/*
* Created on Jul 19, 2006 10:16:26 PM
* Copyright (C) 2006 Aelitis, All Rights Reserved.
*
* This program 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.
* This program 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 this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* AELITIS, SAS au capital de 46,603.30 euros
* 8 Allee Lenotre, La Grille Royale, 78600 Le Mesnil le Roi, France.
*/
package com.aelitis.azureus.ui.swt.browser.txn;
import java.util.Map;
import org.eclipse.swt.browser.Browser;
import com.aelitis.azureus.core.messenger.ClientMessageContext;
/**
* Encapsulates a single transaction that interacts with a single
* SWT {@link Browser}, possibly across multiple pages.
*
* Transactions are started after being created and cannot be restarted.
* They can be marked as cancelled or completed while running.
* Once stopped, they are left as either completed or cancelled.
*
* Subclasses may override starting, canceling, and stopping to perform
* their own specific actions and return <code>false</code> to abort.
*
* @author dharkness
* @created Jul 19, 2006
*/
public abstract class Transaction
{
private int id;
private String type;
private ClientMessageContext context;
private boolean running = false;
private boolean cancelled = false;
private boolean completed = false;
public Transaction ( int id , String type , ClientMessageContext context ) {
this.id = id;
this.type = type;
this.context = context;
}
public int getId ( ) {
return id;
}
public String getType ( ) {
return type;
}
/**
* Starts the transaction if it is not yet running, completed or cancelled.
* A transaction may be started only once. After that, <code>false</code> is returned.
*/
public boolean start ( ) {
debug("start");
if ( running || completed || cancelled ) {
return false;
}
debug("starting");
if ( ! starting() ) {
return false;
}
debug("started");
running = true;
return true;
}
/**
* Performs subclass-specific initialization to start the transaction.
* Return <code>false</code> to abort the start.
*
* @return whether or not the transaction can start
*/
protected boolean starting ( ) {
return true;
}
/**
* Returns <code>true</code> if this transaction has started and is still running.
*/
public boolean isRunning ( ) {
return running;
}
/**
* Marks this transaction as cancelled if it is running and not complete.
* A transaction may be cancelled only once. After that, <code>false</code> is returned.
*/
public boolean cancel ( ) {
debug("cancel");
if ( ! running || completed || cancelled ) {
return false;
}
debug("canceling");
if ( ! canceling() ) {
return false;
}
debug("cancelled");
cancelled = true;
context.getTransactionManager().removeTransaction(this);
return true;
}
/**
* Performs subclass-specific initialization to cancel the transaction.
* Return <code>false</code> to abort the cancellation.
*
* @return whether or not the transaction can be cancelled
*/
protected boolean canceling ( ) {
return true;
}
/**
* Returns <code>true</code> if this transaction has been cancelled.
*/
public boolean isCancelled ( ) {
return cancelled;
}
/**
* Marks this transaction as completed if it is running and not cancelled.
* If it is running and cancelled, it is simply marked as not running.
* A transaction may be stopped only once. After that, <code>false</code> is returned.
*/
protected boolean stop ( ) {
debug("stop");
if ( ! running ) {
return false;
}
debug("stopping");
if ( ! stopping() ) {
return false;
}
debug("stopped");
running = false;
completed = ! cancelled;
context.getTransactionManager().removeTransaction(this);
return true;
}
/**
* Performs subclass-specific initialization to stop the transaction.
* Return <code>false</code> to abort the stop.
*
* @return whether or not the transaction can be stopped
*/
protected boolean stopping ( ) {
return true;
}
/**
* Returns <code>true</code> if this transaction has started and is still running.
*/
public boolean isCompleted ( ) {
return completed;
}
/**
* Sends a message to the JavaScript in the page.
*
* @param key identifies the listener to receive the message
* @param op identifies the operation to perform
*/
protected void sendBrowserMessage ( String key , String op ) {
sendBrowserMessage(key, op, null);
}
/**
* Sends a message to the JavaScript in the page.
*
* @param key identifies the listener to receive the message
* @param op identifies the operation to perform
* @param params optional message parameters
*/
protected void sendBrowserMessage ( String key , String op , Map params ) {
if ( context.getTransaction(type) == this ) {
context.sendBrowserMessage(key, op, params);
}
else {
debug("Non-current transaction cannot send: " + key + "." + op);
}
}
/**
* Executes the given Javascript code in the browser.
*
* @param javascript the code to execute
*/
protected void executeInBrowser ( String javascript ) {
if ( context.getTransaction(type) == this ) {
context.executeInBrowser(javascript);
}
else {
debug("Non-current transaction cannot execute: " + javascript);
}
}
public String toString ( ) {
return type + "-" + id
+ (running ? "-running" : "")
+ (cancelled ? "-cancelled" : "")
+ (completed ? "-completed" : "");
}
/**
* Displays a debug message tagged with the context ID.
*
* @param message sent to the debug log
*/
protected void debug ( String message ) {
context.debug("[" + this + "] " + message);
}
/**
* Displays a debug message and exception tagged with the context ID.
*
* @param message sent to the debug log
* @param t exception to log with message
*/
protected void debug ( String message , Throwable t ) {
context.debug("[" + this + "] " + message, t);
}
}
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