Hi Martin,
On 2020-05-10 21:53, Martin Buchholz wrote:
Thanks for improving the jar/zip code.
thanks!
I wish I had more time to do the same.
My own superficial review only adds one small suggestion:
add a comment as to why isSignatureRelated never hits a negative index
exception.
Yes, it's a bit subtle and deserves a comment.
I still like my ancient "ASCII trick" comment.
Google "oldest ASCII trick in the book" and the first hit is an article
about this trick (or well, the inverse - but it still counts!). :-)
Lance only suggested we clarify what that trick is - hope you're OK with
that:
http://cr.openjdk.java.net/~redestad/8244624/open.02/
/Claes
On Thu, May 7, 2020 at 2:34 PM Claes Redestad <claes.redes...@oracle.com> wrote:
Hi,
currently during ZipFile creation, we create an int[] array of pointers
to META-INF entries. These are then retrieved from three different
places in JarFile.
However, JarFile is only interested in some combination a few things:
the existence of and name of the META-INF/MANIFEST file, the existence
of and the names of various signature related files, i.e., files in
META-INF that have a suffix such as .EC, .SF, .RSA and .DSA
Refactoring the contract between JarFile and ZipFile means we can filter
out such entries that we're not interested when opening the file, and
also remove the need to create the String for each entries unless we
actually want them:
Bug: https://bugs.openjdk.java.net/browse/JDK-8244624
Webrev: http://cr.openjdk.java.net/~redestad/8244624/open.00/
This reduces retained footprint of Jar-/ZipFile by slimming down or
removing the Source.metanames array entirely, and a significant speed-up
in some cases.
In the provided microbenchmark, getManifestFromJarWithManifest and
getManifestFromJarWithSignatureFiles doesn't call
JUZFA.getMetaInfEntryNames but still see small (~5%) speed-up decrease
in allocations.
getManifestFromJarWithNoManifest exercise JUZFA.getMetaInfEntryNames in
the baseline, and now calls JUZFA.getManifestName. Result is a 1.25x
speed-up and 30% reduction in allocations. While unrealistic (most JARs
have a META-INF/MANIFEST.MF), this speed-up will translate to a few
places - such as when loading classes from potentially-signed JAR files.
Testing: tier1-2
Thanks!
/Claes
