XnLemon commented on code in PR #3395:
URL: https://github.com/apache/dubbo-go/pull/3395#discussion_r3401541242
##########
registry/servicediscovery/service_instances_changed_listener_impl.go:
##########
@@ -258,20 +263,61 @@ func GetMetadataInfo(app string, instance
registry.ServiceInstance, revision str
var metadataInfo *info.MetadataInfo
var err error
if instance.GetMetadata() == nil {
+ // No metadata map at all; treat as default (local/RPC) storage
type.
metadataStorageType = constant.DefaultMetadataStorageType
} else {
metadataStorageType =
instance.GetMetadata()[constant.MetadataStorageTypePropertyName]
+ if metadataStorageType == "" {
+ // MetadataStorageTypePropertyName absent (e.g. old
Java provider); default to local storage type.
+ logger.Warnf("[Metadata] MetadataStorageType not set
for instance %s, defaulting to local", instance.GetID())
+ metadataStorageType =
constant.DefaultMetadataStorageType
+ }
}
+
if metadataStorageType == constant.RemoteMetadataStorageType {
- metadataInfo, err =
metadata.GetMetadataFromMetadataReport(revision, instance, registryId)
- if err != nil {
- return nil, err
+ var reportErr error
+ metadataInfo, reportErr =
metadata.GetMetadataFromMetadataReport(revision, instance, registryId)
+ if reportErr == nil && metadataInfo != nil {
+ metaCache.Set(cacheKey, metadataInfo)
+ return metadataInfo, nil
}
- } else {
+ if reportErr != nil {
+ logger.Errorf("[Metadata-Fallback] report failed,
fallback to RPC app=%s registry=%s revision=%s err=%v",
+ app, registryId, revision, reportErr)
+ } else {
+ logger.Warnf("[Metadata-Fallback] report returned nil
metadata, fallback to RPC app=%s registry=%s revision=%s",
+ app, registryId, revision)
+ }
+
metadataInfo, err = metadata.GetMetadataFromRpc(revision,
instance)
if err != nil {
- return nil, err
+ if reportErr != nil {
+ // Wrap rpcErr so callers can use errors.Is/As
on the primary failure;
+ // reportErr is annotated as context since it
triggered the fallback.
+ return nil, perrors.Wrapf(err,
+ "[Metadata-Fallback] both paths failed,
reportErr: %v", reportErr)
+ }
+ // reportErr was nil — the report returned nil metadata
and RPC also failed.
+ return nil, perrors.Wrapf(err,
+ "[Metadata-Fallback] RPC fallback failed after
report returned nil metadata")
Review Comment:
这是不是把L273看成新写的了 以为下面全是死代码（
这段是处理 RPC fallback 也失败的情况
1. report 报错 + RPC 也报错 → "both paths failed, reportErr: ..."
把两个错误都记录下来，调用方能看到完整失败链
2. report 返回 nil + RPC 报错 → "RPC fallback failed after report returned nil
metadata"
说明 report 虽然没报错但返回空，RPC 兜底也失败了
感觉如果不需要这么细粒度降低complexity的话可以直接
`perrors.Wrapf(err,"RPC fallback failed app=%s registry=%s revision=%s,
reportErr: %v"`
看reportErr
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