On Sat, 7 Apr 2012, Jeff King wrote:
> When we pack everything into one big pack with "git repack
> -Ad", any unreferenced objects in to-be-deleted packs are
> exploded into loose objects, with the intent that they will
> be examined and possibly cleaned up by the next run of "git
> prune".
>
> Since the exploded objects will receive the mtime of the
> pack from which they come, if the source pack is old, those
> loose objects will end up pruned immediately. In that case,
> it is much more efficient to skip the exploding step
> entirely for these objects.
>
> This patch teaches pack-objects to receive the expiration
> information and avoid writing these objects out. It also
> teaches "git gc" to pass the value of gc.pruneexpire to
> repack (which in turn learns to pass it along to
> pack-objects) so that this optimization happens
> automatically during "git gc" and "git gc --auto".
>
> Signed-off-by: Jeff King <peff@xxxxxxxx>
Looks fine to me.
Acked-by: Nicolas Pitre <nico@xxxxxxxxxxx>
> ---
> builtin/gc.c | 23 +++++++++++++++--------
> builtin/pack-objects.c | 25 +++++++++++++++++++++++--
> git-repack.sh | 10 +++++++++-
> t/t7701-repack-unpack-unreachable.sh | 14 ++++++++++++++
> 4 files changed, 61 insertions(+), 11 deletions(-)
>
> diff --git a/builtin/gc.c b/builtin/gc.c
> index 271376d..1bc2fe3 100644
> --- a/builtin/gc.c
> +++ b/builtin/gc.c
> @@ -144,6 +144,19 @@ static int too_many_packs(void)
> return gc_auto_pack_limit <= cnt;
> }
>
> +static void add_repack_all_option(void)
> +{
> + if (prune_expire && !strcmp(prune_expire, "now"))
> + append_option(argv_repack, "-a", MAX_ADD);
> + else {
> + append_option(argv_repack, "-A", MAX_ADD);
> + if (prune_expire) {
> + append_option(argv_repack, "--unpack-unreachable", MAX_ADD);
> + append_option(argv_repack, prune_expire, MAX_ADD);
> + }
> + }
> +}
> +
> static int need_to_gc(void)
> {
> /*
> @@ -160,10 +173,7 @@ static int need_to_gc(void)
> * there is no need.
> */
> if (too_many_packs())
> - append_option(argv_repack,
> - prune_expire && !strcmp(prune_expire, "now") ?
> - "-a" : "-A",
> - MAX_ADD);
> + add_repack_all_option();
> else if (!too_many_loose_objects())
> return 0;
>
> @@ -227,10 +237,7 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
> "run \"git gc\" manually. See "
> "\"git help gc\" for more information.\n"));
> } else
> - append_option(argv_repack,
> - prune_expire && !strcmp(prune_expire, "now")
> - ? "-a" : "-A",
> - MAX_ADD);
> + add_repack_all_option();
>
> if (pack_refs && run_command_v_opt(argv_pack_refs, RUN_GIT_CMD))
> return error(FAILED_RUN, argv_pack_refs[0]);
> diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
> index 7b07c09..1861093 100644
> --- a/builtin/pack-objects.c
> +++ b/builtin/pack-objects.c
> @@ -63,6 +63,7 @@ static uint32_t nr_objects, nr_alloc, nr_result, nr_written;
> static int non_empty;
> static int reuse_delta = 1, reuse_object = 1;
> static int keep_unreachable, unpack_unreachable, include_tag;
> +static unsigned long unpack_unreachable_expiration;
> static int local;
> static int incremental;
> static int ignore_packed_keep;
> @@ -2249,6 +2250,10 @@ static void loosen_unused_packed_objects(struct rev_info *revs)
> if (!p->pack_local || p->pack_keep)
> continue;
>
> + if (unpack_unreachable_expiration &&
> + p->mtime < unpack_unreachable_expiration)
> + continue;
> +
> if (open_pack_index(p))
> die("cannot open pack index");
>
