Junio C Hamano <gitster@xxxxxxxxx> writes:
> So let's scrap the abbrevguard thing. I somehow thought that I already
> took your "make DEFAULT_ABBREV tweakable" patch, but apparently I didn't.
> That one is the real fix to the issue of futureproofing.
In return for a free education last night, I now owe you your patch from
October last year, resurrected from the list archive, and here it is.
With a forged sign-off from you, as I know that everything you write is
supposed to be open source.
- I do not think making minimum configurable is worth it, but I left it in
(there is no UI to tweak it anyway).
- I somewhat tweaked "describe" and "describe --abbrev" implementation.
OPT__ABBREV() uses DEFAULT_ABBREV in its callback, so we need to read
from the configuration before calling parse_options(). As it won't
make any sense to call "git describe" outside repository where you
cannot get to your configuration, I think it is safe to add a call to
git_config() in this codepath. Other users of OPT__ABBREV() may need to
be audited.
By the way, I've already reverted the abbrevguard thing away.
-- >8 --
From: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Date: Thu, 28 Oct 2010 11:28:04 -0700
Subject: [PATCH] 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@xxxxxxxxx>
---
Documentation/config.txt | 6 ++++++
builtin/describe.c | 6 +++++-
cache.h | 5 +++--
config.c | 8 ++++++++
environment.c | 1 +
5 files changed, 23 insertions(+), 3 deletions(-)
diff --git a/Documentation/config.txt b/Documentation/config.txt
index c5e1835..30afde9 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -567,6 +567,12 @@ core.sparseCheckout::
Enable "sparse checkout" feature. See section "Sparse checkout" in
linkgit:git-read-tree[1] for more information.
+core.abbrevLength::
+ Set the length object names are abbreviated to. If unspecified,
+ many commands abbreviate to 7 hexdigits, which may not be enough
+ for abbreviated object names to stay unique for sufficiently long
+ time.
+
add.ignore-errors::
add.ignoreErrors::
Tells 'git add' to continue adding files when some files cannot be
diff --git a/builtin/describe.c b/builtin/describe.c
index 342129f..9591596 100644
--- a/builtin/describe.c
+++ b/builtin/describe.c
@@ -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)
diff --git a/cache.h b/cache.h
index d83d68c..8d73d88 100644
--- a/cache.h
+++ b/cache.h
@@ -540,6 +540,7 @@ extern int trust_executable_bit;
extern int trust_ctime;
extern int quote_path_fully;
extern int has_symlinks;
+extern int minimum_abbrev, default_abbrev;
extern int ignore_case;
extern int assume_unchanged;
extern int prefer_symlink_refs;
@@ -758,8 +759,8 @@ static inline unsigned int hexval(unsigned char c)
}
/* Convert to/from hex/sha1 representation */
-#define MINIMUM_ABBREV 4
-#define DEFAULT_ABBREV 7
+#define MINIMUM_ABBREV minimum_abbrev
+#define DEFAULT_ABBREV default_abbrev
struct object_context {
unsigned char tree[20];
diff --git a/config.c b/config.c
index 625e051..e8a6e56 100644
--- a/config.c
+++ b/config.c
@@ -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)
diff --git a/environment.c b/environment.c
index 9564475..f2d90a8 100644
--- a/environment.c
+++ b/environment.c
@@ -15,6 +15,7 @@ int user_ident_explicitly_given;
int trust_executable_bit = 1;
int trust_ctime = 1;
int has_symlinks = 1;
+int minimum_abbrev = 4, default_abbrev = 7;
int ignore_case;
int assume_unchanged;
int prefer_symlink_refs;
--
1.7.4.1.404.g62d316
--
To unsubscribe from this list: send the line "unsubscribe git" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html