Re: [PATCH] Update "gc" behavior in commit, merge, am, rebase and index-pack

> A few attempts have been made in the past to change 'gc --auto' [1]
> [2]. This is another such attempt.
>
> Commit d4bb43e (Invoke "git gc --auto" from commit, merge, am and
> rebase. - 2007-09-05) used the rule to put "gc --auto" is "where
> update-ref occurs". I would argue that this is not a good condition to
> run gc, because (at least current) gc is slow. We encourage commit
> often and rebase to make all patches in good shape and this workflow
> should not be interrupted/slowed down by random "gc --auto".
>
> Instead, we could just inform users that "gc" should be run soon in
> commonly used commands (this patch also reinstates "gc" check in
> commit, which was lost at the sh->C conversion). [1] and [2] can annoy
> users constantly with warnings. This patch shows the warning at most
> once a day.
>
> There are commands that are not expected to return immediately. These
> are more suitable for "gc --auto". One of them is receive-pack, which
> already calls "gc --auto". The other one is index-pack, which "gc
> --auto" is added in by this patch.
>
> In short, after this patch:
>
>  - receive-pack and index-pack (or push, pull/fetch at high level) can
>   do "gc --auto".
>  - commmit, merge, am, rebase warns once a day, no actual gc.
>
> [1] http://thread.gmane.org/gmane.comp.version-control.git/184848
>   adds an config option to turn --auto to warning only
>
> [2] http://thread.gmane.org/gmane.comp.version-control.git/187711
>   make it warn early before actual do the house keeping
>
> Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
> ---
>  builtin/commit.c           |    2 ++
>  builtin/gc.c               |   21 ++++++++++++++++++++-
>  builtin/index-pack.c       |   16 ++++++++++++++--
>  builtin/merge.c            |    2 +-
>  git-am.sh                  |    2 +-
>  git-rebase--interactive.sh |    2 +-
>  6 files changed, 39 insertions(+), 6 deletions(-)
>
> diff --git a/builtin/commit.c b/builtin/commit.c
> index a2ec73d..4ba5677 100644
> --- a/builtin/commit.c
> +++ b/builtin/commit.c
> @@ -1418,6 +1418,7 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
>
>                OPT_END()
>        };
> +       const char *argv_gc_auto[] = { "gc", "--check", NULL };
>
>        struct strbuf sb = STRBUF_INIT;
>        struct strbuf author_ident = STRBUF_INIT;
> @@ -1589,6 +1590,7 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
>                     "new_index file. Check that disk is not full or quota is\n"
>                     "not exceeded, and then \"git reset HEAD\" to recover."));
>
> +       run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
>        rerere(0);
>        run_hook(get_index_file(), "post-commit", NULL);
>        if (amend && !no_post_rewrite) {
> diff --git a/builtin/gc.c b/builtin/gc.c
> index 9b4232c..a85f71c 100644
> --- a/builtin/gc.c
> +++ b/builtin/gc.c
> @@ -171,6 +171,7 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
>  {
>        int aggressive = 0;
>        int auto_gc = 0;
> +       int check_gc = 0;
>        int quiet = 0;
>
>        struct option builtin_gc_options[] = {
> @@ -180,12 +181,16 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
>                        PARSE_OPT_OPTARG, NULL, (intptr_t)prune_expire },
>                OPT_BOOLEAN(0, "aggressive", &aggressive, "be more thorough (increased runtime)"),
>                OPT_BOOLEAN(0, "auto", &auto_gc, "enable auto-gc mode"),
> +               OPT_BOOLEAN(0, "check", &check_gc, "enable auto-gc mode"),
>                OPT_END()
>        };
>
>        if (argc == 2 && !strcmp(argv[1], "-h"))
>                usage_with_options(builtin_gc_usage, builtin_gc_options);
>
> +       if (auto_gc && check_gc)
> +               die(_("--auto and --check are incompatible"));
> +
>        argv_array_pushl(&pack_refs_cmd, "pack-refs", "--all", "--prune", NULL);
>        argv_array_pushl(&reflog, "reflog", "expire", "--all", NULL);
>        argv_array_pushl(&repack, "repack", "-d", "-l", NULL);
> @@ -211,12 +216,26 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
>        if (quiet)
>                argv_array_push(&repack, "-q");
>
> -       if (auto_gc) {
> +       if (auto_gc || check_gc) {
>                /*
>                 * Auto-gc should be least intrusive as possible.
