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提交 2895f2b5 authored 作者: Thomas Mueller's avatar Thomas Mueller
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LIRS cache: use a better secondary hash function.

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h2/src/test/org/h2/test/store/CalculateHashConstant.java 0 → 100644
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/*
* Copyright 2004-2011 H2 Group. Multiple-Licensed under the H2 License,
* Version 1.0, and under the Eclipse Public License, Version 1.0
* (http://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.test.store;
import java.io.File;
import java.io.FileOutputStream;
import java.math.BigInteger;
import java.util.Arrays;
import java.util.BitSet;
import java.util.Collections;
import java.util.HashSet;
import java.util.Random;
import java.util.Set;
import java.util.concurrent.atomic.AtomicInteger;
import org.h2.security.AES;
/**
* Calculate the constant for the secondary hash function, so that the hash
* function mixes the input bits as much as possible.
*/
public class CalculateHashConstant implements Runnable {
private static BitSet primeNumbers = new BitSet();
private static int[] randomValues;
private static AtomicInteger high = new AtomicInteger(0x20);
private static Set<Integer> candidates = Collections.synchronizedSet(new HashSet<Integer>());
private int constant;
private int[] fromTo = new int[32 * 32];
private AES aes = new AES();
{
aes.setKey("Hello Welt Hallo Welt".getBytes());
}
private byte[] data = new byte[16];
/**
* Run just this test.
*
* @param args ignored
*/
public static void main(String... args) throws Exception {
for (int i = 0x0; i < 0x10000; i++) {
if (BigInteger.valueOf(i).isProbablePrime(20)) {
primeNumbers.set(i);
}
}
randomValues = getRandomValues(1000, 1);
Random r = new Random(1);
for (int i = 0; i < randomValues.length; i++) {
randomValues[i] = r.nextInt();
}
Thread[] threads = new Thread[8];
for (int i = 0; i < 8; i++) {
threads[i] = new Thread(new CalculateHashConstant());
threads[i].start();
}
for (int i = 0; i < 8; i++) {
threads[i].join();
}
int finalCount = 10000;
int[] randomValues = getRandomValues(finalCount, 10);
System.out.println();
System.out.println("AES:");
CalculateHashConstant test = new CalculateHashConstant();
int[] minMax;
int av = 0;
test = new CalculateHashConstant() {
public int hash(int x) {
return secureHash(x);
}
};
minMax = test.getDependencies(test, randomValues);
System.out.println("Dependencies: " + minMax[0] + ".." + minMax[1]);
av = 0;
for (int j = 0; j < 100; j++) {
av += test.getAvalanche(test, randomValues[j]);
}
System.out.println("AvalancheSum: " + av);
minMax = test.getEffect(test, finalCount * 10, 11);
System.out.println("Effect: " + minMax[0] + ".." + minMax[1]);
test = new CalculateHashConstant();
int best = 0;
int dist = Integer.MAX_VALUE;
for (int i : new int[] {
0x10b5383, 0x10b65f3, 0x1170d8b, 0x118e97b,
0x1190d8b, 0x11ab37d, 0x11c65f3, 0x1228357, 0x122a837,
0x122a907, 0x12b24f7, 0x12c4d05, 0x131a907, 0x131afa3,
0x131b683, 0x132927d, 0x13298fb, 0x134a837, 0x13698fb,
0x136afa3, 0x138da0b, 0x138f563, 0x13957c5, 0x1470b1b,
0x148e97b, 0x14b5827, 0x150a837, 0x151c97d, 0x151ed3d,
0x1525707, 0x1534b07, 0x1570b9b, 0x158d283, 0x15933eb,
0x15947cb, 0x15b5f33, 0x166da7d, 0x16af4a3, 0x16b0b47,
0x16ca907, 0x16ee585, 0x17609a3, 0x1770b23, 0x17a2507,
0x1855383, 0x18b5383, 0x18d9f3b, 0x18db37d, 0x1922507,
0x1960d3d, 0x1990d4f, 0x1991a7b, 0x19b4b07, 0x19b5383,
0x19d9f3b, 0x1a2b683, 0x1a40d8b, 0x1a4b08d, 0x1a698fb,
0x1a6cf9b, 0x1a714bd, 0x1a89283, 0x1aa86c3, 0x1b14e0b,
0x1b196fb, 0x1b1f2bd, 0x1b30b1b, 0x1b32507, 0x1b44f75,
0x1b50ce3, 0x1b5927d, 0x1b6afa3, 0x1b8a6f7, 0x1baa907,
0x1bb2507, 0x1c2a6f7, 0x1c48357, 0x1c957c5, 0x1cb8357,
0x1cc4d05, 0x1cd9283, 0x1ce2683, 0x1d198fb, 0x1d45383,
0x1d4ed3d, 0x1d598fb, 0x1d8d283, 0x1d95f3b, 0x1db24f7,
0x1db5383, 0x1db997d, 0x1e465f3, 0x1f198fb, 0x1f2b683,
0x1f4a837, 0x20998fb, 0x20eb683, 0x214a907, 0x2152ec3,
0x2169f3b, 0x216ed3d, 0x218a6f7, 0x2194b07, 0x21c5707,
0x22158f9, 0x2250d4f, 0x2252507, 0x2297d63, 0x22aed3d,
0x22b5383, 0x22ca7d7, 0x23596fb, 0x23633eb, 0x23957c5,
0x23b24f7, 0x2476e7b, 0x24a57c5, 0x24b5383, 0x252ebb7,
0x254f547, 0x258d283, 0x2595707, 0x25957c5, 0x25c5707,
0x262a837, 0x2638357, 0x2645827, 0x265f2bd, 0x266f2bd,
0x268a6f7, 0x26a0b23, 0x26cce7b, 0x2730b47, 0x2750b23,
0x275b683, 0x28465f3, 0x2850d4f, 0x28d0b47, 0x291c97d,
0x2922507, 0x2941a7b, 0x294a907, 0x294b683, 0x295f2bd,
0x2969f3b, 0x296cfb5, 0x2976e7b, 0x2989f3b, 0x29933eb,
0x29a907, 0x29b2683, 0x29c8357, 0x29d9f3b, 0x2a1a907,
0x2a45383, 0x2a52f75, 0x2a85383, 0x2aacf9b, 0x2ac5f33,
0x2ad1a7b, 0x2ad2507, 0x2b2b683, 0x2b3af8b, 0x2b63e65,
0x2b8da0b, 0x2b9416b, 0x2bb24f7, 0x2c4b37d, 0x2c6cf9b,
0x2ca0d13, 0x2cb2507, 0x2cb2983, 0x2cce97b, 0x2ce305b,
0x2ceb683, 0x2d14e0b, 0x2d1a7b, 0x2d2507, 0x2d2af8b, 0x2d41a7b,
