Avoid race conditions while create the same topic multiple times

allegro · Apr 6, 2023 · f0c338e · f0c338e
1 parent f11cc0f
commit f0c338e
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Showing 2 changed files with 11 additions and 8 deletions.
diff --git a/...pl/allegro/tech/hermes/management/domain/topic/commands/CreateTopicRepositoryCommand.java b/...pl/allegro/tech/hermes/management/domain/topic/commands/CreateTopicRepositoryCommand.java
@@ -23,7 +23,11 @@ public void execute(DatacenterBoundRepositoryHolder<TopicRepository> holder) {
 
     @Override
     public void rollback(DatacenterBoundRepositoryHolder<TopicRepository> holder) {
-        holder.getRepository().removeTopic(topic.getName());
+        /*
+        We don't want to do a rollback due to possible race conditions with creating a topic on Kafka.
+        It increases the possibility of discrepancies between Kafka and Zookeeper: topic exists in Kafka,
+        but not in the Zookeeper and vice versa.
+         */
     }
 
     @Override

diff --git a/...pl/allegro/tech/hermes/management/domain/topic/commands/RemoveTopicRepositoryCommand.java b/...pl/allegro/tech/hermes/management/domain/topic/commands/RemoveTopicRepositoryCommand.java
@@ -1,6 +1,5 @@
 package pl.allegro.tech.hermes.management.domain.topic.commands;
 
-import pl.allegro.tech.hermes.api.Topic;
 import pl.allegro.tech.hermes.api.TopicName;
 import pl.allegro.tech.hermes.domain.topic.TopicRepository;
 import pl.allegro.tech.hermes.management.domain.dc.DatacenterBoundRepositoryHolder;
@@ -10,16 +9,12 @@ public class RemoveTopicRepositoryCommand extends RepositoryCommand<TopicReposit
 
     private final TopicName topicName;
 
-    private Topic backup;
-
     public RemoveTopicRepositoryCommand(TopicName topicName) {
         this.topicName = topicName;
     }
 
     @Override
-    public void backup(DatacenterBoundRepositoryHolder<TopicRepository> holder) {
-        backup = holder.getRepository().getTopicDetails(topicName);
-    }
+    public void backup(DatacenterBoundRepositoryHolder<TopicRepository> holder) {}
 
     @Override
     public void execute(DatacenterBoundRepositoryHolder<TopicRepository> holder) {
@@ -28,7 +23,11 @@ public void execute(DatacenterBoundRepositoryHolder<TopicRepository> holder) {
 
     @Override
     public void rollback(DatacenterBoundRepositoryHolder<TopicRepository> holder) {
-        holder.getRepository().createTopic(backup);
+        /*
+        We don't want to do a rollback due to possible race conditions with creating a topic on Kafka.
+        It increases the possibility of discrepancies between Kafka and Zookeeper: topic exists in Kafka,
+        but not in the Zookeeper and vice versa.
+         */
     }
 
     @Override