Adapt metrics to Gerrit master API

Gerrit master metrics API have changed and require a different
syntax when creating counters. Reduce also the copy&paste of
the boilerplate across metrics classes.

Change-Id: I14e1ea0d63f57b43e41f3a1d26c8198914de76dd
diff --git a/src/main/java/com/googlesource/gerrit/plugins/multisite/MultiSiteMetrics.java b/src/main/java/com/googlesource/gerrit/plugins/multisite/MultiSiteMetrics.java
new file mode 100644
index 0000000..fbe1152
--- /dev/null
+++ b/src/main/java/com/googlesource/gerrit/plugins/multisite/MultiSiteMetrics.java
@@ -0,0 +1,35 @@
+// Copyright (C) 2019 The Android Open Source Project
+//
+// Licensed 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.
+
+package com.googlesource.gerrit.plugins.multisite;
+
+import com.google.gerrit.metrics.Description;
+import com.google.gerrit.metrics.Field;
+import com.google.gerrit.server.logging.PluginMetadata;
+
+public abstract class MultiSiteMetrics {
+
+  public Field<String> stringField(String metadataKey, String description) {
+    return Field.ofString(
+            metadataKey,
+            (metadataBuilder, fieldValue) ->
+                metadataBuilder.addPluginMetadata(PluginMetadata.create(metadataKey, fieldValue)))
+        .description(description)
+        .build();
+  }
+
+  public Description rateDescription(String unit, String description) {
+    return new Description(description).setRate().setUnit(unit);
+  }
+}
diff --git a/src/main/java/com/googlesource/gerrit/plugins/multisite/broker/BrokerMetrics.java b/src/main/java/com/googlesource/gerrit/plugins/multisite/broker/BrokerMetrics.java
index 3f8aa8d..1d9f46d 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/multisite/broker/BrokerMetrics.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/multisite/broker/BrokerMetrics.java
@@ -15,14 +15,13 @@
 package com.googlesource.gerrit.plugins.multisite.broker;
 
 import com.google.gerrit.metrics.Counter1;
-import com.google.gerrit.metrics.Description;
-import com.google.gerrit.metrics.Field;
 import com.google.gerrit.metrics.MetricMaker;
 import com.google.inject.Inject;
 import com.google.inject.Singleton;
+import com.googlesource.gerrit.plugins.multisite.MultiSiteMetrics;
 
 @Singleton
-public class BrokerMetrics {
+public class BrokerMetrics extends MultiSiteMetrics {
   private static final String PUBLISHER_SUCCESS_COUNTER = "broker_msg_publisher_counter";
   private static final String PUBLISHER_FAILURE_COUNTER = "broker_msg_publisher_failure_counter";
 
@@ -35,21 +34,15 @@
     this.brokerPublisherSuccessCounter =
         metricMaker.newCounter(
             "multi_site/broker/broker_message_publisher_counter",
-            new Description("Number of messages published by the broker publisher")
-                .setRate()
-                .setUnit("messages"),
-            Field.ofString(PUBLISHER_SUCCESS_COUNTER)
-                .description("Broker message published count")
-                .build());
+            rateDescription("messages", "Number of messages published by the broker publisher"),
+            stringField(PUBLISHER_SUCCESS_COUNTER, "Broker message published count"));
+
     this.brokerPublisherFailureCounter =
         metricMaker.newCounter(
             "multi_site/broker/broker_message_publisher_failure_counter",
-            new Description("Number of messages failed to publish by the broker publisher")
-                .setRate()
-                .setUnit("errors"),
-            Field.ofString(PUBLISHER_FAILURE_COUNTER)
-                .description("Broker failed to publish message count")
-                .build());
+            rateDescription(
+                "errors", "Number of messages failed to publish by the broker publisher"),
+            stringField(PUBLISHER_FAILURE_COUNTER, "Broker failed to publish message count"));
   }
 
   public void incrementBrokerPublishedMessage() {
diff --git a/src/main/java/com/googlesource/gerrit/plugins/multisite/validation/ValidationMetrics.java b/src/main/java/com/googlesource/gerrit/plugins/multisite/validation/ValidationMetrics.java
index 7f5c637..cd2129a 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/multisite/validation/ValidationMetrics.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/multisite/validation/ValidationMetrics.java
@@ -15,14 +15,13 @@
 package com.googlesource.gerrit.plugins.multisite.validation;
 
 import com.google.gerrit.metrics.Counter1;
-import com.google.gerrit.metrics.Description;
-import com.google.gerrit.metrics.Field;
 import com.google.gerrit.metrics.MetricMaker;
 import com.google.inject.Inject;
 import com.google.inject.Singleton;
+import com.googlesource.gerrit.plugins.multisite.MultiSiteMetrics;
 
 @Singleton
-public class ValidationMetrics {
+public class ValidationMetrics extends MultiSiteMetrics {
   private static final String GIT_UPDATE_SPLIT_BRAIN_PREVENTED = "git_update_split_brain_prevented";
   private static final String GIT_UPDATE_SPLIT_BRAIN = "git_update_split_brain";
 
@@ -34,18 +33,18 @@
     this.splitBrainPreventionCounter =
         metricMaker.newCounter(
             "multi_site/validation/git_update_split_brain_prevented",
-            new Description("Rate of REST API error responses").setRate().setUnit("errors"),
-            Field.ofString(GIT_UPDATE_SPLIT_BRAIN_PREVENTED)
-                .description("Ref-update operations, split-brain detected and prevented")
-                .build());
+            rateDescription("errors", "Rate of REST API error responses"),
+            stringField(
+                GIT_UPDATE_SPLIT_BRAIN_PREVENTED,
+                "Ref-update operations, split-brain detected and prevented"));
 
     this.splitBrainCounter =
         metricMaker.newCounter(
             "multi_site/validation/git_update_split_brain",
-            new Description("Rate of REST API error responses").setRate().setUnit("errors"),
-            Field.ofString(GIT_UPDATE_SPLIT_BRAIN)
-                .description("Ref-update operation left node in a split-brain scenario")
-                .build());
+            rateDescription("errors", "Rate of REST API error responses"),
+            stringField(
+                GIT_UPDATE_SPLIT_BRAIN,
+                "Ref-update operation left node in a split-brain scenario"));
   }
 
   public void incrementSplitBrainPrevention() {