Reduce allocations when peeking pseudo-headers. #246
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glbrntt
approved these changes
Sep 23, 2020
| var headerValue: String? = nil | ||
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| for (fieldName, fieldValue, _) in self { | ||
| if name == fieldName { |
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The subscript does a case insensitive check, I assume we don't need to do that here because this is only ever called internally and we know that the headers must be lowercase so we'll always provide a lowercased name ?
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Pseudo-headers are required to be lower-case. This is a nice perf win here: if the weren't lowercase, the request was malformed anyway.
Motivation: The 2 to 1 codecs do a number of operations where they "peek" the pseudo-headers. Each of these operations uses the HPACKHeaders subscript, meaning that they allocate a temporary array for a field that can, in a correct request/response, contain only one element. That's very wasteful! Modifications: - Rewrite peekPseudoHeader to iterate instead, avoiding the array. - Add allocaton counter test. Result: 4 fewer allocations per HTTP request transformed on the server side, 2 fewer allocations per HTTP response transformed on the client side.
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PeterAdams-A
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Sep 23, 2020
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Motivation:
The 2 to 1 codecs do a number of operations where they "peek" the
pseudo-headers. Each of these operations uses the HPACKHeaders
subscript, meaning that they allocate a temporary array for a field that
can, in a correct request/response, contain only one element. That's
very wasteful!
Modifications:
Result:
4 fewer allocations per HTTP request transformed on the server side,
2 fewer allocations per HTTP response transformed on the client side.
Resolves #244.