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SnappyData store based off Pivotal GemFireXD
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///////////////////////////////////////////////////////////////////////////////
// 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.
///////////////////////////////////////////////////////////////////////////////
/*
* Contains changes for GemFireXD distributed data platform.
*
* Portions 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.
*/
package com.gemstone.gnu.trove;
import java.io.Serializable;
/**
* An open addressed hashing implementation for long primitives.
*
* Created: Sun Nov 4 08:56:06 2001
*
* @author Eric D. Friedman
* @version $Id: TLongHash.java,v 1.14 2004/02/25 14:05:29 ericdf Exp $
*/
abstract public class TLongHash extends TPrimitiveHash
implements Serializable, TLongHashingStrategy {
/** the set of longs */
protected transient long[] _set;
/** strategy used to hash values in this collection */
protected final TLongHashingStrategy _hashingStrategy;
/**
* Creates a new TLongHash instance with the default
* capacity and load factor.
*/
public TLongHash() {
super();
this._hashingStrategy = this;
}
/**
* Creates a new TLongHash instance whose capacity
* is the next highest prime above initialCapacity + 1
* unless that value is already prime.
*
* @param initialCapacity an int value
*/
public TLongHash(int initialCapacity) {
super(initialCapacity);
this._hashingStrategy = this;
}
/**
* Creates a new TLongHash 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 TLongHash(int initialCapacity, float loadFactor) {
super(initialCapacity, loadFactor);
this._hashingStrategy = this;
}
/**
* Creates a new TLongHash instance with the default
* capacity and load factor.
* @param strategy used to compute hash codes and to compare keys.
*/
public TLongHash(TLongHashingStrategy strategy) {
super();
this._hashingStrategy = strategy;
}
/**
* Creates a new TLongHash 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 TLongHash(int initialCapacity, TLongHashingStrategy strategy) {
super(initialCapacity);
this._hashingStrategy = strategy;
}
/**
* Creates a new TLongHash 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 TLongHash(int initialCapacity, float loadFactor, TLongHashingStrategy strategy) {
super(initialCapacity, loadFactor);
this._hashingStrategy = strategy;
}
/**
* @return a deep clone of this collection
*/
@Override // GemStoneAddition
public Object clone() {
TLongHash h = (TLongHash)super.clone();
h._set = this._set.clone();
return h;
}
/**
* initializes the hashtable to a prime capacity which is at least
* initialCapacity + 1.
*
* @param initialCapacity an int value
* @return the actual capacity chosen
*/
@Override // GemStoneAddition
protected int setUp(int initialCapacity) {
int capacity;
capacity = super.setUp(initialCapacity);
_set = new long[capacity];
return capacity;
}
/**
* Searches the set for val
*
* @param val an long value
* @return a boolean value
*/
public boolean contains(long 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(TLongProcedure procedure) {
byte[] states = _states;
long[] set = _set;
for (int i = set.length; i-- > 0;) {
if (states[i] == FULL && ! procedure.execute(set[i])) {
return false;
}
}
return true;
}
/**
* Releases the element currently stored at index.
*
* @param index an int value
*/
@Override // GemStoneAddition
protected void removeAt(int index) {
super.removeAt(index);
_set[index] = 0;
}
/**
* Locates the index of val.
*
* @param val an long value
* @return the index of val or -1 if it isn't in the set.
*/
protected int index(long val) {
int hash, probe, index, length;
long[] set;
byte[] states;
states = _states;
set = _set;
length = states.length;
hash = _hashingStrategy.computeHashCode(val) & 0x7fffffff;
index = hash % length;
if (states[index] != FREE &&
(states[index] == REMOVED || set[index] != val)) {
// see Knuth, p. 529
probe = 1 + (hash % (length - 2));
do {
index -= probe;
if (index < 0) {
index += length;
}
} while (states[index] != FREE &&
(states[index] == REMOVED || set[index] != val));
}
return states[index] == 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 long value
* @return an int value
*/
protected int insertionIndex(long val) {
int hash, probe, index, length;
long[] set;
byte[] states;
states = _states;
set = _set;
length = states.length;
hash = _hashingStrategy.computeHashCode(val) & 0x7fffffff;
index = hash % length;
if (states[index] == FREE) {
return index; // empty, all done
} else if (states[index] == FULL && 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 FULL (but not removed), probe
// until we find an empty slot, a REMOVED 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 REMOVED slot means that we need to keep searching,
// however we want to remember the offset of that REMOVED slot
// so we can reuse it in case a "new" insertion (i.e. not an update)
// is possible.
// finding a matching value means that we've found that our desired
// key is already in the table
if (states[index] != REMOVED) {
// starting at the natural offset, probe until we find an
// offset that isn't full.
do {
index -= probe;
if (index < 0) {
index += length;
}
} while (states[index] == FULL && set[index] != val);
}
// if the index we found was removed: continue probing until we
// locate a free location or an element which equal()s the
// one we have.
if (states[index] == REMOVED) {
int firstRemoved = index;
while (states[index] != FREE &&
(states[index] == REMOVED || set[index] != val)) {
index -= probe;
if (index < 0) {
index += length;
}
}
return states[index] == FULL ? -index -1 : firstRemoved;
}
// if it's full, the key is already stored
return states[index] == FULL ? -index -1 : index;
}
}
/**
* Default implementation of TLongHashingStrategy:
* delegates hashing to HashFunctions.hash(long).
*
* @param val the value to hash
* @return the hashcode.
*/
public final int computeHashCode(long val) {
return HashFunctions.hash(val);
}
} // TLongHash