Clean-up file watcher keys. (#89429) (#89432)

Clean-up all open watcher keys in FileSettingsService.

Author: grcevski

server/src/main/java/org/elasticsearch/reservedstate/service/FileSettingsService.java

@@ -63,6 +63,7 @@ public class FileSettingsService extends AbstractLifecycleComponent implements C
 
     private volatile FileUpdateState fileUpdateState = null;
     private volatile WatchKey settingsDirWatchKey = null;
+    private volatile WatchKey configDirWatchKey = null;
 
     private volatile boolean active = false;
     private volatile boolean initialState = true;
@@ -207,6 +208,17 @@ boolean watching() {
         return this.watchService != null;
     }
 
+    private void cleanupWatchKeys() {
+        if (settingsDirWatchKey != null) {
+            settingsDirWatchKey.cancel();
+            settingsDirWatchKey = null;
+        }
+        if (configDirWatchKey != null) {
+            configDirWatchKey.cancel();
+            configDirWatchKey = null;
+        }
+    }
+
     synchronized void startWatcher(ClusterState clusterState, boolean onStartup) {
         if (watching() || active == false) {
             refreshExistingFileStateIfNeeded(clusterState);
@@ -246,10 +258,11 @@ synchronized void startWatcher(ClusterState clusterState, boolean onStartup) {
             // We watch the config directory always, even if initially we had an operator directory
             // it can be deleted and created later. The config directory never goes away, we only
             // register it once for watching.
-            enableSettingsWatcher(null, operatorSettingsDir().getParent());
+            configDirWatchKey = enableSettingsWatcher(configDirWatchKey, operatorSettingsDir().getParent());
         } catch (Exception e) {
             if (watchService != null) {
                 try {
+                    cleanupWatchKeys();
                     this.watchService.close();
                 } catch (Exception ignore) {} finally {
                     this.watchService = null;
@@ -323,10 +336,7 @@ synchronized void stopWatcher() {
         logger.debug("stopping watcher ...");
         if (watching()) {
             try {
-                if (settingsDirWatchKey != null) {
-                    settingsDirWatchKey.cancel();
-                    settingsDirWatchKey = null;
-                }
+                cleanupWatchKeys();
                 fileUpdateState = null;
                 watchService.close();
                 if (watcherThreadLatch != null) {