minor fixes in error handling and running exam update

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

@@ -50,13 +50,11 @@ public final class CircuitBreaker<T> {
 
     private static final Logger log = LoggerFactory.getLogger(CircuitBreaker.class);
 
+    public static final String OPEN_CIRCUIT_BREAKER_EXCEPTION = "Open CircuitBreaker";
     public static final int DEFAULT_MAX_FAILING_ATTEMPTS = 5;
     public static final long DEFAULT_MAX_BLOCKING_TIME = Constants.MINUTE_IN_MILLIS;
     public static final long DEFAULT_TIME_TO_RECOVER = Constants.MINUTE_IN_MILLIS * 10;
 
-    public static final RuntimeException OPEN_STATE_EXCEPTION =
-            new RuntimeException("Open CircuitBreaker");
-
     public enum State {
         CLOSED,
         HALF_OPEN,
@@ -243,7 +241,7 @@ public final class CircuitBreaker<T> {
             return protectedRun(supplier);
         }
 
-        return Result.ofError(OPEN_STATE_EXCEPTION);
+        return Result.ofError(new RuntimeException(OPEN_CIRCUIT_BREAKER_EXCEPTION));
     }
 
     private Result<T> attempt(final Supplier<T> supplier) {

src/main/java/ch/ethz/seb/sebserver/gui/service/push/UpdateErrorHandler.java

@@ -63,7 +63,7 @@ public final class UpdateErrorHandler implements Function<Exception, Boolean> {
     @Override
     public Boolean apply(final Exception error) {
         this.errors++;
-        log.error("Failed to update server push: {}", error.getMessage());
+        log.error("Failed to update server push: {}", error.getMessage(), error);
         if (this.errors > 5) {
             checkUserSession();
         }

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

@@ -198,6 +198,9 @@ public class ClientConnectionDetails {
         this.connectionData.getIndicatorValues()
                 .forEach(indValue -> {
                     final IndicatorData indData = this.indicatorMapping.get(indValue.getIndicatorId());
+                    if (indData == null) {
+                        return;
+                    }
                     final double value = indValue.getValue();
                     final String displayValue = IndicatorValue.getDisplayValue(indValue, indData.indicator.type);
 

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

@@ -496,8 +496,9 @@ public final class ClientConnectionTable implements FullPageMonitoringGUIUpdate
 
             for (int i = 0; i < this.connectionData.indicatorValues.size(); i++) {
                 final IndicatorValue indicatorValue = this.connectionData.indicatorValues.get(i);
-                final IndicatorData indicatorData =
+                final IndicatorData indicatorData = ClientConnectionTable.this.indicatorMapping
-                        ClientConnectionTable.this.indicatorMapping.get(indicatorValue.getIndicatorId());
+                        .get(indicatorValue.getIndicatorId());
+
                 if (indicatorData == null) {
                     continue;
                 }

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

@@ -109,7 +109,11 @@ public class ExamDAOImpl implements ExamDAO {
                     final QuizData quizData = this.lmsAPIService
                             .getLmsAPITemplate(record.getLmsSetupId())
                             .flatMap(template -> template.getQuiz(record.getExternalId()))
-                            .getOrThrow();
+                            .onError(error -> log.error(
+                                    "Failed to load quiz data for exam: {} error: {}",
+                                    examId,
+                                    error.getMessage()))
+                            .getOr(null);
                     return toDomainModel(record, quizData, null, true);
                 });
     }
@@ -791,26 +795,11 @@ public class ExamDAOImpl implements ExamDAO {
 
                     log.info("Try to recover quiz data for Moodle quiz with internal identifier: {}", externalId);
 
-                    // get additional quiz name attribute
+                    // get former quiz name attribute
-                    final AdditionalAttributeRecord additionalAttribute =
+                    final String formerName = getFormerName(record.getId());
-                            this.additionalAttributeRecordMapper.selectByExample()
+                    if (formerName != null) {
-                                    .where(
-                                            AdditionalAttributeRecordDynamicSqlSupport.entityType,
-                                            SqlBuilder.isEqualTo(EntityType.EXAM.name()))
-                                    .and(
-                                            AdditionalAttributeRecordDynamicSqlSupport.entityId,
-                                            SqlBuilder.isEqualTo(record.getId()))
-                                    .and(
-                                            AdditionalAttributeRecordDynamicSqlSupport.name,
-                                            SqlBuilder.isEqualTo(QuizData.QUIZ_ATTR_NAME))
-                                    .build()
-                                    .execute()
-                                    .stream()
-                                    .findAny()
-                                    .orElse(null);
-                    if (additionalAttribute != null) {
 
