io.questdb.std.ObjIntHashMap Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of core Show documentation
QuestDB is High Performance Time Series Database
The newest version!
/*******************************************************************************
 *     ___                  _   ____  ____
 *    / _ \ _   _  ___  ___| |_|  _ \| __ )
 *   | | | | | | |/ _ \/ __| __| | | |  _ \
 *   | |_| | |_| |  __/\__ \ |_| |_| | |_) |
 *    \__\_\\__,_|\___||___/\__|____/|____/
 *
 *  Copyright (c) 2014-2019 Appsicle
 *  Copyright (c) 2019-2020 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.
 *
 ******************************************************************************/

package io.questdb.std;

import org.jetbrains.annotations.NotNull;

import java.util.Arrays;
import java.util.Iterator;


public class ObjIntHashMap implements Iterable>, Mutable {
    private static final int MIN_INITIAL_CAPACITY = 16;
    private static final Object noEntryValue = new Object();
    private final int noKeyValue;
    private final double loadFactor;
    private final EntryIterator iterator = new EntryIterator();
    private K[] keys;
    private int[] values;
    private int free;
    private int capacity;
    private int mask;

    public ObjIntHashMap() {
        this(8);
    }

    private ObjIntHashMap(int initialCapacity) {
        this(initialCapacity, 0.5, -1);
    }

    @SuppressWarnings("unchecked")
    private ObjIntHashMap(int initialCapacity, double loadFactor, int noKeyValue) {
        int capacity = Math.max(initialCapacity, (int) (initialCapacity / loadFactor));
        capacity = capacity < MIN_INITIAL_CAPACITY ? MIN_INITIAL_CAPACITY : Numbers.ceilPow2(capacity);
        this.loadFactor = loadFactor;
        this.noKeyValue = noKeyValue;
        keys = (K[]) new Object[capacity];
        values = new int[capacity];
        free = this.capacity = initialCapacity;
        mask = capacity - 1;
        clear();
    }

    public final void clear() {
        Arrays.fill(keys, noEntryValue);
    }

    public int get(K key) {
        return valueAt(keyIndex(key));
    }

    @Override
    @NotNull
    public Iterator> iterator() {
        iterator.index = 0;
        return iterator;
    }

    public int keyIndex(K key) {
        int index = Hash.spread(key.hashCode()) & mask;

        final K kv = keys[index];
        if (kv == noEntryValue) {
            return index;
        }

        if (kv == key || key.equals(kv)) {
            return -index - 1;
        }

        return probe(key, index);
    }

    public void put(K key, int value) {
        putAt(keyIndex(key), key, value);
    }

    public void putAt(int index, K key, int value) {
        if (index < 0) {
            values[-index - 1] = value;
            return;
        }
        putAt0(index, key, value);
    }

    public boolean putIfAbsent(K key, int value) {
        final int index = keyIndex(key);
        if (index > -1) {
            putAt(index, key, value);
            return true;
        }
        return false;
    }

    public int size() {
        return capacity - free;
    }

    public int valueAt(int index) {
        int index1 = -index - 1;
        return index < 0 ? values[index1] : noKeyValue;
    }

    private int probe(K key, int index) {
        do {
            index = (index + 1) & mask;
            final K kv = keys[index];
            if (kv == noEntryValue) {
                return index;
            }
            if (kv == key || key.equals(kv)) {
                return -index - 1;
            }
        } while (true);
    }

    private void putAt0(int index, K key, int value) {
        keys[index] = key;
        values[index] = value;
        if (--free == 0) {
            rehash();
        }
    }

    @SuppressWarnings({"unchecked"})
    private void rehash() {

        int newCapacity = values.length << 1;
        mask = newCapacity - 1;
        free = capacity = (int) (newCapacity * loadFactor);
        int[] oldValues = values;
        K[] oldKeys = keys;
        this.keys = (K[]) new Object[newCapacity];
        this.values = new int[newCapacity];
        Arrays.fill(keys, noEntryValue);

        for (int i = oldKeys.length; i-- > 0; ) {
            if (oldKeys[i] != noEntryValue) {
                put(oldKeys[i], oldValues[i]);
            }
        }
    }

    public static class Entry {
        public V key;
        public int value;
    }

    public class EntryIterator implements ImmutableIterator> {

        private final Entry entry = new Entry<>();
        private int index = 0;

        @Override
        public boolean hasNext() {
            return index < values.length && (keys[index] != noEntryValue || scan());
        }

        @Override
        public Entry next() {
            entry.key = keys[index];
            int index1 = index++;
            entry.value = values[index1];
            return entry;
        }

        private boolean scan() {
            do {
                index++;
            } while (index < values.length && keys[index] == noEntryValue);

            return index < values.length;
        }
    }
}