>                 */
>                if (!need_to_gc())
>                        return 0;
> +               if (check_gc) {
> +                       struct stat st;
> +                       if (stat(git_path("gc_needed"), &st))
> +                               open(git_path("gc_needed"), O_CREAT | O_RDWR);
> +                       else {
> +                               /* do not bother users more than once a day */
> +                               if (time(NULL) - st.st_mtime < 86400)
> +                                       return 0;
> +                               utime(git_path("gc_needed"), NULL);
> +                       }
> +                       warning(_("This repository needs maintenance. "
> +                                 "Please run \"git gc\" as soon as possible."));
> +                       return 0;
> +               }
>                if (quiet)
>                        fprintf(stderr, _("Auto packing the repository for optimum performance.\n"));
>                else
> diff --git a/builtin/index-pack.c b/builtin/index-pack.c
> index 83555e5..438245c 100644
> --- a/builtin/index-pack.c
> +++ b/builtin/index-pack.c
> @@ -9,6 +9,7 @@
>  #include "progress.h"
>  #include "fsck.h"
>  #include "exec_cmd.h"
> +#include "run-command.h"
>
>  static const char index_pack_usage[] =
>  "git index-pack [-v] [-o <index-file>] [--keep | --keep=<msg>] [--verify] [--strict] (<pack-file> | --stdin [--fix-thin] [<pack-file>])";
> @@ -63,6 +64,7 @@ static int nr_resolved_deltas;
>  static int from_stdin;
>  static int strict;
>  static int verbose;
> +static int auto_gc;
>
>  static struct progress *progress;
>
> @@ -968,6 +970,10 @@ static int git_index_pack_config(const char *k, const char *v, void *cb)
>                        die("bad pack.indexversion=%"PRIu32, opts->version);
>                return 0;
>        }
> +       if (strcmp(k, "receive.autogc") == 0) {
> +               auto_gc = git_config_bool(k, v);
> +               return 0;
> +       }
>        return git_default_config(k, v, cb);
>  }
>
> @@ -1254,12 +1260,18 @@ int cmd_index_pack(int argc, const char **argv, const char *prefix)
>        curr_index = write_idx_file(index_name, idx_objects, nr_objects, &opts, pack_sha1);
>        free(idx_objects);
>
> -       if (!verify)
> +       if (!verify) {
>                final(pack_name, curr_pack,
>                      index_name, curr_index,
>                      keep_name, keep_msg,
>                      pack_sha1);
> -       else
> +               if (auto_gc) {
> +                       const char *argv_gc_auto[] = {
> +                               "gc", "--auto", "--quiet", NULL,
> +                       };
> +                       run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
> +               }
> +       } else
>                close(input_fd);
>        free(objects);
>        free(index_name_buf);
> diff --git a/builtin/merge.c b/builtin/merge.c
> index 470fc57..8b8716e 100644
> --- a/builtin/merge.c
> +++ b/builtin/merge.c
> @@ -385,7 +385,7 @@ static void finish(struct commit *head_commit,
>                if (verbosity >= 0 && !merge_msg.len)
>                        printf(_("No merge message -- not updating HEAD\n"));
>                else {
> -                       const char *argv_gc_auto[] = { "gc", "--auto", NULL };
> +                       const char *argv_gc_auto[] = { "gc", "--check", NULL };
>                        update_ref(reflog_message.buf, "HEAD",
>                                new_head, head, 0,
>                                DIE_ON_ERR);
> diff --git a/git-am.sh b/git-am.sh
> index f8b7a0c..0f2dbc4 100755
> --- a/git-am.sh
> +++ b/git-am.sh
> @@ -902,4 +902,4 @@ if test -s "$dotest"/rewritten; then
>  fi
>
>  rm -fr "$dotest"
> -git gc --auto
> +git gc --check
> diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
> index 0c19b7c..89996a3 100644
> --- a/git-rebase--interactive.sh
> +++ b/git-rebase--interactive.sh
> @@ -573,7 +573,7 @@ do_next () {
>                true # we don't care if this hook failed
>        fi &&
>        rm -rf "$state_dir" &&
> -       git gc --auto &&
> +       git gc --check &&
>        warn "Successfully rebased and updated $head_name."
>
>        exit
> --
> 1.7.8.36.g69ee2
>