/**
* JADE - Java Agent DEvelopment Framework is a framework to develop
* multi-agent systems in compliance with the FIPA specifications.
* Copyright (C) 2000 CSELT S.p.A.
* Copyright (C) 2001,2002 TILab S.p.A.
*
* GNU Lesser General Public License
*
* 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,
* version 2.1 of the License.
*
* 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
package jade.util;
//#APIDOC_EXCLUDE_FILE
import jade.util.leap.List;
import jade.util.leap.LinkedList;
/**
* Implementation of a list of objects providing methods to
* synchronize threads acting on the list in such a way to prevent
* concurrent modifications (addition/remotion of elements) and
* concurrent scanning/modification. Concurrent scannings are allowed
* instead.
* @author Giovanni Caire - TILab
*/
public class SynchList extends RWLock {
// The actual list of objects
private List innerList = null;
/**
Default constructor.
*/
public SynchList() {
}
/**
This method grants writing privileges to the calling thread and
grants access to the protected list.
@return The inner, protected list.
*/
public synchronized List startModifying() {
writeLock();
return innerList;
}
/**
This method must be called when a writer thread has finished
modifying the list, so that the associated readers-writer lock
can be relinquished.
*/
public synchronized void stopModifying() {
writeUnlock();
}
/**
This method grants reading privileges to the calling thread and
grants access to the protected list.
@return The inner, protected list.
*/
public synchronized List startScanning() {
if (innerList != null) {
readLock();
}
return innerList;
}
/**
This method must be called when a reader thread has finished
accessing the list, so that the associated readers-writer lock
can be relinquished.
*/
public synchronized void stopScanning() {
if (innerList != null) {
readUnlock();
}
}
//#APIDOC_EXCLUDE_BEGIN
protected void onWriteStart() {
if (innerList == null) {
innerList = new LinkedList();
}
}
protected void onWriteEnd() {
if (innerList != null && innerList.size() == 0) {
innerList = null;
}
}
//#APIDOC_EXCLUDE_END
}