RFR: 8214230: Classes generated by SystemModulesPlugin.java are not reproducable

[Claes Redestad]

Hi Erik,

looks good to me!

(Nit) You could consider the old TreeMap trick to ensure key-sorted map 
iteration order:

// convert to a TreeMap to ensure sorted iteration order for (var e : 
new TreeMap<>(map).entrySet()) { Thanks!

/Claes

On 2018-11-28 10:59, Erik Helin wrote:
> Hi all,
>
> this small patch ensures that two classes generated by jlink's 
> SystemModulePlugin (SystemModules$default and SystemModules$all) are 
> generated in a reproducible manner. That is, if you run jlink two 
> times in a row with identical input, then the generated classes from 
> both runs should be identical. This was almost the case already, the 
> only issue is that some code in SystemModulesPlugin.java are iterating 
> over Sets, and Set does not have a specified iteration order (the 
> iteration order did differ between runs).
>
> This patch ensures that the iteration order over the sets is 
> well-defined by creating an ArrayList from the Set, sorting that 
> ArrayList and then finally iterate over the sorted ArrayList instead 
> of the Set.
>
> For smaller programs jlink will now produce reproducible results, the 
> entire lib/modules file will be reproducible [0]. I have added a JTReg 
> test to verify this property (again, for smaller programs).
>
> Webrev:
> https://cr.openjdk.java.net/~ehelin/8214230/00/
>
> Bug:
> https://bugs.openjdk.java.net/browse/JDK-8214230
>
> Testing:
> - tier1, tier2 and tier3 on macOS, Windows, Linux (all x86-64).
> - Run newly developed JTReg test on macOS, Windows, Linux (all x86-64).
> - Run newly developed JTReg test with the fix absent and verified that
>   the test failed.
>
> Many thanks to Alan Bateman for helping out with the patch!
>
> Thanks,
> Erik
>
> [0]: https://reproducible-builds.org/docs/definition/