feat(metrics): enhance the monitoring metrics of rpc call failure under Triple protocol

[Saramanda9988]

Description

according to https://cn.dubbo.apache.org/en/overview/reference/metrics/standard_metrics/

Implementing a more fine-grained error classification mechanism for the triple protocol to classify and count RPC request failures for both provider and consumer.

Support classification: timeout, flow restriction, service unavailability, business failure and unknown error, and their aggregate version which aline with dubbo-java.

preview:

Checklist

• I confirm the target branch is develop
• Code has passed local testing
• I have added tests that prove my fix is effective or that my feature works

[Saramanda9988]

Currently, It seems that the Dubbo protocol in dubbo-go only propagates plain errors without structured error codes and there is no unified abstraction to align error semantics across protocols. Any further handling would have to rely on comparing error text, which is not a good approach. Therefore, this part is not implemented in this PR.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 24.19355% with 47 lines in your changes missing coverage. Please review.
✅ Project coverage is 48.41%. Comparing base (60d1c2a) to head (8254c38).
⚠️ Report is 726 commits behind head on develop.

Files with missing lines	Patch %	Lines
metrics/rpc/collector.go	0.00%	27 Missing ⚠️
metrics/rpc/metric_set.go	0.00%	20 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #3189      +/-   ##
===========================================
+ Coverage    46.76%   48.41%   +1.64%     
===========================================
  Files          295      462     +167     
  Lines        17172    33498   +16326     
===========================================
+ Hits          8031    16217    +8186     
- Misses        8287    15973    +7686     
- Partials       854     1308     +454     

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[Copilot]

Pull request overview

This PR enhances RPC metrics under the Triple protocol by introducing fine‑grained error classification and associated counters for both providers and consumers, and slightly relaxes some registry metrics time assertions to be less brittle.

Changes:

• Extend rpcCommonMetrics and providerMetrics/consumerMetrics to include per‑error‑type counters (timeout, limit, service unavailable, business failure, unknown) and their aggregate variants.
• Introduce error_classifier.go to map Triple/gRPC error codes into internal ErrorType values, and update rpcCollector.afterInvokeHandler to classify failures and increment the corresponding granular counters per side.
• Adjust metrics/registry/event_test.go time assertions to accept End == Start by checking !End.Before(start) instead of requiring End.After(start).

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
metrics/rpc/metric_set.go	Adds new counter and aggregate counter vectors for each granular error type on both provider and consumer metric sets.
metrics/rpc/error_classifier.go	Introduces ErrorType enum and classifyError helper to translate Triple error codes into high‑level categories used by metrics.
metrics/rpc/collector.go	Wires error classification into the after‑invoke path and updates per‑type failure counters for provider/consumer roles.
metrics/registry/event_test.go	Relaxes event timing expectations to avoid flakiness by only asserting that End is not before Start.

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[Saramanda9988]

@Alanxtl Done

[Alanxtl]

cool work, lgtm

[sonarqubecloud]

Quality Gate passed

Issues
10 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[Saramanda9988]

@AlexStocks Done