HADOOP-2126 Use Bob Jenkins' hash for bloom filters

git-svn-id: https://svn.apache.org/repos/asf/lucene/hadoop/trunk/src/contrib/hbase@590875 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Jim Kellerman 2007-11-01 01:48:46 +00:00
parent e91c531235
commit 0c8412cb79
5 changed files with 248 additions and 56 deletions

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@ -22,6 +22,7 @@ Trunk (unreleased changes)
HADOOP-2401 Add convenience put method that takes writable HADOOP-2401 Add convenience put method that takes writable
(Johan Oskarsson via Stack) (Johan Oskarsson via Stack)
HADOOP-2088 Make hbase runnable in $HADOOP_HOME/build(/contrib/hbase) HADOOP-2088 Make hbase runnable in $HADOOP_HOME/build(/contrib/hbase)
HADOOP-2126 Use Bob Jenkins' hash for bloom filters
Branch 0.15 (unreleased changes) Branch 0.15 (unreleased changes)

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@ -23,46 +23,24 @@ import java.io.DataInput;
import java.io.DataOutput; import java.io.DataOutput;
import java.io.IOException; import java.io.IOException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import org.apache.hadoop.io.Text; import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.WritableComparable; import org.apache.hadoop.io.WritableComparable;
import org.apache.hadoop.hbase.util.JenkinsHash;
/** /**
* HRegion information. * HRegion information.
* Contains HRegion id, start and end keys, a reference to this * Contains HRegion id, start and end keys, a reference to this
* HRegions' table descriptor, etc. * HRegions' table descriptor, etc.
*/ */
public class HRegionInfo implements WritableComparable { public class HRegionInfo implements WritableComparable {
private static MessageDigest encoder = null;
static {
try {
if (encoder == null) {
encoder = MessageDigest.getInstance("SHA");
}
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
}
}
/** /**
* @param regionName * @param regionName
* @return the encodedName * @return the encodedName
*/ */
public static String encodeRegionName(final Text regionName) { public static String encodeRegionName(final Text regionName) {
byte[] bytes = null; return String.valueOf(
synchronized (encoder) { JenkinsHash.hash(regionName.getBytes(), regionName.getLength(), 0));
encoder.update(regionName.getBytes(), 0, regionName.getLength());
bytes = encoder.digest();
encoder.reset();
}
StringBuilder sb = new StringBuilder();
for (int i = 0; i < bytes.length; i++) {
sb.append(bytes[i]);
}
return sb.toString();
} }
/** delimiter used between portions of a region name */ /** delimiter used between portions of a region name */

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@ -0,0 +1,234 @@
/**
* Copyright 2007 The Apache Software Foundation
*
* 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;
/**
* lookup3.c, by Bob Jenkins, May 2006, Public Domain.
* <a href="http://burtleburtle.net/bob/c/lookup3.c">lookup3.c</a>
*
* You can use this free for any purpose. It's in the public domain.
* It has no warranty.
*
* Produces 32-bit hash for hash table lookup.
*/
public class JenkinsHash {
private static long INT_MASK = 0x00000000ffffffffL;
private static long BYTE_MASK = 0x00000000000000ffL;
private static long rot(long val, int pos) {
return Long.valueOf(Integer.rotateLeft(
Long.valueOf(val & INT_MASK).intValue(), pos)).longValue() & INT_MASK;
}
/**
* Alternate form for hashing an entire byte array
*
* @param bytes
* @param initval
* @return hash value
*/
public static int hash(byte[] bytes, int initval) {
return hash(bytes, bytes.length, initval);
}
/**
* taken from hashlittle() -- hash a variable-length key into a 32-bit value
*
* @param key the key (the unaligned variable-length array of bytes)
* @param nbytes number of bytes to include in hash
* @param initval can be any integer value
* @return a 32-bit value. Every bit of the key affects every bit of the
* return value. Two keys differing by one or two bits will have totally
* different hash values.
*
* The best hash table sizes are powers of 2. There is no need to do mod a
* prime (mod is sooo slow!). If you need less than 32 bits, use a bitmask.
* For example, if you need only 10 bits, do h = (h & hashmask(10));
* In which case, the hash table should have hashsize(10) elements.
*
* If you are hashing n strings byte[][] k, do it like this:
* for (int i = 0, h = 0; i < n; ++i) h = hash( k[i], h);
*
* By Bob Jenkins, 2006. bob_jenkins@burtleburtle.net. You may use this
* code any way you wish, private, educational, or commercial. It's free.
