Speed up decoding of large enums #2
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zyla
changed the title
kozak
reviewed
Sep 16, 2024
| genericUnsafeDecodeEnum opts = | ||
| let constructors = Object.fromFoldable (enumConstructors opts :: Array (Tuple String rep)) | ||
| let constructors = Object.fromFoldable (enumConstructors to opts :: Array (Tuple String a)) | ||
| in \value -> | ||
| let tag = decodeString value in | ||
| case Object.lookup tag constructors of |
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So we are returning a lambda here but the lambda doesn't need to call to anymore, because constructors are already returning the final type and not the rep.
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Yes (assuming JS Object is a hashtable, which it will probably be in this case in most implementations)
|
To clarify: the Also, the complexity I provided in PR description is wrong. The generic tree seems to be unbalanced, to it's |
kozak
approved these changes
Sep 16, 2024
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Generic
tois quite slow on datatypes with many constructors, because it runsO(log^2(n))instanceofoperations, wherenis the number of constructors.This change moves this cost from the decoding loop to initialization time. Now we store values of the target type in the lookup table instead of Generic representations. This makes initialization slower, but if there are many enums values to decode, we save time there.
Before:
After:
As seen in the above benchmark results, after this change enum decoding is almost independent of enum size. Which makes sense, because now it's only a hashtable lookup, as it should be.