* @param <R>
* The type of the high-level operation result
* @author David ‘Bombe’ Roden <bombe@freenetproject.org>
- * @version $Id$
*/
public class HighLevelCallback<R extends HighLevelResult> {
/** Object used for synchronization. */
- private final Object syncObject = new Object();
+ protected final Object syncObject = new Object();
/** The list of callback listeners. */
private final List<HighLevelCallbackListener<R>> highLevelCallbackListeners = Collections.synchronizedList(new ArrayList<HighLevelCallbackListener<R>>());
+ /** Whether the result is complete. */
+ protected boolean resultComplete = false;
+
/** The result of the operation. */
private R result = null;
/**
* Package-private construtor.
+ *
+ * @param result
+ * The result of the operation
*/
- HighLevelCallback() {
+ HighLevelCallback(R result) {
+ this.result = result;
}
/**
}
/**
- * Notifies all listeners that the result of the operation is now known.
+ * Notifies all listeners that the result of the operation is now known. As
+ * soon as a listener was notified it will be removed from the list of
+ * listeners!
*
* @see HighLevelCallbackListener#gotResult(HighLevelCallback)
*/
private synchronized void fireGotResult() {
for (HighLevelCallbackListener<R> highLevelCallbackListener: highLevelCallbackListeners) {
- highLevelCallbackListeners.remove(highLevelCallbackListener);
highLevelCallbackListener.gotResult(this);
}
+ highLevelCallbackListeners.clear();
}
/**
*/
public boolean isDone() {
synchronized (syncObject) {
- return result != null;
+ return resultComplete;
}
}
*/
public R getResult(long waitTime) throws InterruptedException {
synchronized (syncObject) {
- if (result == null) {
+ while (!resultComplete) {
syncObject.wait(waitTime);
}
return result;
}
/**
- * Sets the result of the operation. Calling this method will result in all
- * listeners being notified.
+ * Returns the result even if it is not yet complete.
*
- * @see #fireGotResult()
- * @param result
- * The result of the operation
+ * @return The result of the operation
*/
- void setResult(R result) {
+ R getIntermediaryResult() {
synchronized (syncObject) {
- this.result = result;
+ return result;
+ }
+ }
+
+ /**
+ * Marks the result as complete and notify the listeners. If the result was
+ * already complete, nothing will be done.
+ */
+ void setDone() {
+ synchronized (syncObject) {
+ if (resultComplete) {
+ return;
+ }
+ resultComplete = true;
syncObject.notifyAll();
}
fireGotResult();