Make the default abbrev length configurable

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

View File

@ -21,7 +21,7 @@ static int debug; /* Display lots of verbose info */
static int all; /* Any valid ref can be used */
static int tags; /* Allow lightweight tags */
static int longformat;
static int abbrev = DEFAULT_ABBREV;
static int abbrev = -1; /* unspecified */
static int max_candidates = 10;
static struct hash_table names;
static int have_util;
@ -420,7 +420,11 @@ int cmd_describe(int argc, const char **argv, const char *prefix)
OPT_END(),
};
git_config(git_default_config, NULL);
argc = parse_options(argc, argv, prefix, options, describe_usage, 0);
if (abbrev < 0)
abbrev = DEFAULT_ABBREV;
if (max_candidates < 0)
max_candidates = 0;
else if (max_candidates > MAX_TAGS)