On Wed, Oct 03 2018, Ævar Arnfjörð Bjarmason wrote:
> Don't have time to patch this now, but thought I'd send a note / RFC
> about this.
>
> Now that we have the commit graph it's nice to be able to set
> e.g. core.commitGraph=true & gc.writeCommitGraph=true in ~/.gitconfig or
> /etc/gitconfig to apply them to all repos.
>
> But when I clone e.g. linux.git stuff like 'tag --contains' will be slow
> until whenever my first "gc" kicks in, which may be quite some time if
> I'm just using it passively.
>
> So we should make "git gc --auto" be run on clone, and change the
> need_to_gc() / cmd_gc() behavior so that we detect that the
> gc.writeCommitGraph=true setting is on, but we have no commit graph, and
> then just generate that without doing a full repack.
>
> As an aside such more granular "gc" would be nice for e.g. pack-refs
> too. It's possible for us to just have one pack, but to have 100k loose
> refs.
>
> It might also be good to have some gc.autoDetachOnClone option and have
> it false by default, so we don't have a race condition where "clone
> linux && git -C linux tag --contains" is slow because the graph hasn't
> been generated yet, and generating the graph initially doesn't take that
> long compared to the time to clone a large repo (and on a small one it
> won't matter either way).
>
> I was going to say "also for midx", but of course after clone we have
> just one pack, so I can't imagine us needing this. But I can see us
> having other such optional side-indexes in the future generated by gc,
> and they'd also benefit from this.
I don't have time to polish this up for submission now, but here's a WIP
patch that implements this, highlights:
* There's a gc.clone.autoDetach=false default setting which overrides
gc.autoDetach if 'git gc --auto' is run via git-clone (we just pass a
--cloning option to indicate this).
* A clone of say git.git with gc.writeCommitGraph=true looks like:
[...]
Receiving objects: 100% (255262/255262), 100.49 MiB | 17.78 MiB/s, done.
Resolving deltas: 100% (188947/188947), done.
Computing commit graph generation numbers: 100% (55210/55210), done.
* The 'git gc --auto' command also knows to (only) run the commit-graph
(and space is left for future optimization steps) if general GC isn't
needed, but we need "optimization":
$ rm .git/objects/info/commit-graph; ~/g/git/git --exec-path=$PWD -c
gc.writeCommitGraph=true -c gc.autoDetach=false gc --auto;
Annotating commits in commit graph: 341229, done.
Computing commit graph generation numbers: 100% (165969/165969), done.
$
* The patch to gc.c looks less scary with -w, most of it is indenting
the existing pack-refs etc. with a "!auto_gc || should_gc" condition.
* I added a commit_graph_exists() exists function and only care if I
get ENOENT for the purposes of this gc mode. This would need to be
tweaked for the incremental mode Derrick talks about, but if we just
set "should_optimize" that'll also work as far as gc --auto is
concerned (e.g. on fetch, am etc.)
diff --git a/Documentation/config.txt b/Documentation/config.txt
index 1546833213..5759fbb067 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -1621,7 +1621,19 @@ gc.autoPackLimit::
gc.autoDetach::
Make `git gc --auto` return immediately and run in background
- if the system supports it. Default is true.
+ if the system supports it. Default is true. Overridden by
+ `gc.clone.autoDetach` when running linkgit:git-clone[1].
+
+gc.clone.autoDetach::
+ Make `git gc --auto` return immediately and run in background
+ if the system supports it when run via
+ linkgit:git-clone[1]. Default is false.
++
+The reason this defaults to false is because the only time we'll have
+work to do after a 'git clone' is if something like
+`gc.writeCommitGraph` is true, in that case we'd like to compute the
+optimized file before returning, so that say commands that benefit
+from commit graph aren't slow until it's generated in the background.
