HDFS-7434. DatanodeID hashCode should not be mutable. Contributed by Daryn Sharp.

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -1091,6 +1091,8 @@ Release 2.7.0 - UNRELEASED
     HDFS-7879. hdfs.dll does not export functions of the public libhdfs API.
     (Chris Nauroth via wheat9)
 
+    HDFS-7434. DatanodeID hashCode should not be mutable. (daryn via kihwal)
+
     BREAKDOWN OF HDFS-7584 SUBTASKS AND RELATED JIRAS
 
       HDFS-7720. Quota by Storage Type API, tools and ClientNameNode

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/DatanodeID.java

@@ -47,19 +47,23 @@ public class DatanodeID implements Comparable<DatanodeID> {
   private int infoSecurePort; // info server port
   private int ipcPort;       // IPC server port
   private String xferAddr;
-  private int hashCode = -1;
 
   /**
    * UUID identifying a given datanode. For upgraded Datanodes this is the
    * same as the StorageID that was previously used by this Datanode. 
    * For newly formatted Datanodes it is a UUID.
    */
-  private String datanodeUuid = null;
+  private final String datanodeUuid;
 
   public DatanodeID(DatanodeID from) {
+    this(from.getDatanodeUuid(), from);
+  }
+
+  @VisibleForTesting
+  public DatanodeID(String datanodeUuid, DatanodeID from) {
     this(from.getIpAddr(),
         from.getHostName(),
-        from.getDatanodeUuid(),
+        datanodeUuid,
         from.getXferPort(),
         from.getInfoPort(),
         from.getInfoSecurePort(),
@@ -81,19 +85,24 @@ public DatanodeID(DatanodeID from) {
    */
   public DatanodeID(String ipAddr, String hostName, String datanodeUuid,
       int xferPort, int infoPort, int infoSecurePort, int ipcPort) {
-    this.ipAddr = ipAddr;
+    setIpAndXferPort(ipAddr, xferPort);
     this.hostName = hostName;
     this.datanodeUuid = checkDatanodeUuid(datanodeUuid);
-    this.xferPort = xferPort;
     this.infoPort = infoPort;
     this.infoSecurePort = infoSecurePort;
     this.ipcPort = ipcPort;
-    updateXferAddrAndInvalidateHashCode();
   }
   
   public void setIpAddr(String ipAddr) {
+    //updated during registration, preserve former xferPort
+    setIpAndXferPort(ipAddr, xferPort);
+  }
+
+  private void setIpAndXferPort(String ipAddr, int xferPort) {
+    // build xferAddr string to reduce cost of frequent use
     this.ipAddr = ipAddr;
-    updateXferAddrAndInvalidateHashCode();
+    this.xferPort = xferPort;
+    this.xferAddr = ipAddr + ":" + xferPort;
   }
 
   public void setPeerHostName(String peerHostName) {
@@ -107,12 +116,6 @@ public String getDatanodeUuid() {
     return datanodeUuid;
   }
 
-  @VisibleForTesting
-  public void setDatanodeUuidForTesting(String datanodeUuid) {
-    this.datanodeUuid = datanodeUuid;
-    updateXferAddrAndInvalidateHashCode();
-  }
-
   private String checkDatanodeUuid(String uuid) {
     if (uuid == null || uuid.isEmpty()) {
       return null;
@@ -242,11 +245,7 @@ public boolean equals(Object to) {
   
   @Override
   public int hashCode() {
-    if (hashCode == -1) {
+    return datanodeUuid.hashCode();
-      int newHashCode = xferAddr.hashCode() ^ datanodeUuid.hashCode();
-      hashCode = newHashCode & Integer.MAX_VALUE;
-    }
-    return hashCode;
   }
   
   @Override
@@ -259,14 +258,12 @@ public String toString() {
    * Note that this does not update storageID.
    */
   public void updateRegInfo(DatanodeID nodeReg) {
-    ipAddr = nodeReg.getIpAddr();
+    setIpAndXferPort(nodeReg.getIpAddr(), nodeReg.getXferPort());
     hostName = nodeReg.getHostName();
     peerHostName = nodeReg.getPeerHostName();
-    xferPort = nodeReg.getXferPort();
     infoPort = nodeReg.getInfoPort();
     infoSecurePort = nodeReg.getInfoSecurePort();
     ipcPort = nodeReg.getIpcPort();
-    updateXferAddrAndInvalidateHashCode();
   }
     
   /**
@@ -279,13 +276,4 @@ public void updateRegInfo(DatanodeID nodeReg) {
   public int compareTo(DatanodeID that) {
     return getXferAddr().compareTo(that.getXferAddr());
   }
-
-  // NOTE: mutable hash codes are dangerous, however this class chooses to
-  // use them.  this method must be called when a value mutates that is used
-  // to compute the hash, equality, or comparison of instances.
-  private void updateXferAddrAndInvalidateHashCode() {
-    xferAddr = ipAddr + ":" + xferPort;
-    // can't compute new hash yet because uuid might still null...
-    hashCode = -1;
-  }
 }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/protocol/DatanodeRegistration.java

