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From myui <...@git.apache.org>
Subject [GitHub] incubator-hivemall pull request #111: [WIP][HIVEMALL-17] Support SLIM
Date Sat, 02 Sep 2017 10:27:55 GMT
Github user myui commented on a diff in the pull request:

    https://github.com/apache/incubator-hivemall/pull/111#discussion_r136692929
  
    --- Diff: core/src/main/java/hivemall/utils/collections/maps/Int2DoubleOpenHashTable.java
---
    @@ -0,0 +1,417 @@
    +/*
    + * 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 hivemall.utils.collections.maps;
    +
    +import hivemall.utils.math.Primes;
    +
    +import java.io.Externalizable;
    +import java.io.IOException;
    +import java.io.ObjectInput;
    +import java.io.ObjectOutput;
    +import java.util.Arrays;
    +
    +/**
    + * An open-addressing hash table with double hashing
    + *
    + * @see http://en.wikipedia.org/wiki/Double_hashing
    + */
    +public class Int2DoubleOpenHashTable implements Externalizable {
    +    protected static final byte FREE = 0;
    +    protected static final byte FULL = 1;
    +    protected static final byte REMOVED = 2;
    +
    +    private static final float DEFAULT_LOAD_FACTOR = 0.7f;
    +    private static final float DEFAULT_GROW_FACTOR = 2.0f;
    +
    +    protected final transient float _loadFactor;
    +    protected final transient float _growFactor;
    +
    +    protected int _used = 0;
    +    protected int _threshold;
    +    protected double defaultReturnValue = -1.d;
    +
    +    protected int[] _keys;
    +    protected double[] _values;
    +    protected byte[] _states;
    +
    +    protected Int2DoubleOpenHashTable(int size, float loadFactor, float growFactor,
    +            boolean forcePrime) {
    +        if (size < 1) {
    +            throw new IllegalArgumentException();
    +        }
    +        this._loadFactor = loadFactor;
    +        this._growFactor = growFactor;
    +        int actualSize = forcePrime ? Primes.findLeastPrimeNumber(size) : size;
    +        this._keys = new int[actualSize];
    +        this._values = new double[actualSize];
    +        this._states = new byte[actualSize];
    +        this._threshold = (int) (actualSize * _loadFactor);
    +    }
    +
    +    public Int2DoubleOpenHashTable(int size, float loadFactor, float growFactor) {
    +        this(size, loadFactor, growFactor, true);
    +    }
    +
    +    public Int2DoubleOpenHashTable(int size) {
    +        this(size, DEFAULT_LOAD_FACTOR, DEFAULT_GROW_FACTOR, true);
    +    }
    +
    +    /**
    +     * Only for {@link Externalizable}
    +     */
    +    public Int2DoubleOpenHashTable() {// required for serialization
    +        this._loadFactor = DEFAULT_LOAD_FACTOR;
    +        this._growFactor = DEFAULT_GROW_FACTOR;
    +    }
    +
    +    public void defaultReturnValue(double v) {
    +        this.defaultReturnValue = v;
    +    }
    +
    +    public boolean containsKey(int key) {
    +        return findKey(key) >= 0;
    +    }
    +
    +    /**
    +     * @return -1.d if not found
    +     */
    +    public double get(int key) {
    +        int i = findKey(key);
    +        if (i < 0) {
    +            return defaultReturnValue;
    +        }
    +        return _values[i];
    +    }
    +
    +    public double put(int key, double value) {
    +        int hash = keyHash(key);
    +        int keyLength = _keys.length;
    +        int keyIdx = hash % keyLength;
    +
    +        boolean expanded = preAddEntry(keyIdx);
    +        if (expanded) {
    +            keyLength = _keys.length;
    +            keyIdx = hash % keyLength;
    +        }
    +
    +        int[] keys = _keys;
    +        double[] values = _values;
    +        byte[] states = _states;
    +
    +        if (states[keyIdx] == FULL) {// double hashing
    +            if (keys[keyIdx] == key) {
    +                double old = values[keyIdx];
    +                values[keyIdx] = value;
    +                return old;
    +            }
    +            // try second hash
    +            int decr = 1 + (hash % (keyLength - 2));
    +            for (;;) {
    +                keyIdx -= decr;
    +                if (keyIdx < 0) {
    +                    keyIdx += keyLength;
    +                }
    +                if (isFree(keyIdx, key)) {
    +                    break;
    +                }
    +                if (states[keyIdx] == FULL && keys[keyIdx] == key) {
    +                    double old = values[keyIdx];
    +                    values[keyIdx] = value;
    +                    return old;
    +                }
    +            }
    +        }
    +        keys[keyIdx] = key;
    +        values[keyIdx] = value;
    +        states[keyIdx] = FULL;
    +        ++_used;
    +        return defaultReturnValue;
    +    }
    +
    +    /** Return weather the required slot is free for new entry */
    +    protected boolean isFree(int index, int key) {
    +        byte stat = _states[index];
    +        if (stat == FREE) {
    +            return true;
    +        }
    +        if (stat == REMOVED && _keys[index] == key) {
    +            return true;
    +        }
    +        return false;
    +    }
    +
    +    /** @return expanded or not */
    +    protected boolean preAddEntry(int index) {
    --- End diff --
    
    It's for overriding and thus okey as it is.


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