basehashmap.java

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/* Copyright (c) 2001-2005, The HSQL Development Group
 * All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of the HSQL Development Group nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG,
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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 */


package org.hsqldb.store;

import java.util.NoSuchElementException;

import org.hsqldb.lib.ArrayCounter;

public class BaseHashMap {

/**
 * Base class for hash tables or sets. The exact type of the structure is
 * defined by the constructor. Each instance has at least a keyTable array
 * and a HashIndex instance for looking up the keys into this table. Instances
 * that are maps also have a valueTable the same size as the keyTable.
 *
 * Special getOrAddXXX() methods are used for object maps in some subclasses.
 *
 * @author fredt@users
 * @version 1.8.0
 * @since 1.7.2
 */
/*

    data store:
    keys: {array of primitive | array of object}
    values: {none | array of primitive | array of object} same size as keys
    objects support : hashCode(), equals()

    implemented types of keyTable:
    {objectKeyTable: variable size Object[] array for keys |
    intKeyTable: variable size int[] for keys |
    longKeyTable: variable size long[] for keys }

    implemented types of valueTable:
    {objectValueTable: variable size Object[] array for values |
    intValueTable: variable size int[] for values |
    longValueTable: variable size long[] for values}

    valueTable does not exist for sets or for object pools

    hash index:
    hashTable: fixed size int[] array for hash lookup into keyTable
    linkTable: pointer to the next key ; size equal or larger than hashTable
    but equal to the valueTable

    access count table:
    {none |
    variable size int[] array for access count} same size as xxxKeyTable
*/

    //
    boolean isIntKey;
    boolean isLongKey;
    boolean isObjectKey;
    boolean isNoValue;
    boolean isIntValue;
    boolean isLongValue;
    boolean isObjectValue;

    //
    protected HashIndex hashIndex;

    //
    protected int[]    intKeyTable;
    protected Object[] objectKeyTable;
    protected long[]   longKeyTable;

    //
    protected int[]    intValueTable;
    protected Object[] objectValueTable;
    protected long[]   longValueTable;

    //
    int   accessMin;
    int   accessCount;
    int[] accessTable;

    //
    final float       loadFactor;
    final int         initialCapacity;
    int               threshold;
    int               maxCapacity;
    protected int     purgePolicy = NO_PURGE;
    protected boolean minimizeOnEmpty;

    //
    boolean hasZeroKey;
    int     zeroKeyIndex = -1;

    // keyOrValueTypes
    protected static final int noKeyOrValue     = 0;
    protected static final int intKeyOrValue    = 1;
    protected static final int longKeyOrValue   = 2;
    protected static final int objectKeyOrValue = 3;

    // purgePolicy
    protected static final int NO_PURGE      = 0;
    protected static final int PURGE_ALL     = 1;
    protected static final int PURGE_HALF    = 2;
    protected static final int PURGE_QUARTER = 3;

    protected BaseHashMap(int initialCapacity, float loadFactor, int keyType,
                          int valueType,
                          boolean hasAccessCount)
                          throws IllegalArgumentException {

        if (initialCapacity <= 0 || loadFactor <= 0.0) {
            throw new IllegalArgumentException();
        }

        this.loadFactor      = loadFactor;
        this.initialCapacity = initialCapacity;
        threshold            = initialCapacity;

        if (threshold < 3) {
            threshold = 3;
        }

        int hashtablesize = (int) (initialCapacity * loadFactor);

        if (hashtablesize < 3) {
            hashtablesize = 3;
        }

        hashIndex = new HashIndex(hashtablesize, initialCapacity, true);

        int arraySize = threshold;

        if (keyType == BaseHashMap.intKeyOrValue) {
            isIntKey    = true;
            intKeyTable = new int[arraySize];
        } else if (keyType == BaseHashMap.objectKeyOrValue) {
            isObjectKey    = true;
            objectKeyTable = new Object[arraySize];
        } else {
            isLongKey    = true;
            longKeyTable = new long[arraySize];
        }

        if (valueType == BaseHashMap.intKeyOrValue) {
            isIntValue    = true;
            intValueTable = new int[arraySize];
        } else if (valueType == BaseHashMap.objectKeyOrValue) {
            isObjectValue    = true;
            objectValueTable = new Object[arraySize];
        } else if (valueType == BaseHashMap.longKeyOrValue) {
            isLongValue    = true;
            longValueTable = new long[arraySize];
        } else {
            isNoValue = true;
        }

