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HSQLDB - Lightweight 100% Java SQL Database Engine
/* Copyright (c) 2001-2019, The HSQL Development Group
* All rights reserved.
*
* 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,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.hsqldb.map;
import java.math.BigDecimal;
/**
* Supports pooling of Integer, Long, Double, BigDecimal, String and Date
* Java Objects. Leads to reduction in memory use when an Object is used more
* then twice in the database.
*
* getXXX methods are used for retrieval of values. If a value is not in
* the pool, it is added to the pool and returned. When the pool gets
* full, half the contents that have been accessed less recently are purged.
*
* @author Fred Toussi (fredt@users dot sourceforge.net)
* @version 2.4.1
* @since 1.7.2
*/
public class ValuePool {
//
static ValuePoolHashMap intPool;
static ValuePoolHashMap longPool;
static ValuePoolHashMap doublePool;
static ValuePoolHashMap bigdecimalPool;
static ValuePoolHashMap stringPool;
static final int SPACE_STRING_SIZE = 64;
static final int DEFAULT_VALUE_POOL_SIZE = 4096;
static final int[] defaultPoolLookupSize = new int[] {
DEFAULT_VALUE_POOL_SIZE, DEFAULT_VALUE_POOL_SIZE,
DEFAULT_VALUE_POOL_SIZE, DEFAULT_VALUE_POOL_SIZE,
DEFAULT_VALUE_POOL_SIZE
};
static final int POOLS_COUNT = defaultPoolLookupSize.length;
static final int defaultSizeFactor = 2;
static final int defaultMaxStringLength = 16;
//
static ValuePoolHashMap[] poolList;
//
static int maxStringLength;
//
public static final String spaceString;
static {
char[] c = new char[SPACE_STRING_SIZE];
for (int i = 0; i < SPACE_STRING_SIZE; i++) {
c[i] = ' ';
}
spaceString = new String(c);
//
initPool();
}
public static final Integer INTEGER_0 = ValuePool.getInt(0);
public static final Integer INTEGER_1 = ValuePool.getInt(1);
public static final Integer INTEGER_2 = ValuePool.getInt(2);
public static final Integer INTEGER_MAX =
ValuePool.getInt(Integer.MAX_VALUE);
public static final BigDecimal BIG_DECIMAL_0 =
ValuePool.getBigDecimal(BigDecimal.valueOf(0));
public static final BigDecimal BIG_DECIMAL_1 =
ValuePool.getBigDecimal(new BigDecimal(1));
//
public static final String[] emptyStringArray = new String[]{};
public static final Object[] emptyObjectArray = new Object[]{};
public static final int[] emptyIntArray = new int[]{};
//
private static void initPool() {
int[] sizeArray = defaultPoolLookupSize;
int sizeFactor = defaultSizeFactor;
synchronized (ValuePool.class) {
maxStringLength = defaultMaxStringLength;
poolList = new ValuePoolHashMap[POOLS_COUNT];
for (int i = 0; i < POOLS_COUNT; i++) {
int size = sizeArray[i];
poolList[i] = new ValuePoolHashMap(size, size * sizeFactor,
BaseHashMap.PURGE_HALF);
}
intPool = poolList[0];
longPool = poolList[1];
doublePool = poolList[2];
bigdecimalPool = poolList[3];
stringPool = poolList[4];
}
}
public static int getMaxStringLength() {
return maxStringLength;
}
public static void resetPool() {
synchronized (ValuePool.class) {
for (int i = 0; i < POOLS_COUNT; i++) {
poolList[i].clear();
}
}
}
public static void clearPool() {
synchronized (ValuePool.class) {
for (int i = 0; i < POOLS_COUNT; i++) {
poolList[i].clear();
}
}
}
public static Integer getInt(int val) {
synchronized (intPool) {
return intPool.getOrAddInteger(val);
}
}
public static Long getLong(long val) {
synchronized (longPool) {
return longPool.getOrAddLong(val);
}
}
public static Double getDouble(long val) {
synchronized (doublePool) {
return doublePool.getOrAddDouble(val);
}
}
public static String getString(String val) {
if (val == null || val.length() > maxStringLength) {
return val;
}
synchronized (stringPool) {
return stringPool.getOrAddString(val);
}
}
public static String getSubString(String val, int start, int limit) {
synchronized (stringPool) {
return stringPool.getOrAddString(val.substring(start, limit));
}
}
public static BigDecimal getBigDecimal(BigDecimal val) {
if (val == null) {
return val;
}
synchronized (bigdecimalPool) {
return (BigDecimal) bigdecimalPool.getOrAddObject(val);
}
}
public static Boolean getBoolean(boolean b) {
return b ? Boolean.TRUE
: Boolean.FALSE;
}
}