/**
* Copyright (C) 2002-2012 The FreeCol Team
*
* This file is part of FreeCol.
*
* FreeCol is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 of the License, or
* (at your option) any later version.
*
* FreeCol 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 General Public License
* along with FreeCol. If not, see <http://www.gnu.org/licenses/>.
*/
package net.sf.freecol.server.model;
import java.util.HashMap;
import java.util.Map;
import java.util.logging.Logger;
import net.sf.freecol.common.model.FreeColGameObject;
import net.sf.freecol.server.control.ChangeSet;
/**
* Root class for sessions.
*/
public abstract class TransactionSession {
private static final Logger logger = Logger.getLogger(TransactionSession.class.getName());
/**
* A map of all active sessions.
*/
protected static final Map<String, TransactionSession> allSessions
= new HashMap<String, TransactionSession>();
/** Has this session been completed? */
private boolean completed;
/**
* Protected constructor, we only really instantiate specific types
* of transactions.
*
* @param key A unique key to lookup this transaction with.
*/
protected TransactionSession(String key) {
if (allSessions.get(key) != null) {
throw new IllegalArgumentException("Duplicate session: " + key);
}
completed = false;
allSessions.put(key, this);
}
/**
* All transaction types must implement a completion action. The
* last thing they should do is call this to remove reference to
* this transaction.
*
* @param cs A <code>ChangeSet</code> to update with changes that
* occur when completing this session.
*/
public void complete(ChangeSet cs) {
completed = true;
}
/**
* Make a transaction session key.
*
* @param type An identifier for the type of transaction.
* @param o1 A string to uniquely identify the transaction.
* @param o2 Another string to uniquely identify the transaction.
* @return A transaction session key.
*/
protected static String makeSessionKey(Class type,
String o1, String o2) {
return type.toString() + "-" + o1 + "-" + o2;
}
/**
* Make a transaction session key given two game objects.
*
* @param type An identifier for the type of transaction.
* @param o1 A <code>FreeColGameObject</code> involved in the session.
* @param o2 Another <code>FreeColGameObject</code> involved in the session.
* @return A transaction session key.
*/
protected static String makeSessionKey(Class type,
FreeColGameObject o1,
FreeColGameObject o2) {
return makeSessionKey(type, o1.getId(), o2.getId());
}
// Public interface
/**
* Complete all transactions. Useful at the end of turn.
*
* @param cs A <code>ChangeSet</code> to update.
*/
public static void completeAll(ChangeSet cs) {
for (TransactionSession ts : allSessions.values()) {
if (!ts.completed) ts.complete(cs);
}
clearAll();
}
/**
* Clear all transactions.
*/
public static void clearAll() {
allSessions.clear();
}
/**
* Look up a session of specified type given the game objects involved.
*
* @param type The class of session.
* @param o1 The first <code>FreeColGameObject</code> in the session.
* @param o2 The second <code>FreeColGameObject</code> in the session.
* @return A session of the specified type, or null if not found.
*/
public static <T extends TransactionSession> T lookup(Class<T> type,
FreeColGameObject o1, FreeColGameObject o2) {
return lookup(type, o1.getId(), o2.getId());
}
/**
* Look up a session of specified type given the ids of the game objects
* involved. This version is needed for sessions where one of the objects
* may have already been disposed of while the session is still valid.
*
* @param type The class of session.
* @param s1 The id of the first object in the session.
* @param s2 The id of the second object in the session.
* @return A session of the specified type, or null if not found.
*/
public static <T extends TransactionSession> T lookup(Class<T> type,
String s1, String s2) {
String key = makeSessionKey(type, s1, s2);
TransactionSession ts = allSessions.get(key);
if (ts != null && ts.completed) {
allSessions.remove(key);
ts = null;
}
return (ts == null) ? null : type.cast(ts);
}
}