fix ttl not work due to job not close tx

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

@@ -31,7 +31,11 @@ public V call() throws Exception {
 
     @Override
     protected void done() {
-        this.save();
+        try {
+            this.save();
+        } finally {
+            super.done();
+        }
     }
 
     @Override

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

@@ -31,7 +31,11 @@ public V call() throws Exception {
 
     @Override
     protected void done() {
-        this.save();
+        try {
+            this.save();
+        } finally {
+            super.done();
+        }
     }
 
     @Override

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

@@ -22,6 +22,7 @@
 import java.util.Date;
 import java.util.concurrent.Callable;
 
+import org.apache.tinkerpop.gremlin.structure.Transaction;
 import org.slf4j.Logger;
 
 import com.baidu.hugegraph.HugeException;
@@ -48,13 +49,20 @@ public TaskCallable() {
     }
 
     protected void done() {
-        // Do nothing, subclasses may override this method
+        this.closeTx();
     }
 
     protected void cancelled() {
         // Do nothing, subclasses may override this method
     }
 
+    protected void closeTx() {
+        Transaction tx = this.graph().tx();
+        if (tx.isOpen()) {
+            tx.close();
+        }
+    }
+
     public void setMinSaveInterval(long seconds) {
         E.checkArgument(seconds > 0,
                         "Must set interval > 0, bug got '%s'", seconds);