Merge branch 'cc/repack-sift-filtered-objects-to-separate-pack'

"git repack" machinery learns to pay attention to the "--filter="
option.

* cc/repack-sift-filtered-objects-to-separate-pack:
  gc: add `gc.repackFilterTo` config option
  repack: implement `--filter-to` for storing filtered out objects
  gc: add `gc.repackFilter` config option
  repack: add `--filter=<filter-spec>` option
  pack-bitmap-write: rebuild using new bitmap when remapping
  repack: refactor finding pack prefix
  repack: refactor finishing pack-objects command
  t/helper: add 'find-pack' test-tool
  pack-objects: allow `--filter` without `--stdout`

Documentation/config/gc.txt

@@ -145,6 +145,22 @@ Multiple hooks are supported, but all must exit successfully, else the
 operation (either generating a cruft pack or unpacking unreachable
 objects) will be halted.
 
+gc.repackFilter::
+	When repacking, use the specified filter to move certain
+	objects into a separate packfile.  See the
+	`--filter=<filter-spec>` option of linkgit:git-repack[1].
+
+gc.repackFilterTo::
+	When repacking and using a filter, see `gc.repackFilter`, the
+	specified location will be used to create the packfile
+	containing the filtered out objects. **WARNING:** The
+	specified location should be accessible, using for example the
+	Git alternates mechanism, otherwise the repo could be
+	considered corrupt by Git as it migh not be able to access the
+	objects in that packfile. See the `--filter-to=<dir>` option
+	of linkgit:git-repack[1] and the `objects/info/alternates`
+	section of linkgit:gitrepository-layout[5].
+
 gc.rerereResolved::
 	Records of conflicted merge you resolved earlier are
 	kept for this many days when 'git rerere gc' is run.

Documentation/git-pack-objects.txt

@@ -296,8 +296,8 @@ So does `git bundle` (see linkgit:git-bundle[1]) when it creates a bundle.
 	nevertheless.
 
 --filter=<filter-spec>::
-	Requires `--stdout`.  Omits certain objects (usually blobs) from
-	the resulting packfile.  See linkgit:git-rev-list[1] for valid
+	Omits certain objects (usually blobs) from the resulting
+	packfile.  See linkgit:git-rev-list[1] for valid
 	`<filter-spec>` forms.
 
 --no-filter::

Documentation/git-repack.txt

@@ -143,6 +143,29 @@ depth is 4095.
 	a larger and slower repository; see the discussion in
 	`pack.packSizeLimit`.
 
+--filter=<filter-spec>::
+	Remove objects matching the filter specification from the
+	resulting packfile and put them into a separate packfile. Note
+	that objects used in the working directory are not filtered
+	out. So for the split to fully work, it's best to perform it
+	in a bare repo and to use the `-a` and `-d` options along with
+	this option.  Also `--no-write-bitmap-index` (or the
+	`repack.writebitmaps` config option set to `false`) should be
+	used otherwise writing bitmap index will fail, as it supposes
+	a single packfile containing all the objects. See
+	linkgit:git-rev-list[1] for valid `<filter-spec>` forms.
+
+--filter-to=<dir>::
+	Write the pack containing filtered out objects to the
+	directory `<dir>`. Only useful with `--filter`. This can be
+	used for putting the pack on a separate object directory that
+	is accessed through the Git alternates mechanism. **WARNING:**
+	If the packfile containing the filtered out objects is not
+	accessible, the repo can become corrupt as it might not be
+	possible to access the objects in that packfile. See the
+	`objects` and `objects/info/alternates` sections of
+	linkgit:gitrepository-layout[5].
+
 -b::
 --write-bitmap-index::
 	Write a reachability bitmap index as part of the repack. This

