Author: nigel
Date: Wed Nov 24 06:16:03 2010
New Revision: 1038493
URL: http://svn.apache.org/viewvc?rev=1038493&view=rev
Log:
HADOOP-7001. Configuration changes can occur via the Reconfigurable interface.
(Patrick Kline via dhruba and nigel)
Added:
hadoop/common/trunk/src/java/org/apache/hadoop/conf/Reconfigurable.java
Added: hadoop/common/trunk/src/java/org/apache/hadoop/conf/Reconfigurable.java
URL:
http://svn.apache.org/viewvc/hadoop/common/trunk/src/java/org/apache/hadoop/conf/Reconfigurable.java?rev=1038493&view=auto
==============================================================================
--- hadoop/common/trunk/src/java/org/apache/hadoop/conf/Reconfigurable.java
(added)
+++ hadoop/common/trunk/src/java/org/apache/hadoop/conf/Reconfigurable.java Wed
Nov 24 06:16:03 2010
@@ -0,0 +1,57 @@
+/**
+ * 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.conf;
+
+import java.util.Collection;
+
+/**
+ * Something whose {...@link Configuration} can be changed at run time.
+ */
+public interface Reconfigurable extends Configurable {
+
+ /**
+ * Change a configuration property on this object to the value specified.
+ *
+ * Change a configuration property on this object to the value specified
+ * and return the previous value that the configuration property was set to
+ * (or null if it was not previously set). If newVal is null, set the
property
+ * to its default value;
+ *
+ * If the property cannot be changed, throw a
+ * {...@link ReconfigurationException}.
+ */
+ public String reconfigureProperty(String property, String newVal)
+ throws ReconfigurationException;
+
+ /**
+ * Return whether a given property is changeable at run time.
+ *
+ * If isPropertyReconfigurable returns true for a property,
+ * then changeConf should not throw an exception when changing
+ * this property.
+ */
+ public boolean isPropertyReconfigurable(String property);
+
+ /**
+ * Return all the properties that can be changed at run time.
+ */
+ public Collection<String> getReconfigurableProperties();
+
+
+}
