HADOOP-5073. Add annotation mechanism for interface classification. Contributed by Jakob Homan.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@812740 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -184,6 +184,8 @@ Trunk (unreleased changes)
     HADOOP-6234. Add new option dfs.umaskmode to set umask in configuration
     to use octal or symbolic instead of decimal. (Jakob Homan via suresh)
 
+    HADOOP-5073. Add annotation mechanism for interface classification.
+    (Jakob Homan via suresh)
 
   IMPROVEMENTS
 

src/java/org/apache/hadoop/classification/InterfaceAudience.java

@@ -0,0 +1,47 @@
+/*
+ * 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.hadoop.classification;
+
+import java.lang.annotation.Documented;
+
+/**
+ * Annotation to inform users of a package, class or method's intended audience.
+ */
+public class InterfaceAudience {
+  /**
+   * Intended for use by any project or application.
+   */
+  @Documented public @interface Public {};
+  
+  /**
+   * Intended only for the project(s) specified in the annotation
+   */
+  @Documented public @interface LimitedPrivate {
+    public enum Project {COMMON, AVRO, CHUKWA, HBASE, HDFS, 
+                         HIVE, MAPREDUCE, PIG, ZOOKEEPER};
+    
+    Project[] value();
+  };
+  
+  /**
+   * Intended for use only within Hadoop itself.
+   */
+  @Documented public @interface Private {};
+
+  private InterfaceAudience() {} // Audience can't exist on its own
+}

src/java/org/apache/hadoop/classification/InterfaceStability.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.hadoop.classification;
+
+import java.lang.annotation.Documented;
+
+/**
+ * Annotation to inform users of how much to rely on a particular package,
+ * class or method not changing over time.
+ */
+public class InterfaceStability {
+  /**
+   * Can evolve while retaining compatibility for minor release boundaries.; 
+   * can break compatibility only at major release (ie. at m.0).
+   */
+  @Documented
+  public @interface Stable {};
+  
+  /**
+   * Evolving, but can break compatibility at minor release (i.e. m.x)
+   */
+  @Documented
+  public @interface Evolving {};
+  
+  /**
+   * No guarantee is provided as to reliability or stability across any
+   * level of release granularity.
+   */
+  @Documented
+  public @interface Unstable {};
+}