chenBright opened a new pull request, #3424: URL: https://github.com/apache/brpc/pull/3424
### What problem does this PR solve? Issue Number: resolve #3416 Problem Summary: During the RDMA handshake, `RdmaEndpoint::AllocateResources()` arms the send/recv CQs through `ReqNotifyCq()`. If `ibv_req_notify_cq()` fails, `ReqNotifyCq()` calls `_socket->SetFailed()` immediately. However, both handshake paths (`ProcessHandshakeAtClient()` and `ExecuteServerHandshake()`) treat `AllocateResources() < 0` as a *recoverable* error: they only turn RDMA off (`RDMA_OFF`) and move the endpoint to `FALLBACK_TCP`, expecting the connection to keep working over plain TCP. Since the socket has already been failed, the connection cannot carry TCP any more, so a single CQ arm failure turns a "graceful degradation to TCP" into a "broken connection". While fixing this, a second issue was found on the same path. `RdmaConnect::Run()` reports the connect result with `_done(errno, _data)`, i.e. it uses the current `errno` as the connect error code. The client-side fallback branch returns right after `AllocateResources()` fails, leaving `errno` set to the allocation error, while every other path in `ProcessHandshakeAtClient()` ends with `errno = 0`. As a result the connection is reported as failed to the upper layer even after the endpoint has entered `FALLBACK_TCP`. Fixing only `ReqNotifyCq()` is therefore not enough to make the fallback work. ### What is changed and the side effects? Changed: Side effects: - Performance effects: - Breaking backward compatibility: --- ### Check List: - Please make sure your changes are compilable. - When providing us with a new feature, it is best to add related tests. - Please follow [Contributor Covenant Code of Conduct](https://github.com/apache/brpc/blob/master/CODE_OF_CONDUCT.md). -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