        if (hasAccessCount) {
            accessTable = new int[arraySize];
        }
    }

    protected int getLookup(Object key, int hash) {

        int    lookup = hashIndex.getLookup(hash);
        Object tempKey;

        for (; lookup >= 0; lookup = hashIndex.getNextLookup(lookup)) {
            tempKey = objectKeyTable[lookup];

            if (key.equals(tempKey)) {
                return lookup;
            }
        }

        return lookup;
    }

    protected int getLookup(int key) {

        int lookup = hashIndex.getLookup(key);
        int tempKey;

        for (; lookup >= 0; lookup = hashIndex.getNextLookup(lookup)) {
            tempKey = intKeyTable[lookup];

            if (key == tempKey) {
                return lookup;
            }
        }

        return lookup;
    }

    protected int getLookup(long key) {

        int  lookup = hashIndex.getLookup((int) key);
        long tempKey;

        for (; lookup >= 0; lookup = hashIndex.getNextLookup(lookup)) {
            tempKey = longKeyTable[lookup];

            if (key == tempKey) {
                return lookup;
            }
        }

        return lookup;
    }

    /**
     * generic method for adding or removing keys
     */
    protected Object addOrRemove(long longKey, long longValue,
                                 Object objectKey, Object objectValue,
                                 boolean remove) {

        int hash = (int) longKey;

        if (isObjectKey) {
            if (objectKey == null) {
                return null;
            }

            hash = objectKey.hashCode();
        }

        int    index       = hashIndex.getHashIndex(hash);
        int    lookup      = hashIndex.hashTable[index];
        int    lastLookup  = -1;
        Object returnValue = null;

        for (; lookup >= 0;
                lastLookup = lookup,
                lookup = hashIndex.getNextLookup(lookup)) {
            if (isObjectKey) {
                if (objectKeyTable[lookup].equals(objectKey)) {
                    break;
                }
            } else if (isIntKey) {
                if (longKey == intKeyTable[lookup]) {
                    break;
                }
            } else if (isLongKey) {
                if (longKey == longKeyTable[lookup]) {
                    break;
                }
            }
        }

        if (lookup >= 0) {
            if (remove) {
                if (isObjectKey) {
                    objectKeyTable[lookup] = null;
                } else {
                    if (longKey == 0) {
                        hasZeroKey   = false;
                        zeroKeyIndex = -1;
                    }

                    if (isIntKey) {
                        intKeyTable[lookup] = 0;
                    } else {
                        longKeyTable[lookup] = 0;
                    }
                }

                if (isObjectValue) {
                    returnValue              = objectValueTable[lookup];
                    objectValueTable[lookup] = null;
                } else if (isIntValue) {
                    intValueTable[lookup] = 0;
                } else if (isLongValue) {
                    longValueTable[lookup] = 0;
                }

                hashIndex.unlinkNode(index, lastLookup, lookup);

                if (accessTable != null) {
                    accessTable[lookup] = 0;
                }

                if (minimizeOnEmpty && hashIndex.elementCount == 0) {
                    rehash(initialCapacity);
                }

                return returnValue;
            }

            if (isObjectValue) {
                returnValue              = objectValueTable[lookup];
                objectValueTable[lookup] = objectValue;
            } else if (isIntValue) {
                intValueTable[lookup] = (int) longValue;
            } else if (isLongValue) {
                longValueTable[lookup] = longValue;
            }

            if (accessTable != null) {
                accessTable[lookup] = accessCount++;
            }

            return returnValue;
        }

        // not found
        if (remove) {
            return null;
        }

        if (hashIndex.elementCount >= threshold) {

            // should throw maybe, if reset returns false?
            if (reset()) {
                return addOrRemove(longKey, longValue, objectKey,
                                   objectValue, remove);
            } else {
                return null;
            }
        }

        lookup = hashIndex.linkNode(index, lastLookup);

        // type dependent block
        if (isObjectKey) {
            objectKeyTable[lookup] = objectKey;
        } else if (isIntKey) {
            intKeyTable[lookup] = (int) longKey;

            if (longKey == 0) {
                hasZeroKey   = true;
                zeroKeyIndex = lookup;
            }
        } else if (isLongKey) {
            longKeyTable[lookup] = longKey;

            if (longKey == 0) {
                hasZeroKey   = true;
                zeroKeyIndex = lookup;
            }
        }