pack-objects: add list-objects filtering

Teach pack-objects to use the filtering provided by the
traverse_commit_list_filtered() interface to omit unwanted
objects from the resulting packfile.

Filtering requires the use of the "--stdout" option.

Add t5317 test.

In the future, we will introduce a "partial clone" mechanism
wherein an object in a repo, obtained from a remote, may
reference a missing object that can be dynamically fetched from
that remote once needed.  This "partial clone" mechanism will
have a way, sometimes slow, of determining if a missing link
is one of the links expected to be produced by this mechanism.

This patch introduces handling of missing objects to help
debugging and development of the "partial clone" mechanism,
and once the mechanism is implemented, for a power user to
perform operations that are missing-object aware without
incurring the cost of checking if a missing link is expected.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Reviewed-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

3 files changed, 456 insertions, 2 deletions

diff --git a/Documentation/git-pack-objects.txt b/Documentation/git-pack-objects.txt
index 473a161..b924c6c 100644
--- a/Documentation/git-pack-objects.txt
+++ b/Documentation/git-pack-objects.txt
@@ -12,7 +12,8 @@ SYNOPSIS
 'git pack-objects' [-q | --progress | --all-progress] [--all-progress-implied]
 	[--no-reuse-delta] [--delta-base-offset] [--non-empty]
 	[--local] [--incremental] [--window=<n>] [--depth=<n>]
-	[--revs [--unpacked | --all]] [--stdout | base-name]
+	[--revs [--unpacked | --all]]
+	[--stdout [--filter=<filter-spec>] | base-name]
 	[--shallow] [--keep-true-parents] < object-list
 
 
@@ -236,6 +237,22 @@ So does `git bundle` (see linkgit:git-bundle[1]) when it creates a bundle.
 	With this option, parents that are hidden by grafts are packed
 	nevertheless.
 
+--filter=<filter-spec>::
+	Requires `--stdout`.  Omits certain objects (usually blobs) from
+	the resulting packfile.  See linkgit:git-rev-list[1] for valid
+	`<filter-spec>` forms.
+
+--missing=<missing-action>::
+	A debug option to help with future "partial clone" development.
+	This option specifies how missing objects are handled.
++
+The form '--missing=error' requests that pack-objects stop with an error if
+a missing object is encountered.  This is the default action.
++
+The form '--missing=allow-any' will allow object traversal to continue
+if a missing object is encountered.  Missing objects will silently be
+omitted from the results.
+
 SEE ALSO
 --------
 linkgit:git-rev-list[1]
diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 6e77dfd..45ad35d 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -15,6 +15,8 @@
 #include "diff.h"
 #include "revision.h"
 #include "list-objects.h"
+#include "list-objects-filter.h"
+#include "list-objects-filter-options.h"
 #include "pack-objects.h"
 #include "progress.h"
 #include "refs.h"
@@ -79,6 +81,15 @@ static unsigned long cache_max_small_delta_size = 1000;
 
 static unsigned long window_memory_limit = 0;
 
+static struct list_objects_filter_options filter_options;
+
+enum missing_action {
+	MA_ERROR = 0,    /* fail if any missing objects are encountered */
+	MA_ALLOW_ANY,    /* silently allow ALL missing objects */
+};
+static enum missing_action arg_missing_action;
+static show_object_fn fn_show_object;
+
 /*
  * stats
  */
@@ -2552,6 +2563,42 @@ static void show_object(struct object *obj, const char *name, void *data)
 	obj->flags |= OBJECT_ADDED;
 }
 
+static void show_object__ma_allow_any(struct object *obj, const char *name, void *data)
+{
+	assert(arg_missing_action == MA_ALLOW_ANY);
+
+	/*
+	 * Quietly ignore ALL missing objects.  This avoids problems with
+	 * staging them now and getting an odd error later.
+	 */
+	if (!has_object_file(&obj->oid))
+		return;
+
+	show_object(obj, name, data);
+}
+
+static int option_parse_missing_action(const struct option *opt,
+				       const char *arg, int unset)
+{
+	assert(arg);
+	assert(!unset);
+
+	if (!strcmp(arg, "error")) {
+		arg_missing_action = MA_ERROR;
+		fn_show_object = show_object;
+		return 0;
+	}
+
+	if (!strcmp(arg, "allow-any")) {
+		arg_missing_action = MA_ALLOW_ANY;
+		fn_show_object = show_object__ma_allow_any;
+		return 0;
+	}
+
+	die(_("invalid value for --missing"));
+	return 0;
+}
+
 static void show_edge(struct commit *commit)
 {
 	add_preferred_base(commit->object.oid.hash);
@@ -2816,7 +2863,12 @@ static void get_object_list(int ac, const char **av)
 	if (prepare_revision_walk(&revs))
 		die("revision walk setup failed");
 	mark_edges_uninteresting(&revs, show_edge);
-	traverse_commit_list(&revs, show_commit, show_object, NULL);
+
+	if (!fn_show_object)
+		fn_show_object = show_object;
+	traverse_commit_list_filtered(&filter_options, &revs,
+				      show_commit, fn_show_object, NULL,
+				      NULL);
 
