[PERF] BundleWriter: Improve performance #534
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The ENDS_WITH_NEW_LINE RegExp is quite slow on large strings. Therefore the "endsWithNewLine" state is computed after every modification to the "buf" in order to improve performance.
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codeworrior
previously requested changes
Oct 21, 2020
lib/lbt/bundle/BundleWriter.js
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| } | ||
| if ( writeBuf.length >= 1 ) { | ||
| this.buf += writeBuf; | ||
| this.endsWithNewLine = ENDS_WITH_NEW_LINE.test(writeBuf); |
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This can give wrong results when write is called with blanks or tabs only. In that case, the old endsWithNewLine flag must be taken into account as well.
Correct would be something like
ENDS_WITH_NEW_LINE.test(writeBuf) || (this.endsWithNewLine && !writeBuf.trim())
Instead of the trim(), one could use another RegExp /^[ \t]*$/
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Sounds right 👍🏻
As there were no dedicated unit tests, I've added one to cover the whole class.
RandomByte
reviewed
Oct 22, 2020
Co-authored-by: Merlin Beutlberger <[email protected]>
RandomByte
approved these changes
Oct 22, 2020
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The ENDS_WITH_NEW_LINE RegExp is quite slow on large strings.
Therefore the "endsWithNewLine" state is computed after every modification
to the "buf" in order to improve performance.
Measurements
Based on sap.m build in SAP/openui5@0d95920
ui5 build --exclude-task="*" --include-task=generateLibraryPreloadui5 build --exclude-task="*" --include-task=generateLibraryPreload