Better error handling and logging

src/main/java/ch/ethz/seb/sebserver/gbl/async/CircuitBreaker.java

@@ -174,7 +174,7 @@ public final class CircuitBreaker<T> {
                 this.state = State.HALF_OPEN;
                 this.failingCount.set(0);
                 return Result.ofError(new RuntimeException(
-                        "Set CircuitBeaker to half-open state. Cause: ",
+                        "Set CircuitBeaker to half-open state. Cause: " + result.getError().getMessage(),
                         result.getError()));
             } else {
                 // try again
@@ -204,7 +204,7 @@ public final class CircuitBreaker<T> {
 
             this.state = State.OPEN;
             return Result.ofError(new RuntimeException(
-                    "Set CircuitBeaker to open state. Cause: ",
+                    "Set CircuitBeaker to open state. Cause: " + result.getError().getMessage(),
                     result.getError()));
         } else {
             // on success go to CLOSED state

src/main/java/ch/ethz/seb/sebserver/gui/service/remote/webservice/api/RestService.java

@@ -71,4 +71,13 @@ public interface RestService {
             EntityType entityType,
             CallType callType);
 
+    /** Use this to inject the current SEB Server API access RestTemplate to a long living
+     * RestCallBuilder. This is usually used to recover from a disposed API access RestTemplate.
+     * 
+     * @param <T> The generic type of RestCallBuilder
+     * @param builder the RestCallBuilder to inject the current RestTemplate into. */
+    default <T> void injectCurrentRestTemplate(final RestCall<T>.RestCallBuilder builder) {
+        builder.withRestTemplate(getWebserviceAPIRestTemplate());
+    }
+
 }

src/main/java/ch/ethz/seb/sebserver/gui/service/remote/webservice/auth/DisposedOAuth2RestTemplateException.java

@@ -0,0 +1,19 @@
+/*
+ * Copyright (c) 2021 ETH Zürich, Educational Development and Technology (LET)
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+package ch.ethz.seb.sebserver.gui.service.remote.webservice.auth;
+
+public class DisposedOAuth2RestTemplateException extends IllegalStateException {
+
+    private static final long serialVersionUID = -8439656564917103027L;
+
+    public DisposedOAuth2RestTemplateException(final String s) {
+        super(s);
+    }
+
+}

src/main/java/ch/ethz/seb/sebserver/gui/service/remote/webservice/auth/OAuth2AuthorizationContextHolder.java

@@ -132,7 +132,7 @@ public class OAuth2AuthorizationContextHolder implements AuthorizationContextHol
             if (this.enabled) {
                 return super.doExecute(url, method, requestCallback, responseExtractor);
             } else {
-                throw new IllegalStateException(
+                throw new DisposedOAuth2RestTemplateException(
                         "Error: Forbidden execution call on disabled DisposableOAuth2RestTemplate");
             }
         }

src/main/java/ch/ethz/seb/sebserver/gui/service/session/ClientConnectionDetails.java

@@ -40,6 +40,7 @@ import ch.ethz.seb.sebserver.gui.service.page.PageService;
 import ch.ethz.seb.sebserver.gui.service.page.event.ActionEvent;
 import ch.ethz.seb.sebserver.gui.service.page.impl.PageAction;
 import ch.ethz.seb.sebserver.gui.service.remote.webservice.api.RestCall;
+import ch.ethz.seb.sebserver.gui.service.remote.webservice.auth.DisposedOAuth2RestTemplateException;
 import ch.ethz.seb.sebserver.gui.service.session.IndicatorData.ThresholdColor;
 import ch.ethz.seb.sebserver.gui.table.EntityTable;
 
@@ -135,6 +136,7 @@ public class ClientConnectionDetails {
                 .call()
                 .get(error -> {
                     log.error("Unexpected error while trying to get current client connection data: ", error);
+                    recoverFromDisposedRestTemplate(error);
                     return null;
                 });
 
@@ -234,4 +236,13 @@ public class ClientConnectionDetails {
                 pageContext);
     }
 
+    public void recoverFromDisposedRestTemplate(final Exception error) {
+        if (log.isDebugEnabled()) {
+            log.debug("Try to recover from disposed OAuth2 rest template...");
+        }
+        if (error instanceof DisposedOAuth2RestTemplateException) {
+            this.pageService.getRestService().injectCurrentRestTemplate(this.restCallBuilder);
+        }
+    }
+
 }

src/main/java/ch/ethz/seb/sebserver/gui/service/session/ClientConnectionTable.java

