/*
* org.openmicroscopy.shoola.env.data.views.ProcessBatchCall
*
*------------------------------------------------------------------------------
* Copyright (C) 2006-2010 University of Dundee. 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.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
*------------------------------------------------------------------------------
*/
package org.openmicroscopy.shoola.env.data.views;
//Java imports
//Third-party libraries
//Application-internal dependencies
import org.openmicroscopy.shoola.util.concur.tasks.MultiStepTask;
/**
* Subclass of {@link BatchCall} which handles periodically polling for
* server process completion.
*
* @author Jean-Marie Burel
* <a href="mailto:j.burel@dundee.ac.uk">j.burel@dundee.ac.uk</a>
* @author Donald MacDonald
* <a href="mailto:donald@lifesci.dundee.ac.uk">donald@lifesci.dundee.ac.uk</a>
* @version 3.0
* <small>
* (<b>Internal version:</b> $Revision: $Date: $)
* </small>
* @since 3.0-Beta4
*/
public abstract class ProcessBatchCall
extends BatchCall
{
/**
* Creates a new instance.
*
* @param name The name associated to the call.
*/
public ProcessBatchCall(String name)
{
super(name);
}
/** Tells whether or not the first call has been made. */
private boolean initialized;
/**
* The call-back which is needed to poll the server for completion.
*/
private ProcessCallback cb;
/**
* Method call to initialize this BatchCall.
*/
protected abstract ProcessCallback initialize()
throws Exception;
/**
* Disabling this method since we want to enforce the use of
* doStep.
*/
public final void doCall()
throws Exception
{
throw new UnsupportedOperationException();
}
/**
* Forwards the call to the {@link #doCall() doCall} method.
* @see MultiStepTask#doStep()
*/
public Object doStep()
throws Exception
{
//
// 1. If we have not yet been called, then the first thing we will do
// is call the script and get the ScriptCallback instance. We return
// immediately if null is returned.
//
if (!initialized) {
try {
cb = initialize();
} catch (Exception e) {
throw new Exception(e);
// Sorry, not sure what to do here.
} finally {
initialized = true;
}
}
if (cb == null) {
done = true;
return null; // EARLY EXIT!
}
//
// 2. Once we have a ScriptCallback, we will continue to call block on
// it per step until it returns non-null value, at which point we set
// done to true and close the callback.
//
if (!done) {
try {
// Do a unit of work
Object action = cb.block(ProcessCallback.UNIT_OF_WORK);
if (action != null) {
done = true;
}
} catch (Exception e) {
// Also not sure what to do here in terms of logging
// exceptions. InterruptedException is fairly harmless.
// Other exceptions may say that the process has died.
done = true;
}
} else {
if (cb != null) {
try {
cb.close();
} finally {
cb = null;
}
}
}
return null;
}
/**
* Tells whether or not the {@link #doStep() doStep} method has been
* invoked.
* @see MultiStepTask#isDone()
*/
public boolean isDone() { return done; }
}