Proposal: JDK-8231640 - (prop) Canonical property storage

[Magnus Ihse Bursie]

On 2021-08-28 17:16, Alan Bateman wrote:
> On 28/08/2021 05:45, Jaikiran Pai wrote:
>> I hadn't considered the system property approach to switch to old 
>> behaviour in my proposals, so this is a very good input and I 
>> personally think the most logical proposals so far.
>
> Roger may be right that few would care but it would be changing 
> behavior that goes back to JDK 1.0. In your list (and thanks for 
> writing down the options with pros/cons) then your 1a where 
> SOURCE_DATE_EPOCH changes to write the epoch date rather than the 
> current date seems to be most consistent with other tools and the 
> wider eco system. It seems the least disruptive in that it doesn't 
> change existing behavior and would be opt-in when reproducibility is 
> required. Previous discussion was leading towards your option 2 (or 
> variants of) but isn't option doesn't help the cases where build tools 
> use libraries that rely on the older methods.

If I understood the numbering and alternatives correctly, I don't think 
there is a conflict between 1a and 2, and I think both should be 
implemented, for different reasons.

This is my understanding of the options, with the rationale I see for 
choosing them:

* 1a says that we change the store() method to write the date from 
SOURCE_DATE_EPOCH, if it is set -- otherwise it keeps the old behavior. 
This allows users who want to use old Java code (or code they can't 
modify) to produce output in a reproducible way to do so without 
changing the source code of the product.

* 2 says that we add a new override to store() which also takes an 
Instant. This way programmers who write new code and want to make sure 
it is always reproducible can send in Instant.EPOCH, and not rely on the 
user to configure SOURCE_DATE_EPOCH.

(In fact, when thinking of it, this seems overly complex. There is no 
real need to send in a generic Instant, just an override with a boolean 
skipTimestamp, or something like that. Basically, any solution which 
allows programmers who write new code to get property files without 
timestamps easily, is what's needed to fulfill this spot.

/Magnus

>
> -Alan