insert_unique_unchecked operation by stepancheg · Pull Request #293 · rust-lang/...
source link: https://github.com/rust-lang/hashbrown/pull/293
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Sometimes a map is constructed when it is known that all keys are
unique (e. e. if keys are coming from another map or from a
sorted/deduplicated iterator). In this case we can make insertion
faster by skipping a check that a key already exists in the map.
insert_unique_unchecked is guaranteed to be memory-safe, but does
not guarantee anything beyond that: if inserted key is not unique,HashMap can panic, loop forever, return incorrect entry etc.
Added simple benchmark. insert_unique_unchecked is about 30%
faster than insert. Your mileage may vary of course.
Similar PR was
added to indexmap crate
and they asked to discuss the name of the operation with hashbrown
crate owners to come to the same naming convention (if hashbrown
is willing to have the same operation).
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