Makefile

@@ -800,6 +800,7 @@ TEST_BUILTINS_OBJS += test-dump-untracked-cache.o
 TEST_BUILTINS_OBJS += test-env-helper.o
 TEST_BUILTINS_OBJS += test-example-decorate.o
 TEST_BUILTINS_OBJS += test-fast-rebase.o
+TEST_BUILTINS_OBJS += test-find-pack.o
 TEST_BUILTINS_OBJS += test-fsmonitor-client.o
 TEST_BUILTINS_OBJS += test-genrandom.o
 TEST_BUILTINS_OBJS += test-genzeros.o

builtin/gc.c

@@ -61,6 +61,8 @@ static timestamp_t gc_log_expire_time;
 static const char *gc_log_expire = "1.day.ago";
 static const char *prune_expire = "2.weeks.ago";
 static const char *prune_worktrees_expire = "3.months.ago";
+static char *repack_filter;
+static char *repack_filter_to;
 static unsigned long big_pack_threshold;
 static unsigned long max_delta_cache_size = DEFAULT_DELTA_CACHE_SIZE;
 
@@ -170,6 +172,9 @@ static void gc_config(void)
 	git_config_get_ulong("gc.bigpackthreshold", &big_pack_threshold);
 	git_config_get_ulong("pack.deltacachesize", &max_delta_cache_size);
 
+	git_config_get_string("gc.repackfilter", &repack_filter);
+	git_config_get_string("gc.repackfilterto", &repack_filter_to);
+
 	git_config(git_default_config, NULL);
 }
 
@@ -355,6 +360,11 @@ static void add_repack_all_option(struct string_list *keep_pack)
 
 	if (keep_pack)
 		for_each_string_list(keep_pack, keep_one_pack, NULL);
+
+	if (repack_filter && *repack_filter)
+		strvec_pushf(&repack, "--filter=%s", repack_filter);
+	if (repack_filter_to && *repack_filter_to)
+		strvec_pushf(&repack, "--filter-to=%s", repack_filter_to);
 }
 
 static void add_repack_incremental_option(void)

builtin/pack-objects.c

@@ -4402,12 +4402,8 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
 	if (!rev_list_all || !rev_list_reflog || !rev_list_index)
 		unpack_unreachable_expiration = 0;
 
-	if (filter_options.choice) {
-		if (!pack_to_stdout)
-			die(_("cannot use --filter without --stdout"));
-		if (stdin_packs)
-			die(_("cannot use --filter with --stdin-packs"));
-	}
+	if (stdin_packs && filter_options.choice)
+		die(_("cannot use --filter with --stdin-packs"));
 
 	if (stdin_packs && use_internal_rev_list)
 		die(_("cannot use internal rev list with --stdin-packs"));

builtin/repack.c

@@ -21,6 +21,7 @@
 #include "pack.h"
 #include "pack-bitmap.h"
 #include "refs.h"
+#include "list-objects-filter-options.h"
 
 #define ALL_INTO_ONE 1
 #define LOOSEN_UNREACHABLE 2
@@ -56,6 +57,7 @@ struct pack_objects_args {
 	int no_reuse_object;
 	int quiet;
 	int local;
+	struct list_objects_filter_options filter_options;
 };
 
 static int repack_config(const char *var, const char *value,
@@ -806,6 +808,86 @@ static void remove_redundant_bitmaps(struct string_list *include,
 	strbuf_release(&path);
 }
 
