Re: cygwin, 44k files: how to commit only index?

From: Junio C Hamano <junkio@cox.net>
Date: Dec 8, 2006, 07:36 UTC
Message-ID: <7vhcw6n8iz.fsf@assigned-by-dhcp.cox.net>
In-Reply-To: <81b0412b0612072327x77477584jb9131b26b0854f2@mail.gmail.com>

"Alex Riesen" <raa.lkml@gmail.com> writes:

Show 10 quoted lines

>> The current code for "diff-index --cached" reads the whole tree
>> into the index as stage #1 entries (diff-lib.c::run_diff_index),
>> and then compares stage #0 (from the original index contents)
>> and stage #1 (the tree parameter from the command line).  Even
>> if you stop at the first mismatch, you would already have paid
>> the overhead to open and read all tree objects before even
>> starting the comparison.
>
> But I don't have to pay for the overhead of comparing all
> entries, if I can stop at first mismatch and exit with non-0.

Bench it if you doubt me.

I'd bet that the time spent in comparison between stages inside index (and remember, you are not generating textual diff, only comparing the SHA-1) is dwarfed by the overhead of populating the stage #1 of the index with what is read from all the tree objects.