From fa584217422c982199276fcdcfb88479f63231cb Mon Sep 17 00:00:00 2001
From: horizonzy <horizonzy@apache.org>
Date: Fri, 18 Aug 2023 02:35:31 +0800
Subject: [PATCH 1/6] extract metrics-api module.

---
 zookeeper-metrics-providers/pom.xml           |  1 +
 .../zookeeper-metrics-api/pom.xml             | 28 +++++++++++++++++++
 .../org/apache/zookeeper/common/Time.java     |  0
 .../org/apache/zookeeper/metrics/Counter.java |  0
 .../apache/zookeeper/metrics/CounterSet.java  |  0
 .../org/apache/zookeeper/metrics/Gauge.java   |  0
 .../apache/zookeeper/metrics/GaugeSet.java    |  0
 .../zookeeper/metrics/MetricsContext.java     |  0
 .../zookeeper/metrics/MetricsProvider.java    |  2 +-
 .../MetricsProviderLifeCycleException.java    |  0
 .../org/apache/zookeeper/metrics/Summary.java |  0
 .../apache/zookeeper/metrics/SummarySet.java  |  0
 .../apache/zookeeper/server/RateLogger.java   |  0
 .../zookeeper-prometheus-metrics/pom.xml      |  8 ++----
 .../PrometheusMetricsProviderTest.java        | 21 +++++++-------
 zookeeper-server/pom.xml                      |  5 ++++
 16 files changed, 47 insertions(+), 18 deletions(-)
 create mode 100644 zookeeper-metrics-providers/zookeeper-metrics-api/pom.xml
 rename {zookeeper-server => zookeeper-metrics-providers/zookeeper-metrics-api}/src/main/java/org/apache/zookeeper/common/Time.java (100%)
 rename {zookeeper-server => zookeeper-metrics-providers/zookeeper-metrics-api}/src/main/java/org/apache/zookeeper/metrics/Counter.java (100%)
 rename {zookeeper-server => zookeeper-metrics-providers/zookeeper-metrics-api}/src/main/java/org/apache/zookeeper/metrics/CounterSet.java (100%)
 rename {zookeeper-server => zookeeper-metrics-providers/zookeeper-metrics-api}/src/main/java/org/apache/zookeeper/metrics/Gauge.java (100%)
 rename {zookeeper-server => zookeeper-metrics-providers/zookeeper-metrics-api}/src/main/java/org/apache/zookeeper/metrics/GaugeSet.java (100%)
 rename {zookeeper-server => zookeeper-metrics-providers/zookeeper-metrics-api}/src/main/java/org/apache/zookeeper/metrics/MetricsContext.java (100%)
 rename {zookeeper-server => zookeeper-metrics-providers/zookeeper-metrics-api}/src/main/java/org/apache/zookeeper/metrics/MetricsProvider.java (97%)
 rename {zookeeper-server => zookeeper-metrics-providers/zookeeper-metrics-api}/src/main/java/org/apache/zookeeper/metrics/MetricsProviderLifeCycleException.java (100%)
 rename {zookeeper-server => zookeeper-metrics-providers/zookeeper-metrics-api}/src/main/java/org/apache/zookeeper/metrics/Summary.java (100%)
 rename {zookeeper-server => zookeeper-metrics-providers/zookeeper-metrics-api}/src/main/java/org/apache/zookeeper/metrics/SummarySet.java (100%)
 rename {zookeeper-server => zookeeper-metrics-providers/zookeeper-metrics-api}/src/main/java/org/apache/zookeeper/server/RateLogger.java (100%)

diff --git a/zookeeper-metrics-providers/pom.xml b/zookeeper-metrics-providers/pom.xml
index 054763d003a..c5be394651f 100755
--- a/zookeeper-metrics-providers/pom.xml
+++ b/zookeeper-metrics-providers/pom.xml
@@ -33,6 +33,7 @@
 
   <modules>
     <module>zookeeper-prometheus-metrics</module>
+      <module>zookeeper-metrics-api</module>
   </modules>
 
 </project>
diff --git a/zookeeper-metrics-providers/zookeeper-metrics-api/pom.xml b/zookeeper-metrics-providers/zookeeper-metrics-api/pom.xml
new file mode 100644
index 00000000000..ceea2498bde
--- /dev/null
+++ b/zookeeper-metrics-providers/zookeeper-metrics-api/pom.xml
@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <groupId>org.apache.zookeeper</groupId>
+        <artifactId>zookeeper-metrics-providers</artifactId>
+        <version>3.10.0-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>zookeeper-metrics-api</artifactId>
+    <packaging>jar</packaging>
+    <name>Apache ZooKeeper - Metrics API</name>
+    <description>ZooKeeper Metrics API</description>
+
+    <dependencies>
+        <dependency>
+            <groupId>ch.qos.logback</groupId>
+            <artifactId>logback-core</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>ch.qos.logback</groupId>
+            <artifactId>logback-classic</artifactId>
+        </dependency>
+    </dependencies>
+
+</project>
\ No newline at end of file
diff --git a/zookeeper-server/src/main/java/org/apache/zookeeper/common/Time.java b/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/common/Time.java
similarity index 100%
rename from zookeeper-server/src/main/java/org/apache/zookeeper/common/Time.java
rename to zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/common/Time.java
diff --git a/zookeeper-server/src/main/java/org/apache/zookeeper/metrics/Counter.java b/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/Counter.java
similarity index 100%
rename from zookeeper-server/src/main/java/org/apache/zookeeper/metrics/Counter.java
rename to zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/Counter.java
diff --git a/zookeeper-server/src/main/java/org/apache/zookeeper/metrics/CounterSet.java b/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/CounterSet.java
similarity index 100%
rename from zookeeper-server/src/main/java/org/apache/zookeeper/metrics/CounterSet.java
rename to zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/CounterSet.java
diff --git a/zookeeper-server/src/main/java/org/apache/zookeeper/metrics/Gauge.java b/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/Gauge.java
similarity index 100%
rename from zookeeper-server/src/main/java/org/apache/zookeeper/metrics/Gauge.java
rename to zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/Gauge.java
diff --git a/zookeeper-server/src/main/java/org/apache/zookeeper/metrics/GaugeSet.java b/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/GaugeSet.java
similarity index 100%
rename from zookeeper-server/src/main/java/org/apache/zookeeper/metrics/GaugeSet.java
rename to zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/GaugeSet.java
diff --git a/zookeeper-server/src/main/java/org/apache/zookeeper/metrics/MetricsContext.java b/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/MetricsContext.java
similarity index 100%
rename from zookeeper-server/src/main/java/org/apache/zookeeper/metrics/MetricsContext.java
rename to zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/MetricsContext.java
diff --git a/zookeeper-server/src/main/java/org/apache/zookeeper/metrics/MetricsProvider.java b/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/MetricsProvider.java
similarity index 97%
rename from zookeeper-server/src/main/java/org/apache/zookeeper/metrics/MetricsProvider.java
rename to zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/MetricsProvider.java
index 1cc2833ada2..ef5c46747f8 100644
--- a/zookeeper-server/src/main/java/org/apache/zookeeper/metrics/MetricsProvider.java
+++ b/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/MetricsProvider.java
@@ -25,7 +25,7 @@
  * A MetricsProvider is a system which collects Metrics and publishes current values to external facilities.
  *
  * The system will create an instance of the configured class using the default constructor, which must be public.<br>
- * After the instantiation of the provider, the system will call {@link #configure(java.util.Properties) } in order to provide configuration,
