HDFS-16181. [SBN Read] Fix display of JournalNode metric RpcRequestCacheMissAmount (#3317)

Co-authored-by: wangzhaohui8 <[email protected]>

(cherry picked from commit 232fd7cae170de8c6b52c14841a47dca8735c6d2)
(cherry picked from commit 2f73ac1)

Author: wzhallright

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/qjournal/server/Journal.java

@@ -774,7 +774,7 @@ public GetJournaledEditsResponseProto getJournaledEdits(long sinceTxId,
           .setEditLog(output.toByteString())
           .build();
     } catch (JournaledEditsCache.CacheMissException cme) {
-      metrics.rpcRequestCacheMissAmount.add(cme.getCacheMissAmount());
+      metrics.addRpcRequestCacheMissAmount(cme.getCacheMissAmount());
       throw cme;
     }
   }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/qjournal/server/JournalMetrics.java

@@ -51,12 +51,7 @@ class JournalMetrics {
   @Metric("Number of bytes served via RPC")
   MutableCounterLong bytesServedViaRpc;
 
-  @Metric
-  MutableStat rpcRequestCacheMissAmount = new MutableStat(
-      "RpcRequestCacheMissAmount", "Number of RPC requests unable to be " +
-      "served due to lack of availability in cache, and how many " +
-      "transactions away the request was from being in the cache.",
-      "Misses", "Txns");
+  private MutableStat rpcRequestCacheMissAmount;
 
   @Metric("Number of RPC requests with zero edits returned")
   MutableCounterLong rpcEmptyResponses;
@@ -87,6 +82,11 @@ class JournalMetrics {
           "syncs" + interval + "s",
           "Journal sync time", "ops", "latencyMicros", interval);
     }
+    rpcRequestCacheMissAmount = registry
+        .newStat("RpcRequestCacheMissAmount", "Number of RPC requests unable to be " +
+                "served due to lack of availability in cache, and how many " +
+                "transactions away the request was from being in the cache.",
+            "Misses", "Txns");
   }
 
   public static JournalMetrics create(Journal j) {
@@ -149,4 +149,8 @@ public MutableCounterLong getNumEditLogsSynced() {
   public void incrNumEditLogsSynced() {
     numEditLogsSynced.incr();
   }
+
+  public void addRpcRequestCacheMissAmount(long cacheMissAmount) {
+    rpcRequestCacheMissAmount.add(cacheMissAmount);
+  }
 }