0x2d7467b, 0x2d8d283, 0x2d960bb, 0x2dab683, 0x2db5f33,
0x2dd5f3b, 0x2e2ebb7, 0x2e32e85, 0x2e6a7c9, 0x2e85383,
0x2e8e585, 0x2e960bb, 0x2f3afa3, 0x2f62fa5, 0x30e8639,
0x3132983, 0x3150d4f, 0x315cf9b, 0x3162fa5, 0x316ce7b,
0x31914bd, 0x31a927d, 0x31ea83b, 0x31f1a7b, 0x3285383,
0x3289f3b, 0x32933eb, 0x329afa3, 0x32a5707, 0x32a6f7,
0x32ae585, 0x32b1a7b, 0x32b4b07, 0x32b5383, 0x32b5827,
0x32ee97b, 0x330be5b, 0x3314e0b, 0x33317a5, 0x333af8b,
0x335afa3, 0x335b37d, 0x3371a7b, 0x3393e65, 0x339a907,
0x33d1a7b, 0x3425707, 0x34606d3, 0x347b37d, 0x349305b,
0x34b2683, 0x34b683, 0x34dafa3, 0x34ec97d, 0x3512683,
0x3515383, 0x3515707, 0x352e585, 0x353af75, 0x354b683,
0x355ed3d, 0x3562fa5, 0x356f2bd, 0x3574135, 0x359afa3,
0x35ad283, 0x35b2683, 0x35d9f3b, 0x361ed3d, 0x3671a7b,
0x3672fa5, 0x36cbe5b, 0x37598fb, 0x375c97d, 0x37ca907,
0x389a907, 0x38c65f3, 0x38cf547, 0x38e33eb, 0x3931a7b,
0x39598fb, 0x3979283, 0x398ce7b, 0x39933eb, 0x39960bb,
0x39b1a87, 0x39b5f33, 0x39c8333, 0x39d2507, 0x3a55827,
0x3a89f3b, 0x3a9f2bd, 0x3ab2983, 0x3aba7d7, 0x3adafa3,
0x3b196fb, 0x3b29f3b, 0x3b32e85, 0x3b4e97b, 0x3b9260b,
0x3bb5383, 0x3c4a907, 0x3c4c97d, 0x3c6cf9b, 0x3c95707,
0x3ca57c5, 0x3caa907, 0x3cb2683, 0x3cb2983, 0x3ce305b,
0x3d158f9, 0x3d15f65, 0x3d2c685, 0x3d34b07, 0x3d76e7b,
0x3d8d283, 0x3d8f563, 0x3dae585, 0x3dd60bb, 0x3e5c97d,
0x3eb2683, 0x3eb467b, 0x3f5927d, 0x3f596fb, 0x414e585,
0x424b37d, 0x425afa3, 0x42e5383, 0x4315f65, 0x4325707,
0x434b683, 0x4485383, 0x448e97b, 0x44996fb, 0x44b3e65,
0x44eafa3, 0x4515707, 0x4532983, 0x4533e65, 0x453e585,
0x454b683, 0x454e97b, 0x45598fb, 0x455a907, 0x456f2bd,
0x4595f3b, 0x45d9f3b, 0x461a907, 0x462a837, 0x4645827,
0x46a2fa5, 0x46aa213, 0x46acf9b, 0x46b2507, 0x46ba837,
0x4715707, 0x472f547, 0x475c97d, 0x4799283, 0x47a0d3d,
0x47ca907, 0x482a907, 0x4835707, 0x4844b07, 0x48933eb,
0x48ab683, 0x48b5827, 0x491d0e7, 0x4922507, 0x4929f3b,
0x492e97b, 0x4933eb, 0x4934b07, 0x49598fb, 0x495f2bd,
0x4962fa5, 0x496b683, 0x499da7d, 0x499ed3d, 0x49ab683,
0x4a2f547, 0x4a32e85, 0x4a5f2bd, 0x4a696fb, 0x4aacf9b,
0x4ab5383, 0x4aba837, 0x4aeb683, 0x4aeda7d, 0x4b0f69b,
0x4b12fa5, 0x4b13e65, 0x4b5a907, 0x4b5afa3, 0x4b8afa3,
0x4b8e585, 0x4b8f58d, 0x4ba5707, 0x4bc5707, 0x4c2a837,
0x4c5b37d, 0x4c5ed3d, 0x4c67d8d, 0x4c8f58d, 0x4c933eb,
0x4caec5d, 0x4cd17a5, 0x4ce305b, 0x4cf179b, 0x4cfc979,
0x4d0be5b, 0x4d1ed3d, 0x4d2507, 0x4d30d8b, 0x4d32983,
0x4d40ae5, 0x4d40d8b, 0x4d4f697, 0x4d8e97b, 0x4d9f2bd,
0x4da0d3d, 0x4dce585, 0x4dd1a7b, 0x4df467b, 0x4e25707,
0x4e4c97d, 0x4e63833, 0x4eb1a7b, 0x4eb2683, 0x4eb683,
0x4ece97b, 0x4eee585, 0x4f13e65, 0x4f6afa3, 0x504b37d,
0x50e2683, 0x50eb683, 0x5132e85, 0x514b08d, 0x516e97b,
0x5198fb, 0x519f2bd, 0x51ab37d, 0x51b2683, 0x522a837,
0x5232983, 0x52465f3, 0x52660bb, 0x528b3ed, 0x5294193,
0x5294e0b, 0x52a57c5, 0x52eaf8b, 0x52eda7d, 0x52ee585,
0x530be93, 0x5314e0b, 0x532e97b, 0x5340b1b, 0x535279d,
0x53598fb, 0x5429283, 0x54a0b23, 0x54b24f7, 0x54d17a5,
0x54eb683, 0x55198fb, 0x5523e65, 0x55357c5, 0x553e585,
0x555cf9b, 0x55a24f7, 0x55d2507, 0x55eda7d, 0x5645f33,
0x567ecdd, 0x56a0d3d, 0x571305b, 0x5714e0b, 0x574a837,
0x57a5707, 0x57b65f3, 0x57c65f3, 0x5879283, 0x58ba837,
0x58ded3d, 0x59598fb, 0x5989f3b, 0x598a83b, 0x59957c5,
0x599f2bd, 0x59bd37b, 0x59ca907, 0x59d9f3b, 0x59e60bb,
0x5a4b37d, 0x5a64133, 0x5a6cf9b, 0x5a89f3b, 0x5a927d,
0x5a94165, 0x5a94193, 0x5a958f9, 0x5a960bb, 0x5aac3d3,
0x5ad98fb, 0x5ae98fb, 0x5b198fb, 0x5b2e97b, 0x5b40b5d,
0x5b5c97d, 0x5b75f33, 0x5b8afa3, 0x5b94e0b, 0x5ba24f7,
0x5cab683, 0x5cb0b47, 0x5cb0ce5, 0x5cba7d7, 0x5d0be93,
0x5d12683, 0x5d20cc7, 0x5d3e585, 0x5e2a907, 0x5e3467b,
0x5e5c97d, 0x5e89f3b, 0x5eb2683, 0x5f598fb, 0x5f5a907,
0x676e7b, 0x695705, 0x6b2983, 0x8998fb, 0x8ab683, 0x94a837,
0x95f2bd, 0x991a7b, 0x995705, 0xa714bd, 0xa90a63, 0xa933eb,
0xad98fb, 0xb365f3, 0xb4a907, 0xb598fb, 0xb5c97d, 0xb5ed3d,
0xb698fb, 0xbd279d, 0xc55383, 0xc7b37d, 0xc8da0b, 0xca0b23,
0xca96fb, 0xcacf9b, 0xcb2683, 0xcd1a7b, 0xd45383, 0xd4e585,
0xd6afa3, 0xd94e0b, 0xdaf547, 0xdb1a7b, 0xdca907, 0xdd2e85,
0xe6da7d, 0xe94e0b, 0xe9a907, 0xeca7d7, 0xf4a837
}) {
// for(int i : candidates) {
test.constant = i;
System.out.println();
System.out.println("Constant: 0x" + Integer.toHexString(i));
minMax = test.getDependencies(test, randomValues);
System.out.println("Dependencies: " + minMax[0] + ".." + minMax[1]);
int d = minMax[1] - minMax[0];
av = 0;
for (int j = 0; j < 100; j++) {
av += test.getAvalanche(test, randomValues[j]);
}
System.out.println("AvalancheSum: " + av);
minMax = test.getEffect(test, finalCount * 10, 11);
System.out.println("Effect: " + minMax[0] + ".." + minMax[1]);
d += minMax[1] - minMax[0];
if (d < dist) {
dist = d;
best = i;
}
}
System.out.println();
System.out.println("Best constant: 0x" + Integer.toHexString(best));
test.constant = best;
long collisions = test.getCollisionCount();
System.out.println("Collisions: " + collisions);
}
/**
* Store a random file to be analyzed by the Diehard test.
