/**
* 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.hadoop.hbase.util;
import static org.apache.hadoop.hbase.util.Order.ASCENDING;
import static org.apache.hadoop.hbase.util.Order.DESCENDING;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.math.MathContext;
import java.math.RoundingMode;
import java.nio.charset.Charset;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
import com.google.common.annotations.VisibleForTesting;
/**
* Utility class that handles ordered byte arrays. That is, unlike
* {@link Bytes}, these methods produce byte arrays which maintain the sort
* order of the original values.
* <h3>Encoding Format summary</h3>
* <p>
* Each value is encoded as one or more bytes. The first byte of the encoding,
* its meaning, and a terse description of the bytes that follow is given by
* the following table:
* </p>
* <table summary="Encodings">
* <tr><th>Content Type</th><th>Encoding</th></tr>
* <tr><td>NULL</td><td>0x05</td></tr>
* <tr><td>negative infinity</td><td>0x07</td></tr>
* <tr><td>negative large</td><td>0x08, ~E, ~M</td></tr>
* <tr><td>negative medium</td><td>0x13-E, ~M</td></tr>
* <tr><td>negative small</td><td>0x14, -E, ~M</td></tr>
* <tr><td>zero</td><td>0x15</td></tr>
* <tr><td>positive small</td><td>0x16, ~-E, M</td></tr>
* <tr><td>positive medium</td><td>0x17+E, M</td></tr>
* <tr><td>positive large</td><td>0x22, E, M</td></tr>
* <tr><td>positive infinity</td><td>0x23</td></tr>
* <tr><td>NaN</td><td>0x25</td></tr>
* <tr><td>fixed-length 32-bit integer</td><td>0x27, I</td></tr>
* <tr><td>fixed-length 64-bit integer</td><td>0x28, I</td></tr>
* <tr><td>fixed-length 8-bit integer</td><td>0x29</td></tr>
* <tr><td>fixed-length 16-bit integer</td><td>0x2a</td></tr>
* <tr><td>fixed-length 32-bit float</td><td>0x30, F</td></tr>
* <tr><td>fixed-length 64-bit float</td><td>0x31, F</td></tr>
* <tr><td>TEXT</td><td>0x33, T</td></tr>
* <tr><td>variable length BLOB</td><td>0x35, B</td></tr>
* <tr><td>byte-for-byte BLOB</td><td>0x36, X</td></tr>
* </table>
*
* <h3>Null Encoding</h3>
* <p>
* Each value that is a NULL encodes as a single byte of 0x05. Since every
* other value encoding begins with a byte greater than 0x05, this forces NULL
* values to sort first.
* </p>
* <h3>Text Encoding</h3>
* <p>
* Each text value begins with a single byte of 0x33 and ends with a single
* byte of 0x00. There are zero or more intervening bytes that encode the text
* value. The intervening bytes are chosen so that the encoding will sort in
* the desired collating order. The intervening bytes may not contain a 0x00
* character; the only 0x00 byte allowed in a text encoding is the final byte.
* </p>
* <p>
* The text encoding ends in 0x00 in order to ensure that when there are two
* strings where one is a prefix of the other that the shorter string will
* sort first.
* </p>
* <h3>Binary Encoding</h3>
* <p>
* There are two encoding strategies for binary fields, referred to as
* "BlobVar" and "BlobCopy". BlobVar is less efficient in both space and
* encoding time. It has no limitations on the range of encoded values.
* BlobCopy is a byte-for-byte copy of the input data followed by a
* termination byte. It is extremely fast to encode and decode. It carries the
* restriction of not allowing a 0x00 value in the input byte[] as this value
* is used as the termination byte.
* </p>
* <h4>BlobVar</h4>
* <p>
* "BlobVar" encodes the input byte[] in a manner similar to a variable length
* integer encoding. As with the other {@code OrderedBytes} encodings,
* the first encoded byte is used to indicate what kind of value follows. This
* header byte is 0x37 for BlobVar encoded values. As with the traditional
* varint encoding, the most significant bit of each subsequent encoded
* {@code byte} is used as a continuation marker. The 7 remaining bits
* contain the 7 most significant bits of the first unencoded byte. The next
* encoded byte starts with a continuation marker in the MSB. The least
* significant bit from the first unencoded byte follows, and the remaining 6
* bits contain the 6 MSBs of the second unencoded byte. The encoding
* continues, encoding 7 bytes on to 8 encoded bytes. The MSB of the final
* encoded byte contains a termination marker rather than a continuation
* marker, and any remaining bits from the final input byte. Any trailing bits
* in the final encoded byte are zeros.
* </p>
* <h4>BlobCopy</h4>
* <p>
* "BlobCopy" is a simple byte-for-byte copy of the input data. It uses 0x38
* as the header byte, and is terminated by 0x00 in the DESCENDING case. This
* alternative encoding is faster and more space-efficient, but it cannot
* accept values containing a 0x00 byte in DESCENDING order.
* </p>
* <h3>Variable-length Numeric Encoding</h3>
* <p>
* Numeric values must be coded so as to sort in numeric order. We assume that
* numeric values can be both integer and floating point values. Clients must
* be careful to use inspection methods for encoded values (such as
* {@link #isNumericInfinite(PositionedByteRange)} and
* {@link #isNumericNaN(PositionedByteRange)} to protect against decoding
* values into object which do not support these numeric concepts (such as
* {@link Long} and {@link BigDecimal}).
* </p>
* <p>
* Simplest cases first: If the numeric value is a NaN, then the encoding is a
* single byte of 0x25. This causes NaN values to sort after every other
* numeric value.
* </p>
* <p>
* If the numeric value is a negative infinity then the encoding is a single
* byte of 0x07. Since every other numeric value except NaN has a larger
* initial byte, this encoding ensures that negative infinity will sort prior
* to every other numeric value other than NaN.
* </p>
* <p>
* If the numeric value is a positive infinity then the encoding is a single
* byte of 0x23. Every other numeric value encoding begins with a smaller
* byte, ensuring that positive infinity always sorts last among numeric
* values. 0x23 is also smaller than 0x33, the initial byte of a text value,
* ensuring that every numeric value sorts before every text value.
* </p>
* <p>
* If the numeric value is exactly zero then it is encoded as a single byte of
* 0x15. Finite negative values will have initial bytes of 0x08 through 0x14
* and finite positive values will have initial bytes of 0x16 through 0x22.
* </p>
* <p>
* For all numeric values, we compute a mantissa M and an exponent E. The
* mantissa is a base-100 representation of the value. The exponent E
* determines where to put the decimal point.
* </p>
* <p>
* Each centimal digit of the mantissa is stored in a byte. If the value of
* the centimal digit is X (hence X≥0 and X≤99) then the byte value will
* be 2*X+1 for every byte of the mantissa, except for the last byte which
* will be 2*X+0. The mantissa must be the minimum number of bytes necessary
* to represent the value; trailing X==0 digits are omitted. This means that
* the mantissa will never contain a byte with the value 0x00.
* </p>
* <p>
* If we assume all digits of the mantissa occur to the right of the decimal
* point, then the exponent E is the power of one hundred by which one must
* multiply the mantissa to recover the original value.
* </p>
* <p>
* Values are classified as large, medium, or small according to the value of
* E. If E is 11 or more, the value is large. For E between 0 and 10, the
* value is medium. For E less than zero, the value is small.
* </p>
* <p>
* Large positive values are encoded as a single byte 0x22 followed by E as a
* varint and then M. Medium positive values are a single byte of 0x17+E
* followed by M. Small positive values are encoded as a single byte 0x16
* followed by the ones-complement of the varint for -E followed by M.
* </p>
* <p>
* Small negative values are encoded as a single byte 0x14 followed by -E as a
* varint and then the ones-complement of M. Medium negative values are
* encoded as a byte 0x13-E followed by the ones-complement of M. Large
* negative values consist of the single byte 0x08 followed by the
* ones-complement of the varint encoding of E followed by the ones-complement
* of M.
* </p>
* <h3>Fixed-length Integer Encoding</h3>
* <p>
* All 4-byte integers are serialized to a 5-byte, fixed-width, sortable byte
* format. All 8-byte integers are serialized to the equivelant 9-byte format.
* Serialization is performed by writing a header byte, inverting the integer
* sign bit and writing the resulting bytes to the byte array in big endian
* order.
