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Core sketch algorithms used alone and by other Java repositories in the DataSketches library.
/*
* 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.datasketches.hll;
import static org.apache.datasketches.hll.HllUtil.EMPTY;
import static org.apache.datasketches.hll.HllUtil.RESIZE_DENOM;
import static org.apache.datasketches.hll.HllUtil.RESIZE_NUMER;
import static org.apache.datasketches.hll.PreambleUtil.extractInt;
import static org.apache.datasketches.hll.PreambleUtil.extractLgArr;
import org.apache.datasketches.common.SketchesArgumentException;
import org.apache.datasketches.common.SketchesStateException;
import org.apache.datasketches.memory.Memory;
/**
* @author Lee Rhodes
* @author Kevin Lang
*/
class HeapAuxHashMap implements AuxHashMap {
private final int lgConfigK; //required for #slot bits
private int lgAuxArrInts;
private int auxCount;
private int[] auxIntArr; //used by Hll4Array
/**
* Standard constructor
* @param lgAuxArrInts the log size of the aux integer array
* @param lgConfigK must be 7 to 21
*/
HeapAuxHashMap(final int lgAuxArrInts, final int lgConfigK) {
this.lgConfigK = lgConfigK;
this.lgAuxArrInts = lgAuxArrInts;
auxIntArr = new int[1 << lgAuxArrInts];
}
/**
* Copy constructor
* @param that another AuxHashMap
*/
HeapAuxHashMap(final HeapAuxHashMap that) {
lgConfigK = that.lgConfigK;
lgAuxArrInts = that.lgAuxArrInts;
auxCount = that.auxCount;
auxIntArr = that.auxIntArr.clone();
}
static final HeapAuxHashMap heapify(final Memory mem, final long offset, final int lgConfigK,
final int auxCount, final boolean srcCompact) {
final int lgAuxArrInts;
final HeapAuxHashMap auxMap;
if (srcCompact) { //early versions did not use LgArr byte field
lgAuxArrInts = PreambleUtil.computeLgArr(mem, auxCount, lgConfigK);
} else { //updatable
lgAuxArrInts = extractLgArr(mem);
}
auxMap = new HeapAuxHashMap(lgAuxArrInts, lgConfigK);
final int configKmask = (1 << lgConfigK) - 1;
if (srcCompact) {
for (int i = 0; i < auxCount; i++) {
final int pair = extractInt(mem, offset + (i << 2));
final int slotNo = HllUtil.getPairLow26(pair) & configKmask;
final int value = HllUtil.getPairValue(pair);
auxMap.mustAdd(slotNo, value); //increments count
}
} else { //updatable
final int auxArrInts = 1 << lgAuxArrInts;
for (int i = 0; i < auxArrInts; i++) {
final int pair = extractInt(mem, offset + (i << 2));
if (pair == EMPTY) { continue; }
final int slotNo = HllUtil.getPairLow26(pair) & configKmask;
final int value = HllUtil.getPairValue(pair);
auxMap.mustAdd(slotNo, value); //increments count
}
}
return auxMap;
}
@Override
public HeapAuxHashMap copy() {
return new HeapAuxHashMap(this);
}
@Override
public int getAuxCount() {
return auxCount;
}
@Override
public int[] getAuxIntArr() {
return auxIntArr;
}
@Override
public int getCompactSizeBytes() {
return auxCount << 2;
}
@Override
public PairIterator getIterator() {
return new IntArrayPairIterator(auxIntArr, lgConfigK);
}
@Override
public int getLgAuxArrInts() {
return lgAuxArrInts;
}
@Override
public int getUpdatableSizeBytes() {
return 4 << lgAuxArrInts;
}
@Override
public boolean isMemory() {
return false;
}
@Override
public boolean isOffHeap() {
return false;
}
//In C: two-registers.c Line 300.
@Override
public void mustAdd(final int slotNo, final int value) {
final int index = find(auxIntArr, lgAuxArrInts, lgConfigK, slotNo);
final int pair = HllUtil.pair(slotNo, value);
if (index >= 0) {
final String pairStr = HllUtil.pairString(pair);
throw new SketchesStateException("Found a slotNo that should not be there: " + pairStr);
}
//Found empty entry
auxIntArr[~index] = pair;
auxCount++;
checkGrow();
}
//In C: two-registers.c Line 205
@Override
public int mustFindValueFor(final int slotNo) {
final int index = find(auxIntArr, lgAuxArrInts, lgConfigK, slotNo);
if (index >= 0) {
return HllUtil.getPairValue(auxIntArr[index]);
}
throw new SketchesStateException("SlotNo not found: " + slotNo);
}
//In C: two-registers.c Line 321.
@Override
public void mustReplace(final int slotNo, final int value) {
final int idx = find(auxIntArr, lgAuxArrInts, lgConfigK, slotNo);
if (idx >= 0) {
auxIntArr[idx] = HllUtil.pair(slotNo, value); //replace
return;
}
final String pairStr = HllUtil.pairString(HllUtil.pair(slotNo, value));
throw new SketchesStateException("Pair not found: " + pairStr);
}
//Searches the Aux arr hash table for an empty or a matching slotNo depending on the context.
//If entire entry is empty, returns one's complement of index = found empty.
//If entry contains given slotNo, returns its index = found slotNo.
//Continues searching.
//If the probe comes back to original index, throws an exception.
private static final int find(final int[] auxArr, final int lgAuxArrInts, final int lgConfigK,
final int slotNo) {
assert lgAuxArrInts < lgConfigK;
final int auxArrMask = (1 << lgAuxArrInts) - 1;
final int configKmask = (1 << lgConfigK) - 1;
int probe = slotNo & auxArrMask;
final int loopIndex = probe;
do {
final int arrVal = auxArr[probe];
if (arrVal == EMPTY) { //Compares on entire entry
return ~probe; //empty
}
else if (slotNo == (arrVal & configKmask)) { //Compares only on slotNo
return probe; //found given slotNo, return probe = index into aux array
}
final int stride = (slotNo >>> lgAuxArrInts) | 1;
probe = (probe + stride) & auxArrMask;
} while (probe != loopIndex);
throw new SketchesArgumentException("Key not found and no empty slots!");
}
private void checkGrow() {
if ((RESIZE_DENOM * auxCount) > (RESIZE_NUMER * auxIntArr.length)) {
growAuxSpace();
//TODO if direct, ask for more memory
}
}
private void growAuxSpace() {
final int[] oldArray = auxIntArr;
final int configKmask = (1 << lgConfigK) - 1;
auxIntArr = new int[1 << ++lgAuxArrInts];
for (int i = 0; i < oldArray.length; i++) {
final int fetched = oldArray[i];
if (fetched != EMPTY) {
//find empty in new array
final int idx = find(auxIntArr, lgAuxArrInts, lgConfigK, fetched & configKmask);
auxIntArr[~idx] = fetched;
}
}
}
}
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