Record the execution time of TopicValidator with a TraceTimer

At Google this query frequently fails with a deadline exceeded
exception, so we are interested to know how much latency it adds to git
push in general. We also intent to do stale reads from the index to see
if this improves the performance. Having the execution time recorded
with a TraceTimer allows us to see the impact.

Release-Notes: skip
Bug: Google b/465110411
Change-Id: I4f5ec162dd423028496e8ac1d0951a232699c648
Signed-off-by: Edwin Kempin <ekempin@google.com>

java/com/google/gerrit/server/git/validators/TopicValidator.java

diff --git a/java/com/google/gerrit/server/git/validators/TopicValidator.java b/java/com/google/gerrit/server/git/validators/TopicValidator.java
index d9881af..d51e102 100644
--- a/java/com/google/gerrit/server/git/validators/TopicValidator.java
+++ b/java/com/google/gerrit/server/git/validators/TopicValidator.java
@@ -17,6 +17,9 @@
 import com.google.common.base.Strings;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.server.config.GerritServerConfig;
+import com.google.gerrit.server.logging.Metadata;
+import com.google.gerrit.server.logging.TraceContext;
+import com.google.gerrit.server.logging.TraceContext.TraceTimer;
 import com.google.gerrit.server.query.change.InternalChangeQuery;
 import com.google.gerrit.server.validators.ValidationException;
 import com.google.inject.Inject;
@@ -43,14 +46,16 @@
     if (Strings.isNullOrEmpty(topic)) {
       return;
     }
-    int topicSize =
-        queryProvider.get().noFields().setLimit(topicLimit + 1).byTopicOpen(topic).size();
-    if (topicSize >= topicLimit) {
-      throw new ValidationException(
-          String.format(
-              "Topic '%s' already contains maximum number of allowed changes per 'topicLimit'"
-                  + " server config value %d.",
-              topic, topicLimit));
+    try (TraceTimer ignored = TraceContext.newTimer("Validate Topic Size", Metadata.empty())) {
+      int topicSize =
+          queryProvider.get().noFields().setLimit(topicLimit + 1).byTopicOpen(topic).size();
+      if (topicSize >= topicLimit) {
+        throw new ValidationException(
+            String.format(
+                "Topic '%s' already contains maximum number of allowed changes per 'topicLimit'"
+                    + " server config value %d.",
+                topic, topicLimit));
+      }
     }
   }
 }