To repack with a non-zero batch-size, first sort all pack-files by
their modified time. Second, walk those pack-files from oldest
to newest, compute their expected size, and add the packs to a list
if they are smaller than the given batch-size. Stop when the total
expected size is at least the batch size.
If the batch size is zero, select all packs in the multi-pack-index.
Finally, collect the objects from the multi-pack-index that are in
the selected packs and send them to 'git pack-objects'. Write a new
multi-pack-index that includes the new pack.
Using a batch size of zero is very similar to a standard 'git repack'
command, except that we do not delete the old packs and instead rely
on the new multi-pack-index to prevent new processes from reading the
old packs. This does not disrupt other Git processes that are currently
reading the old packs based on the old multi-pack-index.
While first designing a 'git multi-pack-index repack' operation, I
started by collecting the batches based on the actual size of the
objects instead of the size of the pack-files. This allows repacking
a large pack-file that has very few referencd objects. However, this
came at a significant cost of parsing pack-files instead of simply
reading the multi-pack-index and getting the file information for
the pack-files. The "expected size" version provides similar
behavior, but could skip a pack-file if the average object size is
much larger than the actual size of the referenced objects, or
can create a large pack if the actual size of the referenced objects
is larger than the expected size.
Signed-off-by: Derrick Stolee <dstolee@xxxxxxxxxxxxx>
---
midx.c | 150 +++++++++++++++++++++++++++++++++++-
t/t5319-multi-pack-index.sh | 28 +++++++
2 files changed, 177 insertions(+), 1 deletion(-)
diff --git a/midx.c b/midx.c
index 768a7dff73..01c6a05732 100644
--- a/midx.c
+++ b/midx.c
@@ -8,6 +8,7 @@
#include "sha1-lookup.h"
#include "midx.h"
#include "progress.h"
+#include "run-command.h"
#define MIDX_SIGNATURE 0x4d494458 /* "MIDX" */
#define MIDX_VERSION 1
@@ -1113,7 +1114,154 @@ int expire_midx_packs(const char *object_dir)
return result;
}
-int midx_repack(const char *object_dir, size_t batch_size)
+struct repack_info {
+ timestamp_t mtime;
+ uint32_t referenced_objects;
+ uint32_t pack_int_id;
+};
+
+static int compare_by_mtime(const void *a_, const void *b_)
{
+ const struct repack_info *a, *b;
+
+ a = (const struct repack_info *)a_;
+ b = (const struct repack_info *)b_;
+
+ if (a->mtime < b->mtime)
+ return -1;
+ if (a->mtime > b->mtime)
+ return 1;
+ return 0;
+}
+
+static int fill_included_packs_all(struct multi_pack_index *m,
+ unsigned char *include_pack)
+{
+ uint32_t i;
+
+ for (i = 0; i < m->num_packs; i++)
+ include_pack[i] = 1;
+
+ return m->num_packs < 2;
+}
+
+static int fill_included_packs_batch(struct multi_pack_index *m,
+ unsigned char *include_pack,
+ size_t batch_size)
+{
+ uint32_t i, packs_to_repack;
+ size_t total_size;
+ struct repack_info *pack_info = xcalloc(m->num_packs, sizeof(struct repack_info));
+
+ for (i = 0; i < m->num_packs; i++) {
+ pack_info[i].pack_int_id = i;
+
+ if (prepare_midx_pack(m, i))
+ continue;
+
+ pack_info[i].mtime = m->packs[i]->mtime;
+ }
+
+ for (i = 0; batch_size && i < m->num_objects; i++) {
+ uint32_t pack_int_id = nth_midxed_pack_int_id(m, i);
+ pack_info[pack_int_id].referenced_objects++;
+ }
+
