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package org.eclipse.viatra.solver.data.model.hashTests;
import static org.junit.jupiter.api.Assertions.assertEquals;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Random;
import org.eclipse.viatra.solver.data.map.ContinousHashProvider;
import org.eclipse.viatra.solver.data.model.Tuple;
import org.eclipse.viatra.solver.data.model.TupleHashProvider;
import org.eclipse.viatra.solver.data.model.TupleHashProviderBitMagic;
import org.junit.jupiter.api.Test;
class HashEfficiencyTest {
private static List<Tuple> permutations(int range, int arity) {
if(arity == 1) {
List<Tuple> result = new ArrayList<>(range);
for(int i=0; i<range; i++) {
result.add(Tuple.of(i));
}
return result;
} else if(arity > 1) {
List<Tuple> smallers = permutations(range, arity-1);
List<Tuple> result = new ArrayList<>(range*smallers.size());
for(Tuple smaller : smallers) {
for(int i=0; i<range; i++) {
int[] larger = new int[arity];
for(int x = 0; x<smaller.getSize(); x++) {
larger[x] = smaller.get(x);
}
larger[arity-1] = i;
result.add(Tuple.of(larger));
}
}
return result;
} else throw new IllegalArgumentException();
}
private static int amountToRange(int arity, int n) {
int range = 1;
while(Math.pow(range,arity)<n+0.1) {
range++;
}
return 1024;
}
public static List<Tuple> nPermutations(int arity, int n) {
int range = amountToRange(arity, n);
List<Tuple> permutations = permutations(range, arity);
return permutations.subList(0, n);
}
public static List<Tuple> nRandoms(int arity, int n, int seed) {
int range = amountToRange(arity, n);
List<Tuple> permutations = new ArrayList<>(n);
Random r = new Random(seed);
for(int i = 0; i<n; i++) {
int[] tuple = new int[arity];
for(int j=0; j<arity; j++) {
tuple[j] = r.nextInt(range);
}
permutations.add(Tuple.of(tuple));
}
return permutations;
}
@Test
void permutationTest() {
List<Tuple> p = permutations(10, 2);
assertEquals(p.size(),10*10);
}
// private void printTuples(List<Tuple> p) {
// for(Tuple element : p) {
// System.out.println(element);
// }
// }
@Test
void nPermutationTest() {
final int amount = 500;
List<Tuple> p = nPermutations(2, amount);
assertEquals(amount,p.size());
}
@Test
void nRandomTest() {
final int amount = 500;
List<Tuple> p = nRandoms(2, amount, 1);;
assertEquals(amount,p.size());
}
private static double calculateHashClashes(List<Tuple> tuples, ContinousHashProvider<Tuple> chp) {
int sumClashes = 0;
for(int i = 0; i<tuples.size(); i++) {
int height = 0;
for(int j=0; j<tuples.size(); j++) {
int clashes = calculateHashClash(chp, tuples.get(i), tuples.get(j));
height = Math.max(height, clashes);
}
sumClashes += height;
}
return (sumClashes+0.0) / tuples.size();
}
private static int calculateHashClash(ContinousHashProvider<Tuple> chp, Tuple a, Tuple b) {
if(a.equals(b)) return 0;
final int bits = 5;
final int segments = Integer.SIZE/bits;
final int mask = (1<<bits)-1;
for(int i = 0;;i++) {
int index = i/segments;
int depth = i%segments;
int aHash = (chp.getHash(a, index)>>(depth*5))&mask;
int bHash = (chp.getHash(b, index)>>(depth*5))&mask;
if(aHash != bHash) {
return i+1;
}
if(i>400) {
throw new IllegalStateException(a+" vs "+b);
}
}
}
private static double caclulateOptimalHashClash(int size) {
return (Math.log(size)/Math.log(32));
}
public static void main(String[] args) {
List<String> hashNames = new LinkedList<>();
List<ContinousHashProvider<Tuple>> hashes = new LinkedList<>();
hashNames.add("PrimeGroup");
hashes.add(new TupleHashProvider());
hashNames.add("BitMagic");
hashes.add(new TupleHashProviderBitMagic());
int[] arities = new int[] {2,3,4,5};
int[] sizes = new int[] {32*32,32*32*8};
System.out.println("Size,Arity,DataSource,Hash,Chashes,Optimal,Badness");
for(int size : sizes) {
double optimalClashes = caclulateOptimalHashClash(size);
for(int arity : arities) {
List<String> dataSourceNames = new LinkedList<>();
List<List<Tuple>> dataSources = new LinkedList<>();
// dataSourceNames.add("Permutation");
// dataSources.add(nPermutations(arity, size));
dataSourceNames.add("Random");
dataSources.add(nRandoms(arity, size, 0));
for(int dataSourceIndex = 0; dataSourceIndex<dataSourceNames.size(); dataSourceIndex++) {
for(int hashIndex = 0; hashIndex<hashNames.size(); hashIndex++) {
double clashes = calculateHashClashes(dataSources.get(dataSourceIndex),hashes.get(hashIndex));
System.out.println(
size+","+arity+","+dataSourceNames.get(dataSourceIndex)+","+hashNames.get(hashIndex)+","+
clashes+","+optimalClashes+","+(clashes+0.0)/optimalClashes);
}
}
}
}
}
}
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