Format cleanup

Razin Bouzar · Razin Bouzar · commit 90ea5e8c9126 · 2024-05-31T17:56:23.000-04:00
diff --git a/server/src/main/java/org/apache/druid/curator/discovery/CuratorDruidLeaderSelector.java b/server/src/main/java/org/apache/druid/curator/discovery/CuratorDruidLeaderSelector.java
@@ -65,7 +65,6 @@ public CuratorDruidLeaderSelector(CuratorFramework curator, @Self DruidNode self
     this.latchPath = latchPath;
     this.leaderLatch.set(createNewLeaderLatch());
 
-    // Adding ConnectionStateListener to handle session changes using a method reference
     curator.getConnectionStateListenable().addListener(this::handleConnectionStateChanged);
   }
 
@@ -97,13 +96,13 @@ public void isLeader()
 
           // give others a chance to become leader.
           CloseableUtils.closeAndSuppressExceptions(
-              createNewLeaderLatchWithListener(),
-              e -> log.warn("Could not close old leader latch; continuing with new one anyway.")
+                  createNewLeaderLatchWithListener(),
+                  e -> log.warn("Could not close old leader latch; continuing with new one anyway.")
           );
 
           leader = false;
           try {
-            // Small delay before starting the latch so that others waiting are chosen to become leader.
+            //Small delay before starting the latch so that others waiting are chosen to become leader.
             Thread.sleep(ThreadLocalRandom.current().nextInt(1000, 5000));
             leaderLatch.get().start();
           }
@@ -132,7 +131,9 @@ public void notLeader()
           log.makeAlert(ex, "listener.stopBeingLeader() failed. Unable to stopBeingLeader").emit();
         }
       }
-    }, listenerExecutor);
+    },
+            listenerExecutor
+    );
 
     return leaderLatch.getAndSet(newLeaderLatch);
   }
@@ -209,7 +210,9 @@ public void unregisterListener()
     listenerExecutor.shutdownNow();
   }
 
-  // Method to handle connection state changes
+  /**
+   * Handles connection state changes. Recreates the leader latch if connection to zookeeper is lost.
+   */
   private void handleConnectionStateChanged(CuratorFramework client, ConnectionState newState)
   {
     switch (newState) {
@@ -228,17 +231,23 @@ private void handleConnectionStateChanged(CuratorFramework client, ConnectionSta
 
   private void recreateLeaderLatch()
   {
-    // Close existing leader latch
-    CloseableUtils.closeAndSuppressExceptions(leaderLatch.get(), e -> log.warn(e, "Failed to close LeaderLatch."));
+    // give others a chance to become leader.
+    CloseableUtils.closeAndSuppressExceptions(
+            createNewLeaderLatchWithListener(),
+            e -> log.warn("Could not close old leader latch; continuing with new one anyway.")
+    );
 
-    // Create and start a new leader latch
-    LeaderLatch newLeaderLatch = createNewLeaderLatchWithListener();
+    leader = false;
     try {
-      newLeaderLatch.start();
+      //Small delay before starting the latch so that others waiting are chosen to become leader.
+      Thread.sleep(ThreadLocalRandom.current().nextInt(1000, 5000));
+      leaderLatch.get().start();
     }
-    catch (Exception ex) {
-      throw new RuntimeException("Failed to start new LeaderLatch after session change", ex);
+    catch (Exception e) {
+      // If an exception gets thrown out here, then the node will zombie out 'cause it won't be looking for
+      // the latch anymore.  I don't believe it's actually possible for an Exception to throw out here, but
+      // Curator likes to have "throws Exception" on methods so it might happen...
+      log.makeAlert(e, "I am a zombie").emit();
     }
-    leaderLatch.set(newLeaderLatch);
   }
 }
