[Toybox] diff algorithms

[enh]

(heh, the time i spent staring at gmail's progress bar as i attached the
file make me feel more justified in my "get off my lawn!" attitude here.
before now i'm not sure i even knew there _was_ a progress bar when you
attach a file :-) )

On Fri, Aug 13, 2021 at 12:19 PM enh <enh at google.com> wrote:

> ack. i'll send it to you directly, because i was on too many mailing lists
> in the 1990s to feel comfortable sending an 11MiB attachment to a list :-)
>
> (the instructions to generate these files yourself by running the
> https://github.com/gavinhoward/bc tests would be far shorter, but it
> would take too long for me to reverse-engineer how i got into that mess in
> the first place, so...)
>
> On Fri, Aug 13, 2021 at 3:12 AM Rob Landley <rob at landley.net> wrote:
>
>> On 8/12/21 4:27 PM, enh via Toybox wrote:
>> > you know how you (rob) have repeatedly expressed your desire to have a
>> different
>> > diff implementation, and i've always either ignored you or claimed that
>> the
>> > existing one is good enough?
>> >
>> > well ... i finally hit a case where i can tell the difference. it turns
>> out that
>> > if you have 3 million lines in the files you're diffing, GNU diff can
>> get
>> > through that in less than 10s, busybox takes just under an hour (!),
>> and toybox
>> > takes just over an hour.
>> >
>> > i'm assuming you already knew of cases like this, but i'll keep my two
>> 125MiB
>> > files somewhere just in case. they compress pretty well, being _very_
>> repetitive
>> > ASCII, but the zip file is still 11MiB so i won't post it without being
>> asked.
>>
>> I'd love to get a copy of those just for personal development testing if
>> I can.
>> (Running problematic real world data through the thing is always
>> preferable.)
>>
>> I'll add a TODO for figuring out how to reasonably have the test suite
>> address
>> the issue without checking in an 11 megabyte test file. :)
>>
>> Thanks,
>>
>> Rob
>>
>
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