repack: remove pack_geometry API from the builtin

Now that the pack_geometry API is fully factored and isolated from the
rest of the builtin, declare it within repack.h and move its
implementation to "repack-geometry.c" as a separate component.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: ttaylorr

Makefile

@@ -1137,6 +1137,7 @@ LIB_OBJS += refs/ref-cache.o
 LIB_OBJS += refspec.o
 LIB_OBJS += remote.o
 LIB_OBJS += repack.o
+LIB_OBJS += repack-geometry.o
 LIB_OBJS += repack-promisor.o
 LIB_OBJS += replace-object.o
 LIB_OBJS += repo-settings.o

builtin/repack.c

@@ -107,241 +107,6 @@ static int repack_config(const char *var, const char *value,
 	return git_default_config(var, value, ctx, cb);
 }
 
-struct pack_geometry {
-	struct packed_git **pack;
-	uint32_t pack_nr, pack_alloc;
-	uint32_t split;
-
-	int split_factor;
-};
-
-static uint32_t pack_geometry_weight(struct packed_git *p)
-{
-	if (open_pack_index(p))
-		die(_("cannot open index for %s"), p->pack_name);
-	return p->num_objects;
-}
-
-static int pack_geometry_cmp(const void *va, const void *vb)
-{
-	uint32_t aw = pack_geometry_weight(*(struct packed_git **)va),
-		 bw = pack_geometry_weight(*(struct packed_git **)vb);
-
-	if (aw < bw)
-		return -1;
-	if (aw > bw)
-		return 1;
-	return 0;
-}
-
-static void pack_geometry_init(struct pack_geometry *geometry,
-			       struct existing_packs *existing,
-			       const struct pack_objects_args *args,
-			       int pack_kept_objects)
-{
-	struct packfile_store *packs = existing->repo->objects->packfiles;
-	struct packed_git *p;
-	struct strbuf buf = STRBUF_INIT;
-
-	for (p = packfile_store_get_all_packs(packs); p; p = p->next) {
-		if (args->local && !p->pack_local)
-			/*
-			 * When asked to only repack local packfiles we skip
-			 * over any packfiles that are borrowed from alternate
-			 * object directories.
-			 */
-			continue;
-
-		if (!pack_kept_objects) {
-			/*
-			 * Any pack that has its pack_keep bit set will
-			 * appear in existing->kept_packs below, but
-			 * this saves us from doing a more expensive
-			 * check.
-			 */
-			if (p->pack_keep)
-				continue;
-
-			/*
-			 * The pack may be kept via the --keep-pack
-			 * option; check 'existing->kept_packs' to
-			 * determine whether to ignore it.
-			 */
-			strbuf_reset(&buf);
-			strbuf_addstr(&buf, pack_basename(p));
-			strbuf_strip_suffix(&buf, ".pack");
-
-			if (string_list_has_string(&existing->kept_packs, buf.buf))
-				continue;
-		}
-		if (p->is_cruft)
-			continue;
-
-		ALLOC_GROW(geometry->pack,
-			   geometry->pack_nr + 1,
-			   geometry->pack_alloc);
-
-		geometry->pack[geometry->pack_nr] = p;
-		geometry->pack_nr++;
-	}
-
-	QSORT(geometry->pack, geometry->pack_nr, pack_geometry_cmp);
-	strbuf_release(&buf);
-}
-
-static void pack_geometry_split(struct pack_geometry *geometry)
-{
-	uint32_t i;
-	uint32_t split;
-	off_t total_size = 0;
-
-	if (!geometry->pack_nr) {
-		geometry->split = geometry->pack_nr;
-		return;
-	}
-
-	/*
-	 * First, count the number of packs (in descending order of size) which
-	 * already form a geometric progression.
-	 */
-	for (i = geometry->pack_nr - 1; i > 0; i--) {
-		struct packed_git *ours = geometry->pack[i];
-		struct packed_git *prev = geometry->pack[i - 1];
-
-		if (unsigned_mult_overflows(geometry->split_factor,
-					    pack_geometry_weight(prev)))
-			die(_("pack %s too large to consider in geometric "
-			      "progression"),
-			    prev->pack_name);
-
-		if (pack_geometry_weight(ours) <
-		    geometry->split_factor * pack_geometry_weight(prev))
-			break;
-	}
-
-	split = i;
-
-	if (split) {
-		/*
-		 * Move the split one to the right, since the top element in the
