Avoid terminating when a precondition is not met in HTTPServerPipelineHandler #2550
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Lukasa
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@swift-server-bot add to allowlist |
Lukasa
reviewed
Oct 13, 2023
Lukasa
reviewed
Oct 13, 2023
| var file: String | ||
| var line: Int | ||
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| init(base: Base, file: String, line: Int) { |
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This, and the various vars, may as well be private.
FranzBusch
reviewed
Oct 16, 2023
| var description: String { | ||
| switch self { | ||
| case .preconditionViolated(let message): | ||
| return message |
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We should add a "precondition violated" to this description as well
hamzahrmalik
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Lukasa
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Oct 17, 2023
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| /// Calls assert if and only if `self.failOnPreconditions` is true. This allows us to avoid terminating the program in tests | ||
| private func checkPrecondition( |
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I think a minor nit here, but let's replace the word precondition in these two functions with assertion. They only fail in debug mode so they behave like assertions, not preconditions, and it'll be a little less confusing at the call site I think.
We can keep the word precondition in the error, that works well.
Lukasa
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Oct 18, 2023
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Motivation:
HTTPServerPipelineHandlerhas a few preconditionFailures in its state machine. This isn’t really ideal, as while these are important invariants, it is fairly easy for users to accidentally break them.Modifications:
We continue to crash (by calling assertionFailure) when in debug mode, to make it obvious to users that they have violated an invariant
However, an internal flag allows us to disable this behaviour for testing
Result:
Making an illegal state change in
HTTPServerPipelineHandlerwill no longer crash