Add metrics for NoteDb auto-rebuilding

Change-Id: Ia39ec6da3a7a984d5b311164418b548853cd71f2

gerrit-server/src/main/java/com/google/gerrit/server/notedb/ChangeNotes.java

@@ -18,6 +18,7 @@ import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkState;
 import static com.google.gerrit.reviewdb.client.RefNames.changeMetaRef;
+import static com.google.gerrit.server.notedb.NoteDbTable.CHANGES;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Function;
@@ -40,6 +41,7 @@ import com.google.common.util.concurrent.ListenableFuture;
 import com.google.common.util.concurrent.ListeningExecutorService;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.common.data.SubmitRecord;
+import com.google.gerrit.metrics.Timer1;
 import com.google.gerrit.reviewdb.client.Account;
 import com.google.gerrit.reviewdb.client.Change;
 import com.google.gerrit.reviewdb.client.ChangeMessage;
@@ -593,10 +595,11 @@ public class ChangeNotes extends AbstractChangeNotes<ChangeNotes> {
 
   private LoadHandle rebuildAndOpen(Repository repo, ObjectId oldId)
       throws IOException {
+    try (Timer1.Context timer =
+        args.metrics.autoRebuildLatency.start(CHANGES)) {
       Change.Id cid = getChangeId();
       ReviewDb db = args.db.get();
       ChangeRebuilder rebuilder = args.rebuilder.get();
-    try {
       NoteDbUpdateManager manager = rebuilder.stage(db, cid);
       if (manager == null) {
         return super.openHandle(repo, oldId); // May be null in tests.
@@ -615,6 +618,7 @@ public class ChangeNotes extends AbstractChangeNotes<ChangeNotes> {
         //
         // Parse notes from the staged result so we can return something useful
         // to the caller instead of throwing.
+        args.metrics.autoRebuildFailureCount.increment(CHANGES);
         rebuildResult = checkNotNull(r);
         checkNotNull(r.newState());
         checkNotNull(r.staged());

gerrit-server/src/main/java/com/google/gerrit/server/notedb/NoteDbMetrics.java

@@ -14,6 +14,7 @@
 
 package com.google.gerrit.server.notedb;
 
+import com.google.gerrit.metrics.Counter1;
 import com.google.gerrit.metrics.Description;
 import com.google.gerrit.metrics.Description.Units;
 import com.google.gerrit.metrics.Field;
@@ -47,6 +48,17 @@ class NoteDbMetrics {
    */
   final Timer1<NoteDbTable> parseLatency;
 
+  /**
+   * Latency due to auto-rebuilding entities when out of date.
+   * <p>
+   * Excludes latency from reading ref to check whether the entity is up to
+   * date.
+   */
+  final Timer1<NoteDbTable> autoRebuildLatency;
+
+  /** Count of auto-rebuild attempts that failed. */
+  final Counter1<NoteDbTable> autoRebuildFailureCount;
+
   @Inject
   NoteDbMetrics(MetricMaker metrics) {
     Field<NoteDbTable> view = Field.ofEnum(NoteDbTable.class, "table");
@@ -78,5 +90,18 @@ class NoteDbMetrics {
             .setCumulative()
             .setUnit(Units.MICROSECONDS),
         view);
+
+    autoRebuildLatency = metrics.newTimer(
+        "notedb/auto_rebuild_latency",
+        new Description("NoteDb auto-rebuilding latency by table")
+            .setCumulative()
+            .setUnit(Units.MILLISECONDS),
+        view);
+
+    autoRebuildFailureCount = metrics.newCounter(
+        "notedb/auto_rebuild_failure_count",
+        new Description("NoteDb auto-rebuilding attempts that failed by table")
+            .setCumulative(),
+        view);
   }
 }