io.github.jonestimd.swing.table.model.AsyncTableDataProvider Maven / Gradle / Ivy
// Copyright (c) 2016 Timothy D. Jones
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
package io.github.jonestimd.swing.table.model;
import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;
import java.util.LinkedList;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.SwingWorker;
/**
* Base class for loading table data in a background thread.
* @param the class representing a row in the table
* @param the class representing the request for the data (e.g. a {@link java.util.Collection Collection} of IDs)
* @param the class representing the collection of retrieved data (e.g. a {@link java.util.Map Map} of IDs to row data)
*/
public abstract class AsyncTableDataProvider implements TableDataProvider {
private final Logger logger = Logger.getLogger(AsyncTableDataProvider.class.getName());
protected final PropertyChangeSupport changeSupport = new PropertyChangeSupport(this);
private List workers = new LinkedList<>();
@Override
public void addStateChangeListener(PropertyChangeListener listener) {
changeSupport.addPropertyChangeListener(STATE_PROPERTY, listener);
}
@Override
public void removeStateChangeListener(PropertyChangeListener listener) {
changeSupport.removePropertyChangeListener(STATE_PROPERTY, listener);
}
protected void firePropertyChange(String propertyName, Object oldValue, Object newValue) {
changeSupport.firePropertyChange(propertyName, oldValue, newValue);
}
protected void fireStateChanged() {
firePropertyChange(STATE_PROPERTY, null, null);
}
/**
* Execute a query on a background thread.
*/
protected abstract Result getData(Query query) throws Exception;
/**
* Update the model with the result of a query.
* This method will only be called from the Event Dispatch Thread.
*/
protected abstract void setResult(Result result);
/**
* Compare two queries for redundancy.
* @param pendingQuery a query on the queue
* @param newQuery a query to be added to the queue
* @return true if {@code newQuery} is included in {@code pendingQuery}
*/
protected abstract boolean matches(Query pendingQuery, Query newQuery);
/**
* Submit {@code query} if it is not already in the queue.
* Note: this method should only be called from the Event Dispatch Thread.
* @see #matches(Object, Object)
*/
protected void submitIfNotPending(Query query) {
if (! isPending(query)) {
Worker worker = new Worker(query);
workers.add(worker);
worker.execute();
}
}
/**
* @return the number of queries in the queue.
*/
public int activeQueries() {
return workers.size();
}
private boolean isPending(Query query) {
for (Worker worker : workers) {
if (matches(worker.query, query) && !worker.isDone()) {
return true;
}
}
return false;
}
private class Worker extends SwingWorker {
private final Query query;
private Worker(Query query) {
this.query = query;
}
@Override
protected Result doInBackground() throws Exception {
return getData(query);
}
@Override
protected void done() {
if (!isCancelled()) {
super.done();
try {
setResult(get());
workers.remove(this);
fireStateChanged();
} catch (Exception ex) {
logger.log(Level.SEVERE, "failed to get table data", ex);
}
}
}
}
}