refactor(app/core): outline control plane recovery backoff#4450
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refactor(app/core): outline control plane recovery backoff#4450
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`linkerd_app_core::control` provides utilities used by the data plane to communicate with the linkerd control plane. this includes, among other features such as load-balancing and configurability for settings like connection timeout durations, an error recovery that respects DNS record's negative TTL. as of today, we do this within an inline, anonymous closure. this commit pulls this business logic out of an inline closure, and into an explicit pair of structures. ResolveRecover is the Recover implementation that handles identifying the proper backoff strategy, when presented with a given boxed error. ResolveBackoff is the structure that acts as the sum type that encompasses either a TTL-driven interval, or an exponential backoff. see also, #4449. that introduces some additional guardrails to prevent panicking if a negative ttl of zero is encountered. Signed-off-by: katelyn martin <kate@buoyant.io>
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| // If we are recovering due to a DNS resolution error, check for a negative TTL. | ||
| if let Some(e) = crate::errors::cause_ref::<dns::ResolveError>(&*error) { | ||
| if let Some(ttl) = e.negative_ttl() { | ||
| let interval = tokio::time::interval(ttl); | ||
| let stream = IntervalStream::new(interval); | ||
| return Ok(ResolveBackoff::NegativeTtl(stream)); | ||
| } | ||
| } |
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I know this is just keeping the existing behavior, but isn't tokio::time::interval() going to fire immediately so we'll retry right away?
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linkerd_app_core::controlprovides utilities used by the data plane tocommunicate with the linkerd control plane. this includes, among other
features such as load-balancing and configurability for settings like
connection timeout durations, an error recovery that respects DNS
record's negative TTL.
as of today, we do this within an inline, anonymous closure.
this commit pulls this business logic out of an inline closure, and into
an explicit pair of structures.
ResolveRecover is the Recover implementation that handles identifying
the proper backoff strategy, when presented with a given boxed error.
ResolveBackoff is the structure that acts as the sum type that
encompasses either a TTL-driven interval, or an exponential backoff.
see also, #4449. that introduces some additional
guardrails to prevent panicking if a negative ttl of zero is
encountered.
Signed-off-by: katelyn martin kate@buoyant.io