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/*
* Copyright (c) 2010-2015 Pivotal Software, Inc. All rights reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
/*
* Contains code from GNU Trove having the license below.
*
* Copyright (c) 2001, Eric D. Friedman All Rights Reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
package com.gemstone.gemfire.internal.cache;
import com.gemstone.gnu.trove.*;
import java.util.Arrays;
/**
* An open addressed hashing implementation for int primitives.
*
* @author darrel
*/
abstract public class TStatelessIntHash extends TStatelessPrimitiveHash
implements TIntHashingStrategy {
/** the set of ints */
protected transient int[] _set;
protected /*final*/ int _FREE;
/** strategy used to hash values in this collection */
protected TIntHashingStrategy _hashingStrategy;
/**
* Creates a new TStatelessIntHash instance with the default
* capacity and load factor.
*/
public TStatelessIntHash(int freeValue) {
super();
this._hashingStrategy = this;
this._FREE = freeValue;
}
/**
* Creates a new TStatelessIntHash instance whose capacity
* is the next highest prime above initialCapacity + 1
* unless that value is already prime.
*
* @param initialCapacity an int value
*/
public TStatelessIntHash(int freeValue, int initialCapacity) {
super(initialCapacity);
this._hashingStrategy = this;
this._FREE = freeValue;
}
/**
* Creates a new TStatelessIntHash instance with a prime
* value at or near the specified capacity and load factor.
*
* @param initialCapacity used to find a prime capacity for the table.
* @param loadFactor used to calculate the threshold over which
* rehashing takes place.
*/
public TStatelessIntHash(int freeValue, int initialCapacity, float loadFactor) {
super(initialCapacity, loadFactor);
this._hashingStrategy = this;
this._FREE = freeValue;
}
/**
* Creates a new TStatelessIntHash instance with the default
* capacity and load factor.
* @param strategy used to compute hash codes and to compare keys.
*/
public TStatelessIntHash(int freeValue, TIntHashingStrategy strategy) {
super();
this._hashingStrategy = strategy;
this._FREE = freeValue;
}
/**
* Creates a new TStatelessIntHash instance whose capacity
* is the next highest prime above initialCapacity + 1
* unless that value is already prime.
*
* @param initialCapacity an int value
* @param strategy used to compute hash codes and to compare keys.
*/
public TStatelessIntHash(int freeValue, int initialCapacity, TIntHashingStrategy strategy) {
super(initialCapacity);
this._hashingStrategy = strategy;
this._FREE = freeValue;
}
/**
* Creates a new TStatelessIntHash instance with a prime
* value at or near the specified capacity and load factor.
*
* @param initialCapacity used to find a prime capacity for the table.
* @param loadFactor used to calculate the threshold over which
* rehashing takes place.
* @param strategy used to compute hash codes and to compare keys.
*/
public TStatelessIntHash(int freeValue, int initialCapacity, float loadFactor, TIntHashingStrategy strategy) {
super(initialCapacity, loadFactor);
this._hashingStrategy = strategy;
this._FREE = freeValue;
}
public int getFreeValue() {
return this._FREE;
}
/**
* @return a deep clone of this collection
*/
@Override
public Object clone() {
TStatelessIntHash h = (TStatelessIntHash)super.clone();
h._set = this._set.clone();
h._FREE = this._FREE;
return h;
}
/**
* Returns the capacity of the hash table. This is the true
* physical capacity, without adjusting for the load factor.
*
* @return the physical capacity of the hash table.
*/
@Override
protected int capacity() {
return _set.length;
}
/**
* initializes the hashtable to a prime capacity which is at least
* initialCapacity + 1.
*
* @param initialCapacity an int value
* @return the actual capacity chosen
*/
@Override
protected int setUp(int initialCapacity) {
int capacity;
capacity = super.setUp(initialCapacity);
_set = new int[capacity];
if (this._FREE != 0) {
Arrays.fill(_set, this._FREE);
}
return capacity;
}
/**
* Searches the set for val
*
* @param val an int value
* @return a boolean value
*/
public boolean contains(int val) {
return index(val) >= 0;
}
/**
* Executes procedure for each element in the set.
*
* @param procedure a TObjectProcedure value
* @return false if the loop over the set terminated because
* the procedure returned false for some value.
*/
public boolean forEach(TIntProcedure procedure) {
int[] set = _set;
for (int i = set.length; i-- > 0;) {
if (set[i] != this._FREE && ! procedure.execute(set[i])) {
return false;
}
}
return true;
}
// /**
// * Releases the element currently stored at index.
// *
// * @param index an int value
// */
// @Override
// protected void removeAt(int index) {
// super.removeAt(index);
// _set[index] = this._FREE;
// }
/**
* Locates the index of val.
*
* @param val an int value
* @return the index of val or -1 if it isn't in the set.
*/
protected int index(int val) {
int hash, probe, index, length;
int[] set;
if (val == this._FREE) {
return -1;
}
set = _set;
length = set.length;
hash = _hashingStrategy.computeHashCode(val) & 0x7fffffff;
index = hash % length;
if (set[index] != this._FREE && set[index] != val) {
// see Knuth, p. 529
probe = 1 + (hash % (length - 2));
do {
index -= probe;
if (index < 0) {
index += length;
}
} while (set[index] != this._FREE && set[index] != val);
}
return set[index] == this._FREE ? -1 : index;
}
/**
* Locates the index at which val can be inserted. if
* there is already a value equal()ing val in the set,
* returns that value as a negative integer.
*
* @param val an int value
* @return an int value
*/
protected int insertionIndex(int val) {
int hash, probe, index, length;
int[] set;
if (val == this._FREE) {
throw new IllegalArgumentException("can not add the value " + val);
}
set = _set;
length = set.length;
hash = _hashingStrategy.computeHashCode(val) & 0x7fffffff;
index = hash % length;
if (set[index] == this._FREE) {
return index; // empty, all done
} else if (set[index] == val) {
return -index -1; // already stored
} else { // already FULL or REMOVED, must probe
// compute the double hash
probe = 1 + (hash % (length - 2));
// if the slot we landed on is not FREE, probe
// until we find an empty slot or an element
// equal to the one we are trying to insert.
// finding an empty slot means that the value is not present
// and that we should use that slot as the insertion point;
// finding a matching value means that we've found that our desired
// key is already in the table
// starting at the natural offset, probe until we find an
// offset that isn't full.
do {
index -= probe;
if (index < 0) {
index += length;
}
} while (set[index] != this._FREE && set[index] != val);
// if it's not free, the key is already stored
return set[index] != this._FREE ? -index -1 : index;
}
}
/**
* Default implementation of TIntHashingStrategy:
* delegates hashing to HashFunctions.hash(int).
*
* @param val the value to hash
* @return the hashcode.
*/
public final int computeHashCode(int val) {
return HashFunctions.hash(val);
}
} // TStatelessIntHash