* </p>
* <h3>Fixed-length Floating Point Encoding</h3>
* <p>
* 32-bit and 64-bit floating point numbers are encoded to a 5-byte and 9-byte
* encoding format, respectively. The format is identical, save for the
* precision respected in each step of the operation.
* <p>
* This format ensures the following total ordering of floating point values:
* Float.NEGATIVE_INFINITY < -Float.MAX_VALUE < ... <
* -Float.MIN_VALUE < -0.0 < +0.0; < Float.MIN_VALUE < ... <
* Float.MAX_VALUE < Float.POSITIVE_INFINITY < Float.NaN
* </p>
* <p>
* Floating point numbers are encoded as specified in IEEE 754. A 32-bit
* single precision float consists of a sign bit, 8-bit unsigned exponent
* encoded in offset-127 notation, and a 23-bit significand. The format is
* described further in the <a
* href="http://en.wikipedia.org/wiki/Single_precision"> Single Precision
* Floating Point Wikipedia page</a>
* </p>
* <p>
* The value of a normal float is -1 <sup>sign bit</sup> ×
* 2<sup>exponent - 127</sup> × 1.significand
* </p>
* <p>
* The IEE754 floating point format already preserves sort ordering for
* positive floating point numbers when the raw bytes are compared in most
* significant byte order. This is discussed further at <a href=
* "http://www.cygnus-software.com/papers/comparingfloats/comparingfloats.htm">
* http://www.cygnus-software.com/papers/comparingfloats/comparingfloats.htm</a>
* </p>
* <p>
* Thus, we need only ensure that negative numbers sort in the the exact
* opposite order as positive numbers (so that say, negative infinity is less
* than negative 1), and that all negative numbers compare less than any
* positive number. To accomplish this, we invert the sign bit of all floating
* point numbers, and we also invert the exponent and significand bits if the
* floating point number was negative.
* </p>
* <p>
* More specifically, we first store the floating point bits into a 32-bit int
* {@code j} using {@link Float#floatToIntBits}. This method collapses
* all NaNs into a single, canonical NaN value but otherwise leaves the bits
* unchanged. We then compute
* </p>
*
* <pre>
* j ˆ= (j >> (Integer.SIZE - 1)) | Integer.MIN_SIZE
* </pre>
* <p>
* which inverts the sign bit and XOR's all other bits with the sign bit
* itself. Comparing the raw bytes of {@code j} in most significant byte
* order is equivalent to performing a single precision floating point
* comparison on the underlying bits (ignoring NaN comparisons, as NaNs don't
* compare equal to anything when performing floating point comparisons).
* </p>
* <p>
* The resulting integer is then converted into a byte array by serializing
* the integer one byte at a time in most significant byte order. The
* serialized integer is prefixed by a single header byte. All serialized
* values are 5 bytes in length.
* </p>
* <p>
* {@code OrderedBytes} encodings are heavily influenced by the
* <a href="http://sqlite.org/src4/doc/trunk/www/key_encoding.wiki">SQLite4 Key
* Encoding</a>. Slight deviations are make in the interest of order
* correctness and user extensibility. Fixed-width {@code Long} and
* {@link Double} encodings are based on implementations from the now defunct
* Orderly library.
* </p>
*/
@InterfaceAudience.Public
public class OrderedBytes {
/*
* These constants define header bytes used to identify encoded values. Note
* that the values here are not exhaustive as the Numeric format encodes
* portions of its value within the header byte. The values listed here are
* directly applied to persisted data -- DO NOT modify the values specified
* here. Instead, gaps are placed intentionally between values so that new
* implementations can be inserted into the total ordering enforced here.
*/
private static final byte NULL = 0x05;
// room for 1 expansion type
private static final byte NEG_INF = 0x07;
private static final byte NEG_LARGE = 0x08;
private static final byte NEG_MED_MIN = 0x09;
private static final byte NEG_MED_MAX = 0x13;
private static final byte NEG_SMALL = 0x14;
private static final byte ZERO = 0x15;
private static final byte POS_SMALL = 0x16;
private static final byte POS_MED_MIN = 0x17;
private static final byte POS_MED_MAX = 0x21;
private static final byte POS_LARGE = 0x22;
private static final byte POS_INF = 0x23;
// room for 2 expansion type
private static final byte NAN = 0x26;
// room for 2 expansion types
private static final byte FIXED_INT8 = 0x29;
private static final byte FIXED_INT16 = 0x2a;
private static final byte FIXED_INT32 = 0x2b;
private static final byte FIXED_INT64 = 0x2c;
// room for 3 expansion types
private static final byte FIXED_FLOAT32 = 0x30;
private static final byte FIXED_FLOAT64 = 0x31;
// room for 2 expansion type
private static final byte TEXT = 0x34;
// room for 2 expansion type
private static final byte BLOB_VAR = 0x37;
private static final byte BLOB_COPY = 0x38;
/*
* The following constant values are used by encoding implementations
*/
public static final Charset UTF8 = Charset.forName("UTF-8");
private static final byte TERM = 0x00;
private static final BigDecimal E8 = BigDecimal.valueOf(1e8);
private static final BigDecimal E32 = BigDecimal.valueOf(1e32);
private static final BigDecimal EN2 = BigDecimal.valueOf(1e-2);
private static final BigDecimal EN10 = BigDecimal.valueOf(1e-10);
/**
* Max precision guaranteed to fit into a {@code long}.
*/
public static final int MAX_PRECISION = 31;
/**
* The context used to normalize {@link BigDecimal} values.
*/
public static final MathContext DEFAULT_MATH_CONTEXT =
new MathContext(MAX_PRECISION, RoundingMode.HALF_UP);
/**
* Creates the standard exception when the encoded header byte is unexpected for the decoding
* context.
* @param header value used in error message.
*/
private static IllegalArgumentException unexpectedHeader(byte header) {
throw new IllegalArgumentException("unexpected value in first byte: 0x"
+ Long.toHexString(header));
}
/**
* Perform unsigned comparison between two long values. Conforms to the same interface as
* {@link org.apache.hadoop.hbase.CellComparator#COMPARATOR#compare(Object, Object)}.
*/
private static int unsignedCmp(long x1, long x2) {
int cmp;
if ((cmp = (x1 < x2 ? -1 : (x1 == x2 ? 0 : 1))) == 0) return 0;
// invert the result when either value is negative
if ((x1 < 0) != (x2 < 0)) return -cmp;
return cmp;
}
/**
* Write a 32-bit unsigned integer to {@code dst} as 4 big-endian bytes.
* @return number of bytes written.
*/
private static int putUint32(PositionedByteRange dst, int val) {
dst.put((byte) (val >>> 24))
.put((byte) (val >>> 16))
.put((byte) (val >>> 8))
.put((byte) val);
return 4;
}
/**
* Encode an unsigned 64-bit unsigned integer {@code val} into {@code dst}.
* @param dst The destination to which encoded bytes are written.
* @param val The value to write.
* @param comp Compliment the encoded value when {@code comp} is true.
* @return number of bytes written.
*/
@VisibleForTesting
static int putVaruint64(PositionedByteRange dst, long val, boolean comp) {
int w, y, len = 0;
final int offset = dst.getOffset(), start = dst.getPosition();
byte[] a = dst.getBytes();
Order ord = comp ? DESCENDING : ASCENDING;
if (-1 == unsignedCmp(val, 241L)) {
dst.put((byte) val);
len = dst.getPosition() - start;
ord.apply(a, offset + start, len);
return len;
}
if (-1 == unsignedCmp(val, 2288L)) {
y = (int) (val - 240);
dst.put((byte) (y / 256 + 241))
.put((byte) (y % 256));
len = dst.getPosition() - start;
ord.apply(a, offset + start, len);
return len;
}
if (-1 == unsignedCmp(val, 67824L)) {
y = (int) (val - 2288);
dst.put((byte) 249)
.put((byte) (y / 256))
.put((byte) (y % 256));
len = dst.getPosition() - start;
ord.apply(a, offset + start, len);
return len;
}
y = (int) val;
w = (int) (val >>> 32);
if (w == 0) {
if (-1 == unsignedCmp(y, 16777216L)) {
dst.put((byte) 250)
.put((byte) (y >>> 16))
.put((byte) (y >>> 8))
.put((byte) y);
len = dst.getPosition() - start;
ord.apply(a, offset + start, len);
return len;
}
dst.put((byte) 251);
putUint32(dst, y);
len = dst.getPosition() - start;
ord.apply(a, offset + start, len);
return len;
}
if (-1 == unsignedCmp(w, 256L)) {
dst.put((byte) 252)
.put((byte) w);
putUint32(dst, y);
len = dst.getPosition() - start;
ord.apply(a, offset + start, len);
return len;
}
if (-1 == unsignedCmp(w, 65536L)) {
dst.put((byte) 253)
.put((byte) (w >>> 8))
.put((byte) w);
putUint32(dst, y);
len = dst.getPosition() - start;
ord.apply(a, offset + start, len);
return len;
}
if (-1 == unsignedCmp(w, 16777216L)) {
dst.put((byte) 254)
.put((byte) (w >>> 16))
.put((byte) (w >>> 8))
.put((byte) w);
putUint32(dst, y);
len = dst.getPosition() - start;
ord.apply(a, offset + start, len);
return len;
}
dst.put((byte) 255);
putUint32(dst, w);
putUint32(dst, y);
len = dst.getPosition() - start;
ord.apply(a, offset + start, len);
return len;
}
/**
* Inspect {@code src} for an encoded varuint64 for its length in bytes.