gc.bigPackThreshold::
If non-zero, all packs larger than this limit are kept when
diff --git a/builtin/clone.c b/builtin/clone.c
index 15b142d646..824c130ba5 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -897,6 +897,8 @@ int cmd_clone(int argc, const char **argv, const char
*prefix)
struct remote *remote;
int err = 0, complete_refs_before_fetch = 1;
int submodule_progress;
+ const char *argv_gc_auto[] = {"gc", "--auto", "--cloning", NULL};
+ const char *argv_gc_auto_quiet[] = {"gc", "--auto", "--cloning",
"--quiet", NULL};
struct refspec rs = REFSPEC_INIT_FETCH;
struct argv_array ref_prefixes = ARGV_ARRAY_INIT;
@@ -1245,5 +1247,11 @@ int cmd_clone(int argc, const char **argv, const char
*prefix)
refspec_clear(&rs);
argv_array_clear(&ref_prefixes);
+
+ if (0 <= option_verbosity)
+ run_command_v_opt_cd_env(argv_gc_auto, RUN_GIT_CMD, git_dir,
NULL);
+ else
+ run_command_v_opt_cd_env(argv_gc_auto_quiet, RUN_GIT_CMD,
git_dir, NULL);
+
return err;
}
diff --git a/builtin/gc.c b/builtin/gc.c
index 6591ddbe83..27be03890a 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -43,6 +43,7 @@ static int gc_auto_threshold = 6700;
static int gc_auto_pack_limit = 50;
static int gc_write_commit_graph;
static int detach_auto = 1;
+static int detach_clone_auto = 0;
static timestamp_t gc_log_expire_time;
static const char *gc_log_expire = "1.day.ago";
static const char *prune_expire = "2.weeks.ago";
@@ -133,6 +134,7 @@ static void gc_config(void)
git_config_get_int("gc.autopacklimit", &gc_auto_pack_limit);
git_config_get_bool("gc.writecommitgraph", &gc_write_commit_graph);
git_config_get_bool("gc.autodetach", &detach_auto);
+ git_config_get_bool("gc.clone.autodetach", &detach_clone_auto);
git_config_get_expiry("gc.pruneexpire", &prune_expire);
git_config_get_expiry("gc.worktreepruneexpire",
&prune_worktrees_expire);
git_config_get_expiry("gc.logexpiry", &gc_log_expire);
@@ -157,9 +159,6 @@ static int too_many_loose_objects(void)
int num_loose = 0;
int needed = 0;
- if (gc_auto_threshold <= 0)
- return 0;
-
dir = opendir(git_path("objects/17"));
if (!dir)
return 0;
@@ -369,10 +368,21 @@ static int need_to_gc(void)
return 0;
if (run_hook_le(NULL, "pre-auto-gc", NULL))
- return 0;
+ return -1;
return 1;
}
+static int need_to_optimize(void) {
+ if (gc_write_commit_graph) {
+ char *obj_dir = get_object_directory();
+ char *graph_name = get_commit_graph_filename(obj_dir);
+
+ if (commit_graph_exists(graph_name) == 0) /* ENOENT */
+ return 1;
+ }
+ return 0;
+}
+
/* return NULL on success, else hostname running the gc */
static const char *lock_repo_for_gc(int force, pid_t* ret_pid)
{
@@ -491,6 +501,7 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
{
int aggressive = 0;
int auto_gc = 0;
+ int cloning = 0;
int quiet = 0;
int force = 0;
const char *name;
@@ -498,6 +509,8 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
int daemonized = 0;
int keep_base_pack = -1;
timestamp_t dummy;
+ int should_gc;
+ int should_optimize;
struct option builtin_gc_options[] = {
OPT__QUIET(&quiet, N_("suppress progress reporting")),
@@ -507,6 +520,8 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
OPT_BOOL(0, "aggressive", &aggressive, N_("be more thorough
(increased runtime)")),
OPT_BOOL_F(0, "auto", &auto_gc, N_("enable auto-gc mode"),
PARSE_OPT_NOCOMPLETE),
+ OPT_BOOL_F(0, "cloning", &cloning, N_("enable cloning mode"),
+ PARSE_OPT_NOCOMPLETE),
OPT_BOOL_F(0, "force", &force,
N_("force running gc even if there may be another gc
running"),
PARSE_OPT_NOCOMPLETE),
@@ -555,22 +570,27 @@ int cmd_gc(int argc, const char **argv, const char
*prefix)
/*
* Auto-gc should be least intrusive as possible.