+ * After the instantiation of the provider, the system will call {@link #configure(Properties) } in order to provide configuration,
  * and then when the system is ready to work it will call {@link #start() }.
  * <br>
  * Providers can be used both on ZooKeeper servers and on ZooKeeper clients.
diff --git a/zookeeper-server/src/main/java/org/apache/zookeeper/metrics/MetricsProviderLifeCycleException.java b/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/MetricsProviderLifeCycleException.java
similarity index 100%
rename from zookeeper-server/src/main/java/org/apache/zookeeper/metrics/MetricsProviderLifeCycleException.java
rename to zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/MetricsProviderLifeCycleException.java
diff --git a/zookeeper-server/src/main/java/org/apache/zookeeper/metrics/Summary.java b/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/Summary.java
similarity index 100%
rename from zookeeper-server/src/main/java/org/apache/zookeeper/metrics/Summary.java
rename to zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/Summary.java
diff --git a/zookeeper-server/src/main/java/org/apache/zookeeper/metrics/SummarySet.java b/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/SummarySet.java
similarity index 100%
rename from zookeeper-server/src/main/java/org/apache/zookeeper/metrics/SummarySet.java
rename to zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/SummarySet.java
diff --git a/zookeeper-server/src/main/java/org/apache/zookeeper/server/RateLogger.java b/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/server/RateLogger.java
similarity index 100%
rename from zookeeper-server/src/main/java/org/apache/zookeeper/server/RateLogger.java
rename to zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/server/RateLogger.java
diff --git a/zookeeper-metrics-providers/zookeeper-prometheus-metrics/pom.xml b/zookeeper-metrics-providers/zookeeper-prometheus-metrics/pom.xml
index 2d8e48656b6..9531cca66d3 100755
--- a/zookeeper-metrics-providers/zookeeper-prometheus-metrics/pom.xml
+++ b/zookeeper-metrics-providers/zookeeper-prometheus-metrics/pom.xml
@@ -37,13 +37,9 @@
   <dependencies>
     <dependency>
       <groupId>org.apache.zookeeper</groupId>
-      <!-- we can create a metrics-providers-api package
-           once we get rid of ant based build
-           https://issues.apache.org/jira/browse/ZOOKEEPER-3376
-      -->
-      <artifactId>zookeeper</artifactId>
+      <artifactId>zookeeper-metrics-api</artifactId>
       <version>${project.version}</version>
-    </dependency>    
+    </dependency>
     <dependency>
       <groupId>io.prometheus</groupId>
       <artifactId>simpleclient</artifactId>
diff --git a/zookeeper-metrics-providers/zookeeper-prometheus-metrics/src/test/java/org/apache/zookeeper/metrics/prometheus/PrometheusMetricsProviderTest.java b/zookeeper-metrics-providers/zookeeper-prometheus-metrics/src/test/java/org/apache/zookeeper/metrics/prometheus/PrometheusMetricsProviderTest.java
index eb9cf8bd2aa..c66d246f654 100644
--- a/zookeeper-metrics-providers/zookeeper-prometheus-metrics/src/test/java/org/apache/zookeeper/metrics/prometheus/PrometheusMetricsProviderTest.java
+++ b/zookeeper-metrics-providers/zookeeper-prometheus-metrics/src/test/java/org/apache/zookeeper/metrics/prometheus/PrometheusMetricsProviderTest.java
@@ -52,7 +52,6 @@
 import org.apache.zookeeper.metrics.MetricsContext;
 import org.apache.zookeeper.metrics.Summary;
 import org.apache.zookeeper.metrics.SummarySet;
-import org.apache.zookeeper.server.util.QuotaMetricsUtils;
 import org.eclipse.jetty.server.Server;
 import org.eclipse.jetty.server.ServerConnector;
 import org.hamcrest.CoreMatchers;
@@ -127,7 +126,7 @@ public void testCounters() throws Exception {
     @Test
     public void testCounterSet_single() throws Exception {
         // create and register a CounterSet
-        final String name = QuotaMetricsUtils.QUOTA_EXCEEDED_ERROR_PER_NAMESPACE;
+        final String name = "quota_exceeded_error_per_namespace";
         final CounterSet counterSet = provider.getRootContext().getCounterSet(name);
         final String[] keys = {"ns1", "ns2"};
         final int count = 3;
@@ -159,7 +158,7 @@ public void testCounterSet_single() throws Exception {
 