* Preserves the state of {@code src}.
* @param src source buffer
* @param comp if true, parse the compliment of the value.
* @return the number of bytes consumed by this value.
*/
@VisibleForTesting
static int lengthVaruint64(PositionedByteRange src, boolean comp) {
int a0 = (comp ? DESCENDING : ASCENDING).apply(src.peek()) & 0xff;
if (a0 <= 240) return 1;
if (a0 >= 241 && a0 <= 248) return 2;
if (a0 == 249) return 3;
if (a0 == 250) return 4;
if (a0 == 251) return 5;
if (a0 == 252) return 6;
if (a0 == 253) return 7;
if (a0 == 254) return 8;
if (a0 == 255) return 9;
throw unexpectedHeader(src.peek());
}
/**
* Skip {@code src} over the encoded varuint64.
* @param src source buffer
* @param cmp if true, parse the compliment of the value.
* @return the number of bytes skipped.
*/
@VisibleForTesting
static int skipVaruint64(PositionedByteRange src, boolean cmp) {
final int len = lengthVaruint64(src, cmp);
src.setPosition(src.getPosition() + len);
return len;
}
/**
* Decode a sequence of bytes in {@code src} as a varuint64. Compliment the
* encoded value when {@code comp} is true.
* @return the decoded value.
*/
@VisibleForTesting
static long getVaruint64(PositionedByteRange src, boolean comp) {
assert src.getRemaining() >= lengthVaruint64(src, comp);
final long ret;
Order ord = comp ? DESCENDING : ASCENDING;
byte x = src.get();
final int a0 = ord.apply(x) & 0xff, a1, a2, a3, a4, a5, a6, a7, a8;
if (-1 == unsignedCmp(a0, 241)) {
return a0;
}
x = src.get();
a1 = ord.apply(x) & 0xff;
if (-1 == unsignedCmp(a0, 249)) {
return (a0 - 241) * 256 + a1 + 240;
}
x = src.get();
a2 = ord.apply(x) & 0xff;
if (a0 == 249) {
return 2288 + 256 * a1 + a2;
}
x = src.get();
a3 = ord.apply(x) & 0xff;
if (a0 == 250) {
return (a1 << 16) | (a2 << 8) | a3;
}
x = src.get();
a4 = ord.apply(x) & 0xff;
ret = (((long) a1) << 24) | (a2 << 16) | (a3 << 8) | a4;
if (a0 == 251) {
return ret;
}
x = src.get();
a5 = ord.apply(x) & 0xff;
if (a0 == 252) {
return (ret << 8) | a5;
}
x = src.get();
a6 = ord.apply(x) & 0xff;
if (a0 == 253) {
return (ret << 16) | (a5 << 8) | a6;
}
x = src.get();
a7 = ord.apply(x) & 0xff;
if (a0 == 254) {
return (ret << 24) | (a5 << 16) | (a6 << 8) | a7;
}
x = src.get();
a8 = ord.apply(x) & 0xff;
return (ret << 32) | (((long) a5) << 24) | (a6 << 16) | (a7 << 8) | a8;
}
/**
* Strip all trailing zeros to ensure that no digit will be zero and round
* using our default context to ensure precision doesn't exceed max allowed.
* From Phoenix's {@code NumberUtil}.
* @return new {@link BigDecimal} instance
*/
@VisibleForTesting
static BigDecimal normalize(BigDecimal val) {
return null == val ? null : val.stripTrailingZeros().round(DEFAULT_MATH_CONTEXT);
}
/**
* Read significand digits from {@code src} according to the magnitude
* of {@code e}.
* @param src The source from which to read encoded digits.
* @param e The magnitude of the first digit read.
* @param comp Treat encoded bytes as compliments when {@code comp} is true.
* @return The decoded value.
* @throws IllegalArgumentException when read exceeds the remaining length
* of {@code src}.
*/
private static BigDecimal decodeSignificand(PositionedByteRange src, int e, boolean comp) {
// TODO: can this be made faster?
byte[] a = src.getBytes();
final int start = src.getPosition(), offset = src.getOffset(), remaining = src.getRemaining();
Order ord = comp ? DESCENDING : ASCENDING;
BigDecimal m = BigDecimal.ZERO;
e--;
for (int i = 0;; i++) {
if (i > remaining) {
// we've exceeded this range's window
src.setPosition(start);
throw new IllegalArgumentException(
"Read exceeds range before termination byte found. offset: " + offset + " position: "
+ (start + i));
}
// base-100 digits are encoded as val * 2 + 1 except for the termination digit.
m = m.add( // m +=
new BigDecimal(BigInteger.ONE, e * -2).multiply( // 100 ^ p * [decoded digit]
BigDecimal.valueOf((ord.apply(a[offset + start + i]) & 0xff) / 2)));
e--;
// detect termination digit
if ((ord.apply(a[offset + start + i]) & 1) == 0) {
src.setPosition(start + i + 1);
break;
}
}
return normalize(m);
}
/**
* Skip {@code src} over the significand bytes.
* @param src The source from which to read encoded digits.
* @param comp Treat encoded bytes as compliments when {@code comp} is true.
* @return the number of bytes skipped.
*/
private static int skipSignificand(PositionedByteRange src, boolean comp) {
byte[] a = src.getBytes();
final int offset = src.getOffset(), start = src.getPosition();
int i = src.getPosition();
while (((comp ? DESCENDING : ASCENDING).apply(a[offset + i++]) & 1) != 0)
;
src.setPosition(i);
return i - start;
}
/**
* <p>
* Encode the small magnitude floating point number {@code val} using the
* key encoding. The caller guarantees that 1.0 > abs(val) > 0.0.
* </p>
* <p>
* A floating point value is encoded as an integer exponent {@code E} and a
* mantissa {@code M}. The original value is equal to {@code (M * 100^E)}.
* {@code E} is set to the smallest value possible without making {@code M}
* greater than or equal to 1.0.
* </p>
* <p>
* For this routine, {@code E} will always be zero or negative, since the
* original value is less than one. The encoding written by this routine is
* the ones-complement of the varint of the negative of {@code E} followed
* by the mantissa:
* <pre>
* Encoding: ~-E M
* </pre>
* </p>
* @param dst The destination to which encoded digits are written.
* @param val The value to encode.
* @return the number of bytes written.
*/
private static int encodeNumericSmall(PositionedByteRange dst, BigDecimal val) {
// TODO: this can be done faster?
// assert 1.0 > abs(val) > 0.0
BigDecimal abs = val.abs();
assert BigDecimal.ZERO.compareTo(abs) < 0 && BigDecimal.ONE.compareTo(abs) > 0;
byte[] a = dst.getBytes();
boolean isNeg = val.signum() == -1;
final int offset = dst.getOffset(), start = dst.getPosition();
int e = 0, d, startM;
if (isNeg) { /* Small negative number: 0x14, -E, ~M */
dst.put(NEG_SMALL);
} else { /* Small positive number: 0x16, ~-E, M */
dst.put(POS_SMALL);
}
// normalize abs(val) to determine E
while (abs.compareTo(EN10) < 0) { abs = abs.movePointRight(8); e += 4; }
while (abs.compareTo(EN2) < 0) { abs = abs.movePointRight(2); e++; }
putVaruint64(dst, e, !isNeg); // encode appropriate E value.
