From 059290ce3a008f281e7e64fd263cfb09d92da19e Mon Sep 17 00:00:00 2001
From: Aaron Myers <atm@apache.org>
Date: Sat, 17 Dec 2011 00:14:36 +0000
Subject: [PATCH] HADOOP-7931. o.a.h.ipc.WritableRpcEngine should have a way to
 force initialization. Contributed by Aaron T. Myers

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1215358 13f79535-47bb-0310-9956-ffa450edef68
---
 .../hadoop-common/CHANGES.txt                 |  3 ++
 .../apache/hadoop/ipc/WritableRpcEngine.java  | 35 +++++++++++++++----
 2 files changed, 31 insertions(+), 7 deletions(-)

diff --git a/hadoop-common-project/hadoop-common/CHANGES.txt b/hadoop-common-project/hadoop-common/CHANGES.txt
index 21eda1b32f..aba8ce050c 100644
--- a/hadoop-common-project/hadoop-common/CHANGES.txt
+++ b/hadoop-common-project/hadoop-common/CHANGES.txt
@@ -141,6 +141,9 @@ Trunk (unreleased changes)
 
     HADOOP-7892. IPC logs too verbose after "RpcKind" introduction (todd)
 
+    HADOOP-7931. o.a.h.ipc.WritableRpcEngine should have a way to force
+                 initialization (atm)
+
   OPTIMIZATIONS
 
     HADOOP-7761. Improve the performance of raw comparisons. (todd)
diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/WritableRpcEngine.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/WritableRpcEngine.java
index 25f46f13e2..19a496809b 100644
--- a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/WritableRpcEngine.java
+++ b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/WritableRpcEngine.java
@@ -48,17 +48,38 @@
 public class WritableRpcEngine implements RpcEngine {
   private static final Log LOG = LogFactory.getLog(RPC.class);
   
-  static { // Register the rpcRequest deserializer for WritableRpcEngine 
-    org.apache.hadoop.ipc.Server.registerProtocolEngine(RpcKind.RPC_WRITABLE,
-        Invocation.class, new Server.WritableRpcInvoker());
-  }
-
-  
   //writableRpcVersion should be updated if there is a change
   //in format of the rpc messages.
   
   // 2L - added declared class to Invocation
-  public static final long writableRpcVersion = 2L; 
+  public static final long writableRpcVersion = 2L;
+  
+  /**
+   * Whether or not this class has been initialized.
+   */
+  private static boolean isInitialized = false;
+  
+  static { 
+    ensureInitialized();
+  }
+  
+  /**
+   * Initialize this class if it isn't already.
+   */
+  public static synchronized void ensureInitialized() {
+    if (!isInitialized) {
+      initialize();
+    }
+  }
+  
+  /**
+   * Register the rpcRequest deserializer for WritableRpcEngine
+   */
+  private static synchronized void initialize() {
+    org.apache.hadoop.ipc.Server.registerProtocolEngine(RpcKind.RPC_WRITABLE,
+        Invocation.class, new Server.WritableRpcInvoker());
+    isInitialized = true;
+  }
 
   
   /** A method invocation, including the method name and its parameters.*/