GODRIVER-3690 Add ErrorCodesFrom to the mongo package

[prestonvasquez]

GODRIVER-3690

Summary

Add an ErrorCodes function that can be used to parse server error codes from an arbitrary Go error.

Usage:

func publishMetrics(ctx context.Context, evt *event.CommandFailedEvent) {
	attrs := []attribute.KeyValue{}

	if errCodes := mongo.ErrorCodes(evt.Failure); len(errCodes) > 0 {
		// Record the first error code as a status code attribute.
		attrs = append(attrs, semconv.DBResponseStatusCode(errCodes[0]))
	}

	Record(
		ctx,
		evt.Duration.Seconds(),
		dbconv.SystemNameMongoDB,
		attrs...,
	)
}

Background

Would be convenient to get server status codes without caller taking a dependency on the experimental API. For example, OpenTelemetry needs to include db.response.status.code for otelmongo: open-telemetry/opentelemetry-go-contrib#7983 (comment)

An alternative to this design would be to put Codes on event.CommandFailedEvent. Suggest we forgo this solution for two reasons:

1. It breaks unkeyed composite literals for event.CommandFailedEvent
2. There may be non-event cases where users would want to validate for error codes.

[Copilot]

Pull Request Overview

This PR extends the CommandFailedEvent structure to include error codes, addressing GODRIVER-3690. The change enables users to access error codes directly from command failure events without parsing the error themselves.

Key changes:

• Added a Codes field to CommandFailedEvent to expose error codes
• Implemented errorCodes() helper function to extract codes from driver errors
• Added test coverage for the new field

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
event/monitoring.go	Added Codes field to CommandFailedEvent structure
x/mongo/driver/operation.go	Populates the new Codes field when publishing failed events; removed blank line
x/mongo/driver/errors.go	Implemented errorCodes() function to extract error codes from driver errors
mongo/errors.go	Refactored variable declarations to use var() block (style change)
internal/integration/clam_prose_test.go	Added test case for CommandFailedEvent.Codes; removed blank line

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[mongodb-drivers-pr-bot]

🧪 Performance Results

Commit SHA: f498a53

The following benchmark tests for version 6937aa456c1dd00007d64ef4 had statistically significant changes (i.e., |z-score| > 1.96):

Benchmark	Measurement	% Change	Patch Value	Stable Region	H-Score	Z-Score
BenchmarkMultiFindMany	total_mem_allocs	-17.0983	383805.0000	Avg: 462963.7273 Med: 468895.0000 Stdev: 34144.8985	0.7608	-2.3183
BenchmarkMultiFindMany	total_bytes_allocated	-17.0965	623217280.0000	Avg: 751737787.1515 Med: 762006024.0000 Stdev: 55402172.7374	0.7615	-2.3198
BenchmarkBSONDeepDocumentDecoding	allocated_bytes_per_op	0.0119	15101.0000	Avg: 15099.2000 Med: 15099.0000 Stdev: 0.5774	0.8471	3.1177

For a comprehensive view of all microbenchmark results for this PR's commit, please check out the Evergreen perf task for this patch.

[mongodb-drivers-pr-bot]

API Change Report

./v2/mongo

compatible changes

ErrorCodes: added

[RafaelCenzano]

LGTM

[matthewdale]

Can users use errors.As to convert the error to a mongo.ServerError and get the same information?

E.g.

var se mongo.ServerError
if errors.As(err, &se) {
    se.ErrorCodes()
}

[prestonvasquez]

This would only work if mongo.ServerError is in the error tree for the arbitrary error which isn't the case for errors propagated by event monitoring. Here's an example: https://github.com/prestonvasquez/go-playground/blob/01e0e77437bdd9ba0a23d912121e152880dc19e9/mgd_errors_test.go#L17

[matthewdale]

Optional: Consider naming this ErrorCodes, which matches the method name on the error types.

[prestonvasquez]

Good idea 👍

[qingyang-hu]

Do we need to define interface{ ErrorCodes() []int } here and add additional checks that these structs also satisfies the interface? It may prevent ErrorCodes() in ServerError from being modified.

[prestonvasquez]

Nice, will update

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated no new comments.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.