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Make the default abbrev length configurable

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The default of 7 comes from fairly early in git development, when
seven hex digits was a lot (it covers about 250+ million hash
values). Back then I thought that 65k revisions was a lot (it was what
we were about to hit in BK), and each revision tends to be about 5-10
new objects or so, so a million objects was a big number.

These days, the kernel isn't even the largest git project, and even
the kernel has about 220k revisions (_much_ bigger than the BK tree
ever was) and we are approaching two million objects. At that point,
seven hex digits is still unique for a lot of them, but when we're
talking about just two orders of magnitude difference between number
of objects and the hash size, there _will_ be collisions in truncated
hash values. It's no longer even close to unrealistic - it happens all
the time.

We should both increase the default abbrev that was unrealistically
small, _and_ add a way for people to set their own default per-project
in the git config file.

This is the first step to first make it configurable; the default of 7
is not raised yet.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Linus Torvalds
2010-10-28 11:28:04 -07:00
committed by Junio C Hamano
parent 7ed863a85a
commit dce9648916
5 changed files with 23 additions and 3 deletions
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8
config.c
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@ -531,6 +531,14 @@ static int git_default_core_config(const char *var, const char *value)
return 0;
}
if (!strcmp(var, "core.abbrevlength")) {
int abbrev = git_config_int(var, value);
if (abbrev < minimum_abbrev || abbrev > 40)
return -1;
default_abbrev = abbrev;
return 0;
}
if (!strcmp(var, "core.loosecompression")) {
int level = git_config_int(var, value);
if (level == -1)