*/
void storeRandomFile() throws Exception {
File f = new File(System.getProperty("user.home") + "/temp/rand.txt");
FileOutputStream out = new FileOutputStream(f);
CalculateHashConstant test = new CalculateHashConstant();
// Random r = new Random(1);
byte[] buff = new byte[4];
// tt.constant = 0x29a907;
for (int i = 0; i < 10000000 / 8; i++) {
int y = test.hash(i);
// int y = r.nextInt();
writeInt(buff, 0, y);
out.write(buff);
}
out.close();
}
private static int[] getRandomValues(int count, int seed) {
int[] values = new int[count];
Random r = new Random(seed);
for (int i = 0; i < count; i++) {
values[i] = r.nextInt();
}
return values;
}
public void run() {
while (true) {
int currentHigh = high.getAndIncrement();
// if (currentHigh > 0x2d) {
if (currentHigh > 0xffff) {
break;
}
System.out.println("testing " + Integer.toHexString(currentHigh) + "....");
addCandidates(currentHigh);
}
}
private void addCandidates(int currentHigh) {
for (int low = 0; low <= 0xffff; low++) {
// the lower 16 bits have to be a prime number
if (!primeNumbers.get(low)) {
continue;
}
int i = (currentHigh << 16) | low;
constant = i;
// after one bit changes in the input,
// on average 16 bits of the output change
int av = getAvalanche(this, 0);
if (Math.abs(av - 16000) > 130) {
continue;
}
av = getAvalanche(this, 0xffffffff);
if (Math.abs(av - 16000) > 130) {
continue;
}
long es = getEffectSquare(this, randomValues);
if (es > 259000) {
continue;
}
int[] minMax = getEffect(this, 10000, 1);
if (!isWithin(4800, 5200, minMax)) {
continue;
}
minMax = getDependencies(this, randomValues);
// aes: 7788..8183
if (!isWithin(7720, 8240, minMax)) {
continue;
}
minMax = getEffect(this, 100000, 3);
if (!isWithin(49000, 51000, minMax)) {
continue;
}
System.out.println(Integer.toHexString(i) +
" hit av:" + av + " bits:" + Integer.bitCount(i) + " es:" + es + " prime:" +
BigInteger.valueOf(i).isProbablePrime(15));
candidates.add(i);
}
}
long getCollisionCount() {
BitSet set = new BitSet();
BitSet neg = new BitSet();
long collisions = 0;
long t = System.currentTimeMillis();
for (int i = Integer.MIN_VALUE; i != Integer.MAX_VALUE; i++) {
int x = hash(i);
if (x >= 0) {
if (set.get(x)) {
collisions++;
} else {
set.set(x);
}
} else {
x = -(x + 1);
if (neg.get(x)) {
collisions++;
} else {
neg.set(x);
}
}
if ((i & 0xfffff) == 0) {
long n = System.currentTimeMillis();
if (n - t > 5000) {
System.out.println(Integer.toHexString(constant) + " " +
Integer.toHexString(i) + " collisions: " + collisions);
t = n;
}
}
}
return collisions;
}
private static boolean isWithin(int min, int max, int[] range) {
return range[0] >= min && range[1] <= max;
}
/**
* Calculate how much the bit changes (output bits that change if an input
* bit is changed) are independent of each other.
*
* @param the hash object
* @param values the values to test with
* @return the minimum and maximum number of output bits that are changed in
* combination with another output bit
*/
int[] getDependencies(CalculateHashConstant h, int[] values) {
Arrays.fill(fromTo, 0);
for (int x : values) {
for (int shift = 0; shift < 32; shift++) {
int x1 = h.hash(x);
int x2 = h.hash(x ^ (1 << shift));
int x3 = x1 ^ x2;
for (int s = 0; s < 32; s++) {
if ((x3 & (1 << s)) != 0) {
for (int s2 = 0; s2 < 32; s2++) {
if (s == s2) {
continue;
}
if ((x3 & (1 << s2)) != 0) {
fromTo[s * 32 + s2]++;
}
}
}
}
}
}
int a = Integer.MAX_VALUE, b = Integer.MIN_VALUE;
for (int x : fromTo) {
if (x == 0) {
continue;
}
if (x < a) {
a = x;
}
if (x > b) {
b = x;
}
}
return new int[] {a, b};
}
/**
* Calculate the number of bits that change if a single bit is changed
* multiplied by 1000 (expected: 16000 +/- 5%).
*
* @param the hash object
* @param value the base value
* @return the number of bit changes multiplied by 1000
*/
int getAvalanche(CalculateHashConstant h, int value) {
int changedBitsSum = 0;
for (int i = 0; i < 32; i++) {
int x = value ^ (1 << i);
for (int shift = 0; shift < 32; shift++) {
int x1 = h.hash(x);
int x2 = h.hash(x ^ (1 << shift));
int x3 = x1 ^ x2;
changedBitsSum += Integer.bitCount(x3);
}
}
return changedBitsSum * 1000 / 32 / 32;
}
/**
* Calculate the sum of the square of the distance to the expected
* probability that an output bit changes if an input bit is changed. The
* lower the value, the better.
*
* @param the hash object
* @param values the values to test with
* @return sum(distance^2)
*/
long getEffectSquare(CalculateHashConstant h, int[] values) {
Arrays.fill(fromTo, 0);
int total = 0;
for (int x : values) {
for (int shift = 0; shift < 32; shift++) {
int x1 = h.hash(x);
int x2 = h.hash(x ^ (1 << shift));
int x3 = x1 ^ x2;
for (int s = 0; s < 32; s++) {
if ((x3 & (1 << s)) != 0) {
fromTo[shift * 32 + s]++;
total++;
}
}
}
}
long sqDist = 0;
int expected = total / 32 / 32;
for (int x : fromTo) {
int dist = Math.abs(x - expected);
sqDist += dist * dist;
}
return sqDist;
}
/**
* Calculate if the all bit changes (that an output bit changes if an input
* bit is changed) are within a certain range.
*
* @param h the hash object
* @param count the number of values to test
* @param seed the random seed
* @return the minimum and maximum value of all input-to-output bit changes
*/
int[] getEffect(CalculateHashConstant h, int count, int seed) {
Random r = new Random();
r.setSeed(seed);
Arrays.fill(fromTo, 0);
for (int i = 0; i < count; i++) {
int x = r.nextInt();
for (int shift = 0; shift < 32; shift++) {
int x1 = h.hash(x);
int x2 = h.hash(x ^ (1 << shift));
int x3 = x1 ^ x2;
for (int s = 0; s < 32; s++) {
if ((x3 & (1 << s)) != 0) {
fromTo[shift * 32 + s]++;
}
}
}
}
int a = Integer.MAX_VALUE, b = Integer.MIN_VALUE;
for (int x : fromTo) {
if (x < a) {
a = x;
}
if (x > b) {
b = x;
}
}
return new int[] {a, b};
}
/**
* The hash method.
*
* @param x the input
* @return the output
*/
int hash(int x) {
// return secureHash(x);
x = ((x >>> 16) ^ x) * constant;
x = ((x >>> 16) ^ x) * constant;
x = (x >>> 16) ^ x;
return x;
}
/**
* Calculate a hash using AES.
*
* @param x the input
* @return the output
*/
int secureHash(int x) {
Arrays.fill(data, (byte) 0);
writeInt(data, 0, x);
aes.encrypt(data, 0, 16);
return readInt(data, 0);
}
private static void writeInt(byte[] buff, int pos, int x) {
buff[pos++] = (byte) (x >> 24);
buff[pos++] = (byte) (x >> 16);
buff[pos++] = (byte) (x >> 8);
buff[pos++] = (byte) x;
}
private static int readInt(byte[] buff, int pos) {
return (buff[pos++] << 24) + ((buff[pos++] & 0xff) << 16) +
((buff[pos++] & 0xff) << 8) + (buff[pos] & 0xff);
}
}
h2/src/tools/org/h2/dev/store/cache/CacheLIRS.java
浏览文件 @ 2895f2b5
/* /*
* Copyright 2004-2012 H2 Group. Multiple-Licensed under the H2 License, * Copyright 2004-2011 H2 Group. Multiple-Licensed under the H2 License,
* Version 1.0, and under the Eclipse Public License, Version 1.0 * Version 1.0, and under the Eclipse Public License, Version 1.0
* (http://h2database.com/html/license.html). * (http://h2database.com/html/license.html).
* Initial Developer: H2 Group * Initial Developer: H2 Group
...@@ -55,13 +55,14 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> { ...@@ -55,13 +55,14 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> {
*/ */
private int averageMemory; private int averageMemory;
private Segment<K, V>[] segments; private final Segment<K, V>[] segments;
private int segmentCount; private final int segmentCount;
private int segmentShift; private final int segmentShift;
private int segmentMask; private final int segmentMask;
private final int stackMoveDistance; private final int stackMoveDistance;
@SuppressWarnings("unchecked")
private CacheLIRS(long maxMemory, int averageMemory, int segmentCount, int stackMoveDistance) { private CacheLIRS(long maxMemory, int averageMemory, int segmentCount, int stackMoveDistance) {
setMaxMemory(maxMemory); setMaxMemory(maxMemory);
setAverageMemory(averageMemory); setAverageMemory(averageMemory);
...@@ -69,20 +70,22 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> { ...@@ -69,20 +70,22 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> {
throw new IllegalArgumentException("The segment count must be a power of 2, is " + segmentCount); throw new IllegalArgumentException("The segment count must be a power of 2, is " + segmentCount);
} }
this.segmentCount = segmentCount; this.segmentCount = segmentCount;
this.segmentMask = segmentCount - 1;
this.stackMoveDistance = stackMoveDistance; this.stackMoveDistance = stackMoveDistance;
segments = new Segment[segmentCount];
clear(); clear();
this.segmentShift = Integer.numberOfTrailingZeros(segments[0].entries.length);
} }
@SuppressWarnings("unchecked") /**
* Remove all entries.
*/
public void clear() { public void clear() {
segmentMask = segmentCount - 1; long max = Math.max(1, maxMemory / segmentCount);
segments = new Segment[segmentCount];
for (int i = 0; i < segmentCount; i++) { for (int i = 0; i < segmentCount; i++) {
long max = Math.max(1, maxMemory / segmentCount);
segments[i] = new Segment<K, V>( segments[i] = new Segment<K, V>(
max, averageMemory, stackMoveDistance); max, averageMemory, stackMoveDistance);
} }
segmentShift = Integer.numberOfTrailingZeros(segments[0].sizeMapArray());
} }
private Entry<K, V> find(Object key) { private Entry<K, V> find(Object key) {
...@@ -91,8 +94,8 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> { ...@@ -91,8 +94,8 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> {
} }
/** /**
* Check whether there is a resident entry for the given key. This method * Check whether there is a resident entry for the given key. This
* does not adjust the internal state of the cache. * method does not adjust the internal state of the cache.
* *
* @param key the key (may not be null) * @param key the key (may not be null)
* @return true if there is a resident entry * @return true if there is a resident entry
...@@ -115,14 +118,14 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> { ...@@ -115,14 +118,14 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> {
} }
/** /**
* Add an entry to the cache. The entry may or may not exist in the cache * Add an entry to the cache. The entry may or may not exist in the
* yet. This method will usually mark unknown entries as cold and known * cache yet. This method will usually mark unknown entries as cold and
* entries as hot. * known entries as hot.
* *
* @param key the key (may not be null) * @param key the key (may not be null)
* @param value the value (may not be null) * @param value the value (may not be null)
* @param memory the memory used for the given entry * @param memory the memory used for the given entry
* @return the old value, or null if there is no resident entry * @return the old value, or null if there was no resident entry
*/ */
public V put(K key, V value, int memory) { public V put(K key, V value, int memory) {
int hash = getHash(key); int hash = getHash(key);
...@@ -134,17 +137,18 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> { ...@@ -134,17 +137,18 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> {
* *
* @param key the key (may not be null) * @param key the key (may not be null)
* @param value the value (may not be null) * @param value the value (may not be null)
* @return the old value, or null if there is no resident entry * @return the old value, or null if there was no resident entry
*/ */
public V put(K key, V value) { public V put(K key, V value) {
return put(key, value, averageMemory); return put(key, value, averageMemory);
} }
/** /**
* Remove an entry. Both resident and non-resident entries can be removed. * Remove an entry. Both resident and non-resident entries can be
* removed.
* *
* @param key the key (may not be null) * @param key the key (may not be null)
* @return the old value, or null if there is no resident entry * @return the old value, or null if there was no resident entry
*/ */
public synchronized V remove(Object key) { public synchronized V remove(Object key) {
int hash = getHash(key); int hash = getHash(key);
...@@ -164,8 +168,8 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> { ...@@ -164,8 +168,8 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> {
/** /**
* Get the value for the given key if the entry is cached. This method * Get the value for the given key if the entry is cached. This method
* adjusts the internal state of the cache, to ensure commonly used entries * adjusts the internal state of the cache sometimes, to ensure commonly
* stay in the cache. * used entries stay in the cache.
* *
* @param key the key (may not be null) * @param key the key (may not be null)
* @return the value, or null if there is no resident entry * @return the value, or null if there is no resident entry
...@@ -180,12 +184,20 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> { ...@@ -180,12 +184,20 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> {
return segments[segmentIndex]; return segments[segmentIndex];
} }
/**
* Get the hash code for the given key. The hash code is
* further enhanced to spread the values more evenly.
*
* @param key the key
* @return the hash code
*/
static int getHash(Object key) { static int getHash(Object key) {
int hash = key.hashCode(); int hash = key.hashCode();
// Doug Lea's supplemental secondaryHash function (inlined) // a supplemental secondary hash function
// to protect against hash codes that don't differ in low order bits // to protect against hash codes that don't differ much
hash ^= (hash >>> 20) ^ (hash >>> 12); hash = ((hash >>> 16) ^ hash) * 0x45d9f3b;
hash ^= (hash >>> 7) ^ (hash >>> 4); hash = ((hash >>> 16) ^ hash) * 0x45d9f3b;
hash = (hash >>> 16) ^ hash;
return hash; return hash;
} }
...@@ -197,15 +209,15 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> { ...@@ -197,15 +209,15 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> {
public long getUsedMemory() { public long getUsedMemory() {
long x = 0; long x = 0;
for (Segment<K, V> s : segments) { for (Segment<K, V> s : segments) {
x += s.getUsedMemory(); x += s.usedMemory;
} }
return x; return x;
} }
/** /**
* Set the maximum memory this cache should use. This will not immediately * Set the maximum memory this cache should use. This will not
* cause entries to get removed however; it will only change the limit. To * immediately cause entries to get removed however; it will only change
* resize the internal array, call the clear method. * the limit. To resize the internal array, call the clear method.
* *
* @param maxMemory the maximum size (1 or larger) * @param maxMemory the maximum size (1 or larger)
*/ */
...@@ -223,8 +235,8 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> { ...@@ -223,8 +235,8 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> {
} }
/** /**
* Set the average memory used per entry. It is used to calculate the length * Set the average memory used per entry. It is used to calculate the
* of the internal array. * length of the internal array.
