X-Git-Url: https://gerrit.simantics.org/r/gitweb?a=blobdiff_plain;f=bundles%2Forg.simantics.db.layer0%2Fsrc%2Forg%2Fsimantics%2Fdb%2Flayer0%2Futil%2FEvaluatingListener.java;h=1ea261b52e366e49b6e3459a75cd25193ada94b9;hb=1cd631466bc35e05bc585999b2f325f148cd5629;hp=59dcc5910e2e018402945007d0bd28ab8d24519b;hpb=969bd23cab98a79ca9101af33334000879fb60c5;p=simantics%2Fplatform.git
diff --git a/bundles/org.simantics.db.layer0/src/org/simantics/db/layer0/util/EvaluatingListener.java b/bundles/org.simantics.db.layer0/src/org/simantics/db/layer0/util/EvaluatingListener.java
index 59dcc5910..1ea261b52 100644
--- a/bundles/org.simantics.db.layer0/src/org/simantics/db/layer0/util/EvaluatingListener.java
+++ b/bundles/org.simantics.db.layer0/src/org/simantics/db/layer0/util/EvaluatingListener.java
@@ -1,199 +1,199 @@
-/*******************************************************************************
- * Copyright (c) 2012 Association for Decentralized Information Management in
- * Industry THTH ry.
- * All rights reserved. This program and the accompanying materials
- * are made available under the terms of the Eclipse Public License v1.0
- * which accompanies this distribution, and is available at
- * http://www.eclipse.org/legal/epl-v10.html
- *
- * Contributors:
- * VTT Technical Research Centre of Finland - initial API and implementation
- *******************************************************************************/
-package org.simantics.db.layer0.util;
-
-import java.util.concurrent.Semaphore;
-import java.util.concurrent.TimeUnit;
-
-import org.simantics.db.Session;
-import org.simantics.db.exception.DatabaseException;
-import org.simantics.db.procedure.Listener;
-import org.simantics.db.request.Read;
-
-/**
- * A database listener that disposes itself based on a criterion evaluated using
- * the request results received by the listener. If the results pass the
- * criterion, the listener is disposed and the result is either accepted or
- * discarded based on the evaluation.
- *
- *
- * The reason for the existence of this class is that sometimes database
- * requests always perform asynchronously, i.e. return empty results at first
- * and later get updated to their final results. For example, a the results of a
- * web request would take a while to be delivered. This listener makes it a bit
- * easier to deal with these situations when results are needed synchronously.
- *
- *
- * {@link #trySyncRequest(Session, Read, Criterion, long, TimeUnit)} provides a
- * utility for executing a synchronous read request with this listener so that
- * the implementation will wait for a criterion accepted result for the
- * specified amount of time. If an accepted result is reached within the time
- * limit, it will be returned. If the time limit is reached and no accepted
- * result is attained, null will be returned. If the request
- * produces an exception, it will be thrown.
- *
- * @author Tuukka Lehtonen
- *
- * @param database request result type
- *
- * @see EvaluatingListener.Evaluation
- * @see EvaluatingListener.Criterion
- */
-public class EvaluatingListener implements Listener {
-
- public static enum Evaluation {
- /**
- * Keep on listening to further results.
- */
- IGNORE,
- /**
- * Dispose listener and discard the results.
- */
- DISCARD,
- /**
- * Dispose listener and return the latest result.
- */
- ACCEPT
- }
-
- /**
- * An evaluable criterion for the result received by
- * {@link Listener#execute(Object)} to tell whether to accept the result,
- * wait for another result or to consider the listener disposed.
- *
- * @param the type of the result
- */
- public static interface Criterion {
- Evaluation evaluate(T result);
- }
-
- /**
- * The criterion the listener evaluates. When it evaluates to
- * {@value Evaluation#DISCARD}, this field is nullified and the listener is
- * considered disposed.