     @Test
     public void testCounterSet_multiple() throws Exception {
-        final String name = QuotaMetricsUtils.QUOTA_EXCEEDED_ERROR_PER_NAMESPACE;
+        final String name = "quota_exceeded_error_per_namespace";
 
         final String[] names = new String[]{name + "_1", name + "_2"};
         final String[] keys = new String[]{"ns21", "ns22"};
@@ -206,7 +205,7 @@ public void testCounterSet_registerWithNullName() {
     @Test
     public void testCounterSet_negativeValue() {
         // create and register a CounterSet
-        final String name = QuotaMetricsUtils.QUOTA_EXCEEDED_ERROR_PER_NAMESPACE;
+        final String name = "quota_exceeded_error_per_namespace";
         final CounterSet counterSet = provider.getRootContext().getCounterSet(name);
 
         // add negative value and make sure no exception is thrown
@@ -216,7 +215,7 @@ public void testCounterSet_negativeValue() {
     @Test
     public void testCounterSet_nullKey() {
         // create and register a CounterSet
-        final String name = QuotaMetricsUtils.QUOTA_EXCEEDED_ERROR_PER_NAMESPACE;
+        final String name = "quota_exceeded_error_per_namespace";
         final CounterSet counterSet = provider.getRootContext().getCounterSet(name);
 
         // increment the count with null key and make sure no exception is thrown
@@ -508,7 +507,7 @@ private String callServlet() throws ServletException, IOException {
 
     @Test
     public void testGaugeSet_singleGaugeSet() throws Exception {
-        final String name = QuotaMetricsUtils.QUOTA_BYTES_LIMIT_PER_NAMESPACE;
+        final String name = "quota_bytes_limit_per_namespace";
         final Number[] values = {10.0, 100.0};
         final String[] keys = {"ns11", "ns12"};
         final Map<String, Number> metricsMap = new HashMap<>();
@@ -553,8 +552,8 @@ public void testGaugeSet_singleGaugeSet() throws Exception {
     @Test
     public void testGaugeSet_multipleGaugeSets() throws Exception {
         final String[] names = new String[] {
-                QuotaMetricsUtils.QUOTA_COUNT_LIMIT_PER_NAMESPACE,
-                QuotaMetricsUtils.QUOTA_COUNT_USAGE_PER_NAMESPACE
+                "quota_count_limit_per_namespace",
+                "quota_count_usage_per_namespace"
         };
 
         final Number[] values = new Number[] {20.0, 200.0};
@@ -614,8 +613,8 @@ public void testGaugeSet_multipleGaugeSets() throws Exception {
     @Test
     public void testGaugeSet_overwriteRegister() {
         final String[] names = new String[] {
-                QuotaMetricsUtils.QUOTA_COUNT_LIMIT_PER_NAMESPACE,
-                QuotaMetricsUtils.QUOTA_COUNT_USAGE_PER_NAMESPACE
+                "quota_count_limit_per_namespace",
+                "quota_count_usage_per_namespace"
         };
 
         final int count = names.length;
@@ -642,7 +641,7 @@ public void testGaugeSet_overwriteRegister() {
 
     @Test
     public void testGaugeSet_nullKey() {
-        final String name = QuotaMetricsUtils.QUOTA_COUNT_LIMIT_PER_NAMESPACE;
+        final String name = "quota_count_limit_per_namespace";
         final Map<String, Number> metricsMap = new HashMap<>();
         metricsMap.put(null, 10.0);
 
diff --git a/zookeeper-server/pom.xml b/zookeeper-server/pom.xml
index 00a3b533949..d719f17f2c9 100755
--- a/zookeeper-server/pom.xml
+++ b/zookeeper-server/pom.xml
@@ -32,6 +32,11 @@
   <description>ZooKeeper server</description>
 