// encode M by peeling off centimal digits, encoding x as 2x+1
startM = dst.getPosition();
// TODO: 18 is an arbitrary encoding limit. Reevaluate once we have a better handling of
// numeric scale.
for (int i = 0; i < 18 && abs.compareTo(BigDecimal.ZERO) != 0; i++) {
abs = abs.movePointRight(2);
d = abs.intValue();
dst.put((byte) ((2 * d + 1) & 0xff));
abs = abs.subtract(BigDecimal.valueOf(d));
}
a[offset + dst.getPosition() - 1] &= 0xfe; // terminal digit should be 2x
if (isNeg) {
// negative values encoded as ~M
DESCENDING.apply(a, offset + startM, dst.getPosition() - startM);
}
return dst.getPosition() - start;
}
/**
* Encode the large magnitude floating point number {@code val} using
* the key encoding. The caller guarantees that {@code val} will be
* finite and abs(val) >= 1.0.
* <p>
* A floating point value is encoded as an integer exponent {@code E}
* and a mantissa {@code M}. The original value is equal to
* {@code (M * 100^E)}. {@code E} is set to the smallest value
* possible without making {@code M} greater than or equal to 1.0.
* </p>
* <p>
* Each centimal digit of the mantissa is stored in a byte. If the value of
* the centimal digit is {@code X} (hence {@code X>=0} and
* {@code X<=99}) then the byte value will be {@code 2*X+1} for
* every byte of the mantissa, except for the last byte which will be
* {@code 2*X+0}. The mantissa must be the minimum number of bytes
* necessary to represent the value; trailing {@code X==0} digits are
* omitted. This means that the mantissa will never contain a byte with the
* value {@code 0x00}.
* </p>
* <p>
* If {@code E > 10}, then this routine writes of {@code E} as a
* varint followed by the mantissa as described above. Otherwise, if
* {@code E <= 10}, this routine only writes the mantissa and leaves
* the {@code E} value to be encoded as part of the opening byte of the
* field by the calling function.
*
* <pre>
* Encoding: M (if E<=10)
* E M (if E>10)
* </pre>
* </p>
* @param dst The destination to which encoded digits are written.
* @param val The value to encode.
* @return the number of bytes written.
*/
private static int encodeNumericLarge(PositionedByteRange dst, BigDecimal val) {
// TODO: this can be done faster
BigDecimal abs = val.abs();
byte[] a = dst.getBytes();
boolean isNeg = val.signum() == -1;
final int start = dst.getPosition(), offset = dst.getOffset();
int e = 0, d, startM;
if (isNeg) { /* Large negative number: 0x08, ~E, ~M */
dst.put(NEG_LARGE);
} else { /* Large positive number: 0x22, E, M */
dst.put(POS_LARGE);
}
// normalize abs(val) to determine E
while (abs.compareTo(E32) >= 0 && e <= 350) { abs = abs.movePointLeft(32); e +=16; }
while (abs.compareTo(E8) >= 0 && e <= 350) { abs = abs.movePointLeft(8); e+= 4; }
while (abs.compareTo(BigDecimal.ONE) >= 0 && e <= 350) { abs = abs.movePointLeft(2); e++; }
// encode appropriate header byte and/or E value.
if (e > 10) { /* large number, write out {~,}E */
putVaruint64(dst, e, isNeg);
} else {
if (isNeg) { /* Medium negative number: 0x13-E, ~M */
dst.put(start, (byte) (NEG_MED_MAX - e));
} else { /* Medium positive number: 0x17+E, M */
dst.put(start, (byte) (POS_MED_MIN + e));
}
}
// encode M by peeling off centimal digits, encoding x as 2x+1
startM = dst.getPosition();
// TODO: 18 is an arbitrary encoding limit. Reevaluate once we have a better handling of
// numeric scale.
for (int i = 0; i < 18 && abs.compareTo(BigDecimal.ZERO) != 0; i++) {
abs = abs.movePointRight(2);
d = abs.intValue();
dst.put((byte) (2 * d + 1));
abs = abs.subtract(BigDecimal.valueOf(d));
}
a[offset + dst.getPosition() - 1] &= 0xfe; // terminal digit should be 2x
if (isNeg) {
// negative values encoded as ~M
DESCENDING.apply(a, offset + startM, dst.getPosition() - startM);
}
return dst.getPosition() - start;
}
/**
* Encode a numerical value using the variable-length encoding.
* @param dst The destination to which encoded digits are written.
* @param val The value to encode.
* @param ord The {@link Order} to respect while encoding {@code val}.
* @return the number of bytes written.
*/
public static int encodeNumeric(PositionedByteRange dst, long val, Order ord) {
return encodeNumeric(dst, BigDecimal.valueOf(val), ord);
}
/**
* Encode a numerical value using the variable-length encoding.
* @param dst The destination to which encoded digits are written.
* @param val The value to encode.
* @param ord The {@link Order} to respect while encoding {@code val}.
* @return the number of bytes written.
*/
public static int encodeNumeric(PositionedByteRange dst, double val, Order ord) {
if (val == 0.0) {
dst.put(ord.apply(ZERO));
return 1;
}
if (Double.isNaN(val)) {
dst.put(ord.apply(NAN));
return 1;
}
if (val == Double.NEGATIVE_INFINITY) {
dst.put(ord.apply(NEG_INF));
return 1;
}
if (val == Double.POSITIVE_INFINITY) {
dst.put(ord.apply(POS_INF));
return 1;
}
return encodeNumeric(dst, BigDecimal.valueOf(val), ord);
}
/**
* Encode a numerical value using the variable-length encoding.
* @param dst The destination to which encoded digits are written.
* @param val The value to encode.
* @param ord The {@link Order} to respect while encoding {@code val}.
* @return the number of bytes written.
*/
public static int encodeNumeric(PositionedByteRange dst, BigDecimal val, Order ord) {
final int len, offset = dst.getOffset(), start = dst.getPosition();
if (null == val) {
return encodeNull(dst, ord);
} else if (BigDecimal.ZERO.compareTo(val) == 0) {
dst.put(ord.apply(ZERO));
return 1;
}
BigDecimal abs = val.abs();
if (BigDecimal.ONE.compareTo(abs) <= 0) { // abs(v) >= 1.0
len = encodeNumericLarge(dst, normalize(val));
} else { // 1.0 > abs(v) >= 0.0
len = encodeNumericSmall(dst, normalize(val));
}
ord.apply(dst.getBytes(), offset + start, len);
return len;
}
/**
* Decode a {@link BigDecimal} from {@code src}. Assumes {@code src} encodes
* a value in Numeric encoding and is within the valid range of
* {@link BigDecimal} values. {@link BigDecimal} does not support {@code NaN}
* or {@code Infinte} values.
* @see #decodeNumericAsDouble(PositionedByteRange)
*/
private static BigDecimal decodeNumericValue(PositionedByteRange src) {
final int e;
byte header = src.get();
boolean dsc = -1 == Integer.signum(header);
header = dsc ? DESCENDING.apply(header) : header;
if (header == NULL) return null;
if (header == NEG_LARGE) { /* Large negative number: 0x08, ~E, ~M */
e = (int) getVaruint64(src, !dsc);
return decodeSignificand(src, e, !dsc).negate();
}
if (header >= NEG_MED_MIN && header <= NEG_MED_MAX) {
/* Medium negative number: 0x13-E, ~M */
e = NEG_MED_MAX - header;
return decodeSignificand(src, e, !dsc).negate();
}
if (header == NEG_SMALL) { /* Small negative number: 0x14, -E, ~M */
e = (int) -getVaruint64(src, dsc);
return decodeSignificand(src, e, !dsc).negate();
}
if (header == ZERO) {
return BigDecimal.ZERO;
}
if (header == POS_SMALL) { /* Small positive number: 0x16, ~-E, M */
e = (int) -getVaruint64(src, !dsc);
return decodeSignificand(src, e, dsc);
}
if (header >= POS_MED_MIN && header <= POS_MED_MAX) {
/* Medium positive number: 0x17+E, M */
e = header - POS_MED_MIN;
return decodeSignificand(src, e, dsc);
}
if (header == POS_LARGE) { /* Large positive number: 0x22, E, M */
e = (int) getVaruint64(src, dsc);
return decodeSignificand(src, e, dsc);
}
throw unexpectedHeader(header);
}
/**
* Decode a primitive {@code double} value from the Numeric encoding. Numeric
* encoding is based on {@link BigDecimal}; in the event the encoded value is
* larger than can be represented in a {@code double}, this method performs
* an implicit narrowing conversion as described in
* {@link BigDecimal#doubleValue()}.
