Test DropWizard MetricMaker glue

Simple test cases to verify the MetricMaker glues onto DropWizard as
expected.  Here we mostly assume DropWizard works as advertised and
does not itself need to be heavily tested.

Change-Id: I9f8286386e15a9f6d3eba6dc211b5bbf3669ff3f

gerrit-pgm/src/main/java/com/google/gerrit/pgm/Daemon.java

@@ -325,7 +325,8 @@ public class Daemon extends SiteProgram {
   private Injector createSysInjector() {
     final List<Module> modules = new ArrayList<>();
     modules.add(SchemaVersionCheck.module());
-    modules.add(new DropWizardMetricMaker.Module());
+    modules.add(new DropWizardMetricMaker.ApiModule());
+    modules.add(new DropWizardMetricMaker.RestModule());
     modules.add(new LogFileCompressor.Module());
     modules.add(new WorkQueue.Module());
     modules.add(new ChangeHookRunner.Module());

gerrit-server/BUCK

@@ -195,6 +195,7 @@ java_test(
     '//lib:args4j',
     '//lib:grappa',
     '//lib:guava',
+    '//lib/dropwizard:dropwizard-core',
     '//lib/guice:guice-assistedinject',
     '//lib/joda:joda-time',
     '//lib/prolog:runtime',

gerrit-server/src/main/java/com/google/gerrit/metrics/dropwizard/DropWizardMetricMaker.java

@@ -60,7 +60,7 @@ import java.util.concurrent.TimeUnit;
  */
 @Singleton
 public class DropWizardMetricMaker extends MetricMaker {
-  public static class Module extends RestApiModule {
+  public static class ApiModule extends RestApiModule {
     @Override
     protected void configure() {
       bind(MetricRegistry.class).in(Scopes.SINGLETON);
@@ -69,7 +69,12 @@ public class DropWizardMetricMaker extends MetricMaker {
 
       install(new ProcMetricModule());
       install(new JGitMetricModule());
+    }
+  }
 
+  public static class RestModule extends RestApiModule {
+    @Override
+    protected void configure() {
       DynamicMap.mapOf(binder(), METRIC_KIND);
       child(CONFIG_KIND, "metrics").to(MetricsCollection.class);
       get(METRIC_KIND).to(GetMetric.class);

gerrit-server/src/test/java/com/google/gerrit/metrics/proc/ProcMetricModuleTest.java

@@ -0,0 +1,159 @@
+// Copyright (C) 2015 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.google.gerrit.metrics.proc;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.gerrit.common.Version;
+import com.google.gerrit.lifecycle.LifecycleManager;
+import com.google.gerrit.metrics.CallbackMetric0;
+import com.google.gerrit.metrics.Counter0;
+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.gerrit.metrics.dropwizard.DropWizardMetricMaker;
+import com.google.inject.Guice;
+import com.google.inject.Inject;
+import com.google.inject.Injector;
+
+import com.codahale.metrics.Counter;
+import com.codahale.metrics.Gauge;
+import com.codahale.metrics.Metric;
+import com.codahale.metrics.MetricRegistry;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
+
+public class ProcMetricModuleTest {
+  @Inject
+  MetricMaker metrics;
+
+  @Inject
+  MetricRegistry registry;
+
+  @Test
+  public void testConstantBuildLabel() {
+    Gauge<String> buildLabel = gauge("build/label");
+    assertThat(buildLabel.getValue()).isEqualTo(Version.getVersion());
+  }
+
+  @Test
+  public void testProcUptime() {
+    Gauge<Long> birth = gauge("proc/birth_timestamp");
+    assertThat(birth.getValue()).isLessThan(
+        TimeUnit.MILLISECONDS.toMicros(System.currentTimeMillis()));
+
+    Gauge<Long> uptime = gauge("proc/uptime");
+    assertThat(uptime.getValue()).isAtLeast(1L);
+  }
+
+  @Test
+  public void testCounter0() {
+    Counter0 cntr = metrics.newCounter(
+        "test/count",
+        new Description("simple test")
+          .setCumulative());
+
+    Counter raw = get("test/count", Counter.class);
+    assertThat(raw.getCount()).isEqualTo(0);
+
+    cntr.increment();
+    assertThat(raw.getCount()).isEqualTo(1);
+
+    cntr.incrementBy(5);
+    assertThat(raw.getCount()).isEqualTo(6);
+  }
+
+  @Test
+  public void testCounter1() {
+    Counter1<String> cntr = metrics.newCounter(
+        "test/count",
+        new Description("simple test")
+          .setCumulative(),
+        Field.ofString("action"));
+
+    Counter total = get("test/count_total", Counter.class);
+    assertThat(total.getCount()).isEqualTo(0);
+
+    cntr.increment("passed");
+    Counter passed = get("test/count/passed", Counter.class);
+    assertThat(total.getCount()).isEqualTo(1);
+    assertThat(passed.getCount()).isEqualTo(1);
+
+    cntr.incrementBy("failed", 5);
+    Counter failed = get("test/count/failed", Counter.class);
+    assertThat(total.getCount()).isEqualTo(6);
+    assertThat(passed.getCount()).isEqualTo(1);
+    assertThat(failed.getCount()).isEqualTo(5);
+  }
+
+  @Test
+  public void testCallbackMetric0() {
+    final CallbackMetric0<Long> cntr = metrics.newCallbackMetric(
+        "test/count",
+        Long.class,
+        new Description("simple test")
+          .setCumulative());
+
+    final AtomicInteger invocations = new AtomicInteger(0);
+    metrics.newTrigger(cntr, new Runnable() {
+      @Override
+      public void run() {
+        invocations.getAndIncrement();
+        cntr.set(42L);
+      }
+    });
+
+    // Triggers run immediately with DropWizard binding.
+    assertThat(invocations.get()).isEqualTo(1);
+
+    Gauge<Long> raw = gauge("test/count");
+    assertThat(raw.getValue()).isEqualTo(42);
+
+    // Triggers are debounced to avoid being fired too frequently.
+    assertThat(invocations.get()).isEqualTo(1);
+  }
+
+  @SuppressWarnings({"unchecked", "cast"})
+  private <V> Gauge<V> gauge(String name) {
+    return (Gauge<V>) get(name, Gauge.class);
+  }
+
+  private <M extends Metric> M get(String name, Class<M> type) {
+    Metric m = registry.getMetrics().get(name);
+    assertThat(m).named(name).isNotNull();
+    assertThat(m).named(name).isInstanceOf(type);
+
+    @SuppressWarnings("unchecked")
+    M result = (M) m;
+    return result;
+  }
+
+  @Before
+  public void setup() {
+    Injector injector =
+        Guice.createInjector(new DropWizardMetricMaker.ApiModule());
+
+    LifecycleManager mgr = new LifecycleManager();
+    mgr.add(injector);
+    mgr.start();
+
+    injector.injectMembers(this);
+  }
+}

gerrit-war/src/main/java/com/google/gerrit/httpd/WebAppInitializer.java

@@ -289,7 +289,8 @@ public class WebAppInitializer extends GuiceServletContextListener
 
   private Injector createSysInjector() {
     final List<Module> modules = new ArrayList<>();
-    modules.add(new DropWizardMetricMaker.Module());
+    modules.add(new DropWizardMetricMaker.ApiModule());
+    modules.add(new DropWizardMetricMaker.RestModule());
     modules.add(new WorkQueue.Module());
     modules.add(new ChangeHookRunner.Module());
     modules.add(new ReceiveCommitsExecutorModule());