io.questdb.std.Utf8StringIntHashMap Maven / Gradle / Ivy
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*
* Copyright (c) 2014-2019 Appsicle
* Copyright (c) 2019-2024 QuestDB
*
* Licensed 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.
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package io.questdb.std;
import io.questdb.std.str.DirectUtf8Sequence;
import io.questdb.std.str.Utf8String;
import io.questdb.std.str.Utf8s;
import org.jetbrains.annotations.NotNull;
import java.util.Arrays;
public class Utf8StringIntHashMap implements Mutable {
public static final int NO_ENTRY_VALUE = -1;
private static final int MIN_INITIAL_CAPACITY = 16;
private final int initialCapacity;
private final double loadFactor;
private final int noEntryValue;
private int capacity;
private int free;
private int[] hashCodes;
private Utf8String[] keys;
private int mask;
private int[] values;
public Utf8StringIntHashMap() {
this(MIN_INITIAL_CAPACITY);
}
public Utf8StringIntHashMap(int initialCapacity) {
this(initialCapacity, 0.4, NO_ENTRY_VALUE);
}
public Utf8StringIntHashMap(int initialCapacity, double loadFactor, int noEntryValue) {
if (loadFactor <= 0d || loadFactor >= 1d) {
throw new IllegalArgumentException("0 < loadFactor < 1");
}
free = capacity = initialCapacity < MIN_INITIAL_CAPACITY ? MIN_INITIAL_CAPACITY : Numbers.ceilPow2(initialCapacity);
this.initialCapacity = capacity;
this.loadFactor = loadFactor;
int len = Numbers.ceilPow2((int) (capacity / loadFactor));
keys = new Utf8String[len];
hashCodes = new int[len];
mask = len - 1;
this.noEntryValue = noEntryValue;
values = new int[keys.length];
clear();
}
public int capacity() {
return capacity;
}
@Override
public final void clear() {
Arrays.fill(keys, null);
Arrays.fill(hashCodes, 0);
free = capacity;
Arrays.fill(values, noEntryValue);
}
public boolean contains(@NotNull DirectUtf8Sequence key) {
return keyIndex(key) < 0;
}
public boolean excludes(@NotNull DirectUtf8Sequence key) {
return keyIndex(key) > -1;
}
public int get(@NotNull DirectUtf8Sequence key) {
return valueAt(keyIndex(key));
}
public int get(@NotNull Utf8String key) {
return valueAt(keyIndex(key));
}
public int keyIndex(@NotNull DirectUtf8Sequence key) {
int hashCode = Hash.hashUtf8(key);
int index = Hash.spread(hashCode) & mask;
if (keys[index] == null) {
return index;
}
if (hashCode == hashCodes[index] && Utf8s.equals(key, keys[index])) {
return -index - 1;
}
return probe(key, hashCode, index);
}
public int keyIndex(@NotNull Utf8String key) {
int hashCode = Hash.hashUtf8(key);
int index = Hash.spread(hashCode) & mask;
if (keys[index] == null) {
return index;
}
if (hashCode == hashCodes[index] && Utf8s.equals(key, keys[index])) {
return -index - 1;
}
return probe(key, hashCode, index);
}
public boolean put(@NotNull Utf8String key, int value) {
return putAt(keyIndex(key), key, value);
}
public boolean putAt(int index, @NotNull Utf8String key, int value) {
if (index < 0) {
values[-index - 1] = value;
return false;
}
putAt0(index, key, value);
return true;
}
public int remove(@NotNull DirectUtf8Sequence key) {
int index = keyIndex(key);
if (index < 0) {
removeAt(index);
return -index - 1;
}
return -1;
}
public void removeAt(int index) {
if (index < 0) {
int from = -index - 1;
erase(from);
free++;
// after we have freed up a slot
// consider non-empty keys directly below
// they may have been a direct hit but because
// directly hit slot wasn't empty these keys would
// have moved.
//
// After slot if freed these keys require re-hash
from = (from + 1) & mask;
for (
Utf8String key = keys[from];
key != null;
from = (from + 1) & mask, key = keys[from]
) {
int hashCode = Hash.hashUtf8(key);
int idealHit = Hash.spread(hashCode) & mask;
if (idealHit != from) {
int to;
if (keys[idealHit] != null) {
to = probe(key, hashCode, idealHit);
} else {
to = idealHit;
}
if (to > -1) {
move(from, to);
}
}
}
}
}
public void reset() {
if (capacity == initialCapacity) {
clear();
} else {
free = capacity = initialCapacity;
int len = Numbers.ceilPow2((int) (capacity / loadFactor));
keys = new Utf8String[len];
hashCodes = new int[len];
mask = len - 1;
values = new int[keys.length];
clear();
}
}
public int size() {
return capacity - free;
}
public int valueAt(int index) {
int index1 = -index - 1;
return index < 0 ? values[index1] : noEntryValue;
}
private void erase(int index) {
keys[index] = null;
hashCodes[index] = 0;
values[index] = noEntryValue;
}
private void move(int from, int to) {
keys[to] = keys[from];
hashCodes[to] = hashCodes[from];
values[to] = values[from];
erase(from);
}
private int probe(DirectUtf8Sequence key, long hashCode, int index) {
do {
index = (index + 1) & mask;
if (keys[index] == null) {
return index;
}
if (hashCode == hashCodes[index] && Utf8s.equals(key, keys[index])) {
return -index - 1;
}
} while (true);
}
private int probe(Utf8String key, long hashCode, int index) {
do {
index = (index + 1) & mask;
if (keys[index] == null) {
return index;
}
if (hashCode == hashCodes[index] && Utf8s.equals(key, keys[index])) {
return -index - 1;
}
} while (true);
}
private void putAt0(int index, Utf8String key, int value) {
keys[index] = key;
hashCodes[index] = Hash.hashUtf8(key);
values[index] = value;
if (--free == 0) {
rehash();
}
}
private void rehash() {
int[] oldValues = values;
Utf8String[] oldKeys = keys;
int[] oldHashCodes = hashCodes;
int size = capacity - free;
capacity = capacity * 2;
free = capacity - size;
mask = Numbers.ceilPow2((int) (capacity / loadFactor)) - 1;
keys = new Utf8String[mask + 1];
hashCodes = new int[mask + 1];
values = new int[mask + 1];
for (int i = oldKeys.length - 1; i > -1; i--) {
Utf8String key = oldKeys[i];
if (key != null) {
final int index = keyIndex(key);
keys[index] = key;
hashCodes[index] = oldHashCodes[i];
values[index] = oldValues[i];
}
}
}
}
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