Prevent NPE due to race between rotation and retention threads (#3640)

Refs #3637 Fixes #3494 (cherry picked from commit e73fb0f)
Graylog2 · Mar 17, 2017 · dc480ee · dc480ee
1 parent 3d0c584
commit dc480ee
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/...a/org/graylog2/indexer/retention/strategies/AbstractIndexCountBasedRetentionStrategy.java b/...a/org/graylog2/indexer/retention/strategies/AbstractIndexCountBasedRetentionStrategy.java
@@ -27,6 +27,7 @@
 import org.slf4j.LoggerFactory;
 
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.LinkedHashSet;
 import java.util.Map;
 import java.util.Optional;
@@ -85,7 +86,7 @@ public void retain(IndexSet indexSet) {
     private void runRetention(IndexSet indexSet, Map<String, Set<String>> deflectorIndices, int removeCount) {
         final Set<String> orderedIndices = Arrays.stream(indexSet.getManagedIndices())
             .filter(indexName -> !indices.isReopened(indexName))
-            .filter(indexName -> !(deflectorIndices.get(indexName).contains(indexSet.getWriteIndexAlias())))
+            .filter(indexName -> !(deflectorIndices.getOrDefault(indexName, Collections.emptySet()).contains(indexSet.getWriteIndexAlias())))
             .sorted((indexName1, indexName2) -> indexSet.extractIndexNumber(indexName2).orElse(0).compareTo(indexSet.extractIndexNumber(indexName1).orElse(0)))
             .collect(Collectors.toCollection(LinkedHashSet::new));
         orderedIndices