RFR: 8244624: Improve handling of JarFile META-INF resources

[Weijun Wang]

JarFile.java:

734: extra new line?
930: Remove or rewrite the comment.

ZipFile.java:

49: seems not used

Please add links to each other between src/java.base/share/classes/sun/security/util/SignatureFileVerifier.java::isBlockOrSF and src/java.base/share/classes/java/util/zip/ZipFile.java::isSignatureRelated. The 2nd method can also be static.

I assume you cannot put ZipFile::isSignatureRelated into SignatureFileVerifier.java, right?

Thanks,
Max

p.s. How do you run the benchmark test? Both locally and on mach5.

> On May 8, 2020, at 5:28 AM, Claes Redestad <claes.redestad at 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