/*
Copyright (c) 2003-2009 ITerative Consulting Pty Ltd. All Rights Reserved.
Redistribution and use in source and binary forms, with or without modification, are permitted
provided that the following conditions are met:
o Redistributions of source code must retain the above copyright notice, this list of conditions and
the following disclaimer.
o 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.
o This jcTOOL Helper Class software, whether in binary or source form may not be used within,
or to derive, any other product without the specific prior written permission of the copyright holder
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS "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 THE COPYRIGHT OWNER 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 Express.services;
import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;
import java.io.Serializable;
import org.springframework.jdbc.support.SQLErrorCodeSQLExceptionTranslator;
import DisplayProject.binding.beans.ExtendedPropertyChangeSupport;
import DisplayProject.binding.beans.Observable;
import Framework.Constants;
import Framework.HashTable;
import Framework.RuntimeProperties;
import Framework.TextData;
import GenericDBMS.DBConnectionManager;
/**
* Defines a cache that holds SQL statements in a hash table for quick lookup.
* <p>
* @author ITerative Consulting
* @since 26-Feb-2008
*/
@RuntimeProperties(isDistributed=false, isAnchored=false, isShared=true, isTransactional=false)
@SuppressWarnings("serial")
public class SqlStatementCache
implements Serializable, Observable
{
// ----------
// Attributes
// ----------
public PropertyChangeSupport qq_Listeners = new ExtendedPropertyChangeSupport(this, true);
private HashTable cache;
private DBConnectionManager dB;
private SqlStatement head;
private int maxStatements;
private boolean on;
private int statements;
private SqlStatement tail;
// ------------
// Constructors
// ------------
public SqlStatementCache() {
// Explicitly call the superclass constructor to prevent the implicit call
super();
this.maxStatements = 50;
this.head = new SqlStatement();
this.tail = new SqlStatement();
this.head.setNext(this.tail);
this.tail.setPrev(this.head);
this.setup(0);
this.setOn(true);
}
public SqlStatementCache(DBConnectionManager pDB) {
this();
this.setDB( pDB );
}
// ----------------------
// Accessors and Mutators
// ----------------------
public synchronized void setDB(DBConnectionManager dB) {
DBConnectionManager oldValue = this.dB;
this.dB = dB;
this.qq_Listeners.firePropertyChange("DB", oldValue, this.dB);
}
public synchronized DBConnectionManager getDB() {
return this.dB;
}
public synchronized void setOn(boolean on) {
boolean oldValue = this.on;
this.on = on;
this.qq_Listeners.firePropertyChange("on", oldValue, this.on);
}
public synchronized boolean getOn() {
// AD:Aug 15, 2008 - the statement cache always needs to be off in the java environment
// when using pooling
return false;
// return this.on;
}
private synchronized SqlStatement getTail() {
return this.tail;
}
// -------
// Methods
// -------
public void addPropertyChangeListener(String property, PropertyChangeListener listener) {
qq_Listeners.addPropertyChangeListener(property, listener);
}
public void addPropertyChangeListener(PropertyChangeListener listener) {
qq_Listeners.addPropertyChangeListener(listener);
}
public void removePropertyChangeListener(String property, PropertyChangeListener listener) {
qq_Listeners.removePropertyChangeListener(property, listener);
}
public void removePropertyChangeListener(PropertyChangeListener listener) {
qq_Listeners.removePropertyChangeListener(listener);
}
/**
* enter<p>
* <p>
* @param element Type: Object
* @param key Type: TextData
*/
public synchronized void enter(Object element, TextData key) {
if (this.getOn()) {
this.cache.enter(element, key);
//
// Add statement to LRU chain.
//
SqlStatement s = (SqlStatement)element;
s.setKey(key);
s.setNext(this.head.getNext());
s.setPrev(this.head);
this.head.getNext().setPrev(s);
this.head.setNext(s);
this.statements = this.statements+1;
if (this.statements > this.maxStatements) {
//
// too many elements take one out
//
s = this.tail.getPrev();
this.tail.setPrev(this.tail.getPrev().getPrev());
this.tail.getPrev().setNext(this.tail);
this.statements = this.statements-1;
s.setNext(null);
s.setPrev(null);
this.cache.remove(s.getKey());
try {
s.getHandle().close();
} catch (java.sql.SQLException qq_SQLEx) {
throw new SQLErrorCodeSQLExceptionTranslator().translate("SQL tasks", "", qq_SQLEx );
}
}
}
}
/**
* find<p>
* <p>
* @param key Type: TextData
* @return Object
*/
public synchronized Object find(TextData key) {
SqlStatement s = null;
if (this.getOn()) {
s = (SqlStatement)this.cache.find(key);
if (s != null && this.head.getNext() != s) {
//
// Move it to the front of the LRU chain.
//
s.getNext().setPrev(s.getPrev());
s.getPrev().setNext(s.getNext());
s.setNext(this.head.getNext());
s.setPrev(this.head);
this.head.getNext().setPrev(s);
this.head.setNext(s);
}
}
return s;
}
/**
* setup<p>
* <p>
* @param maxStatements Type: int (Input) (default in Forte: 0)
*/
public synchronized void setup(int maxStatements) {
if (this.head.getNext() != this.getTail()) {
throw new Error(Error.SS_CACHE_IN_USE, "Setup", this).getException();
}
if (maxStatements > 0) {
this.maxStatements = maxStatements;
}
this.cache = new HashTable();
this.cache.setup(this.maxStatements*2, new SqlStatementHash(Constants.SP_KT_OBJECT));
}
} // end class SqlStatementCache
// c Pass 2 Conversion Time: 703 milliseconds