On Tue, 10 Sep 2024 18:35:52 GMT, Eirik Bjørsnøs <[email protected]> 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.
>
> 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
>
>
> This purely a cleanup and optimization PR, no functional tests are changed or
> added.
src/java.base/share/classes/java/util/zip/ZipFile.java line 681:
> 679:
> 680: e.flag = CENFLG(cen, pos);
> 681: e.method = CENHOW(cen, pos);
Not reading `nlen` when it's not needed is a good change, and moving `clen` and
`elen` down to be grouped with the others is fine, but some of the other
shuffling around here doesn't seem motivated?
src/java.base/share/classes/java/util/zip/ZipFile.java line 1891:
> 1889: // Return the position of "name/" if we found it
> 1890: if (dirPos != -1) {
> 1891: return new EntryPos(name +"/", dirPos);
Suggestion:
return new EntryPos(name + "/", dirPos);
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/20939#discussion_r1752630171
PR Review Comment: https://git.openjdk.org/jdk/pull/20939#discussion_r1752628607