+ QSORT(pack_info, m->num_packs, compare_by_mtime);
+
+ total_size = 0;
+ packs_to_repack = 0;
+ for (i = 0; total_size < batch_size && i < m->num_packs; i++) {
+ int pack_int_id = pack_info[i].pack_int_id;
+ struct packed_git *p = m->packs[pack_int_id];
+ size_t expected_size;
+
+ if (!p)
+ continue;
+ if (open_pack_index(p) || !p->num_objects)
+ continue;
+
+ expected_size = (size_t)(p->pack_size
+ * pack_info[i].referenced_objects);
+ expected_size /= p->num_objects;
+
+ if (expected_size >= batch_size)
+ continue;
+
+ packs_to_repack++;
+ total_size += expected_size;
+ include_pack[pack_int_id] = 1;
+ }
+
+ free(pack_info);
+
+ if (total_size < batch_size || packs_to_repack < 2)
+ return 1;
+
return 0;
+}
+
+int midx_repack(const char *object_dir, size_t batch_size)
+{
+ int result = 0;
+ uint32_t i;
+ unsigned char *include_pack;
+ struct child_process cmd = CHILD_PROCESS_INIT;
+ struct strbuf base_name = STRBUF_INIT;
+ struct multi_pack_index *m = load_multi_pack_index(object_dir, 1);
+
+ if (!m)
+ return 0;
+
+ include_pack = xcalloc(m->num_packs, sizeof(unsigned char));
+
+ if (batch_size) {
+ if (fill_included_packs_batch(m, include_pack, batch_size))
+ goto cleanup;
+ } else if (fill_included_packs_all(m, include_pack))
+ goto cleanup;
+
+ argv_array_push(&cmd.args, "pack-objects");
+
+ strbuf_addstr(&base_name, object_dir);
+ strbuf_addstr(&base_name, "/pack/pack");
+ argv_array_push(&cmd.args, base_name.buf);
+ strbuf_release(&base_name);
+
+ cmd.git_cmd = 1;
+ cmd.in = cmd.out = -1;
+
+ if (start_command(&cmd)) {
+ error(_("could not start pack-objects"));
+ result = 1;
+ goto cleanup;
+ }
+
+ for (i = 0; i < m->num_objects; i++) {
+ struct object_id oid;
+ uint32_t pack_int_id = nth_midxed_pack_int_id(m, i);
+
+ if (!include_pack[pack_int_id])
+ continue;
+
+ nth_midxed_object_oid(&oid, m, i);
+ xwrite(cmd.in, oid_to_hex(&oid), the_hash_algo->hexsz);
+ xwrite(cmd.in, "\n", 1);
+ }
+ close(cmd.in);
+
+ if (finish_command(&cmd)) {
+ error(_("could not finish pack-objects"));
+ result = 1;
+ goto cleanup;
+ }
+
+ result = write_midx_internal(object_dir, m, NULL);
+ m = NULL;
+
+cleanup:
+ if (m)
+ close_midx(m);
+ free(include_pack);
+ return result;
}
diff --git a/t/t5319-multi-pack-index.sh b/t/t5319-multi-pack-index.sh
index 26ae8b3f62..d6c1353514 100755
--- a/t/t5319-multi-pack-index.sh
+++ b/t/t5319-multi-pack-index.sh
@@ -435,4 +435,32 @@ test_expect_success 'repack with minimum size does not alter existing packs' '
)
'
+test_expect_success 'repack creates a new pack' '
+ (
+ cd dup &&
+ ls .git/objects/pack/*idx >idx-list &&
+ test_line_count = 5 idx-list &&
+ THIRD_SMALLEST_SIZE=$(ls -l .git/objects/pack/*pack | awk "{print \$5;}" | sort -n | head -n 3 | tail -n 1) &&
+ BATCH_SIZE=$(($THIRD_SMALLEST_SIZE + 1)) &&
+ git multi-pack-index repack --batch-size=$BATCH_SIZE &&
+ ls .git/objects/pack/*idx >idx-list &&
+ test_line_count = 6 idx-list &&
+ test-tool read-midx .git/objects | grep idx >midx-list &&
+ test_line_count = 6 midx-list
+ )
+'
+
+test_expect_success 'expire removes repacked packs' '
+ (
+ cd dup &&
+ ls -al .git/objects/pack/*pack &&
+ ls -S .git/objects/pack/*pack | head -n 4 >expect &&
+ git multi-pack-index expire &&
+ ls -S .git/objects/pack/*pack >actual &&
+ test_cmp expect actual &&
+ test-tool read-midx .git/objects | grep idx >midx-list &&
+ test_line_count = 4 midx-list
+ )
+'
+
test_done
--
2.21.0.1096.g1c91fdc207
