From f3ed02a68a2d43ad0cc8c7ac3557da6117bc1f5b Mon Sep 17 00:00:00 2001
From: Todd Lipcon <todd@apache.org>
Date: Wed, 14 Sep 2011 06:48:08 +0000
Subject: [PATCH] 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/CHANGES.txt                 |  3 +++
 .../hadoop/fs/permission/FsPermission.java    | 22 ++++++++++++-------
 2 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/hadoop-common-project/hadoop-common/CHANGES.txt b/hadoop-common-project/hadoop-common/CHANGES.txt
index 0b2206e3538..19d3702b92d 100644
--- a/hadoop-common-project/hadoop-common/CHANGES.txt
+++ b/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
diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/permission/FsPermission.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/permission/FsPermission.java
index 0926bb1dc0d..af3d5148d59 100644
--- a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/permission/FsPermission.java
+++ b/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();
+    }    
+  }
 }