From feb5b9641dcd61781d94c37af267a068dc916e5c Mon Sep 17 00:00:00 2001
From: Tsz-wo Sze <szetszwo@apache.org>
Date: Mon, 1 Jul 2013 01:28:22 +0000
Subject: [PATCH] HDFS-4797. BlockScanInfo does not override equals(..) and
 hashCode() consistently.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1498202 13f79535-47bb-0310-9956-ffa450edef68
---
 hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt   |  3 ++
 .../datanode/BlockPoolSliceScanner.java       | 37 ++++++++++++-------
 2 files changed, 26 insertions(+), 14 deletions(-)

diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index be81c83c81..cd8faef90e 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -251,6 +251,9 @@ Release 2.2.0 - UNRELEASED
 
   BUG FIXES
 
+    HDFS-4797. BlockScanInfo does not override equals(..) and hashCode()
+    consistently.  (szetszwo)
+
 Release 2.1.1-beta - UNRELEASED
 
   INCOMPATIBLE CHANGES
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BlockPoolSliceScanner.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BlockPoolSliceScanner.java
index 8a117546ff..6ae19d6b6e 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BlockPoolSliceScanner.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BlockPoolSliceScanner.java
@@ -24,6 +24,7 @@
 import java.text.DateFormat;
 import java.text.SimpleDateFormat;
 import java.util.Collections;
+import java.util.Comparator;
 import java.util.Date;
 import java.util.HashMap;
 import java.util.Iterator;
@@ -80,7 +81,7 @@ class BlockPoolSliceScanner {
   private final FsDatasetSpi<? extends FsVolumeSpi> dataset;
   
   private final SortedSet<BlockScanInfo> blockInfoSet
-      = new TreeSet<BlockScanInfo>();
+      = new TreeSet<BlockScanInfo>(BlockScanInfo.LAST_SCAN_TIME_COMPARATOR);
   private final Map<Block, BlockScanInfo> blockMap
       = new HashMap<Block, BlockScanInfo>();
   
@@ -107,8 +108,20 @@ private static enum ScanType {
     NONE,
   }
   
-  static class BlockScanInfo implements Comparable<BlockScanInfo> {
-    Block block;
+  static class BlockScanInfo {
+    /** Compare the info by the last scan time. */
+    static final Comparator<BlockScanInfo> LAST_SCAN_TIME_COMPARATOR
+        = new Comparator<BlockPoolSliceScanner.BlockScanInfo>() {
+
+      @Override
+      public int compare(BlockScanInfo left, BlockScanInfo right) {
+        final long l = left.lastScanTime;
+        final long r = right.lastScanTime;
+        return l < r? -1: l > r? 1: 0; 
+      }
+    };
+
+    final Block block;
     long lastScanTime = 0;
     ScanType lastScanType = ScanType.NONE; 
     boolean lastScanOk = true;
@@ -123,22 +136,18 @@ public int hashCode() {
     }
     
     @Override
-    public boolean equals(Object other) {
-      return other instanceof BlockScanInfo &&
-             compareTo((BlockScanInfo)other) == 0;
+    public boolean equals(Object that) {
+      if (this == that) {
+        return true;
+      } else if (that == null || !(that instanceof BlockScanInfo)) {
+        return false;
+      }
+      return block.equals(((BlockScanInfo)that).block);
     }
     
     long getLastScanTime() {
       return (lastScanType == ScanType.NONE) ? 0 : lastScanTime;
     }
-    
-    @Override
-    public int compareTo(BlockScanInfo other) {
-      long t1 = lastScanTime;
-      long t2 = other.lastScanTime;
-      return ( t1 < t2 ) ? -1 : 
-                          (( t1 > t2 ) ? 1 : block.compareTo(other.block)); 
-    }
   }
   
   BlockPoolSliceScanner(String bpid, DataNode datanode,