 	if (unpack_unreachable_expiration) {
 		revs.ignore_missing_links = 1;
@@ -2952,6 +3004,10 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
 			 N_("use a bitmap index if available to speed up counting objects")),
 		OPT_BOOL(0, "write-bitmap-index", &write_bitmap_index,
 			 N_("write a bitmap index together with the pack index")),
+		OPT_PARSE_LIST_OBJECTS_FILTER(&filter_options),
+		{ OPTION_CALLBACK, 0, "missing", NULL, N_("action"),
+		  N_("handling for missing objects"), PARSE_OPT_NONEG,
+		  option_parse_missing_action },
 		OPT_END(),
 	};
 
@@ -3028,6 +3084,12 @@ 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.");
+		use_bitmap_index = 0;
+	}
+
 	/*
 	 * "soft" reasons not to use bitmaps - for on-disk repack by default we want
 	 *
diff --git a/t/t5317-pack-objects-filter-objects.sh b/t/t5317-pack-objects-filter-objects.sh
new file mode 100755
index 0000000..1b0acc3
--- /dev/null
+++ b/t/t5317-pack-objects-filter-objects.sh
@@ -0,0 +1,375 @@
+#!/bin/sh
+
+test_description='git pack-objects using object filtering'
+
+. ./test-lib.sh
+
+# Test blob:none filter.
+
+test_expect_success 'setup r1' '
+	echo "{print \$1}" >print_1.awk &&
+	echo "{print \$2}" >print_2.awk &&
+
+	git init r1 &&
+	for n in 1 2 3 4 5
+	do
+		echo "This is file: $n" > r1/file.$n
+		git -C r1 add file.$n
+		git -C r1 commit -m "$n"
+	done
+'
+
+test_expect_success 'verify blob count in normal packfile' '
+	git -C r1 ls-files -s file.1 file.2 file.3 file.4 file.5 \
+		| awk -f print_2.awk \
+		| sort >expected &&
+	git -C r1 pack-objects --rev --stdout >all.pack <<-EOF &&
+	HEAD
+	EOF
+	git -C r1 index-pack ../all.pack &&
+	git -C r1 verify-pack -v ../all.pack \
+		| grep blob \
+		| awk -f print_1.awk \
+		| sort >observed &&
+	test_cmp observed expected
+'
+
+test_expect_success 'verify blob:none packfile has no blobs' '
+	git -C r1 pack-objects --rev --stdout --filter=blob:none >filter.pack <<-EOF &&
+	HEAD
+	EOF
+	git -C r1 index-pack ../filter.pack &&
+	git -C r1 verify-pack -v ../filter.pack \
+		| grep blob \
+		| awk -f print_1.awk \
+		| sort >observed &&
+	nr=$(wc -l <observed) &&
+	test 0 -eq $nr
+'
+
+test_expect_success 'verify normal and blob:none packfiles have same commits/trees' '
+	git -C r1 verify-pack -v ../all.pack \
+		| grep -E "commit|tree" \
+		| awk -f print_1.awk \
+		| sort >expected &&
+	git -C r1 verify-pack -v ../filter.pack \
+		| grep -E "commit|tree" \
+		| awk -f print_1.awk \
+		| sort >observed &&
+	test_cmp observed expected
+'
+
+# Test blob:limit=<n>[kmg] filter.
+# We boundary test around the size parameter.  The filter is strictly less than
+# the value, so size 500 and 1000 should have the same results, but 1001 should
+# filter more.
+
+test_expect_success 'setup r2' '
+	git init r2 &&
+	for n in 1000 10000
+	do
+		printf "%"$n"s" X > r2/large.$n
+		git -C r2 add large.$n
+		git -C r2 commit -m "$n"
+	done
+'
+
+test_expect_success 'verify blob count in normal packfile' '
+	git -C r2 ls-files -s large.1000 large.10000 \
+		| awk -f print_2.awk \
+		| sort >expected &&
+	git -C r2 pack-objects --rev --stdout >all.pack <<-EOF &&
+	HEAD
+	EOF
+	git -C r2 index-pack ../all.pack &&
+	git -C r2 verify-pack -v ../all.pack \
+		| grep blob \
+		| awk -f print_1.awk \
+		| sort >observed &&
+	test_cmp observed expected
+'
+
