Internal Options Executor Awareness

Be aware of all executors being internal to know whether to shut them down or not on connection close

Author: scottf

src/main/java/io/nats/client/Options.java

@@ -2234,6 +2234,24 @@ private ScheduledExecutorService _getInternalScheduledExecutor() {
         return stpe;
     }
 
+    /**
+     * the callback executor, see {@link Builder#callbackThreadFactory(ThreadFactory) callbackThreadFactory()} in the builder doc
+     * @return the executor
+     */
+    public ExecutorService getCallbackExecutor() {
+        return this.callbackThreadFactory == null ?
+                DEFAULT_SINGLE_THREAD_EXECUTOR.get() : Executors.newSingleThreadExecutor(this.callbackThreadFactory);
+    }
+
+    /**
+     * the connect executor, see {@link Builder#connectThreadFactory(ThreadFactory) connectThreadFactory()} in the builder doc
+     * @return the executor
+     */
+    public ExecutorService getConnectExecutor() {
+        return this.connectThreadFactory == null ?
+                DEFAULT_SINGLE_THREAD_EXECUTOR.get() : Executors.newSingleThreadExecutor(this.connectThreadFactory);
+    }
+
     /**
      * whether the general executor is the internal one versus a user supplied one
      * @return true if the executor is internal
@@ -2251,21 +2269,19 @@ public boolean scheduledExecutorIsInternal() {
     }
 
     /**
-     * the callback executor, see {@link Builder#callbackThreadFactory(ThreadFactory) callbackThreadFactory()} in the builder doc
-     * @return the executor
+     * whether the callback executor is the internal one versus a user supplied one
+     * @return true if the executor is internal
      */
-    public ExecutorService getCallbackExecutor() {
-        return this.callbackThreadFactory == null ?
-                DEFAULT_SINGLE_THREAD_EXECUTOR.get() : Executors.newSingleThreadExecutor(this.callbackThreadFactory);
+    public boolean callbackExecutorIsInternal() {
+        return this.callbackThreadFactory == null;
     }
 
     /**
-     * the connect executor, see {@link Builder#connectThreadFactory(ThreadFactory) connectThreadFactory()} in the builder doc
-     * @return the executor
+     * whether the connect executor is the internal one versus a user supplied one
+     * @return true if the executor is internal
      */
-    public ExecutorService getConnectExecutor() {
-        return this.connectThreadFactory == null ?
-                DEFAULT_SINGLE_THREAD_EXECUTOR.get() : Executors.newSingleThreadExecutor(this.connectThreadFactory);
+    public boolean connectExecutorIsInternal() {
+        return this.connectThreadFactory == null;
     }
 
     /**

src/main/java/io/nats/client/impl/NatsConnection.java

@@ -875,22 +875,26 @@ void close(boolean checkDrainStatus, boolean forceClose) throws InterruptedExcep
             statusLock.unlock();
         }
 
-        // Stop the error handling and connect executors
-        callbackRunner.shutdown();
-        try {
-            // At this point in the flow, the connection is shutting down.
-            // There is really no use in giving this information to the developer,
-            // It's fair to say that an exception here anyway will practically never happen
-            // and if it did, the app is probably already frozen.
-            //noinspection ResultOfMethodCallIgnored
-            callbackRunner.awaitTermination(this.options.getConnectionTimeout().toNanos(), TimeUnit.NANOSECONDS);
-        }
-        finally {
-            callbackRunner.shutdownNow();
+        if (options.callbackExecutorIsInternal()) {
+            // Stop the error handling and connect executors
+            callbackRunner.shutdown();
+            try {
+                // At this point in the flow, the connection is shutting down.
+                // There is really no use in giving this information to the developer,
+                // It's fair to say that an exception here anyway will practically never happen
+                // and if it did, the app is probably already frozen.
+                //noinspection ResultOfMethodCallIgnored
+                callbackRunner.awaitTermination(this.options.getConnectionTimeout().toNanos(), TimeUnit.NANOSECONDS);
+            }
+            finally {
+                callbackRunner.shutdownNow();
+            }
         }
 
-        // There's no need to wait for running tasks since we're told to close
-        connectExecutor.shutdownNow();
+        if (options.connectExecutorIsInternal()) {
+            // There's no need to wait for running tasks since we're told to close
+            connectExecutor.shutdownNow();
+        }
 
         // The callbackRunner and connectExecutor always come from a factory,
         // so we always shut them down.