   <dependencies>
+    <dependency>
+      <groupId>org.apache.zookeeper</groupId>
+      <artifactId>zookeeper-metrics-api</artifactId>
+      <version>${project.version}</version>
+    </dependency>
     <dependency>
       <groupId>com.github.spotbugs</groupId>
       <artifactId>spotbugs-annotations</artifactId>

From 3884ca25ec74d614d02de58ea6facd58a9fd9f60 Mon Sep 17 00:00:00 2001
From: horizonzy <horizonzy@apache.org>
Date: Fri, 18 Aug 2023 02:39:59 +0800
Subject: [PATCH 2/6] code clean.

---
 .../main/java/org/apache/zookeeper/metrics/MetricsProvider.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/MetricsProvider.java b/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/MetricsProvider.java
index ef5c46747f8..1cc2833ada2 100644
--- a/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/MetricsProvider.java
+++ b/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/MetricsProvider.java
@@ -25,7 +25,7 @@
  * A MetricsProvider is a system which collects Metrics and publishes current values to external facilities.
  *
  * The system will create an instance of the configured class using the default constructor, which must be public.<br>
- * After the instantiation of the provider, the system will call {@link #configure(Properties) } in order to provide configuration,
+ * After the instantiation of the provider, the system will call {@link #configure(java.util.Properties) } in order to provide configuration,
  * and then when the system is ready to work it will call {@link #start() }.
  * <br>
  * Providers can be used both on ZooKeeper servers and on ZooKeeper clients.

From bd2f6ec97615a9f7c8d9bf5ac1625e8d21e5021b Mon Sep 17 00:00:00 2001
From: horizonzy <horizonzy@apache.org>
Date: Fri, 18 Aug 2023 02:54:58 +0800
Subject: [PATCH 3/6] Fix ci.

---
 .../zookeeper-metrics-api/pom.xml             | 63 ++++++++++++-------
 1 file changed, 40 insertions(+), 23 deletions(-)

diff --git a/zookeeper-metrics-providers/zookeeper-metrics-api/pom.xml b/zookeeper-metrics-providers/zookeeper-metrics-api/pom.xml
index ceea2498bde..f5fe309a6a8 100644
--- a/zookeeper-metrics-providers/zookeeper-metrics-api/pom.xml
+++ b/zookeeper-metrics-providers/zookeeper-metrics-api/pom.xml
@@ -1,28 +1,45 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0"
-         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
-    <modelVersion>4.0.0</modelVersion>
-    <parent>
-        <groupId>org.apache.zookeeper</groupId>
-        <artifactId>zookeeper-metrics-providers</artifactId>
-        <version>3.10.0-SNAPSHOT</version>
-    </parent>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+  <!--
+  /**
+   * Licensed to the Apache Software Foundation (ASF) under one
+   * or more contributor license agreements.  See the NOTICE file
+   * distributed with this work for additional information
+   * regarding copyright ownership.  The ASF licenses this file
+   * to you under the Apache License, Version 2.0 (the
+   * "License"); you may not use this file except in compliance
+   * with the License.  You may obtain a copy of the License at
+   *
+   *     http://www.apache.org/licenses/LICENSE-2.0
+   *
+   * Unless required by applicable law or agreed to in writing, software
+   * distributed under the License is distributed on an "AS IS" BASIS,
+   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   * See the License for the specific language governing permissions and
+   * limitations under the License.
+   */
+  -->
+  <modelVersion>4.0.0</modelVersion>
+  <parent>
+      <groupId>org.apache.zookeeper</groupId>
+      <artifactId>zookeeper-metrics-providers</artifactId>
+      <version>3.10.0-SNAPSHOT</version>
+  </parent>
 
-    <artifactId>zookeeper-metrics-api</artifactId>
-    <packaging>jar</packaging>
-    <name>Apache ZooKeeper - Metrics API</name>
-    <description>ZooKeeper Metrics API</description>
+  <artifactId>zookeeper-metrics-api</artifactId>
+  <packaging>jar</packaging>
+  <name>Apache ZooKeeper - Metrics API</name>
+  <description>ZooKeeper Metrics API</description>
 
