From d3d37b7c321f92f121856f2c54b112c4594fe5bc Mon Sep 17 00:00:00 2001
From: huiruan <876107431@qq.com>
Date: Wed, 24 May 2023 22:30:04 +0800
Subject: [PATCH 1/4] HBASE-27885 expose metaCacheHits in MetricsConnection

---
 .../org/apache/hadoop/hbase/client/MetricsConnection.java     | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/MetricsConnection.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/MetricsConnection.java
index dd3e571a8b7a..66cdfb3183f8 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/MetricsConnection.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/MetricsConnection.java
@@ -552,6 +552,10 @@ public void incrMetaCacheHit() {
     metaCacheHits.inc();
   }
 
+  public long getMetaCacheHits() {
+    return metaCacheHits.getCount();
+  }
+
   /** Increment the number of meta cache misses. */
   public void incrMetaCacheMiss() {
     metaCacheMisses.inc();

From 986f754c96acdc15127ab6faf689c826402320ac Mon Sep 17 00:00:00 2001
From: huiruan <876107431@qq.com>
Date: Fri, 26 May 2023 01:23:52 +0800
Subject: [PATCH 2/4] add a test case for getMetaCacheHits

---
 .../java/org/apache/hadoop/hbase/client/TestMetaCache.java     | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestMetaCache.java b/hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestMetaCache.java
index ce52918bfe42..f1f37a718154 100644
--- a/hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestMetaCache.java
+++ b/hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestMetaCache.java
@@ -253,6 +253,9 @@ public void testPreserveMetaCacheOnException() throws Exception {
           table.increment(increment);
           table.delete(delete);
           table.mutateRow(mutations);
+          // The value of the metaCacheHits counter is incremented by 6 in each round of the loop,
+          // and the first request will not hit cache
+          assertEquals(6 * i + 5, metrics.getMetaCacheHits());
         } catch (IOException ex) {
           // Only keep track of the last exception that updated the meta cache
           if (ClientExceptionsUtil.isMetaClearingException(ex) || success) {

From 2ea8ebdbc801bde4d6fc43a0b5fa98531d79a225 Mon Sep 17 00:00:00 2001
From: huiruan <876107431@qq.com>
Date: Fri, 26 May 2023 17:01:06 +0800
Subject: [PATCH 3/4] improve test case

---
 .../java/org/apache/hadoop/hbase/client/TestMetaCache.java | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestMetaCache.java b/hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestMetaCache.java
index f1f37a718154..b227dfaf077e 100644
--- a/hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestMetaCache.java
+++ b/hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestMetaCache.java
@@ -241,6 +241,7 @@ public void testPreserveMetaCacheOnException() throws Exception {
 
       Exception exp;
       boolean success;
+      long initialMetaCacheHits = metrics.getMetaCacheHits();
       for (int i = 0; i < 50; i++) {
         exp = null;
         success = false;
@@ -254,8 +255,10 @@ public void testPreserveMetaCacheOnException() throws Exception {
           table.delete(delete);
           table.mutateRow(mutations);
           // The value of the metaCacheHits counter is incremented by 6 in each round of the loop,
-          // and the first request will not hit cache
-          assertEquals(6 * i + 5, metrics.getMetaCacheHits());
+          // for 0th iteration there will be 5 hits + 1 cache miss.
+          assertEquals(initialMetaCacheHits + 6 * i + 5, metrics.getMetaCacheHits());
+          // We will get a cache miss only on the first request, so the value will always be 1.
+          assertEquals(1, metrics.getMetaCacheMisses());
         } catch (IOException ex) {
           // Only keep track of the last exception that updated the meta cache
           if (ClientExceptionsUtil.isMetaClearingException(ex) || success) {

From a825eb02cfe441d249b0553e3f11dd1dce6d04af Mon Sep 17 00:00:00 2001
From: huiruan <876107431@qq.com>
Date: Sat, 27 May 2023 13:24:21 +0800
Subject: [PATCH 4/4] improve test case

---
 .../java/org/apache/hadoop/hbase/client/TestMetaCache.java  | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestMetaCache.java b/hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestMetaCache.java
index b227dfaf077e..f8f853e758e1 100644
--- a/hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestMetaCache.java
+++ b/hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestMetaCache.java
@@ -242,6 +242,7 @@ public void testPreserveMetaCacheOnException() throws Exception {
       Exception exp;
       boolean success;
       long initialMetaCacheHits = metrics.getMetaCacheHits();
+      long initialMetaCacheMisses = metrics.getMetaCacheMisses();
       for (int i = 0; i < 50; i++) {
         exp = null;
         success = false;
@@ -257,8 +258,9 @@ public void testPreserveMetaCacheOnException() throws Exception {
           // The value of the metaCacheHits counter is incremented by 6 in each round of the loop,
           // for 0th iteration there will be 5 hits + 1 cache miss.
           assertEquals(initialMetaCacheHits + 6 * i + 5, metrics.getMetaCacheHits());
-          // We will get a cache miss only on the first request, so the value will always be 1.
-          assertEquals(1, metrics.getMetaCacheMisses());
+          // We will get a cache miss only on the first request, so the value will always be
+          // initialMetaCacheMisses + 1
+          assertEquals(initialMetaCacheMisses + 1, metrics.getMetaCacheMisses());
         } catch (IOException ex) {
           // Only keep track of the last exception that updated the meta cache
           if (ClientExceptionsUtil.isMetaClearingException(ex) || success) {