Merge pull request #25664 from vespa-engine/jonmv/fix-sublist-search

Also match lists which are the tail of the full

2 files changed, 17 insertions, 2 deletions

diff --git a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/dns/NameServiceQueue.java b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/dns/NameServiceQueue.java
index 9c1390788ca..dbcfa6705ec 100644
--- a/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/dns/NameServiceQueue.java
+++ b/controller-server/src/main/java/com/yahoo/vespa/hosted/controller/dns/NameServiceQueue.java
@@ -159,7 +159,7 @@ public record NameServiceQueue(List<NameServiceRequest> requests) {
 
     /** Lowest index {@code i} in {@code list} s.t. {@code list.sublist(i, i + sub.size()).equals(sub)}. Naïve implementation. */
     static <T> int indexOf(List<T> list, List<T> sub) {
-        for (int i = 0; i + sub.size() < list.size(); i++)
+        for (int i = 0; i + sub.size() <= list.size(); i++)
             if (list.subList(i, i + sub.size()).equals(sub))
                 return i;
 
diff --git a/controller-server/src/test/java/com/yahoo/vespa/hosted/controller/maintenance/NameServiceDispatcherTest.java b/controller-server/src/test/java/com/yahoo/vespa/hosted/controller/maintenance/NameServiceDispatcherTest.java
index 540511dbc7f..cf5567f5f2f 100644
--- a/controller-server/src/test/java/com/yahoo/vespa/hosted/controller/maintenance/NameServiceDispatcherTest.java
+++ b/controller-server/src/test/java/com/yahoo/vespa/hosted/controller/maintenance/NameServiceDispatcherTest.java
@@ -66,10 +66,25 @@ class NameServiceDispatcherTest {
         var req8 = new CreateRecord(owner0, rec3);
 
         // Queue initially contains a subsequence of requests, 3–6.
-        // The dispatch of requests owned by owner1 will fail, so the remaining list is subsequence or the original.
         var base = new LinkedList<NameServiceRequest>(List.of(req3, req4, req5, req6));
+
+        // Whole queue is consumed by dispatcher the first time, and a few records prepended.
         tester.curator().writeNameServiceQueue(new NameServiceQueue(base));
+        expectations.add(name -> assertEquals(rec1.name(), name));
+        expectations.add(name -> assertEquals(rec4.name(), name));
+        expectations.add(name -> assertEquals(rec3.name(), name));
+        expectations.add(name -> {
+            assertEquals(rec4.name(), name);
+            tester.curator().writeNameServiceQueue(tester.curator().readNameServiceQueue()
+                                                         .with(req1, Priority.high)
+                                                         .with(req2, Priority.high)
+                                                         .with(req1, Priority.high));
+        });
+        assertEquals(1.0, dispatcher.maintain());
+        assertEquals(List.of(req1, req2, req1), tester.curator().readNameServiceQueue().requests());
 
+        // Now, the dispatch of requests owned by owner1 will fail, so the remaining list is subsequence or the original.
+        tester.curator().writeNameServiceQueue(new NameServiceQueue(base));
         AtomicReference<Consumer<RecordName>> failOwner1 = new AtomicReference<>();
         failOwner1.set(name -> {
             assertEquals(rec4.name(), name);