HADOOP-7629. Allow immutable FsPermission objects to be used as IPC parameters. Contributed by Todd Lipcon.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1170450 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -573,6 +573,9 @@ Release 0.23.0 - Unreleased
 
     HADOOP-7626. Bugfix for a config generator (Eric Yang via ddas)
 
+    HADOOP-7629. Allow immutable FsPermission objects to be used as IPC
+    parameters. (todd)
+
 Release 0.22.0 - Unreleased
 
   INCOMPATIBLE CHANGES

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/permission/FsPermission.java

@@ -44,18 +44,12 @@ public class FsPermission implements Writable {
   };
   static {                                      // register a ctor
     WritableFactories.setFactory(FsPermission.class, FACTORY);
+    WritableFactories.setFactory(ImmutableFsPermission.class, FACTORY);
   }
 
   /** Create an immutable {@link FsPermission} object. */
   public static FsPermission createImmutable(short permission) {
-    return new FsPermission(permission) {
-      public FsPermission applyUMask(FsPermission umask) {
-        throw new UnsupportedOperationException();
-      }
-      public void readFields(DataInput in) throws IOException {
-        throw new UnsupportedOperationException();
-      }
-    };
+    return new ImmutableFsPermission(permission);
   }
 
   //POSIX permission style
@@ -301,4 +295,16 @@ public class FsPermission implements Writable {
 
     return new FsPermission((short)n);
   }
+  
+  private static class ImmutableFsPermission extends FsPermission {
+    public ImmutableFsPermission(short permission) {
+      super(permission);
+    }
+    public FsPermission applyUMask(FsPermission umask) {
+      throw new UnsupportedOperationException();
+    }
+    public void readFields(DataInput in) throws IOException {
+      throw new UnsupportedOperationException();
+    }    
+  }
 }