* @throws NullPointerException when the encoded value is {@code NULL}.
* @throws IllegalArgumentException when the encoded value is not a Numeric.
* @see #encodeNumeric(PositionedByteRange, double, Order)
* @see BigDecimal#doubleValue()
*/
public static double decodeNumericAsDouble(PositionedByteRange src) {
// TODO: should an encoded NULL value throw unexpectedHeader() instead?
if (isNull(src)) {
throw new NullPointerException("A null value cannot be decoded to a double.");
}
if (isNumericNaN(src)) {
src.get();
return Double.NaN;
}
if (isNumericZero(src)) {
src.get();
return Double.valueOf(0.0);
}
byte header = -1 == Integer.signum(src.peek()) ? DESCENDING.apply(src.peek()) : src.peek();
if (header == NEG_INF) {
src.get();
return Double.NEGATIVE_INFINITY;
} else if (header == POS_INF) {
src.get();
return Double.POSITIVE_INFINITY;
} else {
return decodeNumericValue(src).doubleValue();
}
}
/**
* Decode a primitive {@code long} value from the Numeric encoding. Numeric
* encoding is based on {@link BigDecimal}; in the event the encoded value is
* larger than can be represented in a {@code long}, this method performs an
* implicit narrowing conversion as described in
* {@link BigDecimal#doubleValue()}.
* @throws NullPointerException when the encoded value is {@code NULL}.
* @throws IllegalArgumentException when the encoded value is not a Numeric.
* @see #encodeNumeric(PositionedByteRange, long, Order)
* @see BigDecimal#longValue()
*/
public static long decodeNumericAsLong(PositionedByteRange src) {
// TODO: should an encoded NULL value throw unexpectedHeader() instead?
if (isNull(src)) throw new NullPointerException();
if (!isNumeric(src)) throw unexpectedHeader(src.peek());
if (isNumericNaN(src)) throw unexpectedHeader(src.peek());
if (isNumericInfinite(src)) throw unexpectedHeader(src.peek());
if (isNumericZero(src)) {
src.get();
return Long.valueOf(0);
}
return decodeNumericValue(src).longValue();
}
/**
* Decode a {@link BigDecimal} value from the variable-length encoding.
* @throws IllegalArgumentException when the encoded value is not a Numeric.
* @see #encodeNumeric(PositionedByteRange, BigDecimal, Order)
*/
public static BigDecimal decodeNumericAsBigDecimal(PositionedByteRange src) {
if (isNull(src)) {
src.get();
return null;
}
if (!isNumeric(src)) throw unexpectedHeader(src.peek());
if (isNumericNaN(src)) throw unexpectedHeader(src.peek());
if (isNumericInfinite(src)) throw unexpectedHeader(src.peek());
return decodeNumericValue(src);
}
/**
* Encode a String value. String encoding is 0x00-terminated and so it does
* not support {@code \u0000} codepoints in the value.
* @param dst The destination to which the encoded value is written.
* @param val The value to encode.
* @param ord The {@link Order} to respect while encoding {@code val}.
* @return the number of bytes written.
* @throws IllegalArgumentException when {@code val} contains a {@code \u0000}.
*/
public static int encodeString(PositionedByteRange dst, String val, Order ord) {
if (null == val) {
return encodeNull(dst, ord);
}
if (val.contains("\u0000"))
throw new IllegalArgumentException("Cannot encode String values containing '\\u0000'");
final int offset = dst.getOffset(), start = dst.getPosition();
dst.put(TEXT);
// TODO: is there no way to decode into dst directly?
dst.put(val.getBytes(UTF8));
dst.put(TERM);
ord.apply(dst.getBytes(), offset + start, dst.getPosition() - start);
return dst.getPosition() - start;
}
/**
* Decode a String value.
*/
public static String decodeString(PositionedByteRange src) {
final byte header = src.get();
if (header == NULL || header == DESCENDING.apply(NULL))
return null;
assert header == TEXT || header == DESCENDING.apply(TEXT);
Order ord = header == TEXT ? ASCENDING : DESCENDING;
byte[] a = src.getBytes();
final int offset = src.getOffset(), start = src.getPosition();
final byte terminator = ord.apply(TERM);
int rawStartPos = offset + start, rawTermPos = rawStartPos;
for (; a[rawTermPos] != terminator; rawTermPos++)
;
src.setPosition(rawTermPos - offset + 1); // advance position to TERM + 1
if (DESCENDING == ord) {
// make a copy so that we don't disturb encoded value with ord.
byte[] copy = new byte[rawTermPos - rawStartPos];
System.arraycopy(a, rawStartPos, copy, 0, copy.length);
ord.apply(copy);
return new String(copy, UTF8);
} else {
return new String(a, rawStartPos, rawTermPos - rawStartPos, UTF8);
}
}
/**
* Calculate the expected BlobVar encoded length based on unencoded length.
*/
public static int blobVarEncodedLength(int len) {
if (0 == len)
return 2; // 1-byte header + 1-byte terminator
else
return (int)
Math.ceil(
(len * 8) // 8-bits per input byte
/ 7.0) // 7-bits of input data per encoded byte, rounded up
+ 1; // + 1-byte header
}
/**
* Calculate the expected BlobVar decoded length based on encoded length.
*/
@VisibleForTesting
static int blobVarDecodedLength(int len) {
return
((len
- 1) // 1-byte header
* 7) // 7-bits of payload per encoded byte
/ 8; // 8-bits per byte
}
/**
* Encode a Blob value using a modified varint encoding scheme.
* <p>
* This format encodes a byte[] value such that no limitations on the input
* value are imposed. The first byte encodes the encoding scheme that
* follows, {@link #BLOB_VAR}. Each encoded byte thereafter consists of a
* header bit followed by 7 bits of payload. A header bit of '1' indicates
* continuation of the encoding. A header bit of '0' indicates this byte
* contains the last of the payload. An empty input value is encoded as the
* header byte immediately followed by a termination byte {@code 0x00}. This
* is not ambiguous with the encoded value of {@code []}, which results in
* {@code [0x80, 0x00]}.
* </p>
* @return the number of bytes written.
*/
public static int encodeBlobVar(PositionedByteRange dst, byte[] val, int voff, int vlen,
Order ord) {
if (null == val) {
return encodeNull(dst, ord);
}
// Empty value is null-terminated. All other values are encoded as 7-bits per byte.
assert dst.getRemaining() >= blobVarEncodedLength(vlen) : "buffer overflow expected.";
final int offset = dst.getOffset(), start = dst.getPosition();
dst.put(BLOB_VAR);
if (0 == vlen) {
dst.put(TERM);
} else {
byte s = 1, t = 0;
for (int i = voff; i < vlen; i++) {
dst.put((byte) (0x80 | t | ((val[i] & 0xff) >>> s)));
if (s < 7) {
t = (byte) (val[i] << (7 - s));
s++;
} else {
dst.put((byte) (0x80 | val[i]));
s = 1;
t = 0;
}
}
if (s > 1) {
dst.put((byte) (0x7f & t));
} else {
dst.getBytes()[offset + dst.getPosition() - 1] &= 0x7f;
}
}
ord.apply(dst.getBytes(), offset + start, dst.getPosition() - start);
return dst.getPosition() - start;
}
/**
* Encode a blob value using a modified varint encoding scheme.
* @return the number of bytes written.
* @see #encodeBlobVar(PositionedByteRange, byte[], int, int, Order)
*/
public static int encodeBlobVar(PositionedByteRange dst, byte[] val, Order ord) {
return encodeBlobVar(dst, val, 0, null != val ? val.length : 0, ord);
}
/**
* Decode a blob value that was encoded using BlobVar encoding.