-                        log.debug("Found additional quiz name attribute: {}", additionalAttribute);
+                        log.debug("Found formerName quiz name: {}", formerName);
 
                         // get the course name identifier
                         final String shortname = MoodleCourseAccess.getShortname(externalId);
@@ -827,7 +816,7 @@ public class ExamDAOImpl implements ExamDAO {
                                                 final String qShortName = MoodleCourseAccess.getShortname(quiz.id);
                                                 return qShortName != null && qShortName.equals(shortname);
                                             })
-                                            .filter(quiz -> additionalAttribute.getValue().equals(quiz.name))
+                                            .filter(quiz -> formerName.equals(quiz.name))
                                             .findAny()
                                             .get())
                                     .getOrThrow();
@@ -851,7 +840,7 @@ public class ExamDAOImpl implements ExamDAO {
                     }
                 }
             } catch (final Exception e) {
-                log.warn("Failed to try to recover from Moodle quiz restore: {}", e.getMessage());
+                log.debug("Failed to try to recover from Moodle quiz restore: {}", e.getMessage());
             }
             return null;
         }

src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/session/impl/ExamSessionControlTask.java

@@ -156,7 +156,7 @@ public class ExamSessionControlTask implements DisposableBean {
             final Map<Long, String> updated = this.examDAO.allForRunCheck()
                     .getOrThrow()
                     .stream()
-                    .filter(exam -> exam.startTime.minus(this.examTimePrefix).isBefore(now))
+                    .filter(exam -> exam.startTime != null && exam.startTime.minus(this.examTimePrefix).isBefore(now))
                     .filter(exam -> exam.endTime == null || exam.endTime.plus(this.examTimeSuffix).isAfter(now))
                     .flatMap(exam -> Result.skipOnError(this.examUpdateHandler.setRunning(exam, updateId)))
                     .collect(Collectors.toMap(Exam::getId, Exam::getName));

src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/session/impl/ExamSessionServiceImpl.java

@@ -245,12 +245,20 @@ public class ExamSessionServiceImpl implements ExamSessionService {
                 .putIfAbsent(Exam.FILTER_ATTR_ACTIVE, Constants.TRUE_STRING)
                 .putIfAbsent(Exam.FILTER_ATTR_STATUS, ExamStatus.RUNNING.name());
 
-        // NOTE: we evict the exam from the cache (if present) to ensure user is seeing always the current state of the Exam
         return this.examDAO.allMatching(filterMap, predicate)
                 .map(col -> col.stream()
                         .map(exam -> {
-                            this.examSessionCacheService.evict(exam);
+                            final Exam runningExam = this.examSessionCacheService.getRunningExam(exam.id);
-                            return this.examSessionCacheService.getRunningExam(exam.id);
+                            if (runningExam == null) {
+                                return null;
+                            }
+                            if (!isUpToDate(exam, runningExam)) {
+                                // If the cached exam-quiz data differs from the one of the currently loaded exam, cache is updated
+                                this.examSessionCacheService.evict(exam);
+                                return this.examSessionCacheService.getRunningExam(exam.id);
+                            } else {
+                                return runningExam;
+                            }
                         })
                         .filter(Objects::nonNull)
                         .collect(Collectors.toList()));
@@ -514,4 +522,11 @@ public class ExamSessionServiceImpl implements ExamSessionService {
         }
     }
 
+    private boolean isUpToDate(final Exam exam, final Exam runningExam) {
+        return Objects.equals(exam.lastModified, runningExam.lastModified)
+                && Objects.equals(exam.startTime, runningExam.startTime)
+                && Objects.equals(exam.endTime, runningExam.endTime)
+                && Objects.equals(exam.name, runningExam.name);
+    }
+
 }

src/test/java/ch/ethz/seb/sebserver/gbl/async/CircuitBreakerTest.java

@@ -73,7 +73,7 @@ public class CircuitBreakerTest {
         Thread.sleep(100);
         result = circuitBreaker.protectedRun(tester); // 10. call...
         assertEquals(State.OPEN, circuitBreaker.getState());
-        assertEquals(CircuitBreaker.OPEN_STATE_EXCEPTION, result.getError());
+        assertEquals(CircuitBreaker.OPEN_CIRCUIT_BREAKER_EXCEPTION, result.getError().getMessage());
 
         // wait time to recover
         Thread.sleep(1000);