Add metrics for hook execution - Execution latency - Execution count - Error count - Timeout count Change-Id: I7ed95e08608b436ab533929322f951e85a45b7f9

diff --git a/src/main/java/com/googlesource/gerrit/plugins/hooks/HookArgs.java b/src/main/java/com/googlesource/gerrit/plugins/hooks/HookArgs.java
index 7797e05..f68395c 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/hooks/HookArgs.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/hooks/HookArgs.java

@@ -30,14 +30,21 @@
 class HookArgs {
   private final String anonymousCowardName;
   private final Provider<String> urlProvider;
+  private final HookMetrics metrics;
   private final List<String> args;
 
-  HookArgs(String anonymousCowardName, Provider<String> urlProvider) {
+  HookArgs(String anonymousCowardName, Provider<String> urlProvider,
+      HookMetrics metrics) {
     this.anonymousCowardName = anonymousCowardName;
     this.urlProvider = urlProvider;
+    this.metrics = metrics;
     this.args = new ArrayList<>();
   }
 
+  public HookMetrics metrics() {
+    return metrics;
+  }
+
   public ImmutableList<String> get() {
     return ImmutableList.copyOf(args);
   }

diff --git a/src/main/java/com/googlesource/gerrit/plugins/hooks/HookFactory.java b/src/main/java/com/googlesource/gerrit/plugins/hooks/HookFactory.java
index 3ec1d8c..61207b8 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/hooks/HookFactory.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/hooks/HookFactory.java

@@ -36,6 +36,7 @@
   private final HookExecutor syncHookExecutor;
   private final Config config;
   private final String anonymousCowardName;
+  private final HookMetrics metrics;
   private final Provider<String> urlProvider;
   private final Path hooksPath;
 
@@ -45,11 +46,13 @@
       @GerritServerConfig Config config,
       @AnonymousCowardName String anonymousCowardName,
       @CanonicalWebUrl @Nullable Provider<String> urlProvider,
+      HookMetrics metrics,
       SitePaths sitePaths) {
     this.queue = queue;
     this.syncHookExecutor = syncHookExecutor;
     this.config = config;
     this.anonymousCowardName = anonymousCowardName;
+    this.metrics = metrics;
     this.urlProvider = urlProvider;
 
     String v = config.getString("hooks", null, "path");
@@ -75,6 +78,6 @@
   }
 
   public HookArgs createArgs() {
-    return new HookArgs(anonymousCowardName, urlProvider);
+    return new HookArgs(anonymousCowardName, urlProvider, metrics);
   }
 }

diff --git a/src/main/java/com/googlesource/gerrit/plugins/hooks/HookMetrics.java b/src/main/java/com/googlesource/gerrit/plugins/hooks/HookMetrics.java
new file mode 100644
index 0000000..066def0
--- /dev/null
+++ b/src/main/java/com/googlesource/gerrit/plugins/hooks/HookMetrics.java

@@ -0,0 +1,69 @@
+// Copyright (C) 2017 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.hooks;
+
+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.Timer1;
+import com.google.inject.Inject;
+import com.google.inject.Singleton;
+
+@Singleton
+public class HookMetrics {
+  private final Timer1<String> latency;
+  private final Counter1<String> count;
+  private final Counter1<String> error;
+  private final Counter1<String> timeout;
+
+  @Inject
+  HookMetrics(MetricMaker metricMaker) {
+    Field<String> field = Field.ofString("hook");
+    latency = metricMaker.newTimer("latency",
+        new Description("Time spent executing a hook")
+          .setCumulative()
+          .setUnit(Description.Units.MILLISECONDS),
+        field);
+    count = metricMaker.newCounter("count",
+        new Description("Hook executions")
+          .setRate(),
+        field);
+    error = metricMaker.newCounter("error",
+        new Description("Hook execution errors")
+          .setRate(),
+        field);
+    timeout = metricMaker.newCounter("timeout",
+        new Description("Hook execution timeouts")
+          .setRate(),
+        field);
+  }
+
+  public Timer1.Context start(String name) {
+    return latency.start(name);
+  }
+
+  public void count(String name) {
+    count.increment(name);
+  }
+
+  public void error(String name) {
+    error.increment(name);
+  }
+
+  public void timeout(String name) {
+    timeout.increment(name);
+  }
+}

diff --git a/src/main/java/com/googlesource/gerrit/plugins/hooks/HookTask.java b/src/main/java/com/googlesource/gerrit/plugins/hooks/HookTask.java
index f722034..6e87d3d 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/hooks/HookTask.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/hooks/HookTask.java

@@ -17,6 +17,7 @@
 import static java.nio.charset.StandardCharsets.UTF_8;
 
 import com.google.common.io.ByteStreams;
+import com.google.gerrit.metrics.Timer1;
 import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.server.git.GitRepositoryManager;
 
@@ -42,6 +43,7 @@
   private final String projectName;
   private final Path hook;
   private final List<String> args;
+  private final HookMetrics metrics;
   private StringWriter output;
   private Process ps;
 
@@ -79,6 +81,7 @@
     this.projectName = projectName;
     this.hook = hook;
     this.args = args.get();
+    this.metrics = args.metrics();
   }
 
   public void cancel() {
@@ -95,7 +98,9 @@
 
   public HookResult runHook() {
     HookResult result = null;
-    try {
+    String name = getName();
+    try (Timer1.Context timer = metrics.start(name)) {
+      metrics.count(name);
       List<String> argv = new ArrayList<>(1 + args.size());
       argv.add(hook.toAbsolutePath().toString());
       argv.addAll(args);
@@ -122,7 +127,9 @@
       result = new HookResult(ps.exitValue(), output);
     } catch (InterruptedException iex) {
       // InterruptedException - timeout or cancel
+      metrics.timeout(name);
     } catch (Throwable err) {
+      metrics.error(name);
       log.error("Error running hook " + hook.toAbsolutePath(), err);
     }