perf(Concurrency): improve Java object lock for FileWatcher::terminate()

improve Java object lock for FileWatcher::terminate()

BREAKING CHANGE: improve Java object lock for FileWatcher::terminate()

media-streaming-spring-boot-autoconfigure/src/main/java/com/github/johnnymillergh/boot/mediastreamingspringbootautoconfigure/configuration/MediaStreamingBootstrap.java

@@ -83,6 +83,9 @@ public void run(String... args) {
     @PreDestroy
     private void preDestroy() {
         log.debug("Destroying {}, fileWatcher: {}", this.getClass().getSimpleName(), fileWatcher);
-        Optional.ofNullable(fileWatcher).ifPresent(FileWatcher::destroy);
+        Optional.ofNullable(fileWatcher).ifPresent(fileWatcher1 -> {
+            fileWatcher1.terminate();
+            log.debug("FileWatcher terminated: {}", fileWatcher1.isTerminated());
+        });
     }
 }

media-streaming-spring-boot-autoconfigure/src/main/java/com/github/johnnymillergh/boot/mediastreamingspringbootautoconfigure/filewatch/FileWatcher.java

@@ -2,11 +2,8 @@
 
 import com.google.common.util.concurrent.ThreadFactoryBuilder;
 import com.sun.nio.file.SensitivityWatchEventModifier;
-import lombok.AccessLevel;
-import lombok.Setter;
-import lombok.SneakyThrows;
+import lombok.*;
 import lombok.extern.slf4j.Slf4j;
-import lombok.val;
 
 import java.io.IOException;
 import java.nio.file.*;
@@ -53,8 +50,8 @@ public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) th
                                                      new WatchEvent.Kind[]{ENTRY_CREATE, ENTRY_DELETE, ENTRY_MODIFY},
                                                      SensitivityWatchEventModifier.HIGH);
                     WATCH_KEY_MAP.put(watchKey, dir);
-                    log.debug("Registering {} in watcher service. WATCH_KEY_MAP size: {}", dir,
-                              WATCH_KEY_MAP.values().size());
+                    log.debug("WATCH_KEY_MAP size: {}. Registering into watcher service. Path: {}",
+                              WATCH_KEY_MAP.values().size(), dir);
                     return FileVisitResult.CONTINUE;
                 }
             });
@@ -63,7 +60,11 @@ public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) th
         }
     };
     @Setter(AccessLevel.NONE)
+    @Getter
     private volatile boolean terminated = false;
+    @Setter(AccessLevel.NONE)
+    @Getter(AccessLevel.PACKAGE)
+    private final Object terminateLock = new Object();
     private final Path monitoredPath;
     private FileWatcherHandler fileWatcherHandler;
 
@@ -157,10 +158,9 @@ private void monitorRecursively() {
      *
      * @author Johnny Miller (锺俊), email: [email protected], date: 10/27/2020 10:01 AM
      */
-    @SneakyThrows
-    public void destroy() {
+    public void terminate() {
         WatchServiceSingleton.close();
-        synchronized (this) {
+        synchronized (terminateLock) {
             this.terminated = true;
         }
         this.shutdownAndAwaitTermination();
@@ -178,7 +178,7 @@ public void destroy() {
     private void shutdownAndAwaitTermination() {
         // Disable new tasks from being submitted
         THREAD_POOL.shutdown();
-        log.debug("Shutdown THREAD_POOL for FileWatcher done.");
+        log.debug("Shutdown THREAD_POOL for FileWatcher done, disabled new tasks from being submitted.");
         try {
             // Wait a while for existing tasks to terminate
             if (!THREAD_POOL.awaitTermination(INTERVAL, TimeUnit.SECONDS)) {

media-streaming-spring-boot-autoconfigure/src/main/java/com/github/johnnymillergh/boot/mediastreamingspringbootautoconfigure/filewatch/WatchServiceSingleton.java

@@ -43,7 +43,6 @@ public static WatchService getInstance() {
                 }
             }
         }
-        log.debug("WatchService is not null, returned directly");
         return singletonInstance;
     }