On Tue, 10 Sep 2024 18:35:52 GMT, Eirik Bjørsnøs <eir...@openjdk.org> wrote:
> Please review this PR which speeds up `ZipFile.getZipEntry` by removing > slash-checking logic which is already taking place during lookup in > `ZipFile.Source.getEntryPos`. > > `ZipFile.Source.getEntryPos` includes logic to match a lookup for "name" > against a directory entry "name/" (with a trailing slash). However, only the > CEN position is currently returned, so `ZipFile.getZipEntry` needs to re-read > the name from the CEN and determine if a trailing slash needs to be appended > to the name of the returned `ZipEntry`. > > By letting `ZipFile.Source.getEntryPos` return the resolved name along with > the CEN position (in a new record `EntryPos`), `ZipFile.getZipEntry` can now > instead use the already resolved name. > > Since `ZipFile.getZipEntry` now has the name, CEN header fields can now be > read in bulk, separate from the allocation of the `ZipEntry`. This reordering > is unlocked by the other changes in this PR and can alone explain a lot of > the performance gains, probably because of better cache use. > > This results in a nice ~18% speedup in the `ZipFileGetEntry.getEntryHit` > micro: > > Baseline: > > > Benchmark (size) Mode Cnt Score Error Units > ZipFileGetEntry.getEntryHit 512 avgt 15 63.713 ? 2.645 ns/op > ZipFileGetEntry.getEntryHit 1024 avgt 15 67.405 ? 1.474 ns/op > > > PR: > > > Benchmark (size) Mode Cnt Score Error Units > ZipFileGetEntry.getEntryHit 512 avgt 15 52.027 ? 2.669 ns/op > ZipFileGetEntry.getEntryHit 1024 avgt 15 55.211 ? 1.169 ns/op > > The changes in this PR makes `UTF8ZipCoder.compare` the only caller of > `ZipCoder.hasTrailingSlash`, so this method is made private and the > implementation in the base class retired. > > This purely a cleanup and optimization PR, no functional tests are changed or > added. This pull request has now been integrated. Changeset: 7f1dae12 Author: Eirik Bjørsnøs <eir...@openjdk.org> URL: https://git.openjdk.org/jdk/commit/7f1dae12e5e24d204a70cf610a8c482996556931 Stats: 79 lines in 2 files changed: 16 ins; 45 del; 18 mod 8339874: Avoid duplicate checking of trailing slash in ZipFile.getZipEntry Reviewed-by: lancea, redestad ------------- PR: https://git.openjdk.org/jdk/pull/20939