* *
* @param averageMemory the average memory used (1 or larger) * @param averageMemory the average memory used (1 or larger)
*/ */
...@@ -261,7 +273,7 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> { ...@@ -261,7 +273,7 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> {
/** /**
* Create a new cache with the given number of entries, and the default * Create a new cache with the given number of entries, and the default
* settings (an average size of 1 per entry, 16 segments, and stack move * settings (an average size of 1 per entry, 16 segments, and stack move
* distance equals to the max entry size divided by 100). * distance equals to the maximum number of entries divided by 100).
* *
* @param maxEntries the maximum number of entries * @param maxEntries the maximum number of entries
* @return the cache * @return the cache
...@@ -319,7 +331,7 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> { ...@@ -319,7 +331,7 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> {
public int sizeNonResident() { public int sizeNonResident() {
int x = 0; int x = 0;
for (Segment<K, V> s : segments) { for (Segment<K, V> s : segments) {
x += s.sizeNonResident(); x += s.queue2Size;
} }
return x; return x;
} }
...@@ -332,7 +344,7 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> { ...@@ -332,7 +344,7 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> {
public int sizeMapArray() { public int sizeMapArray() {
int x = 0; int x = 0;
for (Segment<K, V> s : segments) { for (Segment<K, V> s : segments) {
x += s.sizeMapArray(); x += s.entries.length;
} }
return x; return x;
} }
...@@ -345,7 +357,7 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> { ...@@ -345,7 +357,7 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> {
public int sizeHot() { public int sizeHot() {
int x = 0; int x = 0;
for (Segment<K, V> s : segments) { for (Segment<K, V> s : segments) {
x += s.sizeHot(); x += s.mapSize - s.queueSize - s.queue2Size;
} }
return x; return x;
} }
...@@ -358,7 +370,7 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> { ...@@ -358,7 +370,7 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> {
public int size() { public int size() {
int x = 0; int x = 0;
for (Segment<K, V> s : segments) { for (Segment<K, V> s : segments) {
x += s.size(); x += s.mapSize - s.queue2Size;
} }
return x; return x;
} }
...@@ -388,56 +400,56 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> { ...@@ -388,56 +400,56 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> {
static class Segment<K, V> { static class Segment<K, V> {
/** /**
* How many other item are to be moved to the top of the stack before * The number of (hot, cold, and non-resident) entries in the map.
* the current item is moved.
*/ */
private final int stackMoveDistance; int mapSize;
/** /**
* The maximum memory this cache should use. * The size of the LIRS queue for resident cold entries.
*/ */
private long maxMemory; int queueSize;
/** /**
* The average memory used by one entry. * The size of the LIRS queue for non-resident cold entries.
*/ */
private int averageMemory; int queue2Size;
/** /**
* The currently used memory. * The map array. The size is always a power of 2.
*/ */
private long usedMemory; Entry<K, V>[] entries;
/** /**
* The number of (hot, cold, and non-resident) entries in the map. * The currently used memory.
*/ */
private int mapSize; long usedMemory;
/** /**
* The bit mask that is applied to the key hash code to get the index in the * How many other item are to be moved to the top of the stack before
* map array. The mask is the length of the array minus one. * the current item is moved.
*/ */
private int mask; private final int stackMoveDistance;
/** /**
* The LIRS stack size. * The maximum memory this cache should use.
*/ */
private int stackSize; private long maxMemory;
/** /**
* The size of the LIRS queue for resident cold entries. * The average memory used by one entry.
*/ */
private int queueSize; private int averageMemory;
/** /**
* The size of the LIRS queue for non-resident cold entries. * The bit mask that is applied to the key hash code to get the index in the
* map array. The mask is the length of the array minus one.
*/ */
private int queue2Size; private int mask;
/** /**
* The map array. The size is always a power of 2. * The LIRS stack size.
*/ */
private Entry<K, V>[] entries; private int stackSize;
/** /**
* The stack of recently referenced elements. This includes all hot entries, * The stack of recently referenced elements. This includes all hot entries,
...@@ -475,7 +487,7 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> { ...@@ -475,7 +487,7 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> {
clear(); clear();
} }
synchronized void clear() { private void clear() {
// calculate the size of the map array // calculate the size of the map array
// assume a fill factor of at most 80% // assume a fill factor of at most 80%
...@@ -509,16 +521,27 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> { ...@@ -509,16 +521,27 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> {
stackSize = queueSize = queue2Size = 0; stackSize = queueSize = queue2Size = 0;
} }
V peek(K key, int hash) { /**
Entry<K, V> e = find(key, hash); * Get the memory used for the given key.
return e == null ? null : e.value; *
} * @param key the key (may not be null)
* @param hash the hash
* @return the memory, or 0 if there is no resident entry
*/
int getMemory(K key, int hash) { int getMemory(K key, int hash) {
Entry<K, V> e = find(key, hash); Entry<K, V> e = find(key, hash);
return e == null ? 0 : e.memory; return e == null ? 0 : e.memory;
} }
/**
* Get the value for the given key if the entry is cached. This method
* adjusts the internal state of the cache sometimes, to ensure commonly
* used entries stay in the cache.
*
* @param key the key (may not be null)
* @param hash the hash
* @return the value, or null if there is no resident entry
*/
V get(Object key, int hash) { V get(Object key, int hash) {
Entry<K, V> e = find(key, hash); Entry<K, V> e = find(key, hash);
if (e == null) { if (e == null) {
...@@ -586,6 +609,17 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> { ...@@ -586,6 +609,17 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> {
} }
} }
/**
* Add an entry to the cache. The entry may or may not exist in the
* cache yet. This method will usually mark unknown entries as cold and
* known entries as hot.
*
* @param key the key (may not be null)
* @param hash the hash
* @param value the value (may not be null)
* @param memory the memory used for the given entry
* @return the old value, or null if there was no resident entry
*/
synchronized V put(K key, int hash, V value, int memory) { synchronized V put(K key, int hash, V value, int memory) {
if (value == null) { if (value == null) {
throw new NullPointerException(); throw new NullPointerException();
...@@ -616,6 +650,14 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> { ...@@ -616,6 +650,14 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> {
return old; return old;
} }
/**
* Remove an entry. Both resident and non-resident entries can be
* removed.
*
* @param key the key (may not be null)
* @param hash the hash
* @return the old value, or null if there was no resident entry
*/
synchronized V remove(Object key, int hash) { synchronized V remove(Object key, int hash) {
int index = hash & mask; int index = hash & mask;
Entry<K, V> e = entries[index]; Entry<K, V> e = entries[index];
...@@ -725,6 +767,7 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> { ...@@ -725,6 +767,7 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> {
* Try to find an entry in the map. * Try to find an entry in the map.
* *
* @param key the key * @param key the key
* @param hash the hash
* @return the entry (might be a non-resident) * @return the entry (might be a non-resident)
*/ */
Entry<K, V> find(Object key, int hash) { Entry<K, V> find(Object key, int hash) {
...@@ -783,6 +826,14 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> { ...@@ -783,6 +826,14 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> {
} }
} }
/**
* Get the list of keys. This method allows to read the internal state of
* the cache.
*
* @param cold if true, only keys for the cold entries are returned
* @param nonResident true for non-resident entries
* @return the key list
*/
synchronized List<K> keys(boolean cold, boolean nonResident) { synchronized List<K> keys(boolean cold, boolean nonResident) {
ArrayList<K> keys = new ArrayList<K>(); ArrayList<K> keys = new ArrayList<K>();
if (cold) { if (cold) {
...@@ -798,15 +849,24 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> { ...@@ -798,15 +849,24 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> {
return keys; return keys;
} }
int size() { /**
return mapSize - queue2Size; * Check whether there is a resident entry for the given key. This
} * method does not adjust the internal state of the cache.
