JavaHeapInformationAction.java

/*******************************************************************************
 * Copyright (c) 1998, 2015 Oracle and/or its affiliates. All rights reserved.
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Oracle - initial API and implementation from Oracle TopLink
******************************************************************************/
package org.eclipse.persistence.tools.workbench.framework.internal;

import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.text.NumberFormat;

import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;

import org.eclipse.persistence.tools.workbench.framework.action.AbstractFrameworkAction;
import org.eclipse.persistence.tools.workbench.framework.context.WorkbenchContext;


/**
 * development-only action that displays the current Java heap information
 */
final class JavaHeapInformationAction
    extends AbstractFrameworkAction
{
    private JLabel totalMemoryLabel;
    private JLabel freeMemoryLabel;
    private JLabel maxMemoryLabel;
    private static final int MB = 1024 * 1024;

    JavaHeapInformationAction(WorkbenchContext context) {
        super(context);
    }

    /**
     * @see org.eclipse.persistence.tools.workbench.framework.action.AbstractFrameworkAction#initialize()
     */
    protected void initialize() {
        super.initialize();
        this.initializeTextAndMnemonic("JAVA_HEAP_INFO");
    }

    /**
     * ignore the selected nodes
     */
    protected void execute() {
        this.totalMemoryLabel = new JLabel();
        this.freeMemoryLabel = new JLabel();
        this.maxMemoryLabel = new JLabel();
        this.refreshLabels();
        JOptionPane.showMessageDialog(
            this.currentWindow(),
            this.buildPanel(),
            this.resourceRepository().getString("JAVA_HEAP_INFO"),
            JOptionPane.INFORMATION_MESSAGE
        );
    }

    private Object buildPanel() {
        JPanel panel = new JPanel(new GridLayout(0, 1));
        panel.add(this.totalMemoryLabel);
        panel.add(this.freeMemoryLabel);
        panel.add(this.maxMemoryLabel);
        panel.add(this.buildGCButton());
        return panel;
    }

    private void refreshLabels() {
        Runtime rt = Runtime.getRuntime();
        NumberFormat nf = NumberFormat.getInstance();
        this.totalMemoryLabel.setText("Current Heap Size: " + nf.format(rt.totalMemory()/MB) + " MB");
        this.freeMemoryLabel.setText("Available Heap Space: " + nf.format(rt.freeMemory()/MB) + " MB");
        this.maxMemoryLabel.setText("Max Heap Size: " + nf.format(rt.maxMemory()/MB) + " MB");
    }

    private JButton buildGCButton() {
        return new JButton(this.buildGCAction());
    }

    private Action buildGCAction() {
        Action action = new AbstractAction("Collect Garbage") {
            public void actionPerformed(ActionEvent event) {
                JavaHeapInformationAction.this.gc();
            }
        };
        action.setEnabled(true);
        return action;
    }

    void gc() {
        System.gc();
        this.refreshLabels();
    }

}