--- /dev/null
+package be.nikiroo.utils.ui;
+
+import java.beans.PropertyChangeEvent;
+import java.beans.PropertyChangeListener;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.TreeSet;
+
+import javax.swing.SwingWorker;
+
+/**
+ * This class helps you delay some graphical actions and execute the most recent
+ * ones when under contention.
+ * <p>
+ * How does it work?
+ * <ul>
+ * <li>it takes an ID and an associated {@link SwingWorker} and will call
+ * {@link SwingWorker#execute()} after a small delay (see
+ * {@link DelayWorker#DelayWorker(int)})</li>
+ * <li>if a second call to {@link DelayWorker#delay(String, SwingWorker)} comes
+ * with the same ID before the first one is done, it will be put on a waiting
+ * queue</li>
+ * <li>if a third call still with the same ID comes, its associated worker will
+ * <b>replace</b> the one in the queue (only one worker per ID in the queue,
+ * always the latest one)</li>
+ * <li>when the first worker is done, it will check the waiting queue and
+ * execute that latest worker if any</li>
+ * </ul>
+ *
+ * @author niki
+ *
+ */
+@SuppressWarnings("rawtypes")
+public class DelayWorker {
+ private Map<String, SwingWorker> lazyEnCours;
+ private Object lazyEnCoursLock;
+
+ private TreeSet<String> wip;
+
+ private Object waiter;
+
+ private boolean cont;
+ private boolean paused;
+ private Thread loop;
+
+ /**
+ * Create a new {@link DelayWorker} with the given delay (in milliseconds)
+ * before each drain of the queue.
+ *
+ * @param delayMs
+ * the delay in milliseconds (can be 0, cannot be negative)
+ */
+ public DelayWorker(final int delayMs) {
+ if (delayMs < 0) {
+ throw new IllegalArgumentException(
+ "A waiting delay cannot be negative");
+ }
+
+ lazyEnCours = new HashMap<String, SwingWorker>();
+ lazyEnCoursLock = new Object();
+ wip = new TreeSet<String>();
+ waiter = new Object();
+ cont = true;
+ paused = false;
+
+ loop = new Thread(new Runnable() {
+ @Override
+ public void run() {
+ while (cont) {
+ try {
+ Thread.sleep(delayMs);
+ } catch (InterruptedException e) {
+ }
+
+ Map<String, SwingWorker> workers = new HashMap<String, SwingWorker>();
+ synchronized (lazyEnCoursLock) {
+ for (String key : new ArrayList<String>(
+ lazyEnCours.keySet())) {
+ if (!wip.contains(key)) {
+ workers.put(key, lazyEnCours.remove(key));
+ }
+ }
+ }
+
+ for (final String key : workers.keySet()) {
+ SwingWorker worker = workers.get(key);
+
+ synchronized (lazyEnCoursLock) {
+ wip.add(key);
+ }
+
+ worker.addPropertyChangeListener(
+ new PropertyChangeListener() {
+ @Override
+ public void propertyChange(
+ PropertyChangeEvent evt) {
+ synchronized (lazyEnCoursLock) {
+ wip.remove(key);
+ }
+ wakeup();
+ }
+ });
+
+ // Start it, at last
+ worker.execute();
+ }
+
+ synchronized (waiter) {
+ do {
+ try {
+ if (cont)
+ waiter.wait();
+ } catch (InterruptedException e) {
+ }
+ } while (cont && paused);
+ }
+ }
+ }
+ });
+
+ loop.setDaemon(true);
+ loop.setName("Loop for DelayWorker");
+ }
+
+ /**
+ * Start the internal loop that will drain the processing queue. <b>MUST
+ * NOT</b> be started twice (but see {@link DelayWorker#pause()} and
+ * {@link DelayWorker#resume()} instead).
+ */
+ public void start() {
+ loop.start();
+ }
+
+ /**
+ * Pause the system until {@link DelayWorker#resume()} is called -- note
+ * that it will still continue on the processes currently scheduled to run,
+ * but will pause after that.
+ * <p>
+ * Can be called even if already paused, will just do nothing in that
+ * context.
+ */
+ public void pause() {
+ paused = true;
+ }
+
+ /**
+ * Check if the {@link DelayWorker} is currently paused.
+ *
+ * @return TRUE if it is
+ */
+ public boolean isPaused() {
+ return paused;
+ }
+
+ /**
+ * Resume the system after a pause.
+ * <p>
+ * Can be called even if already running, will just do nothing in that
+ * context.
+ */
+ public void resume() {
+ synchronized (waiter) {
+ paused = false;
+ wakeup();
+ }
+ }
+
+ /**
+ * Stop the system.
+ * <p>
+ * Note: this is final, you <b>MUST NOT</b> call {@link DelayWorker#start()}
+ * a second time (but see {@link DelayWorker#pause()} and
+ * {@link DelayWorker#resume()} instead).
+ */
+ public void stop() {
+ synchronized (waiter) {
+ cont = false;
+ wakeup();
+ }
+ }
+
+ /**
+ * Clear all the processes that were put on the queue but not yet scheduled
+ * to be executed -- note that it will still continue on the processes
+ * currently scheduled to run.
+ */
+ public void clear() {
+ synchronized (lazyEnCoursLock) {
+ lazyEnCours.clear();
+ wip.clear();
+ }
+ }
+
+ /**
+ * Put a new process in the delay queue.
+ *
+ * @param id
+ * the ID of this process (if you want to skip workers when they
+ * are superseded by a new one, you need to use the same ID key)
+ * @param worker
+ * the process to delay
+ */
+ public void delay(final String id, final SwingWorker worker) {
+ synchronized (lazyEnCoursLock) {
+ lazyEnCours.put(id, worker);
+ }
+
+ wakeup();
+ }
+
+ /**
+ * Wake up the loop thread.
+ */
+ private void wakeup() {
+ synchronized (waiter) {
+ waiter.notifyAll();
+ }
+ }
+}
git://git.nikiroo.be / fanfix.git / blobdiff