- */
- private volatile Criterion criterion;
- private T result;
- private Throwable exception;
- private Semaphore wait = new Semaphore(0);
-
- public EvaluatingListener(Criterion criterion) {
- if (criterion == null)
- throw new NullPointerException("null criterion");
- this.criterion = criterion;
- }
-
- /**
- * @param session
- * @param request
- * @param criterion
- * @param timeout
- * @param unit
- * @return
- * @throws InterruptedException
- * @throws DatabaseException
- */
- public static T trySyncRequest(Session session, Read request, Criterion criterion, long timeout, TimeUnit unit) throws InterruptedException, DatabaseException {
- EvaluatingListener l = new EvaluatingListener(criterion);
- session.asyncRequest(request, l);
- l.tryWaitForResult(timeout, unit);
- // Make sure the listener is disposed.
- l.dispose();
- l.throwPossibleException();
- return l.getResult();
- }
-
- public T waitForResult() throws InterruptedException {
- wait.acquire();
- return getResult();
- }
-
- public boolean tryWaitForResult(long timeout, TimeUnit unit) throws InterruptedException {
- return wait.tryAcquire(timeout, unit);
- }
-
- public T getResult() {
- return result;
- }
-
- public Throwable getException() {
- return exception;
- }
-
- public void throwPossibleException() throws DatabaseException {
- if (exception != null) {
- if (exception instanceof DatabaseException)
- throw (DatabaseException) exception;
- throw new DatabaseException(exception);
- }
- }
-
- @Override
- public void execute(T result) {
- Criterion crit = criterion;
- if (crit == null)
- return;
- EvaluatingListener.Evaluation e = crit.evaluate(result);
- switch (e) {
- case IGNORE:
- ignored(result);
- return;
- case ACCEPT:
- this.result = result;
- try {
- accepted(result);
- } finally {
- dispose();
- wait.release();
- }
- return;
- case DISCARD:
- dispose();
- wait.release();
- return;
- }
- }
-
- /**
- * Override to process results that were ignored.
- *
- * @param result
- */
- public void ignored(T result) {
- }
-
- /**
- * Override this to immediately process an accepted result in the listener.
- * This method is invoked before the listener is disposed
- *
- * @param result
- */
- public void accepted(T result) {
- }
-
- @Override
- public void exception(Throwable t) {
- this.exception = t;
- dispose();
- wait.release();
- }
-
- private void dispose() {
- this.criterion = null;
- }
-
- @Override
- public boolean isDisposed() {
- return criterion == null;
- }
-
+/*******************************************************************************
+ * Copyright (c) 2012 Association for Decentralized Information Management in
+ * Industry THTH ry.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ * VTT Technical Research Centre of Finland - initial API and implementation
+ *******************************************************************************/
+package org.simantics.db.layer0.util;
+
+import java.util.concurrent.Semaphore;
+import java.util.concurrent.TimeUnit;
+
+import org.simantics.db.Session;
+import org.simantics.db.exception.DatabaseException;
+import org.simantics.db.procedure.Listener;
+import org.simantics.db.request.Read;
+
+/**
+ * A database listener that disposes itself based on a criterion evaluated using
+ * the request results received by the listener. If the results pass the
+ * criterion, the listener is disposed and the result is either accepted or
+ * discarded based on the evaluation.
+ *
+ *
+ * The reason for the existence of this class is that sometimes database
+ * requests always perform asynchronously, i.e. return empty results at first
+ * and later get updated to their final results. For example, a the results of a
+ * web request would take a while to be delivered. This listener makes it a bit
+ * easier to deal with these situations when results are needed synchronously.
+ *
+ *
+ * {@link #trySyncRequest(Session, Read, Criterion, long, TimeUnit)} provides a
+ * utility for executing a synchronous read request with this listener so that
+ * the implementation will wait for a criterion accepted result for the
+ * specified amount of time. If an accepted result is reached within the time
+ * limit, it will be returned. If the time limit is reached and no accepted
+ * result is attained, null will be returned. If the request
+ * produces an exception, it will be thrown.