@@ -62,6 +62,7 @@ import ch.ethz.seb.sebserver.gui.service.i18n.LocTextKey;
 import ch.ethz.seb.sebserver.gui.service.page.PageService;
 import ch.ethz.seb.sebserver.gui.service.page.impl.PageAction;
 import ch.ethz.seb.sebserver.gui.service.remote.webservice.api.RestCall;
+import ch.ethz.seb.sebserver.gui.service.remote.webservice.auth.DisposedOAuth2RestTemplateException;
 import ch.ethz.seb.sebserver.gui.service.session.IndicatorData.ThresholdColor;
 import ch.ethz.seb.sebserver.gui.widget.WidgetFactory;
 
@@ -90,8 +91,7 @@ public final class ClientConnectionTable {
     private final static LocTextKey CONNECTION_STATUS_TOOLTIP_TEXT_KEY =
             new LocTextKey("sebserver.monitoring.connection.list.column.status" + Constants.TOOLTIP_TEXT_KEY_SUFFIX);
 
-    private final WidgetFactory widgetFactory;
+    private final PageService pageService;
-    private final ResourceService resourceService;
     private final AsyncRunner asyncRunner;
     private final Exam exam;
     private final RestCall<Collection<ClientConnectionData>>.RestCallBuilder restCallBuilder;
@@ -124,12 +124,14 @@ public final class ClientConnectionTable {
             final Collection<Indicator> indicators,
             final RestCall<Collection<ClientConnectionData>>.RestCallBuilder restCallBuilder) {
 
-        this.widgetFactory = pageService.getWidgetFactory();
+        this.pageService = pageService;
-        this.resourceService = pageService.getResourceService();
         this.asyncRunner = asyncRunner;
         this.exam = exam;
         this.restCallBuilder = restCallBuilder;
 
+        final WidgetFactory widgetFactory = pageService.getWidgetFactory();
+        final ResourceService resourceService = pageService.getResourceService();
+
         final Display display = tableRoot.getDisplay();
         this.colorData = new ColorData(display);
 
@@ -143,11 +145,11 @@ public final class ClientConnectionTable {
                 NUMBER_OF_NONE_INDICATOR_COLUMNS);
 
         this.localizedClientConnectionStatusNameFunction =
-                this.resourceService.localizedClientConnectionStatusNameFunction();
+                resourceService.localizedClientConnectionStatusNameFunction();
         this.statusFilter = EnumSet.noneOf(ConnectionStatus.class);
         loadStatusFilter();
 
-        this.table = this.widgetFactory.tableLocalized(tableRoot, SWT.MULTI | SWT.V_SCROLL);
+        this.table = widgetFactory.tableLocalized(tableRoot, SWT.MULTI | SWT.V_SCROLL);
         final GridLayout gridLayout = new GridLayout(3 + indicators.size(), false);
         gridLayout.horizontalSpacing = 100;
         gridLayout.marginWidth = 100;
@@ -161,20 +163,20 @@ public final class ClientConnectionTable {
         this.table.addListener(SWT.Selection, event -> this.notifySelectionChange());
         this.table.addListener(SWT.MouseUp, this::notifyTableInfoClick);
 
-        this.widgetFactory.tableColumnLocalized(
+        widgetFactory.tableColumnLocalized(
                 this.table,
                 CONNECTION_ID_TEXT_KEY,
                 CONNECTION_ID_TOOLTIP_TEXT_KEY);
-        this.widgetFactory.tableColumnLocalized(
+        widgetFactory.tableColumnLocalized(
                 this.table,
                 CONNECTION_ADDRESS_TEXT_KEY,
                 CONNECTION_ADDRESS_TOOLTIP_TEXT_KEY);
-        this.widgetFactory.tableColumnLocalized(
+        widgetFactory.tableColumnLocalized(
                 this.table,
                 CONNECTION_STATUS_TEXT_KEY,
                 CONNECTION_STATUS_TOOLTIP_TEXT_KEY);
         for (final Indicator indDef : indicators) {
-            final TableColumn tableColumn = this.widgetFactory.tableColumnLocalized(
+            final TableColumn tableColumn = widgetFactory.tableColumnLocalized(
                     this.table,
                     new LocTextKey(INDICATOR_NAME_TEXT_KEY_PREFIX + indDef.name),
                     new LocTextKey(INDICATOR_NAME_TEXT_KEY_PREFIX + indDef.type.name));
@@ -187,7 +189,7 @@ public final class ClientConnectionTable {
     }
 