*
* @param key the key (may not be null)
* @param hash the hash
* @return true if there is a resident entry
*/
boolean containsKey(Object key, int hash) { boolean containsKey(Object key, int hash) {
Entry<K, V> e = find(key, hash); Entry<K, V> e = find(key, hash);
return e != null && e.value != null; return e != null && e.value != null;
} }
/**
* Get the set of keys for resident entries.
*
* @return the set of keys
*/
synchronized Set<K> keySet() { synchronized Set<K> keySet() {
HashSet<K> set = new HashSet<K>(); HashSet<K> set = new HashSet<K>();
for (Entry<K, V> e = stack.stackNext; e != stack; e = e.stackNext) { for (Entry<K, V> e = stack.stackNext; e != stack; e = e.stackNext) {
...@@ -818,22 +878,13 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> { ...@@ -818,22 +878,13 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> {
return set; return set;
} }
int sizeHot() { /**
return mapSize - queueSize - queue2Size; * Set the maximum memory this cache should use. This will not
} * immediately cause entries to get removed however; it will only change
* the limit. To resize the internal array, call the clear method.
int sizeNonResident() { *
return queue2Size; * @param maxMemory the maximum size (1 or larger)
} */
int sizeMapArray() {
return entries.length;
}
long getUsedMemory() {
return usedMemory;
}
void setMaxMemory(long maxMemory) { void setMaxMemory(long maxMemory) {
if (maxMemory <= 0) { if (maxMemory <= 0) {
throw new IllegalArgumentException("Max memory must be larger than 0"); throw new IllegalArgumentException("Max memory must be larger than 0");
...@@ -841,6 +892,12 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> { ...@@ -841,6 +892,12 @@ public class CacheLIRS<K, V> extends AbstractMap<K, V> implements Map<K, V> {
this.maxMemory = maxMemory; this.maxMemory = maxMemory;
} }
/**
* Set the average memory used per entry. It is used to calculate the
* length of the internal array.
*
* @param averageMemory the average memory used (1 or larger)
*/
void setAverageMemory(int averageMemory) { void setAverageMemory(int averageMemory) {
if (averageMemory <= 0) { if (averageMemory <= 0) {
throw new IllegalArgumentException("Average memory must be larger than 0"); throw new IllegalArgumentException("Average memory must be larger than 0");
......
h2/src/tools/org/h2/dev/store/cache/CacheLongKeyLIRS.java
浏览文件 @ 2895f2b5
/* /*
* Copyright 2004-2012 H2 Group. Multiple-Licensed under the H2 License, * Copyright 2004-2011 H2 Group. Multiple-Licensed under the H2 License,
* Version 1.0, and under the Eclipse Public License, Version 1.0 * Version 1.0, and under the Eclipse Public License, Version 1.0
* (http://h2database.com/html/license.html). * (http://h2database.com/html/license.html).
* Initial Developer: H2 Group * Initial Developer: H2 Group
...@@ -53,13 +53,14 @@ public class CacheLongKeyLIRS<V> { ...@@ -53,13 +53,14 @@ public class CacheLongKeyLIRS<V> {
*/ */
private int averageMemory; private int averageMemory;
private Segment<V>[] segments; private final Segment<V>[] segments;
private int segmentCount; private final int segmentCount;
private int segmentShift; private final int segmentShift;
private int segmentMask; private final int segmentMask;
private final int stackMoveDistance; private final int stackMoveDistance;
@SuppressWarnings("unchecked")
private CacheLongKeyLIRS(long maxMemory, int averageMemory, int segmentCount, int stackMoveDistance) { private CacheLongKeyLIRS(long maxMemory, int averageMemory, int segmentCount, int stackMoveDistance) {
setMaxMemory(maxMemory); setMaxMemory(maxMemory);
setAverageMemory(averageMemory); setAverageMemory(averageMemory);
...@@ -67,20 +68,22 @@ public class CacheLongKeyLIRS<V> { ...@@ -67,20 +68,22 @@ public class CacheLongKeyLIRS<V> {
throw new IllegalArgumentException("The segment count must be a power of 2, is " + segmentCount); throw new IllegalArgumentException("The segment count must be a power of 2, is " + segmentCount);
} }
this.segmentCount = segmentCount; this.segmentCount = segmentCount;
this.segmentMask = segmentCount - 1;
this.stackMoveDistance = stackMoveDistance; this.stackMoveDistance = stackMoveDistance;
segments = new Segment[segmentCount];
clear(); clear();
this.segmentShift = Integer.numberOfTrailingZeros(segments[0].entries.length);
} }
@SuppressWarnings("unchecked") /**
* Remove all entries.
*/
public void clear() { public void clear() {
segmentMask = segmentCount - 1; long max = Math.max(1, maxMemory / segmentCount);
segments = new Segment[segmentCount];
for (int i = 0; i < segmentCount; i++) { for (int i = 0; i < segmentCount; i++) {
long max = Math.max(1, maxMemory / segmentCount);
segments[i] = new Segment<V>( segments[i] = new Segment<V>(
max, averageMemory, stackMoveDistance); max, averageMemory, stackMoveDistance);
} }
segmentShift = Integer.numberOfTrailingZeros(segments[0].sizeMapArray());
} }
private Entry<V> find(long key) { private Entry<V> find(long key) {
...@@ -89,8 +92,8 @@ public class CacheLongKeyLIRS<V> { ...@@ -89,8 +92,8 @@ public class CacheLongKeyLIRS<V> {
} }
/** /**
* Check whether there is a resident entry for the given key. This method * Check whether there is a resident entry for the given key. This
* does not adjust the internal state of the cache. * method does not adjust the internal state of the cache.
* *
* @param key the key (may not be null) * @param key the key (may not be null)
* @return true if there is a resident entry * @return true if there is a resident entry
...@@ -113,14 +116,14 @@ public class CacheLongKeyLIRS<V> { ...@@ -113,14 +116,14 @@ public class CacheLongKeyLIRS<V> {
} }
/** /**
* Add an entry to the cache. The entry may or may not exist in the cache * Add an entry to the cache. The entry may or may not exist in the
* yet. This method will usually mark unknown entries as cold and known * cache yet. This method will usually mark unknown entries as cold and
* entries as hot. * known entries as hot.
* *
* @param key the key (may not be null) * @param key the key (may not be null)
* @param value the value (may not be null) * @param value the value (may not be null)
* @param memory the memory used for the given entry * @param memory the memory used for the given entry
* @return the old value, or null if there is no resident entry * @return the old value, or null if there was no resident entry
*/ */
public V put(long key, V value, int memory) { public V put(long key, V value, int memory) {
int hash = getHash(key); int hash = getHash(key);
...@@ -132,17 +135,18 @@ public class CacheLongKeyLIRS<V> { ...@@ -132,17 +135,18 @@ public class CacheLongKeyLIRS<V> {
* *
* @param key the key (may not be null) * @param key the key (may not be null)
* @param value the value (may not be null) * @param value the value (may not be null)
* @return the old value, or null if there is no resident entry * @return the old value, or null if there was no resident entry
*/ */
public V put(long key, V value) { public V put(long key, V value) {
return put(key, value, averageMemory); return put(key, value, averageMemory);
} }
/** /**
* Remove an entry. Both resident and non-resident entries can be removed. * Remove an entry. Both resident and non-resident entries can be
* removed.
* *
* @param key the key (may not be null) * @param key the key (may not be null)
* @return the old value, or null if there is no resident entry * @return the old value, or null if there was no resident entry
*/ */
public synchronized V remove(long key) { public synchronized V remove(long key) {
int hash = getHash(key); int hash = getHash(key);
...@@ -162,8 +166,8 @@ public class CacheLongKeyLIRS<V> { ...@@ -162,8 +166,8 @@ public class CacheLongKeyLIRS<V> {
/** /**
* Get the value for the given key if the entry is cached. This method * Get the value for the given key if the entry is cached. This method
* adjusts the internal state of the cache, to ensure commonly used entries * adjusts the internal state of the cache sometimes, to ensure commonly
* stay in the cache. * used entries stay in the cache.
