From 4924c7f12545bd110bce8c2ad8fb28172cf89886 Mon Sep 17 00:00:00 2001
From: anhefti <andreas.hefti@let.ethz.ch>
Date: Tue, 6 Jun 2023 09:01:18 +0200
Subject: [PATCH] fix concurrency error

---
 .../impl/SEBClientEventBatchService.java      | 68 +++++++++++--------
 1 file changed, 38 insertions(+), 30 deletions(-)

diff --git a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/session/impl/SEBClientEventBatchService.java b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/session/impl/SEBClientEventBatchService.java
index d1bb9181..3a3852b0 100644
--- a/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/session/impl/SEBClientEventBatchService.java
+++ b/src/main/java/ch/ethz/seb/sebserver/webservice/servicelayer/session/impl/SEBClientEventBatchService.java
@@ -79,7 +79,7 @@ public class SEBClientEventBatchService {
     }
 
     private final BlockingDeque<EventData> eventDataQueue = new LinkedBlockingDeque<>();
-    private final Collection<EventData> events = new ArrayList<>();
+    //private final Collection<EventData> events = new ArrayList<>();
 
     public void accept(final String connectionToken, final String jsonBody) {
         this.eventDataQueue.add(new EventData(
@@ -92,39 +92,47 @@ public class SEBClientEventBatchService {
         this.eventDataQueue.add(eventData);
     }
 
+    private final Collection<EventData> events1 = new ArrayList<>();
+
     @Scheduled(
-            fixedDelayString = "${sebserver.webservice.api.exam.session.event.batch.interval:500}",
+            fixedDelayString = "${sebserver.webservice.api.exam.session.event.batch.interval:1000}",
             initialDelay = 100)
     public void worker1() {
-        processEvents("worker1");
+        processEvents("worker1", this.events1);
     }
 
-//    @Scheduled(
-//            fixedDelayString = "${sebserver.webservice.api.exam.session.event.batch.interval:1000}",
-//            initialDelay = 300)
-//    public void worker2() {
-//        processEvents("worker2");
-//    }
-//
-//    @Scheduled(
-//            fixedDelayString = "${sebserver.webservice.api.exam.session.event.batch.interval:1000}",
-//            initialDelay = 600)
-//    public void worker3() {
-//        processEvents("worker3");
-//    }
-//
-//    @Scheduled(
-//            fixedDelayString = "${sebserver.webservice.api.exam.session.event.batch.interval:1000}",
-//            initialDelay = 900)
-//    public void worker4() {
-//        processEvents("worker4");
-//    }
+    private final Collection<EventData> events2 = new ArrayList<>();
+
+    @Scheduled(
+            fixedDelayString = "${sebserver.webservice.api.exam.session.event.batch.interval:1000}",
+            initialDelay = 300)
+    public void worker2() {
+        processEvents("worker2", this.events2);
+    }
+
+    private final Collection<EventData> events3 = new ArrayList<>();
+
+    @Scheduled(
+            fixedDelayString = "${sebserver.webservice.api.exam.session.event.batch.interval:1000}",
+            initialDelay = 600)
+    public void worker3() {
+        processEvents("worker3", this.events3);
+    }
+
+    private final Collection<EventData> events4 = new ArrayList<>();
+
+    @Scheduled(
+            fixedDelayString = "${sebserver.webservice.api.exam.session.event.batch.interval:1000}",
+            initialDelay = 900)
+    public void worker4() {
+        processEvents("worker4", this.events4);
+    }
 
     public void processOneTime() {
-        processEvents("One Time Call");
+        processEvents("One Time Call", new ArrayList<>());
     }
 
-    private void processEvents(final String workerName) {
+    private void processEvents(final String workerName, final Collection<EventData> events) {
 
         long start = 0L;
         if (log.isDebugEnabled()) {
@@ -144,14 +152,14 @@ public class SEBClientEventBatchService {
 
         try {
 
-            this.events.clear();
-            this.eventDataQueue.drainTo(this.events);
+            events.clear();
+            this.eventDataQueue.drainTo(events);
 
-            if (this.events.isEmpty()) {
+            if (events.isEmpty()) {
                 return;
             }
 
-            final List<ClientEventRecord> events = this.events
+            final List<ClientEventRecord> records = events
                     .stream()
                     .map(this::convertData)
                     .map(this::storeNotifications)
@@ -162,7 +170,7 @@ public class SEBClientEventBatchService {
 
             this.transactionTemplate
                     .execute(status -> {
-                        events.stream().forEach(this.clientEventMapper::insert);
+                        records.stream().forEach(this.clientEventMapper::insert);
                         return null;
                     });