RFR: 8242959: Optimize ZipFile.getEntry by folding lookups for name and name+'/'

[Lance Andersen]

HI Claes,

I think this looks good.

Best
Lance

> On Apr 17, 2020, at 7:33 AM, Claes Redestad <claes.redestad at oracle.com> wrote:
> 
> Hi,
> 
> please review this patch to get rid of the back-to-back lookup of name
> and name+'/' in ZipFile.getEntry. This is done by first adjusting the
> hash function so that a trailing slash is not included in an entry's
> hash code, and adjusting appropriately when matching the arrays.
> 
> This means we do fewer table lookups, less arithmetic and potentially
> less allocation on lookup misses.
> 
> Patch contributed by Eirik Bjørsnøs.
> 
> Webrev: http://cr.openjdk.java.net/~redestad/8242959/open.00/
> Bug:    https://bugs.openjdk.java.net/browse/JDK-8242959
> 
> Testing: tier1+2, verified neutral performance for hits and a
> significant reduction in cost of misses (~30-50ms improvement on
> Spring PetClinic startup).
> 
> Thanks!
> 
> /Claes

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 <http://oracle.com/us/design/oracle-email-sig-198324.gif>Lance Andersen| Principal Member of Technical Staff | +1.781.442.2037
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