fix(server): fix some issues of the distributed scheduler

Author: Tsukilc

hugegraph-server/hugegraph-core/src/main/java/org/apache/hugegraph/task/HugeTask.java

@@ -740,26 +740,19 @@ private void checkPropertySize(int propertyLength, String propertyName) {
 
     public void syncWait() {
         // This method is just called by tests
-        /*
-         * For ephemeral tasks (negative ID), directly wait on the Future.
-         * Ephemeral tasks are not saved to DB, so we can't query them by ID.
-         * Since HugeTask extends FutureTask, we can directly wait for completion.
-         */
-        if (this.id().asLong() < 0) {
-            try {
-                this.get();
-            } catch (Exception e) {
-                throw new HugeException("Failed to wait for task '%s' completed",
-                                        e, this.id);
-            }
-            return;
-        }
-
-        // For normal tasks, wait through scheduler
         HugeTask<?> task = null;
         try {
             task = this.scheduler().waitUntilTaskCompleted(this.id());
         } catch (Throwable e) {
+            if (this.callable() instanceof EphemeralJob &&
+                e.getClass() == NotFoundException.class &&
+                e.getMessage().contains("Can't find task with id")) {
+                /*
+                 * The task with EphemeralJob won't saved in backends and
+                 * will be removed from memory when completed
+                 */
+                return;
+            }
             throw new HugeException("Failed to wait for task '%s' completed",
                                     e, this.id);
         }