package vtk;

import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;

import javax.swing.SwingUtilities;

/**
 * This class helps to provide a solution in concurrent garbage collection issue
 * with VTK. This class allow automatic garbage collection done in a specific
 * thread such as the EDT.
 *
 * @author sebastien jourdain - sebastien.jourdain@kitware.com
 */
public class vtkJavaGarbageCollector {

 private ScheduledExecutorService executor;
 private Runnable deleteRunnable;
 private Runnable deferredEdtRunnable;
 private long periodTime;
 private TimeUnit timeUnit;
 private boolean autoCollectionRunning;
 private boolean debug;

 /**
 * Build a garbage collector which is configured to garbage collect every
 * seconds but has not been started yet. The user has to call
 * SetAutoGarbageCollection(true) to make it start.
 */
 public vtkJavaGarbageCollector() {
 // Default settings
 debug = false;
 periodTime = 1;
 timeUnit = TimeUnit.SECONDS;
 autoCollectionRunning = false;
 //
 executor = Executors.newSingleThreadScheduledExecutor();
 deleteRunnable = new Runnable() {

 public void run() {
 // Do the delete here
 vtkReferenceInformation info = vtkObjectBase.JAVA_OBJECT_MANAGER.gc(debug);
 if (debug) {
 System.out.println(info);
 System.out.println(info.listKeptReferenceToString());
 System.out.println(info.listRemovedReferenceToString());
 }
 }
 };
 deferredEdtRunnable = new Runnable() {

 public void run() {
 SwingUtilities.invokeLater(deleteRunnable);
 }
 };
 }

 /**
 * Set the schedule time that should be used to send a garbage collection
 * request to the EDT.
 *
 * @param period
 * @param timeUnit
 */
 public void SetScheduleTime(long period, TimeUnit timeUnit) {
 this.periodTime = period;
 this.timeUnit = timeUnit;
 SetAutoGarbageCollection(autoCollectionRunning);
 }

 /**
 * Whether to print out when garbage collection is run.
 *
 * @param debug
 */
 public void SetDebug(boolean debug) {
 this.debug = debug;
 }

 /**
 * Start or stop the automatic garbage collection in the EDT.
 *
 * @param doGarbageCollectionInEDT
 */
 public void SetAutoGarbageCollection(boolean doGarbageCollectionInEDT) {
 autoCollectionRunning = doGarbageCollectionInEDT;
 executor.shutdown();
 if (doGarbageCollectionInEDT) {
 executor = Executors.newSingleThreadScheduledExecutor();
 executor.scheduleAtFixedRate(deferredEdtRunnable, periodTime, periodTime, timeUnit);
 }
 }

 /**
 * Shortcut for SetAutoGarbageCollection(true)
 * @see SetAutoGarbageCollection
 */
 public void Start() {
 this.SetAutoGarbageCollection(true);
 }

 /**
 * Shortcut for SetAutoGarbageCollection(false)
 * @see SetAutoGarbageCollection
 */
 public void Stop() {
 this.SetAutoGarbageCollection(false);
 }

 /**
 * @return the runnable that do the garbage collection. This could be used
 * if you want to execute the garbage collection in another thread
 * than the EDT.
 */
 public Runnable GetDeleteRunnable() {
 return deleteRunnable;
 }
}