     public WidgetFactory getWidgetFactory() {
-        return this.widgetFactory;
+        return this.pageService.getWidgetFactory();
     }
 
     public boolean isEmpty() {
@@ -325,7 +327,11 @@ public final class ClientConnectionTable {
         this.restCallBuilder
                 .withHeader(API.EXAM_MONITORING_STATE_FILTER, this.statusFilterParam)
                 .call()
-                .getOrThrow()
+                .get(error -> {
+                    log.error("Unexpected error while trying to get client connection table data: ", error);
+                    recoverFromDisposedRestTemplate(error);
+                    return Collections.emptyList();
+                })
                 .forEach(data -> {
                     final UpdatableTableItem tableItem = this.tableMapping.computeIfAbsent(
                             data.getConnectionId(),
@@ -425,7 +431,7 @@ public final class ClientConnectionTable {
 
     private void saveStatusFilter() {
         try {
-            this.resourceService
+            this.pageService
                     .getCurrentUser()
                     .putAttribute(
                             USER_SESSION_STATUS_FILTER_ATTRIBUTE,
@@ -440,7 +446,7 @@ public final class ClientConnectionTable {
 
     private void loadStatusFilter() {
         try {
-            final String attribute = this.resourceService
+            final String attribute = this.pageService
                     .getCurrentUser()
                     .getAttribute(USER_SESSION_STATUS_FILTER_ATTRIBUTE);
             this.statusFilter.clear();
@@ -707,4 +713,13 @@ public final class ClientConnectionTable {
 
     }
 
+    public void recoverFromDisposedRestTemplate(final Exception error) {
+        if (log.isDebugEnabled()) {
+            log.debug("Try to recover from disposed OAuth2 rest template...");
+        }
+        if (error instanceof DisposedOAuth2RestTemplateException) {
+            this.pageService.getRestService().injectCurrentRestTemplate(this.restCallBuilder);
+        }
+    }
+
 }

src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/dao/impl/ExamDAOImpl.java

@@ -941,7 +941,7 @@ public class ExamDAOImpl implements ExamDAO {
                     }
                 }
             } catch (final Exception e) {
-                log.warn("Failed to try to recover from Moodle quiz restore: ", e.getMessage());
+                log.warn("Failed to try to recover from Moodle quiz restore: {}", e.getMessage());
             }
             return null;
         }

src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/lms/impl/moodle/MoodleCourseAccess.java

@@ -448,14 +448,14 @@ public class MoodleCourseAccess extends CourseAccess {
 
             if (courses == null) {
                 log.error("No courses found for ids: {} on LMS: {}", ids, this.lmsSetup.name);
-                Collections.emptyList();
+                return Collections.emptyList();
             }
 
             logMoodleWarnings(courses.warnings);
 
             if (courses.courses == null || courses.courses.isEmpty()) {
                 log.error("No courses found for ids: {} on LMS: {}", ids, this.lmsSetup.name);
-                Collections.emptyList();
+                return Collections.emptyList();
             }
 
             return courses.courses;

src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/lms/impl/moodle/MoodleRestTemplateFactory.java

@@ -324,9 +324,14 @@ class MoodleRestTemplateFactory {
             }
 
             final String body = response.getBody();
+
             // NOTE: for some unknown reason, Moodles API error responses come with a 200 OK response HTTP Status
             //       So this is a special Moodle specific error handling here...
-            if (body.startsWith("{exception")) {
+            if (body.startsWith("{exception") || body.contains("\"exception\":")) {
+                // Reset access token to get new on next call (fix access if token is expired)
+                // TODO find a way to verify token invalidity response from Moodle.
+                //      Unfortunately there is not a lot of Moodle documentation for the API error handling around.
+                this.accessToken = null;
                 throw new RuntimeException(
                         "Failed to call Moodle webservice API function: " + functionName + " lms setup: " +
                                 MoodleRestTemplateFactory.this.lmsSetup + " response: " + body);