
    }

    /**
     * Converts a byte array to a long.
     *
     * @param buffer
     *        buffer to convert
     * @return vint bytes as an integer.
     */
    public static long bytesToVint(final byte[] buffer) {
        int offset = 0;
        byte firstByte = buffer[offset++];
        int len = WritableUtils.decodeVIntSize(firstByte);
        if (len == 1) {
            return firstByte;
        }
        long i = 0;
        for (int idx = 0; idx < len - 1; idx++) {
            byte b = buffer[offset++];
            i = i << 8;
            i = i | (b & 0xFF);
        }
        return WritableUtils.isNegativeVInt(firstByte) ? ~i : i;
    }

    /**
     * Reads a zero-compressed encoded long from input stream and returns it.
     *
     * @param buffer
     *        Binary array
     * @param offset
     *        Offset into array at which vint begins.
     * @throws java.io.IOException
     *         e
     * @return deserialized long from stream.
     */
    public static long readVLong(final byte[] buffer, final int offset) throws IOException {
        byte firstByte = buffer[offset];
        int len = WritableUtils.decodeVIntSize(firstByte);
        if (len == 1) {
            return firstByte;
        }
        long i = 0;
        for (int idx = 0; idx < len - 1; idx++) {
            byte b = buffer[offset + 1 + idx];
            i = i << 8;
            i = i | (b & 0xFF);
        }
        return WritableUtils.isNegativeVInt(firstByte) ? ~i : i;
    }

    /**
     * Lexographically compare two arrays.
     *
     * @param left Left operand
     * @param right Right operand
     * @return 0 if equal, < 0 if left is less than right, etc.
     */
    public static int compareTo(final byte[] left, final byte[] right) {
        return compareTo(left, 0, left.length, right, 0, right.length);
    }

    /**
     * Lexographically compare two arrays.
     *
     * @param b1
     *        left operand
     * @param b2
     *        right operand
     * @param s1
     *        Where to start comparing in the left buffer
     * @param s2
     *        Where to start comparing in the right buffer
     * @param l1
     *        How much to compare from the left buffer
     * @param l2
     *        How much to compare from the right buffer
     * @return 0 if equal, < 0 if left is less than right, etc.
     */
    public static int compareTo(byte[] b1, int s1, int l1, byte[] b2, int s2, int l2) {
        // Bring WritableComparator code local
        int end1 = s1 + l1;
        int end2 = s2 + l2;
        for (int i = s1, j = s2; i < end1 && j < end2; i++, j++) {
            int a = b1[i] & 0xff;
            int b = b2[j] & 0xff;
            if (a != b) {
                return a - b;
            }
        }
        return l1 - l2;
    }

    /**
     * To judge whether the two arrays are equal.
     *
     * @param left
     *        left operand
     * @param right
     *        right operand
     * @return True if equal
     */
    public static boolean equals(final byte[] left, final byte[] right) {
        // Could use Arrays.equals?
        // noinspection SimplifiableConditionalExpression
        if (left == null && right == null) {
            return true;
        }
        return left == null || right == null || (left.length != right.length) ? false : compareTo(left, right) == 0;
    }

    /**
     * Compute hash for binary data.
     *
     * @param b
     *        bytes to hash
     * @return Runs {@link WritableComparator#hashBytes(byte[], int)} on the
     *         passed in array. This method is what
     *         {@link org.apache.hadoop.io.Text} use calculating hash code.
     */
    public static int hashCode(final byte[] b) {
        return hashCode(b, b.length);
    }

    /**
     * Compute hash for binary data.
     *
     * @param b
     *        value
     * @param length
     *        length of the value
     * @return Runs {@link WritableComparator#hashBytes(byte[], int)} on the
     *         passed in array. This method is what
     *         {@link org.apache.hadoop.io.Text} use calculating hash code.
     */
    public static int hashCode(final byte[] b, final int length) {
        return WritableComparator.hashBytes(b, length);
    }

    /**
     * Compute hash for binary data.
     *
     * @param b
     *        bytes to hash
     * @return A hash of <code>b</code> as an Integer that can be used as key in
     *         Maps.
     */
    public static Integer mapKey(final byte[] b) {
        return hashCode(b);
    }

    /**
     * Compute hash for binary data.
     *
     * @param b
     *        bytes to hash
     * @param length
     *        length to hash
     * @return A hash of <code>b</code> as an Integer that can be used as key in
     *         Maps.
     */
    public static Integer mapKey(final byte[] b, final int length) {
        return hashCode(b, length);
    }

    /**
     * Add a and b to a new array.
     *
     * @param a
     *        lower half
     * @param b
     *        upper half
     * @return New array that has a in lower half and b in upper half.
     */
    public static byte[] add(final byte[] a, final byte[] b) {
        return add(a, b, Constants.EMPTY_BYTE_ARRAY);
    }