> @@ -2315,6 +2320,21 @@ static int option_parse_index_version(const struct option *opt,
> return 0;
> }
>
> +static int option_parse_unpack_unreachable(const struct option *opt,
> + const char *arg, int unset)
> +{
> + if (unset) {
> + unpack_unreachable = 0;
> + unpack_unreachable_expiration = 0;
> + }
> + else {
> + unpack_unreachable = 1;
> + if (arg)
> + unpack_unreachable_expiration = approxidate(arg);
> + }
> + return 0;
> +}
> +
> static int option_parse_ulong(const struct option *opt,
> const char *arg, int unset)
> {
> @@ -2392,8 +2412,9 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
> "include tag objects that refer to objects to be packed"),
> OPT_BOOL(0, "keep-unreachable", &keep_unreachable,
> "keep unreachable objects"),
> - OPT_BOOL(0, "unpack-unreachable", &unpack_unreachable,
> - "unpack unreachable objects"),
> + { OPTION_CALLBACK, 0, "unpack-unreachable", NULL, "time",
> + "unpack unreachable objects newer than <time>",
> + PARSE_OPT_OPTARG, option_parse_unpack_unreachable },
> OPT_BOOL(0, "thin", &thin,
> "create thin packs"),
> OPT_BOOL(0, "honor-pack-keep", &ignore_packed_keep,
> diff --git a/git-repack.sh b/git-repack.sh
> index 624feec..7579331 100755
> --- a/git-repack.sh
> +++ b/git-repack.sh
> @@ -15,6 +15,7 @@ F pass --no-reuse-object to git-pack-objects
> n do not run git-update-server-info
> q,quiet be quiet
> l pass --local to git-pack-objects
> +unpack-unreachable= with -A, do not loosen objects older than this
> Packing constraints
> window= size of the window used for delta compression
> window-memory= same as the above, but limit memory size instead of entries count
> @@ -33,6 +34,8 @@ do
> -a) all_into_one=t ;;
> -A) all_into_one=t
> unpack_unreachable=--unpack-unreachable ;;
> + --unpack-unreachable)
> + unpack_unreachable="--unpack-unreachable=$2"; shift ;;
> -d) remove_redundant=t ;;
> -q) GIT_QUIET=t ;;
> -f) no_reuse=--no-reuse-delta ;;
> @@ -76,7 +79,12 @@ case ",$all_into_one," in
> if test -n "$existing" -a -n "$unpack_unreachable" -a \
> -n "$remove_redundant"
> then
> - args="$args $unpack_unreachable"
> + # This may have arbitrary user arguments, so we
> + # have to protect it against whitespace splitting
> + # when it gets run as "pack-objects $args" later.
> + # Fortunately, we know it's an approxidate, so we
> + # can just use dots instead.
> + args="$args $(echo "$unpack_unreachable" | tr ' ' .)"
> fi
> fi
> ;;
> diff --git a/t/t7701-repack-unpack-unreachable.sh b/t/t7701-repack-unpack-unreachable.sh
> index 200ab61..b8d4cde 100755
> --- a/t/t7701-repack-unpack-unreachable.sh
> +++ b/t/t7701-repack-unpack-unreachable.sh
> @@ -95,4 +95,18 @@ test_expect_success 'unpacked objects receive timestamp of pack file' '
> compare_mtimes < mtimes
> '
>
> +test_expect_success 'do not bother loosening old objects' '
> + obj1=$(echo one | git hash-object -w --stdin) &&
> + obj2=$(echo two | git hash-object -w --stdin) &&
> + pack1=$(echo $obj1 | git pack-objects .git/objects/pack/pack) &&
> + pack2=$(echo $obj2 | git pack-objects .git/objects/pack/pack) &&
> + git prune-packed &&
> + git cat-file -p $obj1 &&
> + git cat-file -p $obj2 &&
> + test-chmtime =-86400 .git/objects/pack/pack-$pack2.pack &&
> + git repack -A -d --unpack-unreachable=1.hour.ago &&
> + git cat-file -p $obj1 &&
> + test_must_fail git cat-file -p $obj2
> +'
> +
> test_done
> --
> 1.7.10.11.g901cee
>
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