Add metric to count how often requests are automatically retried

Signed-off-by: Edwin Kempin <ekempin@google.com>
Change-Id: Idd0e11babea2de2813ffbd741f58b3d0a43d7d4a

Documentation/metrics.txt

@@ -19,6 +19,7 @@ The following metrics are reported.
 by RetryHelper to execute an action (0 == single attempt, no retry)
 * `action/retry_timeout_count`: Number of action executions of RetryHelper
 that ultimately timed out
+* `action/auto_retry_count`: Number of automatic retries with tracing
 
 === Pushes
 

java/com/google/gerrit/server/logging/Metadata.java

@@ -89,6 +89,9 @@ public abstract class Metadata {
   // One or more resources
   public abstract Optional<Boolean> multiple();
 
+  // The name of an operation that is performed.
+  public abstract Optional<String> operationName();
+
   // Partial or full computation
   public abstract Optional<Boolean> partial();
 
@@ -185,6 +188,8 @@ public abstract class Metadata {
 
     public abstract Builder multiple(boolean multiple);
 
+    public abstract Builder operationName(String operationName);
+
     public abstract Builder partial(boolean partial);
 
     public abstract Builder noteDbFilePath(@Nullable String noteDbFilePath);

java/com/google/gerrit/server/update/RetryHelper.java

@@ -35,6 +35,7 @@ import com.google.gerrit.common.Nullable;
 import com.google.gerrit.extensions.restapi.RestApiException;
 import com.google.gerrit.git.LockFailureException;
 import com.google.gerrit.metrics.Counter1;
+import com.google.gerrit.metrics.Counter2;
 import com.google.gerrit.metrics.Description;
 import com.google.gerrit.metrics.Field;
 import com.google.gerrit.metrics.MetricMaker;
@@ -120,6 +121,7 @@ public class RetryHelper {
   public static class Metrics {
     final Counter1<ActionType> attemptCounts;
     final Counter1<ActionType> timeoutCount;
+    final Counter2<ActionType, String> autoRetryCount;
 
     @Inject
     Metrics(MetricMaker metricMaker) {
@@ -142,6 +144,16 @@ public class RetryHelper {
                   .setCumulative()
                   .setUnit("timeouts"),
               actionTypeField);
+      autoRetryCount =
+          metricMaker.newCounter(
+              "action/auto_retry_count",
+              new Description("Number of automatic retries with tracing")
+                  .setCumulative()
+                  .setUnit("retries"),
+              actionTypeField,
+              Field.ofString("operation_name", Metadata.Builder::operationName)
+                  .description("The name of the operation that was retried.")
+                  .build());
     }
   }
 
@@ -286,22 +298,21 @@ public class RetryHelper {
                 if (retryWithTraceOnFailure
                     && opts.retryWithTrace().isPresent()
                     && opts.retryWithTrace().get().test(t)) {
+                  String caller = opts.caller().map(Class::getSimpleName).orElse("N/A");
                   if (!traceContext.isTracing()) {
                     traceContext
                         .addTag(RequestId.Type.TRACE_ID, "retry-on-failure-" + new RequestId())
                         .forceLogging();
                     logger.atFine().withCause(t).log(
-                        "%s failed, retry with tracing enabled",
-                        opts.caller().map(Class::getSimpleName).orElse("N/A"));
+                        "%s failed, retry with tracing enabled", caller);
+                    metrics.autoRetryCount.increment(actionType, caller);
                     return true;
                   }
 
                   // A non-recoverable failure occurred. We retried the operation with tracing
                   // enabled and it failed again. Log the failure so that admin can see if it
                   // differs from the failure that triggered the retry.
-                  logger.atFine().withCause(t).log(
-                      "auto-retry of %s has failed",
-                      opts.caller().map(Class::getSimpleName).orElse("N/A"));
+                  logger.atFine().withCause(t).log("auto-retry of %s has failed", caller);
                   return false;
                 }