    /**
     * Add a, b and c to a new array.
     *
     * @param a
     *        first third
     * @param b
     *        second third
     * @param c
     *        third third
     * @return New array made from a, b and c
     */
    public static byte[] add(final byte[] a, final byte[] b, final byte[] c) {
        byte[] result = new byte[a.length + b.length + c.length];
        System.arraycopy(a, 0, result, 0, a.length);
        System.arraycopy(b, 0, result, a.length, b.length);
        System.arraycopy(c, 0, result, a.length + b.length, c.length);
        return result;
    }

    /**
     * @param a
     *        array
     * @param length
     *        amount of bytes to grab
     * @return First <code>length</code> bytes from <code>a</code>
     */
    public static byte[] head(final byte[] a, final int length) {
        if (a.length < length) {
            return null;
        }
        byte[] result = new byte[length];
        System.arraycopy(a, 0, result, 0, length);
        return result;
    }

    /**
     * @param a
     *        array
     * @param length
     *        amount of bytes to snarf
     * @return Last <code>length</code> bytes from <code>a</code>
     */
    public static byte[] tail(final byte[] a, final int length) {
        if (a.length < length) {
            return null;
        }
        byte[] result = new byte[length];
        System.arraycopy(a, a.length - length, result, 0, length);
        return result;
    }

    /**
     * @param a
     *        array
     * @param length
     *        new array size
     * @return Value in <code>a</code> plus <code>length</code> prepended 0 bytes
     */
    public static byte[] padHead(final byte[] a, final int length) {
        byte[] padding = new byte[length];
        for (int i = 0; i < length; i++) {
            padding[i] = 0;
        }
        return add(padding, a);
    }

    /**
     * @param a
     *        array
     * @param length
     *        new array size
     * @return Value in <code>a</code> plus <code>length</code> appended 0 bytes
     */
    public static byte[] padTail(final byte[] a, final int length) {
        byte[] padding = new byte[length];
        for (int i = 0; i < length; i++) {
            padding[i] = 0;
        }
        return add(a, padding);
    }

    /**
     * Split passed range. Expensive operation relatively. Uses BigInteger math.
     * Useful splitting ranges for MapReduce jobs.
     *
     * @param a
     *        Beginning of range
     * @param b
     *        End of range
     * @param num
     *        Number of times to split range. Pass 1 if you want to split the
     *        range in two; i.e. one split.
     * @return Array of dividing values
     */
    public static byte[][] split(final byte[] a, final byte[] b, final int num) {
        byte[] aPadded;
        byte[] bPadded;
        if (a.length < b.length) {
            aPadded = padTail(a, b.length - a.length);
            bPadded = b;
        } else if (b.length < a.length) {
            aPadded = a;
            bPadded = padTail(b, a.length - b.length);
        } else {
            aPadded = a;
            bPadded = b;
        }
        if (compareTo(aPadded, bPadded) >= 0) {
            throw new IllegalArgumentException("b <= a");
        }
        if (num <= 0) {
            throw new IllegalArgumentException("num cannot be < 0");
        }
        byte[] prependHeader = { 1, 0 };
        BigInteger startBI = new BigInteger(add(prependHeader, aPadded));
        BigInteger stopBI = new BigInteger(add(prependHeader, bPadded));
        BigInteger diffBI = stopBI.subtract(startBI);
        BigInteger splitsBI = BigInteger.valueOf(num + 1);
        if (diffBI.compareTo(splitsBI) < 0) {
            return null;
        }
        BigInteger intervalBI;
        try {
            intervalBI = diffBI.divide(splitsBI);
        } catch (Exception e) {
            LOG.error("Exception caught during division", e);
            return null;
        }
        byte[][] result = new byte[num + 2][];
        result[0] = a;
        for (int i = 1; i <= num; i++) {
            BigInteger curBI = startBI.add(intervalBI.multiply(BigInteger.valueOf(i)));
            byte[] padded = curBI.toByteArray();
            if (padded[1] == 0) {
                padded = tail(padded, padded.length - 2);
            } else {
                padded = tail(padded, padded.length - 1);
            }
            result[i] = padded;
        }
        result[num + 1] = b;
        return result;
    }

    /**
     * Converts a string array to a UTF-8 byte binary array.
     *
     * @param t
     *        operands
     * @return Array of byte arrays made from passed array of Text
     */
    public static byte[][] toByteArrays(final String[] t) {
        byte[][] result = new byte[t.length][];
        for (int i = 0; i < t.length; i++) {
            result[i] = Bytes.toBytes(t[i]);
        }
        return result;
    }