*/
public static byte[] decodeBlobVar(PositionedByteRange src) {
final byte header = src.get();
if (header == NULL || header == DESCENDING.apply(NULL)) {
return null;
}
assert header == BLOB_VAR || header == DESCENDING.apply(BLOB_VAR);
Order ord = BLOB_VAR == header ? ASCENDING : DESCENDING;
if (src.peek() == ord.apply(TERM)) {
// skip empty input buffer.
src.get();
return new byte[0];
}
final int offset = src.getOffset(), start = src.getPosition();
int end;
byte[] a = src.getBytes();
for (end = start; (byte) (ord.apply(a[offset + end]) & 0x80) != TERM; end++)
;
end++; // increment end to 1-past last byte
// create ret buffer using length of encoded data + 1 (header byte)
PositionedByteRange ret = new SimplePositionedMutableByteRange(blobVarDecodedLength(end - start
+ 1));
int s = 6;
byte t = (byte) ((ord.apply(a[offset + start]) << 1) & 0xff);
for (int i = start + 1; i < end; i++) {
if (s == 7) {
ret.put((byte) (t | (ord.apply(a[offset + i]) & 0x7f)));
i++;
// explicitly reset t -- clean up overflow buffer after decoding
// a full cycle and retain assertion condition below. This happens
t = 0; // when the LSB in the last encoded byte is 1. (HBASE-9893)
} else {
ret.put((byte) (t | ((ord.apply(a[offset + i]) & 0x7f) >>> s)));
}
if (i == end) break;
t = (byte) ((ord.apply(a[offset + i]) << 8 - s) & 0xff);
s = s == 1 ? 7 : s - 1;
}
src.setPosition(end);
assert t == 0 : "Unexpected bits remaining after decoding blob.";
assert ret.getPosition() == ret.getLength() : "Allocated unnecessarily large return buffer.";
return ret.getBytes();
}
/**
* Encode a Blob value as a byte-for-byte copy. BlobCopy encoding in
* DESCENDING order is NULL terminated so as to preserve proper sorting of
* {@code []} and so it does not support {@code 0x00} in the value.
* @return the number of bytes written.
* @throws IllegalArgumentException when {@code ord} is DESCENDING and
* {@code val} contains a {@code 0x00} byte.
*/
public static int encodeBlobCopy(PositionedByteRange dst, byte[] val, int voff, int vlen,
Order ord) {
if (null == val) {
encodeNull(dst, ord);
if (ASCENDING == ord) return 1;
else {
// DESCENDING ordered BlobCopy requires a termination bit to preserve
// sort-order semantics of null values.
dst.put(ord.apply(TERM));
return 2;
}
}
// Blobs as final entry in a compound key are written unencoded.
assert dst.getRemaining() >= vlen + (ASCENDING == ord ? 1 : 2);
if (DESCENDING == ord) {
for (int i = 0; i < vlen; i++) {
if (TERM == val[voff + i]) {
throw new IllegalArgumentException("0x00 bytes not permitted in value.");
}
}
}
final int offset = dst.getOffset(), start = dst.getPosition();
dst.put(BLOB_COPY);
dst.put(val, voff, vlen);
// DESCENDING ordered BlobCopy requires a termination bit to preserve
// sort-order semantics of null values.
if (DESCENDING == ord) dst.put(TERM);
ord.apply(dst.getBytes(), offset + start, dst.getPosition() - start);
return dst.getPosition() - start;
}
/**
* Encode a Blob value as a byte-for-byte copy. BlobCopy encoding in
* DESCENDING order is NULL terminated so as to preserve proper sorting of
* {@code []} and so it does not support {@code 0x00} in the value.
* @return the number of bytes written.
* @throws IllegalArgumentException when {@code ord} is DESCENDING and
* {@code val} contains a {@code 0x00} byte.
* @see #encodeBlobCopy(PositionedByteRange, byte[], int, int, Order)
*/
public static int encodeBlobCopy(PositionedByteRange dst, byte[] val, Order ord) {
return encodeBlobCopy(dst, val, 0, null != val ? val.length : 0, ord);
}
/**
* Decode a Blob value, byte-for-byte copy.
* @see #encodeBlobCopy(PositionedByteRange, byte[], int, int, Order)
*/
public static byte[] decodeBlobCopy(PositionedByteRange src) {
byte header = src.get();
if (header == NULL || header == DESCENDING.apply(NULL)) {
return null;
}
assert header == BLOB_COPY || header == DESCENDING.apply(BLOB_COPY);
Order ord = header == BLOB_COPY ? ASCENDING : DESCENDING;
final int length = src.getRemaining() - (ASCENDING == ord ? 0 : 1);
byte[] ret = new byte[length];
src.get(ret);
ord.apply(ret, 0, ret.length);
// DESCENDING ordered BlobCopy requires a termination bit to preserve
// sort-order semantics of null values.
if (DESCENDING == ord) src.get();
return ret;
}
/**
* Encode a null value.
* @param dst The destination to which encoded digits are written.
* @param ord The {@link Order} to respect while encoding {@code val}.
* @return the number of bytes written.
*/
public static int encodeNull(PositionedByteRange dst, Order ord) {
dst.put(ord.apply(NULL));
return 1;
}
/**
* Encode an {@code int8} value using the fixed-length encoding.
* @return the number of bytes written.
* @see #encodeInt64(PositionedByteRange, long, Order)
* @see #decodeInt8(PositionedByteRange)
*/
public static int encodeInt8(PositionedByteRange dst, byte val, Order ord) {
final int offset = dst.getOffset(), start = dst.getPosition();
dst.put(FIXED_INT8)
.put((byte) (val ^ 0x80));
ord.apply(dst.getBytes(), offset + start, 2);
return 2;
}
/**
* Decode an {@code int8} value.
* @see #encodeInt8(PositionedByteRange, byte, Order)
*/
public static byte decodeInt8(PositionedByteRange src) {
final byte header = src.get();
assert header == FIXED_INT8 || header == DESCENDING.apply(FIXED_INT8);
Order ord = header == FIXED_INT8 ? ASCENDING : DESCENDING;
return (byte)((ord.apply(src.get()) ^ 0x80) & 0xff);
}
/**
* Encode an {@code int16} value using the fixed-length encoding.
* @return the number of bytes written.
* @see #encodeInt64(PositionedByteRange, long, Order)
* @see #decodeInt16(PositionedByteRange)
*/
public static int encodeInt16(PositionedByteRange dst, short val, Order ord) {
final int offset = dst.getOffset(), start = dst.getPosition();
dst.put(FIXED_INT16)
.put((byte) ((val >> 8) ^ 0x80))
.put((byte) val);
ord.apply(dst.getBytes(), offset + start, 3);
return 3;
}
/**
* Decode an {@code int16} value.
* @see #encodeInt16(PositionedByteRange, short, Order)
*/
public static short decodeInt16(PositionedByteRange src) {
final byte header = src.get();
assert header == FIXED_INT16 || header == DESCENDING.apply(FIXED_INT16);
Order ord = header == FIXED_INT16 ? ASCENDING : DESCENDING;
short val = (short) ((ord.apply(src.get()) ^ 0x80) & 0xff);
val = (short) ((val << 8) + (ord.apply(src.get()) & 0xff));
return val;
}
/**
* Encode an {@code int32} value using the fixed-length encoding.
* @return the number of bytes written.
* @see #encodeInt64(PositionedByteRange, long, Order)
* @see #decodeInt32(PositionedByteRange)
*/
public static int encodeInt32(PositionedByteRange dst, int val, Order ord) {
final int offset = dst.getOffset(), start = dst.getPosition();
dst.put(FIXED_INT32)
.put((byte) ((val >> 24) ^ 0x80))
.put((byte) (val >> 16))
.put((byte) (val >> 8))
.put((byte) val);
ord.apply(dst.getBytes(), offset + start, 5);
return 5;
}
/**
* Decode an {@code int32} value.
* @see #encodeInt32(PositionedByteRange, int, Order)
*/
public static int decodeInt32(PositionedByteRange src) {
final byte header = src.get();
assert header == FIXED_INT32 || header == DESCENDING.apply(FIXED_INT32);
Order ord = header == FIXED_INT32 ? ASCENDING : DESCENDING;
int val = (ord.apply(src.get()) ^ 0x80) & 0xff;
for (int i = 1; i < 4; i++) {
val = (val << 8) + (ord.apply(src.get()) & 0xff);
}
return val;
}
/**
* Encode an {@code int64} value using the fixed-length encoding.
* <p>
* This format ensures that all longs sort in their natural order, as they
* would sort when using signed long comparison.
* </p>
* <p>
* All Longs are serialized to an 8-byte, fixed-width sortable byte format.
* Serialization is performed by inverting the integer sign bit and writing
* the resulting bytes to the byte array in big endian order. The encoded
* value is prefixed by the {@link #FIXED_INT64} header byte. This encoding
* is designed to handle java language primitives and so Null values are NOT
* supported by this implementation.