* *
* @param key the key (may not be null) * @param key the key (may not be null)
* @return the value, or null if there is no resident entry * @return the value, or null if there is no resident entry
...@@ -178,12 +182,20 @@ public class CacheLongKeyLIRS<V> { ...@@ -178,12 +182,20 @@ public class CacheLongKeyLIRS<V> {
return segments[segmentIndex]; return segments[segmentIndex];
} }
/**
* Get the hash code for the given key. The hash code is
* further enhanced to spread the values more evenly.
*
* @param key the key
* @return the hash code
*/
static int getHash(long key) { static int getHash(long key) {
int hash = (int) ((key >>> 32) ^ key); int hash = (int) ((key >>> 32) ^ key);
// Doug Lea's supplemental secondaryHash function (inlined) // a supplemental secondary hash function
// to protect against hash codes that don't differ in low order bits // to protect against hash codes that don't differ much
hash ^= (hash >>> 20) ^ (hash >>> 12); hash = ((hash >>> 16) ^ hash) * 0x45d9f3b;
hash ^= (hash >>> 7) ^ (hash >>> 4); hash = ((hash >>> 16) ^ hash) * 0x45d9f3b;
hash = (hash >>> 16) ^ hash;
return hash; return hash;
} }
...@@ -195,15 +207,15 @@ public class CacheLongKeyLIRS<V> { ...@@ -195,15 +207,15 @@ public class CacheLongKeyLIRS<V> {
public long getUsedMemory() { public long getUsedMemory() {
long x = 0; long x = 0;
for (Segment<V> s : segments) { for (Segment<V> s : segments) {
x += s.getUsedMemory(); x += s.usedMemory;
} }
return x; return x;
} }
/** /**
* Set the maximum memory this cache should use. This will not immediately * Set the maximum memory this cache should use. This will not
* cause entries to get removed however; it will only change the limit. To * immediately cause entries to get removed however; it will only change
* resize the internal array, call the clear method. * the limit. To resize the internal array, call the clear method.
* *
* @param maxMemory the maximum size (1 or larger) * @param maxMemory the maximum size (1 or larger)
*/ */
...@@ -221,8 +233,8 @@ public class CacheLongKeyLIRS<V> { ...@@ -221,8 +233,8 @@ public class CacheLongKeyLIRS<V> {
} }
/** /**
* Set the average memory used per entry. It is used to calculate the length * Set the average memory used per entry. It is used to calculate the
* of the internal array. * length of the internal array.
* *
* @param averageMemory the average memory used (1 or larger) * @param averageMemory the average memory used (1 or larger)
*/ */
...@@ -259,7 +271,7 @@ public class CacheLongKeyLIRS<V> { ...@@ -259,7 +271,7 @@ public class CacheLongKeyLIRS<V> {
/** /**
* Create a new cache with the given number of entries, and the default * Create a new cache with the given number of entries, and the default
* settings (an average size of 1 per entry, 16 segments, and stack move * settings (an average size of 1 per entry, 16 segments, and stack move
* distance equals to the max entry size divided by 100). * distance equals to the maximum number of entries divided by 100).
* *
* @param maxEntries the maximum number of entries * @param maxEntries the maximum number of entries
* @return the cache * @return the cache
...@@ -317,7 +329,7 @@ public class CacheLongKeyLIRS<V> { ...@@ -317,7 +329,7 @@ public class CacheLongKeyLIRS<V> {
public int sizeNonResident() { public int sizeNonResident() {
int x = 0; int x = 0;
for (Segment<V> s : segments) { for (Segment<V> s : segments) {
x += s.sizeNonResident(); x += s.queue2Size;
} }
return x; return x;
} }
...@@ -330,7 +342,7 @@ public class CacheLongKeyLIRS<V> { ...@@ -330,7 +342,7 @@ public class CacheLongKeyLIRS<V> {
public int sizeMapArray() { public int sizeMapArray() {
int x = 0; int x = 0;
for (Segment<V> s : segments) { for (Segment<V> s : segments) {
x += s.sizeMapArray(); x += s.entries.length;
} }
return x; return x;
} }
...@@ -343,7 +355,7 @@ public class CacheLongKeyLIRS<V> { ...@@ -343,7 +355,7 @@ public class CacheLongKeyLIRS<V> {
public int sizeHot() { public int sizeHot() {
int x = 0; int x = 0;
for (Segment<V> s : segments) { for (Segment<V> s : segments) {
x += s.sizeHot(); x += s.mapSize - s.queueSize - s.queue2Size;
} }
return x; return x;
} }
...@@ -356,7 +368,7 @@ public class CacheLongKeyLIRS<V> { ...@@ -356,7 +368,7 @@ public class CacheLongKeyLIRS<V> {
public int size() { public int size() {
int x = 0; int x = 0;
for (Segment<V> s : segments) { for (Segment<V> s : segments) {
x += s.size(); x += s.mapSize - s.queue2Size;
} }
return x; return x;
} }
...@@ -393,14 +405,30 @@ public class CacheLongKeyLIRS<V> { ...@@ -393,14 +405,30 @@ public class CacheLongKeyLIRS<V> {
return list; return list;
} }
/**
* Check whether the cache is empty.
*
* @return true if it is empty
*/
public boolean isEmpty() { public boolean isEmpty() {
return size() == 0; return size() == 0;
} }
/**
* Check whether the given value is stored.
*
* @param value the value
* @return true if it is stored
*/
public boolean containsValue(Object value) { public boolean containsValue(Object value) {
return getMap().containsValue(value); return getMap().containsValue(value);
} }
/**
* Convert this cache to a map.
*
* @return the map
*/
public Map<Long, V> getMap() { public Map<Long, V> getMap() {
HashMap<Long, V> map = new HashMap<Long, V>(); HashMap<Long, V> map = new HashMap<Long, V>();
for (long k : keySet()) { for (long k : keySet()) {
...@@ -412,6 +440,11 @@ public class CacheLongKeyLIRS<V> { ...@@ -412,6 +440,11 @@ public class CacheLongKeyLIRS<V> {
return map; return map;
} }
/**
* Add all elements of the map to this cache.
*
* @param m the map
*/
public void putAll(Map<Long, ? extends V> m) { public void putAll(Map<Long, ? extends V> m) {
for (Map.Entry<Long, ? extends V> e : m.entrySet()) { for (Map.Entry<Long, ? extends V> e : m.entrySet()) {
// copy only non-null entries // copy only non-null entries
...@@ -427,56 +460,56 @@ public class CacheLongKeyLIRS<V> { ...@@ -427,56 +460,56 @@ public class CacheLongKeyLIRS<V> {
static class Segment<V> { static class Segment<V> {
/** /**
* How many other item are to be moved to the top of the stack before * The number of (hot, cold, and non-resident) entries in the map.
* the current item is moved.
*/ */
private final int stackMoveDistance; int mapSize;
/** /**
* The maximum memory this cache should use. * The size of the LIRS queue for resident cold entries.
*/ */
private long maxMemory; int queueSize;
/** /**
* The average memory used by one entry. * The size of the LIRS queue for non-resident cold entries.
*/ */
private int averageMemory; int queue2Size;
/** /**
* The currently used memory. * The map array. The size is always a power of 2.
*/ */
private long usedMemory; Entry<V>[] entries;
/** /**
* The number of (hot, cold, and non-resident) entries in the map. * The currently used memory.
