feat(bigtable): add AttemptLatency2 metric and populate peer info labels by elinorli · Pull Request #16095 · googleapis/google-cloud-cpp

elinorli · 2026-05-13T23:55:02Z

This introduces the AttemptLatency2 metric for DirectPath to record attempt latencies with the fields extracted from the decoded PeerInfo trailing metadata, populating peer_info_labels_ and forwarding them to IntoLabelMap.

Also added
AttemptLatency2Test to test the newly populated peer info labels. Refactored SetClusterZone to use the new helper function CreateServerMetadata.

gemini-code-assist

Code Review

This pull request introduces the AttemptLatency2 metric, which extends latency tracking by including peer information such as transport type, region, and subzone extracted from gRPC trailing metadata. The implementation includes new data structures for peer labels, utility functions for decoding metadata, and the integration of this metric into various Bigtable operations. Review feedback suggests a performance optimization in GetPeerInfoFromTrailingMetadata to use a constant reference when accessing trailing metadata to avoid an unnecessary copy of the multimap.

gemini-code-assist · 2026-05-14T00:05:05Z


+absl::optional<google::bigtable::v2::PeerInfo> GetPeerInfoFromTrailingMetadata(
+    grpc::ClientContext const& client_context) {
+  auto metadata = client_context.GetServerTrailingMetadata();


The GetServerTrailingMetadata() method returns a reference to a std::multimap. Using auto here results in a copy of the entire map, which is inefficient. Prefer using auto const& to avoid the unnecessary copy.

auto const& metadata = client_context.GetServerTrailingMetadata();

Agreed. Let's avoid making a copy if we don't have to.

sushanb · 2026-05-14T00:05:54Z

+  auto iter = metadata.find("bigtable-peer-info");
+  if (iter == metadata.end()) return absl::nullopt;
+  std::string decoded;
+  if (!absl::Base64Unescape(


check if we need [WebSafeBase64Unescape]

codecov · 2026-05-14T00:47:56Z

Codecov Report

❌ Patch coverage is 99.02913% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.71%. Comparing base (cf931ff) to head (c621978).

Files with missing lines	Patch %	Lines
...oud/bigtable/internal/operation_context_factory.cc	77.77%	2 Missing ⚠️
google/cloud/bigtable/internal/metrics.cc	98.21%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #16095      +/-   ##
==========================================
+ Coverage   92.70%   92.71%   +0.01%     
==========================================
  Files        2353     2353              
  Lines      218354   218643     +289     
==========================================
+ Hits       202419   202719     +300     
+ Misses      15935    15924      -11

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

scotthart · 2026-05-14T15:11:05Z

 absl::optional<google::bigtable::v2::ResponseParams>
 GetResponseParamsFromTrailingMetadata(
    grpc::ClientContext const& client_context);
+absl::optional<google::bigtable::v2::PeerInfo> GetPeerInfoFromTrailingMetadata(


Let's use std::optional instead of absl::optional in new code.

scotthart · 2026-05-14T15:12:57Z


+absl::optional<google::bigtable::v2::PeerInfo> GetPeerInfoFromTrailingMetadata(
+    grpc::ClientContext const& client_context) {
+  auto metadata = client_context.GetServerTrailingMetadata();


Agreed. Let's avoid making a copy if we don't have to.

scotthart · 2026-05-14T15:13:36Z

+  auto metadata = client_context.GetServerTrailingMetadata();
+  // Base64 encoded peer info header key defined by the server.
+  auto iter = metadata.find("bigtable-peer-info");
+  if (iter == metadata.end()) return absl::nullopt;


std::nullopt instead of absl::nullopt

scotthart · 2026-05-14T15:14:08Z

+  }
+  google::bigtable::v2::PeerInfo p;
+  if (p.ParseFromString(decoded)) return p;
+  return absl::nullopt;


std::nullopt

scotthart · 2026-05-14T15:15:22Z

+
+void AttemptLatency2::PreCall(opentelemetry::context::Context const&,
+                              PreCallParams const& p) {
+  attempt_start_ = std::move(p.attempt_start);


p is passed by const& and cannot be moved from.

Done. I've also changed it for AttemptLatency.

scotthart · 2026-05-14T15:16:50Z

+  SetServerMetadata(client_context, server_metadata);
+
+  EXPECT_THAT(GetPeerInfoFromTrailingMetadata(client_context),
+              Eq(absl::nullopt));


std::nullopt

scotthart · 2026-05-14T15:17:07Z

+  SetServerMetadata(client_context, server_metadata);
+
+  EXPECT_THAT(GetPeerInfoFromTrailingMetadata(client_context),
+              Eq(absl::nullopt));


std::nullopt

sushanb · 2026-05-15T20:05:02Z

Looks good. You can run this client with quickstart and verify that attempt_latencies2 is being populated from your workload.

This introduces the `AttemptLatency2` metric for DirectPath to record attempt latencies with the fields extracted from the decoded `PeerInfo` trailing metadata, populating `peer_info_labels_` and forwarding them to `IntoLabelMap`. Also added `AttemptLatency2Test` to test the newly populated peer info labels. Refactored `SetClusterZone` to use the new helper function `CreateServerMetadata`.

elinorli requested a review from a team as a code owner May 13, 2026 23:55

product-auto-label Bot added the api: bigtable Issues related to the Bigtable API. label May 13, 2026

gemini-code-assist Bot reviewed May 14, 2026

View reviewed changes

sushanb reviewed May 14, 2026

View reviewed changes

scotthart requested changes May 14, 2026

View reviewed changes

elinorli force-pushed the directpath branch from 1abbcd6 to 5145ea7 Compare May 14, 2026 22:53

elinorli added 2 commits May 18, 2026 15:43

elinorli force-pushed the directpath branch from 5145ea7 to c621978 Compare May 18, 2026 19:43

scotthart approved these changes May 18, 2026

View reviewed changes

elinorli merged commit 1735f56 into googleapis:main May 19, 2026
53 of 59 checks passed

elinorli deleted the directpath branch May 19, 2026 14:25

Conversation

elinorli commented May 13, 2026

Uh oh!

gemini-code-assist Bot left a comment

Choose a reason for hiding this comment

Code Review

Uh oh!

gemini-code-assist Bot May 14, 2026

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

codecov Bot commented May 14, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Codecov Report

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

sushanb commented May 15, 2026

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

codecov Bot commented May 14, 2026 •

edited

Loading