@@ -25,6 +25,8 @@
 import org.apache.hadoop.hdfs.server.common.Storage;
 import org.apache.hadoop.hdfs.server.common.StorageInfo;
 
+import com.google.common.annotations.VisibleForTesting;
+
 /** 
  * DatanodeRegistration class contains all information the name-node needs
  * to identify and verify a data-node when it contacts the name-node.
@@ -39,6 +41,14 @@ public class DatanodeRegistration extends DatanodeID
   private ExportedBlockKeys exportedKeys;
   private final String softwareVersion;
 
+  @VisibleForTesting
+  public DatanodeRegistration(String uuid, DatanodeRegistration dnr) {
+    this(new DatanodeID(uuid, dnr),
+         dnr.getStorageInfo(),
+         dnr.getExportedKeys(),
+         dnr.getSoftwareVersion());
+  }
+
   public DatanodeRegistration(DatanodeID dn, StorageInfo info,
       ExportedBlockKeys keys, String softwareVersion) {
     super(dn);

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestBlockManager.java

@@ -538,10 +538,6 @@ public void testHighestPriReplSrcChosenDespiteMaxReplLimit() throws Exception {
   public void testSafeModeIBR() throws Exception {
     DatanodeDescriptor node = spy(nodes.get(0));
     DatanodeStorageInfo ds = node.getStorageInfos()[0];
-
-    // TODO: Needs to be fixed. DatanodeUuid is not storageID.
-    node.setDatanodeUuidForTesting(ds.getStorageID());
-
     node.isAlive = true;
 
     DatanodeRegistration nodeReg =
@@ -587,9 +583,6 @@ public void testSafeModeIBRAfterIncremental() throws Exception {
     DatanodeDescriptor node = spy(nodes.get(0));
     DatanodeStorageInfo ds = node.getStorageInfos()[0];
 
-    // TODO: Needs to be fixed. DatanodeUuid is not storageID.
-    node.setDatanodeUuidForTesting(ds.getStorageID());
-
     node.isAlive = true;
 
     DatanodeRegistration nodeReg =

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestComputeInvalidateWork.java

@@ -38,7 +38,6 @@
 import org.apache.hadoop.hdfs.server.protocol.DatanodeRegistration;
 import org.apache.hadoop.util.VersionInfo;
 import org.junit.After;
-import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 import org.mockito.internal.util.reflection.Whitebox;
@@ -119,10 +118,17 @@ public void testCompInvalidate() throws Exception {
   public void testDatanodeReformat() throws Exception {
     namesystem.writeLock();
     try {
+      // Change the datanode UUID to emulate a reformat
+      String poolId = cluster.getNamesystem().getBlockPoolId();
+      DatanodeRegistration dnr = cluster.getDataNode(nodes[0].getIpcPort())
+                                        .getDNRegistrationForBP(poolId);
+      dnr = new DatanodeRegistration(UUID.randomUUID().toString(), dnr);
+      cluster.stopDataNode(nodes[0].getXferAddr());
+
       Block block = new Block(0, 0, GenerationStamp.LAST_RESERVED_STAMP);
       bm.addToInvalidates(block, nodes[0]);
-      // Change the datanode UUID to emulate a reformation
+      bm.getDatanodeManager().registerDatanode(dnr);
-      nodes[0].setDatanodeUuidForTesting("fortesting");
+
       // Since UUID has changed, the invalidation work should be skipped
       assertEquals(0, bm.computeInvalidateWork(1));
       assertEquals(0, bm.getPendingDeletionBlocksCount());
@@ -158,8 +164,8 @@ public void testDatanodeReRegistration() throws Exception {
     // Re-register each DN and see that it wipes the invalidation work
     for (DataNode dn : cluster.getDataNodes()) {
       DatanodeID did = dn.getDatanodeId();
-      did.setDatanodeUuidForTesting(UUID.randomUUID().toString());
+      DatanodeRegistration reg = new DatanodeRegistration(
-      DatanodeRegistration reg = new DatanodeRegistration(did,
+          new DatanodeID(UUID.randomUUID().toString(), did),
           new StorageInfo(HdfsServerConstants.NodeType.DATA_NODE),
           new ExportedBlockKeys(),
           VersionInfo.getVersion());

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestDatanodeProtocolRetryPolicy.java

@@ -173,7 +173,8 @@ public DatanodeRegistration answer(InvocationOnMock invocation)
         } else {
           DatanodeRegistration dr =
               (DatanodeRegistration) invocation.getArguments()[0];
-          datanodeRegistration.setDatanodeUuidForTesting(dr.getDatanodeUuid());
+          datanodeRegistration =
+              new DatanodeRegistration(dr.getDatanodeUuid(), dr);
           LOG.info("mockito succeeded " + datanodeRegistration);
           return datanodeRegistration;
         }