fix: ensure that onStopLeading is called

CHANGELOG.md

@@ -5,6 +5,7 @@
 #### Bugs
 * Fix #5382: [java-generator] Allow to deserialize more valid RFC3339 date-time and make the format customizable
 * Fix #5380: [java-generator] Avoid to emit Java Keywords as package names
+* Fix #5463: ensures that onStopLeading is called with releaseOnCancel even when leadership is already lost
 * Fix #5423: OkHttpClientImpl supports setting request method for empty payload requests
 
 #### Improvements

kubernetes-client-api/src/main/java/io/fabric8/kubernetes/client/extended/leaderelection/LeaderElector.java

@@ -23,6 +23,7 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import java.net.HttpURLConnection;
 import java.time.Duration;
 import java.time.LocalDateTime;
 import java.time.ZoneOffset;
@@ -121,36 +122,44 @@ private synchronized void stopLeading() {
       return; // not leading
     }
     if (leaderElectionConfig.isReleaseOnCancel()) {
-      release();
-    } else {
-      leaderElectionConfig.getLeaderCallbacks().onStopLeading();
+      try {
+        if (release()) {
+          return;
+        }
+      } catch (KubernetesClientException e) {
+        final String lockDescription = leaderElectionConfig.getLock().describe();
+        if (e.getCode() != HttpURLConnection.HTTP_CONFLICT) {
+          LOGGER.error("Exception occurred while releasing lock '{}' on cancel", lockDescription, e);
+        } else {
+          LOGGER.debug("Leadership was likely already lost '{}'", lockDescription, e);
+        }
+      }
     }
+    leaderElectionConfig.getLeaderCallbacks().onStopLeading();
   }
 
   /**
    * Release the leadership if currently held. If not cancelled, the elector will
    * continue to try and re-acquire the lock.
+   *
+   * @return true if the lock was successfully released. false if there is no lock, or this is not the leader
    */
-  public synchronized void release() {
+  public synchronized boolean release() {
     LeaderElectionRecord current = leaderElectionConfig.getLock().get(kubernetesClient);
     if (current == null || !isLeader(current)) {
-      return; // lost leadership already
+      return false; // lost leadership already
     }
-    try {
-      ZonedDateTime now = now();
-      final LeaderElectionRecord newLeaderElectionRecord = new LeaderElectionRecord(
-          "",
-          Duration.ofSeconds(1),
-          now,
-          now,
-          current.getLeaderTransitions());
+    ZonedDateTime now = now();
+    final LeaderElectionRecord newLeaderElectionRecord = new LeaderElectionRecord(
+        "",
+        Duration.ofSeconds(1),
+        now,
+        now,
+        current.getLeaderTransitions());
 
-      leaderElectionConfig.getLock().update(kubernetesClient, newLeaderElectionRecord);
-      updateObserved(newLeaderElectionRecord);
-    } catch (KubernetesClientException e) {
-      final String lockDescription = leaderElectionConfig.getLock().describe();
-      LOGGER.error("Exception occurred while releasing lock '{}'", lockDescription, e);
-    }
+    leaderElectionConfig.getLock().update(kubernetesClient, newLeaderElectionRecord);
+    updateObserved(newLeaderElectionRecord);
+    return true;
   }
 
   private CompletableFuture<Void> acquire() {

kubernetes-client-api/src/test/java/io/fabric8/kubernetes/client/extended/leaderelection/LeaderElectorTest.java

@@ -15,6 +15,7 @@
  */
 package io.fabric8.kubernetes.client.extended.leaderelection;
 
+import io.fabric8.kubernetes.api.model.StatusBuilder;
 import io.fabric8.kubernetes.client.KubernetesClientException;
 import io.fabric8.kubernetes.client.NamespacedKubernetesClient;
 import io.fabric8.kubernetes.client.extended.leaderelection.resourcelock.LeaderElectionRecord;
@@ -26,6 +27,7 @@
 import org.mockito.Answers;
 import org.mockito.Mockito;
 
+import java.net.HttpURLConnection;
 import java.time.Duration;
 import java.time.Instant;
 import java.time.ZoneOffset;
@@ -144,6 +146,36 @@ void shouldReleaseWhenCanceled() throws Exception {
     assertEquals(1, activeLer.get().getLeaderTransitions());
   }
 
+  @Test
+  void shouldStopOnReleaseWhenCanceled() throws Exception {
+    // Given
+    AtomicReference<LeaderElectionRecord> activeLer = new AtomicReference<>();
+    final LeaderElectionConfig lec = mockLeaderElectionConfiguration(activeLer);
+    final CountDownLatch signal = new CountDownLatch(1);
+    final Lock mockedLock = lec.getLock();
+    when(lec.isReleaseOnCancel()).thenReturn(true);
+    AtomicInteger count = new AtomicInteger();
+    doAnswer(invocation -> {
+      if (count.addAndGet(1) == 2) {
+        // simulate that we've already lost election
+        throw new KubernetesClientException(new StatusBuilder().withCode(HttpURLConnection.HTTP_CONFLICT).build());
+      }
+      LeaderElectionRecord leaderRecord = invocation.getArgument(1, LeaderElectionRecord.class);
+      activeLer.set(leaderRecord);
+      signal.countDown();
+      return null;
+    }).when(mockedLock).update(any(), any());
+
+    // When
+    LeaderElector leaderElector = new LeaderElector(mock(NamespacedKubernetesClient.class), lec, CommonThreadPool.get());
+    CompletableFuture<?> started = leaderElector.start();
+    assertTrue(signal.await(10, TimeUnit.SECONDS));
+    started.cancel(true);
+
+    // Then
+    verify(lec.getLeaderCallbacks(), times(1)).onStopLeading();
+  }
+
   @Test
   void shouldRelease() throws Exception {
     // Given