*/
- if (!need_to_gc())
+ should_gc = need_to_gc();
+ if (should_gc == -1)
+ return 0;
+ should_optimize = need_to_optimize();
+ if (!should_gc && !should_optimize)
return 0;
- if (!quiet) {
+ if (!quiet && should_gc) {
if (detach_auto)
fprintf(stderr, _("Auto packing the repository
in background for optimum performance.\n"));
else
fprintf(stderr, _("Auto packing the repository
for optimum performance.\n"));
fprintf(stderr, _("See \"git help gc\" for manual
housekeeping.\n"));
}
- if (detach_auto) {
+ if (detach_auto &&
+ (!cloning || (cloning && detach_clone_auto))) {
if (report_last_gc_error())
return -1;
if (lock_repo_for_gc(force, &pid))
return 0;
- if (gc_before_repack())
+ if (should_gc && gc_before_repack())
return -1;
delete_tempfile(&pidfile);
@@ -611,45 +631,48 @@ int cmd_gc(int argc, const char **argv, const char
*prefix)
atexit(process_log_file_at_exit);
}
- if (gc_before_repack())
- return -1;
-
- if (!repository_format_precious_objects) {
- close_all_packs(the_repository->objects);
- if (run_command_v_opt(repack.argv, RUN_GIT_CMD))
- return error(FAILED_RUN, repack.argv[0]);
-
- if (prune_expire) {
- argv_array_push(&prune, prune_expire);
- if (quiet)
- argv_array_push(&prune, "--no-progress");
- if (repository_format_partial_clone)
- argv_array_push(&prune,
- "--exclude-promisor-objects");
- if (run_command_v_opt(prune.argv, RUN_GIT_CMD))
- return error(FAILED_RUN, prune.argv[0]);
+ if (!auto_gc || should_gc) {
+ if (gc_before_repack())
+ return -1;
+
+ if (!repository_format_precious_objects) {
+ close_all_packs(the_repository->objects);
+ if (run_command_v_opt(repack.argv, RUN_GIT_CMD))
+ return error(FAILED_RUN, repack.argv[0]);
+
+ if (prune_expire) {
+ argv_array_push(&prune, prune_expire);
+ if (quiet)
+ argv_array_push(&prune,
"--no-progress");
+ if (repository_format_partial_clone)
+ argv_array_push(&prune,
+
"--exclude-promisor-objects");
+ if (run_command_v_opt(prune.argv, RUN_GIT_CMD))
+ return error(FAILED_RUN, prune.argv[0]);
+ }
}
- }
- if (prune_worktrees_expire) {
- argv_array_push(&prune_worktrees, prune_worktrees_expire);
- if (run_command_v_opt(prune_worktrees.argv, RUN_GIT_CMD))
- return error(FAILED_RUN, prune_worktrees.argv[0]);
- }
- if (run_command_v_opt(rerere.argv, RUN_GIT_CMD))
- return error(FAILED_RUN, rerere.argv[0]);
+ if (prune_worktrees_expire) {
+ argv_array_push(&prune_worktrees,
prune_worktrees_expire);
+ if (run_command_v_opt(prune_worktrees.argv,
RUN_GIT_CMD))
+ return error(FAILED_RUN,
prune_worktrees.argv[0]);
+ }
- report_garbage = report_pack_garbage;
- reprepare_packed_git(the_repository);
- if (pack_garbage.nr > 0)
- clean_pack_garbage();
+ if (run_command_v_opt(rerere.argv, RUN_GIT_CMD))
+ return error(FAILED_RUN, rerere.argv[0]);
+
+ report_garbage = report_pack_garbage;
+ reprepare_packed_git(the_repository);
+ if (pack_garbage.nr > 0)
+ clean_pack_garbage();
+ }
if (gc_write_commit_graph)
write_commit_graph_reachable(get_object_directory(), 0,
!quiet && !daemonized);
- if (auto_gc && too_many_loose_objects())
+ if (auto_gc && should_gc && too_many_loose_objects())
warning(_("There are too many unreachable loose objects; "
"run 'git prune' to remove them."));
diff --git a/commit-graph.c b/commit-graph.c
index 5908bd4e34..a4a7c94cec 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -57,6 +57,18 @@ static struct commit_graph *alloc_commit_graph(void)
return g;
}
+int commit_graph_exists(const char *graph_file)
+{
+ struct stat st;
+ if (stat(graph_file, &st)) {
+ if (errno == ENOENT)
+ return 0;
+ else
+ return -1;
+ }
+ return 1;
+}
+
struct commit_graph *load_commit_graph_one(const char *graph_file)
{
void *graph_map;
diff --git a/commit-graph.h b/commit-graph.h
index 5678a8f4ca..a251f1bc32 100644
--- a/commit-graph.h
+++ b/commit-graph.h
@@ -11,6 +11,7 @@
struct commit;
char *get_commit_graph_filename(const char *obj_dir);
+int commit_graph_exists(const char *graph_file);
/*
* Given a commit struct, try to fill the commit struct info, including:
