fix(transport): return Poll::ready until error is consumed #495
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When a lazy connection fails to connect it first returns Poll::ready from the reconnect service, yet the subsequent call returns Poll::pending making tower_balance loop forever. Instead, on error we return Ready until the error is consumed in the call method.
LucioFranco
requested changes
Jan 5, 2021
| @@ -13,6 +14,7 @@ use tracing::trace; | |||
| pub(crate) struct Reconnect<M, Target> | |||
| where | |||
| M: Service<Target>, | |||
| M::Error: Debug, | |||
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I think we actually want to use Into<Box<dyn Error + Send + Sync>> here and then convert it. If it impls that trait and you call into() then it will automatically impl Debug because of the Error trait.
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I think I've done what you've suggested in the last comment.
LucioFranco
reviewed
Jan 14, 2021
| @@ -52,6 +54,7 @@ where | |||
| M::Future: Unpin, | |||
| Error: From<M::Error> + From<S::Error>, | |||
| Target: Clone, | |||
| <M as tower_service::Service<Target>>::Error: fmt::Debug, | |||
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This still needs to be Into<Error> or else it might break the stack down the line.
|
Closing in favor of #536 |
|
Thanks @tl-helge-hoff for getting this started! |
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When a lazy connection fails to connect the first time it returns Poll::ready and saves the error in the Reconnect service.
Subsequent calls to
Reconnect::poll_readyreturnPoll::Pendingwhich makes tower_balance loop forever as it will never get a ready service.This is due to
Reconnect::poll_readybeing called twice bytower_balanceand returning firstPoll::Readyand thenPoll::Pending.Motivation
We bumped into the infinite-looping issue while using the
Channel::balance_channeltogether with tls,when our tls config was incorrect and triggering an error during the handshake.
Solution
Reconnect::poll_readywill consistently returnPoll::Readyuntil the error is consumed inReconnect::call.After the error is consumed, and the error is surfaced through a client call, the
Reconnectservice will try to connect again.The PR also adds trace logging in the
Reconnectservice.