*
* Use for hash table lookup, or anything where one collision in 2^^32 is
* acceptable. Do NOT use for cryptographic purposes.
*/
public static int hash(byte[] key, int nbytes, int initval) {
int length = nbytes;
long a, b, c; // We use longs because we don't have unsigned ints
a = b = c = (0x00000000deadbeefL + length + initval) & INT_MASK;
int offset = 0;
for (; length > 12; offset += 12, length -= 12) {
a = (a + (key[offset + 0] & BYTE_MASK)) & INT_MASK;
a = (a + (((key[offset + 1] & BYTE_MASK) << 8) & INT_MASK)) & INT_MASK;
a = (a + (((key[offset + 2] & BYTE_MASK) << 16) & INT_MASK)) & INT_MASK;
a = (a + (((key[offset + 3] & BYTE_MASK) << 24) & INT_MASK)) & INT_MASK;
b = (b + (key[offset + 4] & BYTE_MASK)) & INT_MASK;
b = (b + (((key[offset + 5] & BYTE_MASK) << 8) & INT_MASK)) & INT_MASK;
b = (b + (((key[offset + 6] & BYTE_MASK) << 16) & INT_MASK)) & INT_MASK;
b = (b + (((key[offset + 7] & BYTE_MASK) << 24) & INT_MASK)) & INT_MASK;
c = (c + (key[offset + 8] & BYTE_MASK)) & INT_MASK;
c = (c + (((key[offset + 9] & BYTE_MASK) << 8) & INT_MASK)) & INT_MASK;
c = (c + (((key[offset + 10] & BYTE_MASK) << 16) & INT_MASK)) & INT_MASK;
c = (c + (((key[offset + 11] & BYTE_MASK) << 24) & INT_MASK)) & INT_MASK;
/*
* mix -- mix 3 32-bit values reversibly.
* This is reversible, so any information in (a,b,c) before mix() is
* still in (a,b,c) after mix().
*
* If four pairs of (a,b,c) inputs are run through mix(), or through
* mix() in reverse, there are at least 32 bits of the output that
* are sometimes the same for one pair and different for another pair.
*
* This was tested for:
* - pairs that differed by one bit, by two bits, in any combination
* of top bits of (a,b,c), or in any combination of bottom bits of
* (a,b,c).
* - "differ" is defined as +, -, ^, or ~^. For + and -, I transformed
* the output delta to a Gray code (a^(a>>1)) so a string of 1's (as
* is commonly produced by subtraction) look like a single 1-bit
* difference.
* - the base values were pseudorandom, all zero but one bit set, or
* all zero plus a counter that starts at zero.
*
* Some k values for my "a-=c; a^=rot(c,k); c+=b;" arrangement that
* satisfy this are
* 4 6 8 16 19 4
* 9 15 3 18 27 15
* 14 9 3 7 17 3
* Well, "9 15 3 18 27 15" didn't quite get 32 bits diffing for
* "differ" defined as + with a one-bit base and a two-bit delta. I
* used http://burtleburtle.net/bob/hash/avalanche.html to choose
* the operations, constants, and arrangements of the variables.
*
* This does not achieve avalanche. There are input bits of (a,b,c)
* that fail to affect some output bits of (a,b,c), especially of a.
* The most thoroughly mixed value is c, but it doesn't really even
* achieve avalanche in c.
*
* This allows some parallelism. Read-after-writes are good at doubling
* the number of bits affected, so the goal of mixing pulls in the
* opposite direction as the goal of parallelism. I did what I could.
* Rotates seem to cost as much as shifts on every machine I could lay
* my hands on, and rotates are much kinder to the top and bottom bits,
* so I used rotates.