* </p>
* <p>
* For example:
* </p>
* <pre>
* Input: 0x0000000000000005 (5)
* Result: 0x288000000000000005
*
* Input: 0xfffffffffffffffb (-4)
* Result: 0x280000000000000004
*
* Input: 0x7fffffffffffffff (Long.MAX_VALUE)
* Result: 0x28ffffffffffffffff
*
* Input: 0x8000000000000000 (Long.MIN_VALUE)
* Result: 0x287fffffffffffffff
* </pre>
* <p>
* This encoding format, and much of this documentation string, is based on
* Orderly's {@code FixedIntWritableRowKey}.
* </p>
* @return the number of bytes written.
* @see #decodeInt64(PositionedByteRange)
*/
public static int encodeInt64(PositionedByteRange dst, long val, Order ord) {
final int offset = dst.getOffset(), start = dst.getPosition();
dst.put(FIXED_INT64)
.put((byte) ((val >> 56) ^ 0x80))
.put((byte) (val >> 48))
.put((byte) (val >> 40))
.put((byte) (val >> 32))
.put((byte) (val >> 24))
.put((byte) (val >> 16))
.put((byte) (val >> 8))
.put((byte) val);
ord.apply(dst.getBytes(), offset + start, 9);
return 9;
}
/**
* Decode an {@code int64} value.
* @see #encodeInt64(PositionedByteRange, long, Order)
*/
public static long decodeInt64(PositionedByteRange src) {
final byte header = src.get();
assert header == FIXED_INT64 || header == DESCENDING.apply(FIXED_INT64);
Order ord = header == FIXED_INT64 ? ASCENDING : DESCENDING;
long val = (ord.apply(src.get()) ^ 0x80) & 0xff;
for (int i = 1; i < 8; i++) {
val = (val << 8) + (ord.apply(src.get()) & 0xff);
}
return val;
}
/**
* Encode a 32-bit floating point value using the fixed-length encoding.
* Encoding format is described at length in
* {@link #encodeFloat64(PositionedByteRange, double, Order)}.
* @return the number of bytes written.
* @see #decodeFloat32(PositionedByteRange)
* @see #encodeFloat64(PositionedByteRange, double, Order)
*/
public static int encodeFloat32(PositionedByteRange dst, float val, Order ord) {
final int offset = dst.getOffset(), start = dst.getPosition();
int i = Float.floatToIntBits(val);
i ^= ((i >> Integer.SIZE - 1) | Integer.MIN_VALUE);
dst.put(FIXED_FLOAT32)
.put((byte) (i >> 24))
.put((byte) (i >> 16))
.put((byte) (i >> 8))
.put((byte) i);
ord.apply(dst.getBytes(), offset + start, 5);
return 5;
}
/**
* Decode a 32-bit floating point value using the fixed-length encoding.
* @see #encodeFloat32(PositionedByteRange, float, Order)
*/
public static float decodeFloat32(PositionedByteRange src) {
final byte header = src.get();
assert header == FIXED_FLOAT32 || header == DESCENDING.apply(FIXED_FLOAT32);
Order ord = header == FIXED_FLOAT32 ? ASCENDING : DESCENDING;
int val = ord.apply(src.get()) & 0xff;
for (int i = 1; i < 4; i++) {
val = (val << 8) + (ord.apply(src.get()) & 0xff);
}
val ^= (~val >> Integer.SIZE - 1) | Integer.MIN_VALUE;
return Float.intBitsToFloat(val);
}
/**
* Encode a 64-bit floating point value using the fixed-length encoding.
* <p>
* This format ensures the following total ordering of floating point
* values: Double.NEGATIVE_INFINITY < -Double.MAX_VALUE < ... <
* -Double.MIN_VALUE < -0.0 < +0.0; < Double.MIN_VALUE < ...
* < Double.MAX_VALUE < Double.POSITIVE_INFINITY < Double.NaN
* </p>
* <p>
* Floating point numbers are encoded as specified in IEEE 754. A 64-bit
* double precision float consists of a sign bit, 11-bit unsigned exponent
* encoded in offset-1023 notation, and a 52-bit significand. The format is
* described further in the <a
* href="http://en.wikipedia.org/wiki/Double_precision"> Double Precision
* Floating Point Wikipedia page</a> </p>
* <p>
* The value of a normal float is -1 <sup>sign bit</sup> ×
* 2<sup>exponent - 1023</sup> × 1.significand
* </p>
* <p>
* The IEE754 floating point format already preserves sort ordering for
* positive floating point numbers when the raw bytes are compared in most
* significant byte order. This is discussed further at <a href=
* "http://www.cygnus-software.com/papers/comparingfloats/comparingfloats.htm"
* > http://www.cygnus-software.com/papers/comparingfloats/comparingfloats.
* htm</a>
* </p>
* <p>
* Thus, we need only ensure that negative numbers sort in the the exact
* opposite order as positive numbers (so that say, negative infinity is
* less than negative 1), and that all negative numbers compare less than
* any positive number. To accomplish this, we invert the sign bit of all
* floating point numbers, and we also invert the exponent and significand
* bits if the floating point number was negative.
* </p>
* <p>
* More specifically, we first store the floating point bits into a 64-bit
* long {@code l} using {@link Double#doubleToLongBits}. This method
* collapses all NaNs into a single, canonical NaN value but otherwise
* leaves the bits unchanged. We then compute
* </p>
* <pre>
* l ˆ= (l >> (Long.SIZE - 1)) | Long.MIN_SIZE
* </pre>
* <p>
* which inverts the sign bit and XOR's all other bits with the sign bit
* itself. Comparing the raw bytes of {@code l} in most significant
* byte order is equivalent to performing a double precision floating point
* comparison on the underlying bits (ignoring NaN comparisons, as NaNs
* don't compare equal to anything when performing floating point
* comparisons).
* </p>
* <p>
* The resulting long integer is then converted into a byte array by
* serializing the long one byte at a time in most significant byte order.
* The serialized integer is prefixed by a single header byte. All
* serialized values are 9 bytes in length.
* </p>
* <p>
* This encoding format, and much of this highly detailed documentation
* string, is based on Orderly's {@code DoubleWritableRowKey}.
* </p>
* @return the number of bytes written.
* @see #decodeFloat64(PositionedByteRange)
*/
public static int encodeFloat64(PositionedByteRange dst, double val, Order ord) {
final int offset = dst.getOffset(), start = dst.getPosition();
long lng = Double.doubleToLongBits(val);
lng ^= ((lng >> Long.SIZE - 1) | Long.MIN_VALUE);
dst.put(FIXED_FLOAT64)
.put((byte) (lng >> 56))
.put((byte) (lng >> 48))
.put((byte) (lng >> 40))
.put((byte) (lng >> 32))
.put((byte) (lng >> 24))
.put((byte) (lng >> 16))
.put((byte) (lng >> 8))
.put((byte) lng);
ord.apply(dst.getBytes(), offset + start, 9);
return 9;
}
/**
* Decode a 64-bit floating point value using the fixed-length encoding.
* @see #encodeFloat64(PositionedByteRange, double, Order)
*/
public static double decodeFloat64(PositionedByteRange src) {
final byte header = src.get();
assert header == FIXED_FLOAT64 || header == DESCENDING.apply(FIXED_FLOAT64);
Order ord = header == FIXED_FLOAT64 ? ASCENDING : DESCENDING;
long val = ord.apply(src.get()) & 0xff;
for (int i = 1; i < 8; i++) {
val = (val << 8) + (ord.apply(src.get()) & 0xff);
}
val ^= (~val >> Long.SIZE - 1) | Long.MIN_VALUE;
return Double.longBitsToDouble(val);
}
/**
* Returns true when {@code src} appears to be positioned an encoded value,
* false otherwise.
*/
public static boolean isEncodedValue(PositionedByteRange src) {
return isNull(src) || isNumeric(src) || isFixedInt8(src) || isFixedInt16(src)
|| isFixedInt32(src) || isFixedInt64(src)
|| isFixedFloat32(src) || isFixedFloat64(src) || isText(src) || isBlobCopy(src)
|| isBlobVar(src);
}
/**
* Return true when the next encoded value in {@code src} is null, false
* otherwise.
*/
public static boolean isNull(PositionedByteRange src) {
return NULL ==
(-1 == Integer.signum(src.peek()) ? DESCENDING : ASCENDING).apply(src.peek());
}
/**
* Return true when the next encoded value in {@code src} uses Numeric
* encoding, false otherwise. {@code NaN}, {@code +/-Inf} are valid Numeric
* values.