*/ */
private int mapSize; long usedMemory;
/** /**
* The bit mask that is applied to the key hash code to get the index in the * How many other item are to be moved to the top of the stack before
* map array. The mask is the length of the array minus one. * the current item is moved.
*/ */
private int mask; private final int stackMoveDistance;
/** /**
* The LIRS stack size. * The maximum memory this cache should use.
*/ */
private int stackSize; private long maxMemory;
/** /**
* The size of the LIRS queue for resident cold entries. * The average memory used by one entry.
*/ */
private int queueSize; private int averageMemory;
/** /**
* The size of the LIRS queue for non-resident cold entries. * The bit mask that is applied to the key hash code to get the index in the
* map array. The mask is the length of the array minus one.
*/ */
private int queue2Size; private int mask;
/** /**
* The map array. The size is always a power of 2. * The LIRS stack size.
*/ */
private Entry<V>[] entries; private int stackSize;
/** /**
* The stack of recently referenced elements. This includes all hot entries, * The stack of recently referenced elements. This includes all hot entries,
...@@ -514,7 +547,7 @@ public class CacheLongKeyLIRS<V> { ...@@ -514,7 +547,7 @@ public class CacheLongKeyLIRS<V> {
clear(); clear();
} }
synchronized void clear() { private void clear() {
// calculate the size of the map array // calculate the size of the map array
// assume a fill factor of at most 80% // assume a fill factor of at most 80%
...@@ -548,16 +581,27 @@ public class CacheLongKeyLIRS<V> { ...@@ -548,16 +581,27 @@ public class CacheLongKeyLIRS<V> {
stackSize = queueSize = queue2Size = 0; stackSize = queueSize = queue2Size = 0;
} }
V peek(long key, int hash) { /**
Entry<V> e = find(key, hash); * Get the memory used for the given key.
return e == null ? null : e.value; *
} * @param key the key (may not be null)
* @param hash the hash
* @return the memory, or 0 if there is no resident entry
*/
int getMemory(long key, int hash) { int getMemory(long key, int hash) {
Entry<V> e = find(key, hash); Entry<V> e = find(key, hash);
return e == null ? 0 : e.memory; return e == null ? 0 : e.memory;
} }
/**
* Get the value for the given key if the entry is cached. This method
* adjusts the internal state of the cache sometimes, to ensure commonly
* used entries stay in the cache.
*
* @param key the key (may not be null)
* @param hash the hash
* @return the value, or null if there is no resident entry
*/
V get(long key, int hash) { V get(long key, int hash) {
Entry<V> e = find(key, hash); Entry<V> e = find(key, hash);
if (e == null) { if (e == null) {
...@@ -625,6 +669,17 @@ public class CacheLongKeyLIRS<V> { ...@@ -625,6 +669,17 @@ public class CacheLongKeyLIRS<V> {
} }
} }
/**
* Add an entry to the cache. The entry may or may not exist in the
* cache yet. This method will usually mark unknown entries as cold and
* known entries as hot.
*
* @param key the key (may not be null)
* @param hash the hash
* @param value the value (may not be null)
* @param memory the memory used for the given entry
* @return the old value, or null if there was no resident entry
*/
synchronized V put(long key, int hash, V value, int memory) { synchronized V put(long key, int hash, V value, int memory) {
if (value == null) { if (value == null) {
throw new NullPointerException(); throw new NullPointerException();
...@@ -655,6 +710,14 @@ public class CacheLongKeyLIRS<V> { ...@@ -655,6 +710,14 @@ public class CacheLongKeyLIRS<V> {
return old; return old;
} }
/**
* Remove an entry. Both resident and non-resident entries can be
* removed.
*
* @param key the key (may not be null)
* @param hash the hash
* @return the old value, or null if there was no resident entry
*/
synchronized V remove(long key, int hash) { synchronized V remove(long key, int hash) {
int index = hash & mask; int index = hash & mask;
Entry<V> e = entries[index]; Entry<V> e = entries[index];
...@@ -764,6 +827,7 @@ public class CacheLongKeyLIRS<V> { ...@@ -764,6 +827,7 @@ public class CacheLongKeyLIRS<V> {
* Try to find an entry in the map. * Try to find an entry in the map.
* *
* @param key the key * @param key the key
* @param hash the hash
* @return the entry (might be a non-resident) * @return the entry (might be a non-resident)
*/ */
Entry<V> find(long key, int hash) { Entry<V> find(long key, int hash) {
...@@ -822,6 +886,14 @@ public class CacheLongKeyLIRS<V> { ...@@ -822,6 +886,14 @@ public class CacheLongKeyLIRS<V> {
} }
} }
/**
* Get the list of keys. This method allows to read the internal state of
* the cache.
*
* @param cold if true, only keys for the cold entries are returned
* @param nonResident true for non-resident entries
* @return the key list
*/
synchronized List<Long> keys(boolean cold, boolean nonResident) { synchronized List<Long> keys(boolean cold, boolean nonResident) {
ArrayList<Long> keys = new ArrayList<Long>(); ArrayList<Long> keys = new ArrayList<Long>();
if (cold) { if (cold) {
...@@ -837,15 +909,24 @@ public class CacheLongKeyLIRS<V> { ...@@ -837,15 +909,24 @@ public class CacheLongKeyLIRS<V> {
return keys; return keys;
} }
int size() { /**
return mapSize - queue2Size; * Check whether there is a resident entry for the given key. This
} * method does not adjust the internal state of the cache.
*
* @param key the key (may not be null)
* @param hash the hash
* @return true if there is a resident entry
*/
boolean containsKey(long key, int hash) { boolean containsKey(long key, int hash) {
Entry<V> e = find(key, hash); Entry<V> e = find(key, hash);
return e != null && e.value != null; return e != null && e.value != null;
} }
/**
* Get the set of keys for resident entries.
*
* @return the set of keys
*/
synchronized Set<Long> keySet() { synchronized Set<Long> keySet() {
HashSet<Long> set = new HashSet<Long>(); HashSet<Long> set = new HashSet<Long>();
for (Entry<V> e = stack.stackNext; e != stack; e = e.stackNext) { for (Entry<V> e = stack.stackNext; e != stack; e = e.stackNext) {
...@@ -857,22 +938,13 @@ public class CacheLongKeyLIRS<V> { ...@@ -857,22 +938,13 @@ public class CacheLongKeyLIRS<V> {
return set; return set;
} }
int sizeHot() { /**
return mapSize - queueSize - queue2Size; * Set the maximum memory this cache should use. This will not
} * immediately cause entries to get removed however; it will only change
* the limit. To resize the internal array, call the clear method.
int sizeNonResident() { *
return queue2Size; * @param maxMemory the maximum size (1 or larger)
} */
int sizeMapArray() {
return entries.length;
}
long getUsedMemory() {
return usedMemory;
}
void setMaxMemory(long maxMemory) { void setMaxMemory(long maxMemory) {
if (maxMemory <= 0) { if (maxMemory <= 0) {
throw new IllegalArgumentException("Max memory must be larger than 0"); throw new IllegalArgumentException("Max memory must be larger than 0");
...@@ -880,6 +952,12 @@ public class CacheLongKeyLIRS<V> { ...@@ -880,6 +952,12 @@ public class CacheLongKeyLIRS<V> {
this.maxMemory = maxMemory; this.maxMemory = maxMemory;
} }
/**
* Set the average memory used per entry. It is used to calculate the
* length of the internal array.
*
* @param averageMemory the average memory used (1 or larger)
*/
void setAverageMemory(int averageMemory) { void setAverageMemory(int averageMemory) {
if (averageMemory <= 0) { if (averageMemory <= 0) {
throw new IllegalArgumentException("Average memory must be larger than 0"); throw new IllegalArgumentException("Average memory must be larger than 0");
......
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