Check if master node before schedule gremlin job

hugegraph-api/src/main/java/com/baidu/hugegraph/auth/HugeGraphAuthProxy.java

@@ -974,6 +974,12 @@ public void waitUntilAllTasksCompleted(long seconds)
             this.taskScheduler.waitUntilAllTasksCompleted(seconds);
         }
 
+        @Override
+        public void checkRequirement(String op) {
+            verifyStatusPermission();
+            this.taskScheduler.checkRequirement(op);
+        }
+
         private void verifyTaskPermission(HugePermission actionPerm) {
             verifyPermission(actionPerm, ResourceType.TASK);
         }

hugegraph-core/src/main/java/com/baidu/hugegraph/job/JobBuilder.java

@@ -71,6 +71,9 @@ public HugeTask<V> schedule() {
         E.checkArgumentNotNull(this.job, "Job callable can't be null");
         E.checkArgument(this.job instanceof TaskCallable,
                         "Job must be instance of TaskCallable");
+
+        this.graph.taskScheduler().checkRequirement("schedule");
+
         @SuppressWarnings("unchecked")
         TaskCallable<V> job = (TaskCallable<V>) this.job;
 

hugegraph-core/src/main/java/com/baidu/hugegraph/task/StandardTaskScheduler.java

@@ -659,6 +659,11 @@ public void waitUntilAllTasksCompleted(long seconds)
                   taskSize, seconds));
     }
 
+    @Override
+    public void checkRequirement(String op) {
+        this.checkOnMasterNode(op);
+    }
+
     private <V> Iterator<HugeTask<V>> queryTask(String key, Object value,
                                                 long limit, String page) {
         return this.queryTask(ImmutableMap.of(key, value), limit, page);

hugegraph-core/src/main/java/com/baidu/hugegraph/task/TaskScheduler.java

@@ -61,4 +61,6 @@ public <V> HugeTask<V> waitUntilTaskCompleted(Id id)
 
     public void waitUntilAllTasksCompleted(long seconds)
                                            throws TimeoutException;
+
+    public void checkRequirement(String op);
 }