On Mon, 9 Jan 2023 08:33:09 GMT, Viktor Klang <d...@openjdk.org> wrote:
>> Currently Set.copyOf allocates both a HashSet and a new empty array when the >> input collection is empty. >> >> This patch avoids allocating anything for the case where the parameter >> collection's isEmpty returns true. > > Viktor Klang has updated the pull request incrementally with two additional > commits since the last revision: > > - 8299444: java.util.Set.copyOf allocates needlessly for empty input > collections > > Modifies ImmutableCollections.listCopy: > Introduces a check for isEmpty to avoid allocation in the case of an > empty input collection. > - 8299444: java.util.Set.copyOf allocates needlessly for empty input > collections > > Modifies Map.copyOf: > Introduces a check for isEmpty to avoid allocation in the case of an empty > input Map. On the note of `CHM::isEmpty`: It would be better to rewrite this method as a short-circuitable reduction of the many CounterCells' values. As soon as at least one of them are >0 then the map is not empty. In contrast, today we sum all of the values, in many cases, unnecessary. ------------- PR: https://git.openjdk.org/jdk/pull/11847
