Retry name resolution on errors and completion #139
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Motivation: Previously, when a name resolver threw an error or returned nil, the channel would immediately call beginGracefulShutdown() and become permanently unavailable. This made channels fragile to transient failures like DNS timeouts, network interruptions, etc. It also breaks an API contract: the client shouldn't shutdown unless the user explicitly asked it to. Modifications: - Documented expected behaviour for name resolvers - Added ResolverWithBackoff wrapper which acts as a state machine for resolving with retries and backoff - Modified push based resolution to retry indefinitely on errors and nil completion by creating new iterators, with exponential backoff between attempts - Modified pull based resolution to retry on errors and nil completion with exponential backoff Result: - Channels are more resilient to transient name resolution failures. - Resolves grpc/grpc-swift-2#25
gjcairo
reviewed
Dec 4, 2025
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Shouldn't we propagate CancellationErrors here?
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No, this is running in a non-throwing task group, just retuning is fine.
Sources/GRPCNIOTransportCore/Client/Resolver/NameResolver.swift
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Co-authored-by: Gus Cairo <[email protected]>
gjcairo
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Dec 8, 2025
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Motivation:
Previously, when a name resolver threw an error or returned nil, the
channel would immediately call beginGracefulShutdown() and become
permanently unavailable. This made channels fragile to transient
failures like DNS timeouts, network interruptions, etc. It also breaks
an API contract: the client shouldn't shutdown unless the user
explicitly asked it to.
Modifications:
resolving with retries and backoff
and nil completion by creating new iterators, with exponential backoff
between attempts
with exponential backoff
Result: