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

---

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[mongodb-drivers-pr-bot]

🧪 Performance Results

Commit SHA: 03fda7a

The following benchmark tests for version 69335dbe9bbda10007c74eb0 had statistically significant changes (i.e., |z-score| > 1.96):

Benchmark	Measurement	% Change	Patch Value	Stable Region	H-Score	Z-Score
BenchmarkSingleRunCommand	ns_per_op	15.1227	158166.0000	Avg: 137389.0303 Med: 134746.0000 Stdev: 8166.0827	0.7984	2.5443
BenchmarkSingleRunCommand	ops_per_second_med	-12.9561	6691.0444	Avg: 7686.9751 Med: 7819.6171 Stdev: 390.8930	0.7929	-2.5478
BenchmarkSingleFindOneByID	ns_per_op	11.0930	274874.0000	Avg: 247426.8485 Med: 245742.0000 Stdev: 10140.0996	0.8010	2.7068
BenchmarkSingleFindOneByID	total_mem_allocs	-9.8037	1495287.0000	Avg: 1657814.7500 Med: 1669065.0000 Stdev: 81358.2818	0.7376	-1.9977
BenchmarkSingleFindOneByID	ops_per_second_med	-9.5669	3756.2777	Avg: 4153.6555 Med: 4188.7448 Stdev: 166.7453	0.7748	-2.3831
BenchmarkSingleFindOneByID	ops_per_second_max	-7.9284	4349.0930	Avg: 4723.6006 Med: 4720.1469 Stdev: 154.9727	0.7769	-2.4166
BenchmarkSmallDocInsertOne	ops_per_second_max	-7.6144	5747.9193	Avg: 6221.6591 Med: 6255.1605 Stdev: 235.0399	0.7324	-2.0156
BenchmarkBSONFullDocumentDecoding	total_mem_allocs	-4.3462	9423022.0000	Avg: 9851175.1200 Med: 9862458.0000 Stdev: 202458.9840	0.7437	-2.1148
BenchmarkBSONFullDocumentDecoding	total_bytes_allocated	-4.3459	389863000.0000	Avg: 407575990.7200 Med: 408022784.0000 Stdev: 8407879.2257	0.7428	-2.1067
BenchmarkBSONDeepDocumentDecoding	total_time_seconds	1.5220	1.2174	Avg: 1.1992 Med: 1.1988 Stdev: 0.0057	0.8455	3.2080
BenchmarkBSONFlatDocumentDecoding	total_time_seconds	1.1055	1.2127	Avg: 1.1995 Med: 1.1994 Stdev: 0.0066	0.7400	1.9947

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 👍