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Improve ByteBuffer.setSubstring(_:at:)
performance
#1975
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…rageIfAvailable(_:)` starting in Swift 5.3. Update `ByteBuffer.setSubstring(_:at:)` to use it to avoid a conversion to `String` in the common case.
We should aim to add #1976 first, so that we have some perf numbers to compare with. |
@swift-nio-bot test perf please |
performance reportbuild id: 102 timestamp: Fri Feb 4 17:39:31 UTC 2022 results
comparison
significant differences found |
Lukasa
approved these changes
Feb 7, 2022
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LGTM, thanks!
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Substring.UTF8View
began implementingCollection.withContiguousStorageIfAvailable(_:)
starting in Swift 5.3.Motivation:
The conversion from
Substring
toString
is usually inexpensive, but not always, and can be avoided in most cases when using Swift 5.3 or later; the gain is minor, but worthwhile.Modifications:
Updates
ByteBuffer.setSubstring(_:at:)
to try usingSubstring.UTF8View.withContiguousStorageIfAvailable(_:)
before falling back tosetString(_:at:)
Result:
ByteBuffer.setSubstring(_:at:)
(and callers such aswriteSubstring(_:)
) may see a minor performance improvement. (I have no measurements handy, unfortunately.)Big shout-out to @Lukasa for a ton of help understanding what was going on in the existing code!