[Scons-users] timing issues and protecting from them

[William Blevins]

On Wed, Dec 9, 2015 at 12:27 AM, Bill Deegan <bill at baddogconsulting.com>
wrote:

> Seems like this would need a special --paranoid flag.
> I'm not sure there's a foolproof way to do this even?
>
> For example this sequence of events if scons was to record the md5 of the
> generated file.
> scons creates file.
> User modified file.
> scons reads md5 of file as it's "Golden" record of file and uses it going
> forward.
>

Yeah, I am more assuming that this should be caught and fixed in later
builds versus caught in the current build steps.


>
>
> On Tue, Dec 8, 2015 at 3:50 PM, Tom Tanner <trtanner at btinternet.com>
> wrote:
>
>> I've had an issue recently where someone updated a file while it was
>> being used for a build (please, don't ask).
>>
>> This results in an interesting sort of race hazard where the generated
>> file information in the database says it's made from one version of a file,
>> but it's actually made from another. If this happens it tends to result in
>> errors, especially if that generated file ends up in your cache.
>>
>> So it seemed to me that once you'd built a target it'd be a good idea to
>> at least check all the prerequisites of the target hadn't changed their
>> timestamp (as that would presumably be rather quicker than checking the md5
>> and just as effective) and generate an error.
>>
>> But I'm not sure where the best place to  do that check would be or how
>> to list all the prerequisites of a node. Has anyone come across this or
>> know where I might want to start looking.
>>
>> Cheers
>> _______________________________________________
>> Scons-users mailing list
>> Scons-users at scons.org
>> https://pairlist4.pair.net/mailman/listinfo/scons-users
>>
>
>
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