---
(If this PR fixes a github issue, please add `Fixes #<xyz>`)
Fixes#13023
(or if this PR is one task of a github issue, please add `Master Issue: #<xyz>`
to link to the master issue)
Master Issue: #13023
*Motivation*
Currently, StubServer can stop itself (by Stop()) before it start its
grpc server (created by Start()). This race condition may lead to a
goroutine leak mentioned by #13023.
*Modifications*
This PR add a channel to force the Stop() started after Start()
*Verify this change*
Please pick either of following options.
- This change is already covered by existing tests, such as *(please describe tests)*.
Test/TestEtcdGrpcResolver
Used github.com/stretchr/testify/assert to replace the AssertEqual function definition. Required the use of copyToInterface to copy a string slice to the empty interface slice
Due to flakes in CI and locally which resulted due to shared servers
there is suspcion that fixed port numbers are to blame. This reuses port
and address.
- ErrGRPCNotCapable("etcdserver: not capable") -> codes.FailedPrecondition (it will not autofix, it requires new version of server)
- ErrGPRCNotSupportedForLearner("etcdserver: rpc not supported for learner") -> codes.FailedPrecondition (as long as its learner, the call will not work)
- ErrGRPCClusterVersionUnavailable("etcdserver: cluster version not found during downgrade") -> codes.FailedPrecondition (backend does not contain the version (old etcd?) so retry will not help)
https://github.com/etcd-io/etcd/runs/2599598633?check_suite_focus=true
```
{"level":"warn","ts":"2021-05-17T09:55:30.246Z","logger":"etcd-client","caller":"v3/retry_interceptor.go:62","msg":"retrying of unary invoker failed","target":"etcd-endpoints://0xc000539880/#initially=[unix://localhost:m30]","attempt":0,"error":"rpc error: code = Unavailable desc = etcdserver: rpc not supported for learner"}
{"level":"warn","ts":"2021-05-17T09:55:30.270Z","logger":"etcd-client","caller":"v3/retry_interceptor.go:62","msg":"retrying
of unary invoker
failed","target":"etcd-endpoints://0xc000539880/#initially=[unix://localhost:m30]","attempt":1,"error":"rpc
error: code = Unavailable desc = etcdserver: rpc not supported for
learner"}`
```
During review of: https://github.com/etcd-io/etcd/pull/12988 spotted
that PUT is actially writing to v3-backend.
If we are replaying WAL log, it might happened that backend's
applied_index is > than the WAL's log entry. In such situation we should
skip applying on backend V3.
I think both the methods (setVersion, setMembersAttributes) are in
practice idempotent so its not that 'serious' problem, but for
formal correctness adding the proper checks.
