ZOOKEEPER-3376: Extract metrics-api module.

zookeeper-metrics-providers/pom.xml

@@ -33,6 +33,7 @@
 
   <modules>
     <module>zookeeper-prometheus-metrics</module>
+      <module>zookeeper-metrics-api</module>
   </modules>
 
 </project>

zookeeper-metrics-providers/zookeeper-metrics-api/pom.xml

@@ -0,0 +1,41 @@
+<?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/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>
+
+  <dependencies>
+      <dependency>
+          <groupId>org.slf4j</groupId>
+          <artifactId>slf4j-api</artifactId>
+      </dependency>
+  </dependencies>
+
+</project>

zookeeper-server/src/main/java/org/apache/zookeeper/metrics/CounterSet.java → 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 {

zookeeper-server/src/main/java/org/apache/zookeeper/metrics/GaugeSet.java → 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 {

zookeeper-server/src/main/java/org/apache/zookeeper/metrics/MetricsContext.java → 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,
         /**

zookeeper-server/src/main/java/org/apache/zookeeper/metrics/MetricsProvider.java → 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.
  */

zookeeper-server/src/main/java/org/apache/zookeeper/server/RateLogger.java → 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);
         }
     }
 

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>

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);
 

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>