*
* #define mix(a,b,c) \
* { \
* a -= c; a ^= rot(c, 4); c += b; \
* b -= a; b ^= rot(a, 6); a += c; \
* c -= b; c ^= rot(b, 8); b += a; \
* a -= c; a ^= rot(c,16); c += b; \
* b -= a; b ^= rot(a,19); a += c; \
* c -= b; c ^= rot(b, 4); b += a; \
* }
*
* mix(a,b,c);
*/
a = (a - c) & INT_MASK; a ^= rot(c, 4); c = (c + b) & INT_MASK;
b = (b - a) & INT_MASK; b ^= rot(a, 6); a = (a + c) & INT_MASK;
c = (c - b) & INT_MASK; c ^= rot(b, 8); b = (b + a) & INT_MASK;
a = (a - c) & INT_MASK; a ^= rot(c,16); c = (c + b) & INT_MASK;
b = (b - a) & INT_MASK; b ^= rot(a,19); a = (a + c) & INT_MASK;
c = (c - b) & INT_MASK; c ^= rot(b, 4); b = (b + a) & INT_MASK;
}
//-------------------------------- last block: affect all 32 bits of (c)
switch (length) { // all the case statements fall through
case 12:
c = (c + (((key[offset + 11] & BYTE_MASK) << 24) & INT_MASK)) & INT_MASK;
case 11:
c = (c + (((key[offset + 10] & BYTE_MASK) << 16) & INT_MASK)) & INT_MASK;
case 10:
c = (c + (((key[offset + 9] & BYTE_MASK) << 8) & INT_MASK)) & INT_MASK;
case 9:
c = (c + (key[offset + 8] & BYTE_MASK)) & INT_MASK;
case 8:
b = (b + (((key[offset + 7] & BYTE_MASK) << 24) & INT_MASK)) & INT_MASK;
case 7:
b = (b + (((key[offset + 6] & BYTE_MASK) << 16) & INT_MASK)) & INT_MASK;
case 6:
b = (b + (((key[offset + 5] & BYTE_MASK) << 8) & INT_MASK)) & INT_MASK;
case 5:
b = (b + (key[offset + 4] & BYTE_MASK)) & INT_MASK;
case 4:
a = (a + (((key[offset + 3] & BYTE_MASK) << 24) & INT_MASK)) & INT_MASK;
case 3:
a = (a + (((key[offset + 2] & BYTE_MASK) << 16) & INT_MASK)) & INT_MASK;
case 2:
a = (a + (((key[offset + 1] & BYTE_MASK) << 8) & INT_MASK)) & INT_MASK;
case 1:
a = (a + (key[offset + 0] & BYTE_MASK)) & INT_MASK;
break;
case 0:
return Long.valueOf(c & INT_MASK).intValue();
}
/*
* final -- final mixing of 3 32-bit values (a,b,c) into c
*
* Pairs of (a,b,c) values differing in only a few bits will usually
* produce values of c that look totally different. This was tested for
* - pairs that differed by one bit, by two bits, in any combination
* of top bits of (a,b,c), or in any combination of bottom bits of
* (a,b,c).
*
* - "differ" is defined as +, -, ^, or ~^. For + and -, I transformed
* the output delta to a Gray code (a^(a>>1)) so a string of 1's (as
* is commonly produced by subtraction) look like a single 1-bit
* difference.
*
* - the base values were pseudorandom, all zero but one bit set, or
* all zero plus a counter that starts at zero.
*
* These constants passed:
* 14 11 25 16 4 14 24
* 12 14 25 16 4 14 24
* and these came close:
* 4 8 15 26 3 22 24
* 10 8 15 26 3 22 24
* 11 8 15 26 3 22 24
*
* #define final(a,b,c) \
* {
* c ^= b; c -= rot(b,14); \
* a ^= c; a -= rot(c,11); \
* b ^= a; b -= rot(a,25); \
* c ^= b; c -= rot(b,16); \
* a ^= c; a -= rot(c,4); \
* b ^= a; b -= rot(a,14); \
* c ^= b; c -= rot(b,24); \
* }
*
*/
c ^= b; c = (c - rot(b,14)) & INT_MASK;
a ^= c; a = (a - rot(c,11)) & INT_MASK;
b ^= a; b = (b - rot(a,25)) & INT_MASK;
c ^= b; c = (c - rot(b,16)) & INT_MASK;
a ^= c; a = (a - rot(c,4)) & INT_MASK;
b ^= a; b = (b - rot(a,14)) & INT_MASK;
c ^= b; c = (c - rot(b,24)) & INT_MASK;
return Long.valueOf(c & INT_MASK).intValue();
}
}

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@ -49,7 +49,7 @@
*/ */
package org.onelab.filter; package org.onelab.filter;
import java.security.*; import org.apache.hadoop.hbase.util.JenkinsHash;
/** /**
* Implements a hash object that returns a certain number of hashed values. * Implements a hash object that returns a certain number of hashed values.
