Reduce allocations in the GRPCClientStateMachine #653
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Motivation: There were some unnecessary allocations in the client state machine. Modifications: - Use `HPACKHeader`s new `first(name:)` method to avoid allocating an array of headers before taking the first. - Turn LengthPrefixedMessageWriter into a struct. - Turn LengthPrefixedMessageReader into a struct. Result: - Reduce allocations, a small perf gain.
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I also had more targeted benchmark for just the state machine (which involved making a bunch of things public) which saw a decrease from ~60ms to ~50ms. |
| @@ -544,21 +544,20 @@ extension GRPCClientStateMachine.State { | |||
| // responses as well as a variety of non-GRPC content-types and to omit Status & Status-Message. | |||
| // Implementations must synthesize a Status & Status-Message to propagate to the application | |||
| // layer when this occurs." | |||
| let statusHeader = headers[":status"].first | |||
| let responseStatus = statusHeader.flatMap(Int.init).map { code in | |||
| let responseStatus = headers.first(name: ":status").flatMap(Int.init).map { code in | |||
| HTTPResponseStatus(statusCode: code) | |||
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.map(HTTPResponseStatus.init)?
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Unfortunately the init has a default second arg: init(statusCode: Int, reasonPhrase: String = "") so this isn't possible.
We could make those public if we declare them as not part of the public API. |
True, I think I'll leave that for another PR though! |
Motivation:
There were some unnecessary allocations in the client state machine.
Modifications:
HPACKHeaders newfirst(name:)method to avoid allocating anarray of headers before taking the first.
Result: