1 files changed, 46 insertions, 0 deletions
diff --git a/sql/hive-thriftserver/src/main/java/org/apache/hive/service/ServiceStateChangeListener.java b/sql/hive-thriftserver/src/main/java/org/apache/hive/service/ServiceStateChangeListener.java
new file mode 100644
index 0000000000..16ad9a991e
--- /dev/null
+++ b/sql/hive-thriftserver/src/main/java/org/apache/hive/service/ServiceStateChangeListener.java
@@ -0,0 +1,46 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hive.service;
+
+/**
+ * ServiceStateChangeListener.
+ *
+ */
+public interface ServiceStateChangeListener {
+
+  /**
+   * Callback to notify of a state change. The service will already
+   * have changed state before this callback is invoked.
+   *
+   * This operation is invoked on the thread that initiated the state change,
+   * while the service itself in in a sychronized section.
+   * <ol>
+   *   <li>Any long-lived operation here will prevent the service state
+   *   change from completing in a timely manner.</li>
+   *   <li>If another thread is somehow invoked from the listener, and
+   *   that thread invokes the methods of the service (including
+   *   subclass-specific methods), there is a risk of a deadlock.</li>
+   * </ol>
+   *
+   *
+   * @param service the service that has changed.
+   */
+  void stateChanged(Service service);
+
+}