    /**
     * Converts a string to a UTF-8 byte binary array.
     *
     * @param column
     *        operand
     * @return A byte array of a byte array where first and only entry is
     *         <code>column</code>
     */
    public static byte[][] toByteArrays(final String column) {
        return toByteArrays(toBytes(column));
    }

    /**
     * @param column
     *        operand
     * @return A byte array of a byte array where first and only entry is
     *         <code>column</code>
     */
    public static byte[][] toByteArrays(final byte[] column) {
        byte[][] result = new byte[1][];
        result[0] = column;
        return result;
    }

    /**
     * Binary search for keys in indexes.
     *
     * @param arr
     *        array of byte arrays to search for
     * @param key
     *        the key you want to find
     * @param offset
     *        the offset in the key you want to find
     * @param length
     *        the length of the key
     * @param comparator
     *        a comparator to compare.
     * @return index of key
     */
    public static int binarySearch(byte[][] arr, byte[] key, int offset, int length,
            RawComparator<byte[]> comparator) {
        int low = 0;
        int high = arr.length - 1;
        while (low <= high) {
            int mid = (low + high) >>> 1;
            // we have to compare in this order, because the comparator order
            // has special logic when the 'left side' is a special key.
            int cmp = comparator.compare(key, offset, length, arr[mid], 0, arr[mid].length);
            // key lives above the midpoint
            if (cmp > 0) {
                low = mid + 1;
            } else if (cmp < 0) {
                // key lives below the midpoint
                high = mid - 1;
            } else {
                // BAM. how often does this really happen?
                return mid;
            }
        }
        return -(low + 1);
    }

    /**
     * Bytewise binary increment/deincrement of long contained in byte array on
     * given amount.
     *
     * @param value
     *        - array of bytes containing long (length <= SIZEOF_LONG)
     * @param amount
     *        value will be incremented on (deincremented if negative)
     * @return array of bytes containing incremented long (length == SIZEOF_LONG)
     * @throws IOException
     *         - if value.length > SIZEOF_LONG
     */
    public static byte[] incrementBytes(byte[] value, long amount) throws IOException {
        byte[] val = value;
        if (val.length < SIZEOF_LONG) {
            // Hopefully this doesn't happen too often.
            byte[] newvalue;
            if (val[0] < 0) {
                newvalue = new byte[] { -1, -1, -1, -1, -1, -1, -1, -1 };
            } else {
                newvalue = new byte[SIZEOF_LONG];
            }
            System.arraycopy(val, 0, newvalue, newvalue.length - val.length, val.length);
            val = newvalue;
        } else if (val.length > SIZEOF_LONG) {
            throw new IllegalArgumentException("Increment Bytes - value too big: " + val.length);
        }
        if (amount == 0) {
            return val;
        }
        if (val[0] < 0) {
            return binaryIncrementNeg(val, amount);
        }
        return binaryIncrementPos(val, amount);
    }

    /**Array of bytes containing incremented long (length == SIZEOF_LONG)
     * increment/deincrement for positive value
     *
     * @param value
     *        - array of bytes containing long (length <= SIZEOF_LONG)
     * @param amount
     *        value will be incremented on (deincremented if negative)
     * @return array of bytes containing incremented long.
     */
    private static byte[] binaryIncrementPos(byte[] value, long amount) {
        long amo = amount;
        int sign = 1;
        if (amount < 0) {
            amo = -amount;
            sign = -1;
        }
        for (int i = 0; i < value.length; i++) {
            int cur = ((int) amo % 256) * sign;
            amo = amo >> 8;
            int val = value[value.length - i - 1] & 0x0ff;
            int total = val + cur;
            if (total > 255) {
                amo += sign;
                total %= 256;
            } else if (total < 0) {
                amo -= sign;
            }
            value[value.length - i - 1] = (byte) total;
            if (amo == 0) {
                return value;
            }
        }
        return value;
    }

    /** array of bytes containing incremented long (length == SIZEOF_LONG)
     * increment/deincrement for negative value
     *
     * @param value
     *        - array of bytes containing long (length <= SIZEOF_LONG)
     * @param amount
     *        value will be incremented on (deincremented if negative)
     * @return array of bytes containing incremented long.
     */
    private static byte[] binaryIncrementNeg(byte[] value, long amount) {
        long amo = amount;
        int sign = 1;
        if (amount < 0) {
            amo = -amount;
            sign = -1;
        }
        for (int i = 0; i < value.length; i++) {
            int cur = ((int) amo % 256) * sign;
            amo = amo >> 8;
            int val = ((~value[value.length - i - 1]) & 0x0ff) + 1;
            int total = cur - val;
            if (total >= 0) {
                amo += sign;
            } else if (total < -256) {
                amo -= sign;
                total %= 256;
            }
            value[value.length - i - 1] = (byte) total;
            if (amo == 0) {
                return value;
            }
        }
        return value;
    }
}