+static int finish_pack_objects_cmd(struct child_process *cmd,
+				   struct string_list *names,
+				   int local)
+{
+	FILE *out;
+	struct strbuf line = STRBUF_INIT;
+
+	out = xfdopen(cmd->out, "r");
+	while (strbuf_getline_lf(&line, out) != EOF) {
+		struct string_list_item *item;
+
+		if (line.len != the_hash_algo->hexsz)
+			die(_("repack: Expecting full hex object ID lines only "
+			      "from pack-objects."));
+		/*
+		 * Avoid putting packs written outside of the repository in the
+		 * list of names.
+		 */
+		if (local) {
+			item = string_list_append(names, line.buf);
+			item->util = populate_pack_exts(line.buf);
+		}
+	}
+	fclose(out);
+
+	strbuf_release(&line);
+
+	return finish_command(cmd);
+}
+
+static int write_filtered_pack(const struct pack_objects_args *args,
+			       const char *destination,
+			       const char *pack_prefix,
+			       struct existing_packs *existing,
+			       struct string_list *names)
+{
+	struct child_process cmd = CHILD_PROCESS_INIT;
+	struct string_list_item *item;
+	FILE *in;
+	int ret;
+	const char *caret;
+	const char *scratch;
+	int local = skip_prefix(destination, packdir, &scratch);
+
+	prepare_pack_objects(&cmd, args, destination);
+
+	strvec_push(&cmd.args, "--stdin-packs");
+
+	if (!pack_kept_objects)
+		strvec_push(&cmd.args, "--honor-pack-keep");
+	for_each_string_list_item(item, &existing->kept_packs)
+		strvec_pushf(&cmd.args, "--keep-pack=%s", item->string);
+
+	cmd.in = -1;
+
+	ret = start_command(&cmd);
+	if (ret)
+		return ret;
+
+	/*
+	 * Here 'names' contains only the pack(s) that were just
+	 * written, which is exactly the packs we want to keep. Also
+	 * 'existing_kept_packs' already contains the packs in
+	 * 'keep_pack_list'.
+	 */
+	in = xfdopen(cmd.in, "w");
+	for_each_string_list_item(item, names)
+		fprintf(in, "^%s-%s.pack\n", pack_prefix, item->string);
+	for_each_string_list_item(item, &existing->non_kept_packs)
+		fprintf(in, "%s.pack\n", item->string);
+	for_each_string_list_item(item, &existing->cruft_packs)
+		fprintf(in, "%s.pack\n", item->string);
+	caret = pack_kept_objects ? "" : "^";
+	for_each_string_list_item(item, &existing->kept_packs)
+		fprintf(in, "%s%s.pack\n", caret, item->string);
+	fclose(in);
+
+	return finish_pack_objects_cmd(&cmd, names, local);
+}
+
 static int write_cruft_pack(const struct pack_objects_args *args,
 			    const char *destination,
 			    const char *pack_prefix,
@@ -814,9 +896,8 @@ static int write_cruft_pack(const struct pack_objects_args *args,
 			    struct existing_packs *existing)
 {
 	struct child_process cmd = CHILD_PROCESS_INIT;
-	struct strbuf line = STRBUF_INIT;
 	struct string_list_item *item;
-	FILE *in, *out;
+	FILE *in;
 	int ret;
 	const char *scratch;
 	int local = skip_prefix(destination, packdir, &scratch);
@@ -861,27 +942,18 @@ static int write_cruft_pack(const struct pack_objects_args *args,
 		fprintf(in, "%s.pack\n", item->string);
 	fclose(in);
 
-	out = xfdopen(cmd.out, "r");
-	while (strbuf_getline_lf(&line, out) != EOF) {
-		struct string_list_item *item;
-
-		if (line.len != the_hash_algo->hexsz)
-			die(_("repack: Expecting full hex object ID lines only "
-			      "from pack-objects."));
-		/*
-		 * avoid putting packs written outside of the repository in the
-		 * list of names
-		 */
-		if (local) {
-			item = string_list_append(names, line.buf);
-			item->util = populate_pack_exts(line.buf);
-		}
-	}
-	fclose(out);
-
-	strbuf_release(&line);
+	return finish_pack_objects_cmd(&cmd, names, local);
+}
 
-	return finish_command(&cmd);
+static const char *find_pack_prefix(const char *packdir, const char *packtmp)
+{
+	const char *pack_prefix;
+	if (!skip_prefix(packtmp, packdir, &pack_prefix))
+		die(_("pack prefix %s does not begin with objdir %s"),
+		    packtmp, packdir);
+	if (*pack_prefix == '/')
+		pack_prefix++;
+	return pack_prefix;
 }
 
 int cmd_repack(int argc, const char **argv, const char *prefix)
@@ -891,10 +963,8 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 	struct string_list names = STRING_LIST_INIT_DUP;
 	struct existing_packs existing = EXISTING_PACKS_INIT;
 	struct pack_geometry geometry = { 0 };
-	struct strbuf line = STRBUF_INIT;
 	struct tempfile *refs_snapshot = NULL;
 	int i, ext, ret;
-	FILE *out;
 	int show_progress;
 
