From dce96489162b05ae3463741f7f0365ff56f0de36 Mon Sep 17 00:00:00 2001 From: Linus Torvalds 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 --- 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 c5e183516..30afde98a 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 342129fdb..95915960d 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 d83d68c85..8d73d8896 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 625e05187..e8a6e5679 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 9564475f4..f2d90a807 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; -- 2.26.2