@ -66,9 +66,6 @@ import java.security.*;
* @see <a href="http://www.itl.nist.gov/fipspubs/fip180-1.htm">SHA-1 algorithm</a> * @see <a href="http://www.itl.nist.gov/fipspubs/fip180-1.htm">SHA-1 algorithm</a>
*/ */
public final class HashFunction{ public final class HashFunction{
/** The SHA-1 algorithm. */
private MessageDigest sha;
/** The number of hashed values. */ /** The number of hashed values. */
private int nbHash; private int nbHash;
@ -83,13 +80,6 @@ public final class HashFunction{
* @param nbHash The number of resulting hashed values. * @param nbHash The number of resulting hashed values.
*/ */
public HashFunction(int maxValue, int nbHash) { public HashFunction(int maxValue, int nbHash) {
try {
sha = MessageDigest.getInstance("SHA-1");
} catch(NoSuchAlgorithmException e) {
throw new AssertionError(e);
}
if(maxValue <= 0) { if(maxValue <= 0) {
throw new IllegalArgumentException("maxValue must be > 0"); throw new IllegalArgumentException("maxValue must be > 0");
} }
@ -102,9 +92,8 @@ public final class HashFunction{
this.nbHash = nbHash; this.nbHash = nbHash;
}//end constructor }//end constructor
/** Clears <i>this</i> hash function. */ /** Clears <i>this</i> hash function. A NOOP */
public void clear(){ public void clear(){
sha.reset();
}//end clear() }//end clear()
/** /**
@ -121,19 +110,9 @@ public final class HashFunction{
if(b.length == 0) { if(b.length == 0) {
throw new IllegalArgumentException("key length must be > 0"); throw new IllegalArgumentException("key length must be > 0");
} }
sha.update(b);
byte[] digestBytes = sha.digest();
int[] result = new int[nbHash]; int[] result = new int[nbHash];
int nbBytePerInt = digestBytes.length/nbHash; for (int i = 0, initval = 0; i < nbHash; i++) {
int offset = 0; result[i] = Math.abs(JenkinsHash.hash(b, initval)) % maxValue;
for(int i = 0; i < nbHash; i++){
int val = 0;
for(int j = offset; j < offset + nbBytePerInt; j++) {
val |=
(digestBytes[offset] & 0xff) << ((nbBytePerInt - 1 - (j - offset)) * 8);
}
result[i] = Math.abs(val) % maxValue;
offset += nbBytePerInt;
} }
return result; return result;
}//end hash() }//end hash()

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@ -75,8 +75,8 @@ public class TestFilter extends TestCase {
bf.add(k3); bf.add(k3);
assertTrue(bf.membershipTest(key)); assertTrue(bf.membershipTest(key));
assertFalse(bf.membershipTest(new StringKey("graknyl"))); assertFalse(bf.membershipTest(new StringKey("graknyl")));
assertTrue(bf.membershipTest(new StringKey("xyzzy"))); // False positive assertFalse(bf.membershipTest(new StringKey("xyzzy")));
assertTrue(bf.membershipTest(new StringKey("abcd"))); // False positive assertFalse(bf.membershipTest(new StringKey("abcd")));
} }
/** Test a CountingBloomFilter /** Test a CountingBloomFilter
@ -92,8 +92,8 @@ public class TestFilter extends TestCase {
bf.add(k3); bf.add(k3);
assertTrue(bf.membershipTest(key)); assertTrue(bf.membershipTest(key));
assertFalse(bf.membershipTest(new StringKey("graknyl"))); assertFalse(bf.membershipTest(new StringKey("graknyl")));
assertTrue(bf.membershipTest(new StringKey("xyzzy"))); // False positive assertFalse(bf.membershipTest(new StringKey("xyzzy")));
assertTrue(bf.membershipTest(new StringKey("abcd"))); // False positive assertFalse(bf.membershipTest(new StringKey("abcd")));
} }
/** Test a DynamicBloomFilter /** Test a DynamicBloomFilter
@ -110,6 +110,6 @@ public class TestFilter extends TestCase {
assertTrue(bf.membershipTest(key)); assertTrue(bf.membershipTest(key));
assertFalse(bf.membershipTest(new StringKey("graknyl"))); assertFalse(bf.membershipTest(new StringKey("graknyl")));
assertFalse(bf.membershipTest(new StringKey("xyzzy"))); assertFalse(bf.membershipTest(new StringKey("xyzzy")));
assertTrue(bf.membershipTest(new StringKey("abcd"))); // False positive assertFalse(bf.membershipTest(new StringKey("abcd")));
} }
}//end class }//end class