*/
public static boolean isNumeric(PositionedByteRange src) {
byte x = (-1 == Integer.signum(src.peek()) ? DESCENDING : ASCENDING).apply(src.peek());
return x >= NEG_INF && x <= NAN;
}
/**
* Return true when the next encoded value in {@code src} uses Numeric
* encoding and is {@code Infinite}, false otherwise.
*/
public static boolean isNumericInfinite(PositionedByteRange src) {
byte x = (-1 == Integer.signum(src.peek()) ? DESCENDING : ASCENDING).apply(src.peek());
return NEG_INF == x || POS_INF == x;
}
/**
* Return true when the next encoded value in {@code src} uses Numeric
* encoding and is {@code NaN}, false otherwise.
*/
public static boolean isNumericNaN(PositionedByteRange src) {
return NAN == (-1 == Integer.signum(src.peek()) ? DESCENDING : ASCENDING).apply(src.peek());
}
/**
* Return true when the next encoded value in {@code src} uses Numeric
* encoding and is {@code 0}, false otherwise.
*/
public static boolean isNumericZero(PositionedByteRange src) {
return ZERO ==
(-1 == Integer.signum(src.peek()) ? DESCENDING : ASCENDING).apply(src.peek());
}
/**
* Return true when the next encoded value in {@code src} uses fixed-width
* Int8 encoding, false otherwise.
*/
public static boolean isFixedInt8(PositionedByteRange src) {
return FIXED_INT8 ==
(-1 == Integer.signum(src.peek()) ? DESCENDING : ASCENDING).apply(src.peek());
}
/**
* Return true when the next encoded value in {@code src} uses fixed-width
* Int16 encoding, false otherwise.
*/
public static boolean isFixedInt16(PositionedByteRange src) {
return FIXED_INT16 ==
(-1 == Integer.signum(src.peek()) ? DESCENDING : ASCENDING).apply(src.peek());
}
/**
* Return true when the next encoded value in {@code src} uses fixed-width
* Int32 encoding, false otherwise.
*/
public static boolean isFixedInt32(PositionedByteRange src) {
return FIXED_INT32 ==
(-1 == Integer.signum(src.peek()) ? DESCENDING : ASCENDING).apply(src.peek());
}
/**
* Return true when the next encoded value in {@code src} uses fixed-width
* Int64 encoding, false otherwise.
*/
public static boolean isFixedInt64(PositionedByteRange src) {
return FIXED_INT64 ==
(-1 == Integer.signum(src.peek()) ? DESCENDING : ASCENDING).apply(src.peek());
}
/**
* Return true when the next encoded value in {@code src} uses fixed-width
* Float32 encoding, false otherwise.
*/
public static boolean isFixedFloat32(PositionedByteRange src) {
return FIXED_FLOAT32 ==
(-1 == Integer.signum(src.peek()) ? DESCENDING : ASCENDING).apply(src.peek());
}
/**
* Return true when the next encoded value in {@code src} uses fixed-width
* Float64 encoding, false otherwise.
*/
public static boolean isFixedFloat64(PositionedByteRange src) {
return FIXED_FLOAT64 ==
(-1 == Integer.signum(src.peek()) ? DESCENDING : ASCENDING).apply(src.peek());
}
/**
* Return true when the next encoded value in {@code src} uses Text encoding,
* false otherwise.
*/
public static boolean isText(PositionedByteRange src) {
return TEXT ==
(-1 == Integer.signum(src.peek()) ? DESCENDING : ASCENDING).apply(src.peek());
}
/**
* Return true when the next encoded value in {@code src} uses BlobVar
* encoding, false otherwise.
*/
public static boolean isBlobVar(PositionedByteRange src) {
return BLOB_VAR ==
(-1 == Integer.signum(src.peek()) ? DESCENDING : ASCENDING).apply(src.peek());
}
/**
* Return true when the next encoded value in {@code src} uses BlobCopy
* encoding, false otherwise.
*/
public static boolean isBlobCopy(PositionedByteRange src) {
return BLOB_COPY ==
(-1 == Integer.signum(src.peek()) ? DESCENDING : ASCENDING).apply(src.peek());
}
/**
* Skip {@code buff}'s position forward over one encoded value.
* @return number of bytes skipped.
*/
public static int skip(PositionedByteRange src) {
final int start = src.getPosition();
byte header = src.get();
Order ord = (-1 == Integer.signum(header)) ? DESCENDING : ASCENDING;
header = ord.apply(header);
switch (header) {
case NULL:
case NEG_INF:
return 1;
case NEG_LARGE: /* Large negative number: 0x08, ~E, ~M */
skipVaruint64(src, DESCENDING != ord);
skipSignificand(src, DESCENDING != ord);
return src.getPosition() - start;
case NEG_MED_MIN: /* Medium negative number: 0x13-E, ~M */
case NEG_MED_MIN + 0x01:
case NEG_MED_MIN + 0x02:
case NEG_MED_MIN + 0x03:
case NEG_MED_MIN + 0x04:
case NEG_MED_MIN + 0x05:
case NEG_MED_MIN + 0x06:
case NEG_MED_MIN + 0x07:
case NEG_MED_MIN + 0x08:
case NEG_MED_MIN + 0x09:
case NEG_MED_MAX:
skipSignificand(src, DESCENDING != ord);
return src.getPosition() - start;
case NEG_SMALL: /* Small negative number: 0x14, -E, ~M */
skipVaruint64(src, DESCENDING == ord);
skipSignificand(src, DESCENDING != ord);
return src.getPosition() - start;
case ZERO:
return 1;
case POS_SMALL: /* Small positive number: 0x16, ~-E, M */
skipVaruint64(src, DESCENDING != ord);
skipSignificand(src, DESCENDING == ord);
return src.getPosition() - start;
case POS_MED_MIN: /* Medium positive number: 0x17+E, M */
case POS_MED_MIN + 0x01:
case POS_MED_MIN + 0x02:
case POS_MED_MIN + 0x03:
case POS_MED_MIN + 0x04:
case POS_MED_MIN + 0x05:
case POS_MED_MIN + 0x06:
case POS_MED_MIN + 0x07:
case POS_MED_MIN + 0x08:
case POS_MED_MIN + 0x09:
case POS_MED_MAX:
skipSignificand(src, DESCENDING == ord);
return src.getPosition() - start;
case POS_LARGE: /* Large positive number: 0x22, E, M */
skipVaruint64(src, DESCENDING == ord);
skipSignificand(src, DESCENDING == ord);
return src.getPosition() - start;
case POS_INF:
return 1;
case NAN:
return 1;
case FIXED_INT8:
src.setPosition(src.getPosition() + 1);
return src.getPosition() - start;
case FIXED_INT16:
src.setPosition(src.getPosition() + 2);
return src.getPosition() - start;
case FIXED_INT32:
src.setPosition(src.getPosition() + 4);
return src.getPosition() - start;
case FIXED_INT64:
src.setPosition(src.getPosition() + 8);
return src.getPosition() - start;
case FIXED_FLOAT32:
src.setPosition(src.getPosition() + 4);
return src.getPosition() - start;
case FIXED_FLOAT64:
src.setPosition(src.getPosition() + 8);
return src.getPosition() - start;
case TEXT:
// for null-terminated values, skip to the end.
do {
header = ord.apply(src.get());
} while (header != TERM);
return src.getPosition() - start;
case BLOB_VAR:
// read until we find a 0 in the MSB
do {
header = ord.apply(src.get());
} while ((byte) (header & 0x80) != TERM);
return src.getPosition() - start;
case BLOB_COPY:
if (Order.DESCENDING == ord) {
// if descending, read to termination byte.
do {
header = ord.apply(src.get());
} while (header != TERM);
return src.getPosition() - start;
} else {
// otherwise, just skip to the end.
src.setPosition(src.getLength());
return src.getPosition() - start;
}
default:
throw unexpectedHeader(header);
}
}
/**
* Return the number of encoded entries remaining in {@code buff}. The
* state of {@code buff} is not modified through use of this method.
*/
public static int length(PositionedByteRange buff) {
PositionedByteRange b =
new SimplePositionedMutableByteRange(buff.getBytes(), buff.getOffset(), buff.getLength());
b.setPosition(buff.getPosition());
int cnt = 0;
for (; isEncodedValue(b); skip(b), cnt++)
;
return cnt;
}
}