fix: Added handling of ClosedWatchServiceException in ConfigWatcher (#22030)

Signed-off-by: Alex Kehayov <[email protected]>

Author: AlexKehayov

hedera-node/hedera-app/src/main/java/com/hedera/node/app/blocks/impl/streaming/BlockNodeConnectionManager.java

@@ -22,6 +22,7 @@
 import java.net.InetAddress;
 import java.net.URI;
 import java.net.URL;
+import java.nio.file.ClosedWatchServiceException;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
@@ -599,7 +600,7 @@ private void startConfigWatcher() {
                                         }
                                     }
                                 }
-                            } catch (final InterruptedException e) {
+                            } catch (final InterruptedException | ClosedWatchServiceException e) {
                                 break;
                             } catch (Exception e) {
                                 logger.info("Exception in config watcher loop.", e);

hedera-node/hedera-app/src/test/java/com/hedera/node/app/blocks/impl/streaming/BlockNodeConnectionManagerTest.java

@@ -39,7 +39,6 @@
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.StandardOpenOption;
-import java.nio.file.WatchService;
 import java.time.Duration;
 import java.time.Instant;
 import java.util.ArrayList;
@@ -1502,34 +1501,28 @@ void testConfigWatcher_handlesExceptionInRefresh() throws Exception {
     }
 
     @Test
-    void testConfigWatcher_handlesInterruptedException() throws Exception {
-        final Path file = tempDir.resolve("block-nodes.json");
-        final List<BlockNodeConfig> configs = new ArrayList<>();
-        configs.add(newBlockNodeConfig(PBJ_UNIT_TEST_HOST, 8080, 1));
-        final BlockNodeConnectionInfo connectionInfo = new BlockNodeConnectionInfo(configs);
-        final String valid = BlockNodeConnectionInfo.JSON.toJSON(connectionInfo);
-        Files.writeString(
-                file, valid, StandardCharsets.UTF_8, StandardOpenOption.CREATE, StandardOpenOption.TRUNCATE_EXISTING);
+    void testStartConfigWatcher_handlesIOException() throws Exception {
+        // Create a file instead of directory to trigger IOException when trying to watch it
+        final Path fileNotDir = tempDir.resolve("not-a-directory.txt");
+        Files.writeString(fileNotDir, "test", StandardOpenOption.CREATE);
 
-        connectionManager.start();
-        awaitCondition(() -> !availableNodes().isEmpty(), 2_000);
+        final var configProvider = createConfigProvider(createDefaultConfigProvider()
+                .withValue(
+                        "blockNode.blockNodeConnectionFileDir",
+                        fileNotDir.toAbsolutePath().toString()));
 
-        // Shutdown will interrupt the watcher thread
-        connectionManager.shutdown();
+        // This should trigger IOException when trying to create WatchService on a file
+        final var manager = new BlockNodeConnectionManager(configProvider, bufferService, metrics);
+        manager.start();
 
-        // Verify the watcher thread is no longer running
-        @SuppressWarnings("unchecked")
-        final AtomicReference<Thread> threadRef =
-                (AtomicReference<Thread>) configWatcherThreadRef.get(connectionManager);
-        final Thread watcherThread = threadRef.get();
-        if (watcherThread != null) {
-            watcherThread.join(1000);
-            assertThat(watcherThread.isAlive()).isFalse();
-        }
+        // Manager should start successfully even though config watcher failed
+        Thread.sleep(500);
+
+        manager.shutdown();
     }
 
     @Test
-    void testConfigWatcher_generalExceptionThenInterrupt_exitsCleanly() throws Exception {
+    void testConfigWatcher_handlesInterruptedException() throws Exception {
         final Path file = tempDir.resolve("block-nodes.json");
         final List<BlockNodeConfig> configs = new ArrayList<>();
         configs.add(newBlockNodeConfig(PBJ_UNIT_TEST_HOST, 8080, 1));
@@ -1541,30 +1534,18 @@ void testConfigWatcher_generalExceptionThenInterrupt_exitsCleanly() throws Excep
         connectionManager.start();
         awaitCondition(() -> !availableNodes().isEmpty(), 2_000);
 
-        // Force the watch service to throw from take() by closing it,
-        // which will cause a ClosedWatchServiceException wrapped as a general Exception path
-        @SuppressWarnings("unchecked")
-        final AtomicReference<WatchService> wsRef =
-                (AtomicReference<WatchService>) configWatchServiceHandle.get(connectionManager);
-        final WatchService ws = wsRef.get();
-        assertThat(ws).isNotNull();
-        ws.close();
-
-        // Give time for watcher loop to hit the catch(Exception) and evaluate interrupted branch (should be false)
-        Thread.sleep(500);
+        // Shutdown will interrupt the watcher thread
+        connectionManager.shutdown();
 
-        // Now interrupt the watcher thread to exercise the interrupted branch inside the exception handler
+        // Verify the watcher thread is no longer running
         @SuppressWarnings("unchecked")
         final AtomicReference<Thread> threadRef =
                 (AtomicReference<Thread>) configWatcherThreadRef.get(connectionManager);
         final Thread watcherThread = threadRef.get();
         if (watcherThread != null) {
-            watcherThread.interrupt();
             watcherThread.join(1000);
+            assertThat(watcherThread.isAlive()).isFalse();
         }
-
-        // Ensure we can shutdown cleanly
-        connectionManager.shutdown();
     }
 
     @Test