-		 * last-compared pair can't be in the progression. Only do this
-		 * when we split in the middle of the array (otherwise if we got
-		 * to the end, then the split is in the right place).
-		 */
-		split++;
-	}
-
-	/*
-	 * Then, anything to the left of 'split' must be in a new pack. But,
-	 * creating that new pack may cause packs in the heavy half to no longer
-	 * form a geometric progression.
-	 *
-	 * Compute an expected size of the new pack, and then determine how many
-	 * packs in the heavy half need to be joined into it (if any) to restore
-	 * the geometric progression.
-	 */
-	for (i = 0; i < split; i++) {
-		struct packed_git *p = geometry->pack[i];
-
-		if (unsigned_add_overflows(total_size, pack_geometry_weight(p)))
-			die(_("pack %s too large to roll up"), p->pack_name);
-		total_size += pack_geometry_weight(p);
-	}
-	for (i = split; i < geometry->pack_nr; i++) {
-		struct packed_git *ours = geometry->pack[i];
-
-		if (unsigned_mult_overflows(geometry->split_factor,
-					    total_size))
-			die(_("pack %s too large to roll up"), ours->pack_name);
-
-		if (pack_geometry_weight(ours) <
-		    geometry->split_factor * total_size) {
-			if (unsigned_add_overflows(total_size,
-						   pack_geometry_weight(ours)))
-				die(_("pack %s too large to roll up"),
-				    ours->pack_name);
-
-			split++;
-			total_size += pack_geometry_weight(ours);
-		} else
-			break;
-	}
-
-	geometry->split = split;
-}
-
-static struct packed_git *pack_geometry_preferred_pack(struct pack_geometry *geometry)
-{
-	uint32_t i;
-
-	if (!geometry) {
-		/*
-		 * No geometry means either an all-into-one repack (in which
-		 * case there is only one pack left and it is the largest) or an
-		 * incremental one.
-		 *
-		 * If repacking incrementally, then we could check the size of
-		 * all packs to determine which should be preferred, but leave
-		 * this for later.
-		 */
-		return NULL;
-	}
-	if (geometry->split == geometry->pack_nr)
-		return NULL;
-
-	/*
-	 * The preferred pack is the largest pack above the split line. In
-	 * other words, it is the largest pack that does not get rolled up in
-	 * the geometric repack.
-	 */
-	for (i = geometry->pack_nr; i > geometry->split; i--)
-		/*
-		 * A pack that is not local would never be included in a
-		 * multi-pack index. We thus skip over any non-local packs.
-		 */
-		if (geometry->pack[i - 1]->pack_local)
-			return geometry->pack[i - 1];
-
-	return NULL;
-}
-
-static void pack_geometry_remove_redundant(struct pack_geometry *geometry,
-					   struct string_list *names,
-					   struct existing_packs *existing,
-					   const char *packdir)
-{
-	const struct git_hash_algo *algop = existing->repo->hash_algo;
-	struct strbuf buf = STRBUF_INIT;
-	uint32_t i;
-
-	for (i = 0; i < geometry->split; i++) {
-		struct packed_git *p = geometry->pack[i];
-		if (string_list_has_string(names, hash_to_hex_algop(p->hash,
-								    algop)))
-			continue;
-
-		strbuf_reset(&buf);
-		strbuf_addstr(&buf, pack_basename(p));
-		strbuf_strip_suffix(&buf, ".pack");
-
-		if ((p->pack_keep) ||
-		    (string_list_has_string(&existing->kept_packs, buf.buf)))
-			continue;
-
-		repack_remove_redundant_pack(existing->repo, packdir, buf.buf);
-	}
-
-	strbuf_release(&buf);
-}
-
-static void pack_geometry_release(struct pack_geometry *geometry)
-{
-	if (!geometry)
-		return;
-
-	free(geometry->pack);
-}
-
 static int midx_has_unknown_packs(char **midx_pack_names,
 				  size_t midx_pack_names_nr,
 				  struct string_list *include,

meson.build

@@ -463,6 +463,7 @@ libgit_sources = [
   'reftable/writer.c',
   'remote.c',
   'repack.c',
+  'repack-geometry.c',
   'repack-promisor.c',
   'replace-object.c',
   'repo-settings.c',