Add EPP metrics to flows

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=132591518

java/google/registry/flows/EppMetrics.java

@@ -0,0 +1,72 @@
+// Copyright 2016 The Domain Registry Authors. All Rights Reserved.
+//
+// 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 google.registry.flows;
+
+import com.google.common.collect.ImmutableSet;
+import google.registry.monitoring.metrics.EventMetric;
+import google.registry.monitoring.metrics.IncrementableMetric;
+import google.registry.monitoring.metrics.LabelDescriptor;
+import google.registry.monitoring.metrics.MetricRegistryImpl;
+import google.registry.monitoring.whitebox.EppMetric;
+import javax.inject.Inject;
+
+/** EPP Instrumentation. */
+public class EppMetrics {
+
+  private static final ImmutableSet<LabelDescriptor> LABEL_DESCRIPTORS =
+      ImmutableSet.of(
+          LabelDescriptor.create("command", "The name of the command."),
+          LabelDescriptor.create("client_id", "The name of the client."),
+          LabelDescriptor.create("status", "The return status of the command."));
+
+  private static final IncrementableMetric eppRequests =
+      MetricRegistryImpl.getDefault()
+          .newIncrementableMetric(
+              "/epp/requests", "Count of EPP Requests", "count", LABEL_DESCRIPTORS);
+
+  private static final EventMetric processingTime =
+      MetricRegistryImpl.getDefault()
+          .newEventMetric(
+              "/epp/processing_time",
+              "EPP Processing Time",
+              "milliseconds",
+              LABEL_DESCRIPTORS,
+              EventMetric.DEFAULT_FITTER);
+
+  @Inject
+  public EppMetrics() {}
+
+  /**
+   * Increment a counter which tracks EPP requests.
+   *
+   * @see EppController
+   * @see FlowRunner
+   */
+  public void incrementEppRequests(EppMetric metric) {
+    eppRequests.increment(
+        metric.getCommandName().or(""),
+        metric.getClientId().or(""),
+        metric.getStatus().isPresent() ? metric.getStatus().toString() : "");
+  }
+
+  /** Record the server-side processing time for an EPP request. */
+  public void recordProcessingTime(EppMetric metric) {
+    processingTime.record(
+        metric.getEndTimestamp().getMillis() - metric.getStartTimestamp().getMillis(),
+        metric.getCommandName().or(""),
+        metric.getClientId().or(""),
+        metric.getStatus().isPresent() ? metric.getStatus().toString() : "");
+  }
+}