From cd7c34f9b4005d27886f73e58bef88e706fcccf9 Mon Sep 17 00:00:00 2001
From: Wei-Chiu Chuang <weichiu@apache.org>
Date: Fri, 24 Sep 2021 23:35:23 +0800
Subject: [PATCH] HDFS-16233. Do not use exception handler to implement
 copy-on-write for EnumCounters. (#3468)

(cherry picked from commit 87632bbacf064e9b07564ba66ed1fbb1d42290d1)
(cherry picked from commit bb08de559a36fd56c7d4023c6dcac66da3fbacc5)
(cherry picked from commit 978ec57445f4178b31a6bfc383c6be032692c288)
---
 .../apache/hadoop/hdfs/server/namenode/QuotaCounts.java  | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/QuotaCounts.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/QuotaCounts.java
index bcb21929c8b9f..d5387d1093559 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/QuotaCounts.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/QuotaCounts.java
@@ -23,7 +23,6 @@
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.util.ConstEnumCounters;
 import org.apache.hadoop.hdfs.util.EnumCounters;
-import org.apache.hadoop.hdfs.util.ConstEnumCounters.ConstEnumException;
 
 import java.util.function.Consumer;
 
@@ -57,14 +56,10 @@ public class QuotaCounts {
    */
   static <T extends Enum<T>> EnumCounters<T> modify(EnumCounters<T> counter,
       Consumer<EnumCounters<T>> action) {
-    try {
-      action.accept(counter);
-    } catch (ConstEnumException cee) {
-      // We don't call clone here because ConstEnumCounters.clone() will return
-      // an object of class ConstEnumCounters. We want EnumCounters.
+    if (counter instanceof ConstEnumCounters) {
       counter = counter.deepCopyEnumCounter();
-      action.accept(counter);
     }
+    action.accept(counter);
     return counter;
   }