+ *
+ * @author Tuukka Lehtonen
+ *
+ * @param database request result type
+ *
+ * @see EvaluatingListener.Evaluation
+ * @see EvaluatingListener.Criterion
+ */
+public class EvaluatingListener implements Listener {
+
+ public static enum Evaluation {
+ /**
+ * Keep on listening to further results.
+ */
+ IGNORE,
+ /**
+ * Dispose listener and discard the results.
+ */
+ DISCARD,
+ /**
+ * Dispose listener and return the latest result.
+ */
+ ACCEPT
+ }
+
+ /**
+ * An evaluable criterion for the result received by
+ * {@link Listener#execute(Object)} to tell whether to accept the result,
+ * wait for another result or to consider the listener disposed.
+ *
+ * @param the type of the result
+ */
+ public static interface Criterion {
+ Evaluation evaluate(T result);
+ }
+
+ /**
+ * The criterion the listener evaluates. When it evaluates to
+ * {@value Evaluation#DISCARD}, this field is nullified and the listener is
+ * considered disposed.
+ */
+ private volatile Criterion criterion;
+ private T result;
+ private Throwable exception;
+ private Semaphore wait = new Semaphore(0);
+
+ public EvaluatingListener(Criterion criterion) {
+ if (criterion == null)
+ throw new NullPointerException("null criterion");
+ this.criterion = criterion;
+ }
+
+ /**
+ * @param session
+ * @param request
+ * @param criterion
+ * @param timeout
+ * @param unit
+ * @return
+ * @throws InterruptedException
+ * @throws DatabaseException
+ */
+ public static T trySyncRequest(Session session, Read request, Criterion criterion, long timeout, TimeUnit unit) throws InterruptedException, DatabaseException {
+ EvaluatingListener l = new EvaluatingListener(criterion);
+ session.asyncRequest(request, l);
+ l.tryWaitForResult(timeout, unit);
+ // Make sure the listener is disposed.
+ l.dispose();
+ l.throwPossibleException();
+ return l.getResult();
+ }
+
+ public T waitForResult() throws InterruptedException {
+ wait.acquire();
+ return getResult();
+ }
+
+ public boolean tryWaitForResult(long timeout, TimeUnit unit) throws InterruptedException {
+ return wait.tryAcquire(timeout, unit);
+ }
+
+ public T getResult() {
+ return result;
+ }
+
+ public Throwable getException() {
+ return exception;
+ }
+
+ public void throwPossibleException() throws DatabaseException {
+ if (exception != null) {
+ if (exception instanceof DatabaseException)
+ throw (DatabaseException) exception;
+ throw new DatabaseException(exception);
+ }
+ }
+
+ @Override
+ public void execute(T result) {
+ Criterion crit = criterion;
+ if (crit == null)
+ return;
+ EvaluatingListener.Evaluation e = crit.evaluate(result);
+ switch (e) {
+ case IGNORE:
+ ignored(result);
+ return;
+ case ACCEPT:
+ this.result = result;
+ try {
+ accepted(result);
+ } finally {
+ dispose();
+ wait.release();
+ }
+ return;
+ case DISCARD:
+ dispose();
+ wait.release();
+ return;
+ }
+ }
+
+ /**
+ * Override to process results that were ignored.
+ *
+ * @param result
+ */
+ public void ignored(T result) {
+ }
+
+ /**
+ * Override this to immediately process an accepted result in the listener.
+ * This method is invoked before the listener is disposed
+ *
+ * @param result
+ */
+ public void accepted(T result) {
+ }
+
+ @Override
+ public void exception(Throwable t) {
+ this.exception = t;
+ dispose();
+ wait.release();
+ }
+
+ private void dispose() {
+ this.criterion = null;
+ }
+
+ @Override
+ public boolean isDisposed() {
+ return criterion == null;
+ }
+
}
\ No newline at end of file