From: Derrick Stolee <dsto...@microsoft.com>
In an environment where the multi-pack-index is useful, it is due
to many pack-files and an inability to repack the object store
into a single pack-file. However, it is likely that many of these
pack-files are rather small, and could be repacked into a slightly
larger pack-file without too much effort. It may also be important
to ensure the object store is highly available and the repack
operation does not interrupt concurrent git commands.
Introduce a 'repack' subcommand to 'git multi-pack-index' that
takes a '--batch-size' option. The verb will inspect the
multi-pack-index for referenced pack-files whose size is smaller
than the batch size, until collecting a list of pack-files whose
sizes sum to larger than the batch size. Then, a new pack-file
will be created containing the objects from those pack-files that
are referenced by the multi-pack-index. The resulting pack is
likely to actually be smaller than the batch size due to
compression and the fact that there may be objects in the pack-
files that have duplicate copies in other pack-files.
The current change introduces the command-line arguments, and we
add a test that ensures we parse these options properly. Since
we specify a small batch size, we will guarantee that future
implementations do not change the list of pack-files.
Signed-off-by: Derrick Stolee <dsto...@microsoft.com>
---
Documentation/git-multi-pack-index.txt | 11 +++++++++++
builtin/multi-pack-index.c | 10 +++++++++-
midx.c | 5 +++++
midx.h | 1 +
t/t5319-multi-pack-index.sh | 11 +++++++++++
5 files changed, 37 insertions(+), 1 deletion(-)
diff --git a/Documentation/git-multi-pack-index.txt
b/Documentation/git-multi-pack-index.txt
index 6186c4c936..cc63531cc0 100644
--- a/Documentation/git-multi-pack-index.txt
+++ b/Documentation/git-multi-pack-index.txt
@@ -36,6 +36,17 @@ expire::
have no objects referenced by the MIDX. Rewrite the MIDX file
afterward to remove all references to these pack-files.
+repack::
+ Collect a batch of pack-files whose size are all at most the
+ size given by --batch-size, but whose sizes sum to larger
+ than --batch-size. The batch is selected by greedily adding
+ small pack-files starting with the oldest pack-files that fit
+ the size. Create a new pack-file containing the objects the
+ multi-pack-index indexes into those pack-files, and rewrite
+ the multi-pack-index to contain that pack-file. A later run
+ of 'git multi-pack-index expire' will delete the pack-files
+ that were part of this batch.
+
EXAMPLES
--------
diff --git a/builtin/multi-pack-index.c b/builtin/multi-pack-index.c
index 145de3a46c..d87a2235e3 100644
--- a/builtin/multi-pack-index.c
+++ b/builtin/multi-pack-index.c
@@ -5,12 +5,13 @@
#include "midx.h"
static char const * const builtin_multi_pack_index_usage[] = {
- N_("git multi-pack-index [--object-dir=<dir>] (write|verify|expire)"),
+ N_("git multi-pack-index [--object-dir=<dir>]
(write|verify|expire|repack --batch-size=<size>)"),
NULL
};
static struct opts_multi_pack_index {
const char *object_dir;
+ unsigned long batch_size;
} opts;
int cmd_multi_pack_index(int argc, const char **argv,
@@ -19,6 +20,8 @@ int cmd_multi_pack_index(int argc, const char **argv,
static struct option builtin_multi_pack_index_options[] = {
OPT_FILENAME(0, "object-dir", &opts.object_dir,
N_("object directory containing set of packfile and
pack-index pairs")),
+ OPT_MAGNITUDE(0, "batch-size", &opts.batch_size,
+ N_("during repack, collect pack-files of smaller size into a
batch that is larger than this size")),
OPT_END(),
};
@@ -40,6 +43,11 @@ int cmd_multi_pack_index(int argc, const char **argv,
return 1;
}
+ if (!strcmp(argv[0], "repack"))
+ return midx_repack(opts.object_dir, (size_t)opts.batch_size);
+ if (opts.batch_size)
+ die(_("--batch-size option is only for 'repack' verb"));
+
if (!strcmp(argv[0], "write"))
return write_midx_file(opts.object_dir);
if (!strcmp(argv[0], "verify"))
diff --git a/midx.c b/midx.c
index 043cd1fd97..127c43f7b0 100644
--- a/midx.c
+++ b/midx.c
@@ -1110,3 +1110,8 @@ int expire_midx_packs(const char *object_dir)
string_list_clear(&packs_to_drop, 0);
return result;
}
+
+int midx_repack(const char *object_dir, size_t batch_size)
+{
+ return 0;
+}
diff --git a/midx.h b/midx.h
index e3a2b740b5..394a21ee96 100644
--- a/midx.h
+++ b/midx.h
@@ -50,6 +50,7 @@ int write_midx_file(const char *object_dir);
void clear_midx_file(struct repository *r);
int verify_midx_file(const char *object_dir);
int expire_midx_packs(const char *object_dir);
+int midx_repack(const char *object_dir, size_t batch_size);
void close_midx(struct multi_pack_index *m);
diff --git a/t/t5319-multi-pack-index.sh b/t/t5319-multi-pack-index.sh
index 210279a3cf..f675621080 100755
--- a/t/t5319-multi-pack-index.sh
+++ b/t/t5319-multi-pack-index.sh
@@ -410,4 +410,15 @@ test_expect_success 'expire removes unreferenced packs' '
)
'
+test_expect_success 'repack with minimum size does not alter existing packs' '
+ (
+ cd dup &&
+ ls .git/objects/pack >expect &&
+ MINSIZE=$(ls -l .git/objects/pack/*pack | awk "{print \$5;}" |
sort -n | head -n 1) &&
+ git multi-pack-index repack --batch-size=$MINSIZE &&
+ ls .git/objects/pack >actual &&
+ test_cmp expect actual
+ )
+'
+
test_done
--
gitgitgadget