-    <dependencies>
-        <dependency>
-            <groupId>ch.qos.logback</groupId>
-            <artifactId>logback-core</artifactId>
-        </dependency>
-        <dependency>
-            <groupId>ch.qos.logback</groupId>
-            <artifactId>logback-classic</artifactId>
-        </dependency>
-    </dependencies>
+  <dependencies>
+      <dependency>
+          <groupId>ch.qos.logback</groupId>
+          <artifactId>logback-core</artifactId>
+      </dependency>
+      <dependency>
+          <groupId>ch.qos.logback</groupId>
+          <artifactId>logback-classic</artifactId>
+      </dependency>
+  </dependencies>
 
 </project>
\ No newline at end of file

From 0f4d718fdcb64c68e683fdcbaadf0f72bb2be839 Mon Sep 17 00:00:00 2001
From: horizonzy <horizonzy@apache.org>
Date: Fri, 18 Aug 2023 11:25:28 +0800
Subject: [PATCH 4/6] Fix checkstyle.

---
 .../org/apache/zookeeper/metrics/CounterSet.java   |  3 +--
 .../org/apache/zookeeper/metrics/GaugeSet.java     |  1 -
 .../apache/zookeeper/metrics/MetricsProvider.java  |  5 ++---
 .../org/apache/zookeeper/server/RateLogger.java    | 14 +++++++-------
 4 files changed, 10 insertions(+), 13 deletions(-)

diff --git a/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/CounterSet.java b/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/CounterSet.java
index c9c7c13c489..be512652870 100644
--- a/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/CounterSet.java
+++ b/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/CounterSet.java
@@ -21,8 +21,7 @@
 /**
  * A counter refers to a value which can only increase.
  * Usually the value is reset when the process starts.
- *
- *  A CounterSet is a set of {@link Counter} grouped by keys.
+ * A CounterSet is a set of {@link Counter} grouped by keys.
  */
 
 public interface CounterSet {
diff --git a/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/GaugeSet.java b/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/GaugeSet.java
index 15fd93f3c39..60daa0a8aa2 100644
--- a/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/GaugeSet.java
+++ b/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/GaugeSet.java
@@ -22,7 +22,6 @@
 
 /**
  * A Gauge is an application provided object which will be called by the metrics framework to sample a numeric value.
- *
  * A GaugeSet is a set of {@link Gauge} grouped by keys.
  */
 public interface GaugeSet {
diff --git a/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/MetricsProvider.java b/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/MetricsProvider.java
index 1cc2833ada2..eb4b20d4fb4 100644
--- a/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/MetricsProvider.java
+++ b/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/MetricsProvider.java
@@ -23,10 +23,9 @@
 
 /**
  * A MetricsProvider is a system which collects Metrics and publishes current values to external facilities.
- *
  * The system will create an instance of the configured class using the default constructor, which must be public.<br>
- * After the instantiation of the provider, the system will call {@link #configure(java.util.Properties) } in order to provide configuration,
- * and then when the system is ready to work it will call {@link #start() }.
+ * After the instantiation of the provider, the system will call {@link #configure(java.util.Properties) } in order
+ * to provide configuration, and then when the system is ready to work it will call {@link #start() }.
  * <br>
  * Providers can be used both on ZooKeeper servers and on ZooKeeper clients.
  */
diff --git a/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/server/RateLogger.java b/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/server/RateLogger.java
index 21e41b4fbba..32463ef70fa 100644
--- a/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/server/RateLogger.java
+++ b/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/server/RateLogger.java
@@ -27,18 +27,18 @@
  */
 public class RateLogger {
 