 	/* variables to be filled by option parsing */
@@ -907,6 +977,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 	int write_midx = 0;
 	const char *cruft_expiration = NULL;
 	const char *expire_to = NULL;
+	const char *filter_to = NULL;
 
 	struct option builtin_repack_options[] = {
 		OPT_BIT('a', NULL, &pack_everything,
@@ -948,6 +1019,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 				N_("limits the maximum number of threads")),
 		OPT_STRING(0, "max-pack-size", &po_args.max_pack_size, N_("bytes"),
 				N_("maximum size of each packfile")),
+		OPT_PARSE_LIST_OBJECTS_FILTER(&po_args.filter_options),
 		OPT_BOOL(0, "pack-kept-objects", &pack_kept_objects,
 				N_("repack objects in packs marked with .keep")),
 		OPT_STRING_LIST(0, "keep-pack", &keep_pack_list, N_("name"),
@@ -958,9 +1030,13 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 			   N_("write a multi-pack index of the resulting packs")),
 		OPT_STRING(0, "expire-to", &expire_to, N_("dir"),
 			   N_("pack prefix to store a pack containing pruned objects")),
+		OPT_STRING(0, "filter-to", &filter_to, N_("dir"),
+			   N_("pack prefix to store a pack containing filtered out objects")),
 		OPT_END()
 	};
 
+	list_objects_filter_init(&po_args.filter_options);
+
 	git_config(repack_config, &cruft_po_args);
 
 	argc = parse_options(argc, argv, prefix, builtin_repack_options,
@@ -1101,6 +1177,12 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 		strvec_push(&cmd.args, "--incremental");
 	}
 
+	if (po_args.filter_options.choice)
+		strvec_pushf(&cmd.args, "--filter=%s",
+			     expand_list_objects_filter_spec(&po_args.filter_options));
+	else if (filter_to)
+		die(_("option '%s' can only be used along with '%s'"), "--filter-to", "--filter");
+
 	if (geometry.split_factor)
 		cmd.in = -1;
 	else
@@ -1124,31 +1206,15 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 		fclose(in);
 	}
 
-	out = xfdopen(cmd.out, "r");
-	while (strbuf_getline_lf(&line, out) != EOF) {
-		struct string_list_item *item;
-
-		if (line.len != the_hash_algo->hexsz)
-			die(_("repack: Expecting full hex object ID lines only from pack-objects."));
-		item = string_list_append(&names, line.buf);
-		item->util = populate_pack_exts(item->string);
-	}
-	strbuf_release(&line);
-	fclose(out);
-	ret = finish_command(&cmd);
+	ret = finish_pack_objects_cmd(&cmd, &names, 1);
 	if (ret)
 		goto cleanup;
 
 	if (!names.nr && !po_args.quiet)
 		printf_ln(_("Nothing new to pack."));
 
 	if (pack_everything & PACK_CRUFT) {
-		const char *pack_prefix;
-		if (!skip_prefix(packtmp, packdir, &pack_prefix))
-			die(_("pack prefix %s does not begin with objdir %s"),
-			    packtmp, packdir);
-		if (*pack_prefix == '/')
-			pack_prefix++;
+		const char *pack_prefix = find_pack_prefix(packdir, packtmp);
 
 		if (!cruft_po_args.window)
 			cruft_po_args.window = po_args.window;
@@ -1203,6 +1269,19 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 		}
 	}
 
+	if (po_args.filter_options.choice) {
+		if (!filter_to)
+			filter_to = packtmp;
+
+		ret = write_filtered_pack(&po_args,
+					  filter_to,
+					  find_pack_prefix(packdir, packtmp),
+					  &existing,
+					  &names);
+		if (ret)
+			goto cleanup;
+	}
+
 	string_list_sort(&names);
 
 	close_object_store(the_repository->objects);
@@ -1295,6 +1374,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 	string_list_clear(&names, 1);
 	existing_packs_release(&existing);
 	free_pack_geometry(&geometry);
+	list_objects_filter_release(&po_args.filter_options);
 
 	return ret;
 }