From 9660bfa84c900afd4824feb62d14256584edfb95 Mon Sep 17 00:00:00 2001
From: Arpit Agarwal <arp@apache.org>
Date: Mon, 4 Nov 2013 02:13:04 +0000
Subject: [PATCH] HDFS-5448. Datanode should generate its ID on first
 registration

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-2832@1538496 13f79535-47bb-0310-9956-ffa450edef68
---
 .../hadoop-hdfs/CHANGES_HDFS-2832.txt         |  5 +++-
 .../hadoop/hdfs/protocol/DatanodeID.java      |  5 ----
 .../blockmanagement/DatanodeManager.java      | 12 --------
 .../hadoop/hdfs/server/datanode/DataNode.java | 29 ++++++++++++++-----
 4 files changed, 25 insertions(+), 26 deletions(-)

diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES_HDFS-2832.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES_HDFS-2832.txt
index 20ec6aafdd2..74483081067 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES_HDFS-2832.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES_HDFS-2832.txt
@@ -61,4 +61,7 @@ IMPROVEMENTS:
     HDFS-5447. Fix TestJspHelper. (Arpit Agarwal)
 
     HDFS-5452. Fix TestReplicationPolicy and TestBlocksScheduledCounter.
-    (szetszwo)
+
+    HDFS-5448. Datanode should generate its ID on first registration. (Arpit
+    Agarwal)
+
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/DatanodeID.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/DatanodeID.java
index b8b84f56662..a00fdf47fab 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/DatanodeID.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/DatanodeID.java
@@ -113,11 +113,6 @@ private String checkDatanodeUuid(String uuid) {
     }
   }
 
-  public String generateNewDatanodeUuid() {
-    datanodeUuid = UUID.randomUUID().toString();
-    return datanodeUuid;
-  }
-
   /**
    * @return ipAddr;
    */
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/DatanodeManager.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/DatanodeManager.java
index 892caa0c596..ec943a5a094 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/DatanodeManager.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/DatanodeManager.java
@@ -845,18 +845,6 @@ nodes with its data cleared (or user can just remove the StorageID
         return;
       }
 
-      // This is a new datanode.
-      if (nodeReg.getDatanodeUuid() == null ||
-          nodeReg.getDatanodeUuid().isEmpty()) {
-        // this data node has never been registered
-        nodeReg.generateNewDatanodeUuid();
-        if (NameNode.stateChangeLog.isDebugEnabled()) {
-          NameNode.stateChangeLog.debug(
-              "BLOCK* NameSystem.registerDatanode: "
-              + "new Datanode UUID " + nodeReg.getDatanodeUuid() + " assigned.");
-        }
-      }
-      
       DatanodeDescriptor nodeDescr 
         = new DatanodeDescriptor(nodeReg, NetworkTopology.DEFAULT_RACK);
       boolean success = false;
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataNode.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataNode.java
index a493423695a..fbccecae67f 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataNode.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataNode.java
@@ -693,16 +693,35 @@ void startDataNode(Configuration conf,
     readaheadPool = ReadaheadPool.getInstance();
   }
   
+  /**
+   * Verify that the DatanodeUuid has been initialized. If this is a new
+   * datanode then we generate a new Datanode Uuid and persist it to disk.
+   *
+   * @throws IOException
+   */
+  private synchronized void checkDatanodeUuid() throws IOException {
+    if (storage.getDatanodeUuid() == null) {
+      storage.setDatanodeUuid(UUID.randomUUID().toString());
+      storage.writeAll();
+      LOG.info("Generated and persisted new Datanode UUID " +
+               storage.getDatanodeUuid());
+    }
+  }
+
   /**
    * Create a DatanodeRegistration for a specific block pool.
    * @param nsInfo the namespace info from the first part of the NN handshake
    */
-  DatanodeRegistration createBPRegistration(NamespaceInfo nsInfo) {
+  DatanodeRegistration createBPRegistration(NamespaceInfo nsInfo)
+      throws IOException {
     StorageInfo storageInfo = storage.getBPStorage(nsInfo.getBlockPoolID());
     if (storageInfo == null) {
       // it's null in the case of SimulatedDataSet
       storageInfo = new StorageInfo(nsInfo);
     }
+
+    checkDatanodeUuid();
+
     DatanodeID dnId = new DatanodeID(
         streamingAddr.getAddress().getHostAddress(), hostName, 
         storage.getDatanodeUuid(), getXferPort(), getInfoPort(),
@@ -724,13 +743,7 @@ synchronized void bpRegistrationSucceeded(DatanodeRegistration bpRegistration,
       id = bpRegistration;
     }
 
-    if (storage.getDatanodeUuid() == null) {
-      // This is a fresh datanode, persist the NN-provided Datanode ID
-      storage.setDatanodeUuid(bpRegistration.getDatanodeUuid());
-      storage.writeAll();
-      LOG.info("Datanode ID " + bpRegistration.getDatanodeUuid()
-          + " is assigned to new storage " + bpRegistration);
-    } else if(!storage.getDatanodeUuid().equals(bpRegistration.getDatanodeUuid())) {
+    if(!storage.getDatanodeUuid().equals(bpRegistration.getDatanodeUuid())) {
       throw new IOException("Inconsistent Datanode IDs. Name-node returned "
           + bpRegistration.getDatanodeUuid()
           + ". Expecting " + storage.getDatanodeUuid());