HADOOP-9686. Easy access to final parameters in Configuration (Jason Lowe via jeagles)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1515991 13f79535-47bb-0310-9956-ffa450edef68

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -8,6 +8,9 @@ Release 0.23.10 - UNRELEASED
 
   IMPROVEMENTS
 
+    HADOOP-9686. Easy access to final parameters in Configuration (Jason Lowe
+    via jeagles)
+
   OPTIMIZATIONS
 
     HADOOP-9748. Reduce blocking on UGI.ensureInitialized (daryn)

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/conf/Configuration.java

@@ -1737,6 +1737,15 @@ public class Configuration implements Iterable<Map.Entry<String,String>>,
     }
   }
 
+  /**
+   * Get the set of parameters marked final.
+   *
+   * @return final parameter set.
+   */
+  public Set<String> getFinalParameters() {
+    return new HashSet<String>(finalParameters);
+  }
+
   protected synchronized Properties getProps() {
     if (properties == null) {
       properties = new Properties();

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/conf/TestConfiguration.java

@@ -1022,6 +1022,22 @@ public class TestConfiguration extends TestCase {
     assertTrue("Picked out wrong key " + key4, !res.containsKey(key4));
   }
 
+  public void testGetFinalParameters() throws Exception {
+    out=new BufferedWriter(new FileWriter(CONFIG));
+    startConfig();
+    declareProperty("my.var", "x", "x", true);
+    endConfig();
+    Path fileResource = new Path(CONFIG);
+    Configuration conf = new Configuration();
+    Set<String> finalParameters = conf.getFinalParameters();
+    assertFalse("my.var already exists", finalParameters.contains("my.var"));
+    conf.addResource(fileResource);
+    assertEquals("my.var is undefined", "x", conf.get("my.var"));
+    assertFalse("finalparams not copied", finalParameters.contains("my.var"));
+    finalParameters = conf.getFinalParameters();
+    assertTrue("my.var is not final", finalParameters.contains("my.var"));
+  }
+
   public static void main(String[] argv) throws Exception {
     junit.textui.TestRunner.main(new String[]{
       TestConfiguration.class.getName()