-    private final long LOG_INTERVAL; // Duration is in ms
+    private final long interval; // Duration is in ms
 
     public RateLogger(Logger log) {
         this(log, 100);
     }
 
     public RateLogger(Logger log, long interval) {
-        LOG = log;
-        LOG_INTERVAL = interval;
+        this.log = log;
+        this.interval = interval;
     }
 
-    private final Logger LOG;
+    private final Logger log;
     private String msg = null;
     private long timestamp;
     private int count = 0;
@@ -54,7 +54,7 @@ public void flush() {
             if (value != null) {
                 log += " Last value:" + value;
             }
-            LOG.warn(log);
+            this.log.warn(log);
         }
         msg = null;
         value = null;
@@ -73,7 +73,7 @@ public void rateLimitLog(String newMsg, String newValue) {
         if (Objects.equals(newMsg, msg)) {
             ++count;
             value = newValue;
-            if (now - timestamp >= LOG_INTERVAL) {
+            if (now - timestamp >= interval) {
                 flush();
                 msg = newMsg;
                 timestamp = now;
@@ -84,7 +84,7 @@ public void rateLimitLog(String newMsg, String newValue) {
             msg = newMsg;
             value = newValue;
             timestamp = now;
-            LOG.warn("Message:{} Value:{}", msg, value);
+            log.warn("Message:{} Value:{}", msg, value);
         }
     }
 

From a819d31fd39634bd2b1db795fac55208660614f6 Mon Sep 17 00:00:00 2001
From: horizonzy <horizonzy@apache.org>
Date: Fri, 18 Aug 2023 11:28:25 +0800
Subject: [PATCH 5/6] Fix checkstyle.

---
 .../java/org/apache/zookeeper/metrics/MetricsContext.java    | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/MetricsContext.java b/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/MetricsContext.java
index 18ff1180cf7..f70f0af9d69 100644
--- a/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/MetricsContext.java
+++ b/zookeeper-metrics-providers/zookeeper-metrics-api/src/main/java/org/apache/zookeeper/metrics/MetricsContext.java
@@ -52,7 +52,7 @@ public interface MetricsContext {
 
     /**
      * Returns the CounterSet identified by the given name
-     * Null name is not allowed
+     * Null name is not allowed.
      *
      * @param name
      * @return CounterSet identified by the name in this context.
@@ -94,7 +94,6 @@ public interface MetricsContext {
 
     /**
      * Unregisters the user provided {@link GaugeSet} bound to the given name.
-     *
      * Unregistering with a null name is not allowed.
      * @param name unique name of the GaugeSet in this context
      *
@@ -104,7 +103,7 @@ public interface MetricsContext {
     enum DetailLevel {
         /**
          * The returned Summary is expected to track only simple aggregated
-         * values, like min/max/avg
+         * values, like min/max/avg.
          */
         BASIC,
         /**

From 873a35f5a81045c0afa51be8e0a23cb9064493d2 Mon Sep 17 00:00:00 2001
From: horizonzy <horizonzy@apache.org>
Date: Fri, 18 Aug 2023 22:50:35 +0800
Subject: [PATCH 6/6] Address the comments.

---
 zookeeper-metrics-providers/zookeeper-metrics-api/pom.xml | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/zookeeper-metrics-providers/zookeeper-metrics-api/pom.xml b/zookeeper-metrics-providers/zookeeper-metrics-api/pom.xml
index f5fe309a6a8..b47fcede502 100644
--- a/zookeeper-metrics-providers/zookeeper-metrics-api/pom.xml
+++ b/zookeeper-metrics-providers/zookeeper-metrics-api/pom.xml
@@ -33,12 +33,8 @@
 
   <dependencies>
       <dependency>
-          <groupId>ch.qos.logback</groupId>
-          <artifactId>logback-core</artifactId>
-      </dependency>
-      <dependency>
-          <groupId>ch.qos.logback</groupId>
-          <artifactId>logback-classic</artifactId>
+          <groupId>org.slf4j</groupId>
+          <artifactId>slf4j-api</artifactId>
       </dependency>
   </dependencies>