+test_expect_success 'verify blob:limit=500 omits all blobs' '
+	git -C r2 pack-objects --rev --stdout --filter=blob:limit=500 >filter.pack <<-EOF &&
+	HEAD
+	EOF
+	git -C r2 index-pack ../filter.pack &&
+	git -C r2 verify-pack -v ../filter.pack \
+		| grep blob \
+		| awk -f print_1.awk \
+		| sort >observed &&
+	nr=$(wc -l <observed) &&
+	test 0 -eq $nr
+'
+
+test_expect_success 'verify blob:limit=1000' '
+	git -C r2 pack-objects --rev --stdout --filter=blob:limit=1000 >filter.pack <<-EOF &&
+	HEAD
+	EOF
+	git -C r2 index-pack ../filter.pack &&
+	git -C r2 verify-pack -v ../filter.pack \
+		| grep blob \
+		| awk -f print_1.awk \
+		| sort >observed &&
+	nr=$(wc -l <observed) &&
+	test 0 -eq $nr
+'
+
+test_expect_success 'verify blob:limit=1001' '
+	git -C r2 ls-files -s large.1000 \
+		| awk -f print_2.awk \
+		| sort >expected &&
+	git -C r2 pack-objects --rev --stdout --filter=blob:limit=1001 >filter.pack <<-EOF &&
+	HEAD
+	EOF
+	git -C r2 index-pack ../filter.pack &&
+	git -C r2 verify-pack -v ../filter.pack \
+		| grep blob \
+		| awk -f print_1.awk \
+		| sort >observed &&
+	test_cmp observed expected
+'
+
+test_expect_success 'verify blob:limit=10001' '
+	git -C r2 ls-files -s large.1000 large.10000 \
+		| awk -f print_2.awk \
+		| sort >expected &&
+	git -C r2 pack-objects --rev --stdout --filter=blob:limit=10001 >filter.pack <<-EOF &&
+	HEAD
+	EOF
+	git -C r2 index-pack ../filter.pack &&
+	git -C r2 verify-pack -v ../filter.pack \
+		| grep blob \
+		| awk -f print_1.awk \
+		| sort >observed &&
+	test_cmp observed expected
+'
+
+test_expect_success 'verify blob:limit=1k' '
+	git -C r2 ls-files -s large.1000 \
+		| awk -f print_2.awk \
+		| sort >expected &&
+	git -C r2 pack-objects --rev --stdout --filter=blob:limit=1k >filter.pack <<-EOF &&
+	HEAD
+	EOF
+	git -C r2 index-pack ../filter.pack &&
+	git -C r2 verify-pack -v ../filter.pack \
+		| grep blob \
+		| awk -f print_1.awk \
+		| sort >observed &&
+	test_cmp observed expected
+'
+
+test_expect_success 'verify blob:limit=1m' '
+	git -C r2 ls-files -s large.1000 large.10000 \
+		| awk -f print_2.awk \
+		| sort >expected &&
+	git -C r2 pack-objects --rev --stdout --filter=blob:limit=1m >filter.pack <<-EOF &&
+	HEAD
+	EOF
+	git -C r2 index-pack ../filter.pack &&
+	git -C r2 verify-pack -v ../filter.pack \
+		| grep blob \
+		| awk -f print_1.awk \
+		| sort >observed &&
+	test_cmp observed expected
+'
+
+test_expect_success 'verify normal and blob:limit packfiles have same commits/trees' '
+	git -C r2 verify-pack -v ../all.pack \
+		| grep -E "commit|tree" \
+		| awk -f print_1.awk \
+		| sort >expected &&
+	git -C r2 verify-pack -v ../filter.pack \
+		| grep -E "commit|tree" \
+		| awk -f print_1.awk \
+		| sort >observed &&
+	test_cmp observed expected
+'
+
+# Test sparse:path=<path> filter.
+# Use a local file containing a sparse-checkout specification to filter
+# out blobs not required for the corresponding sparse-checkout.  We do not
+# require sparse-checkout to actually be enabled.
+
+test_expect_success 'setup r3' '
+	git init r3 &&
+	mkdir r3/dir1 &&
+	for n in sparse1 sparse2
+	do
+		echo "This is file: $n" > r3/$n
+		git -C r3 add $n
+		echo "This is file: dir1/$n" > r3/dir1/$n
+		git -C r3 add dir1/$n
+	done &&
+	git -C r3 commit -m "sparse" &&
+	echo dir1/ >pattern1 &&
+	echo sparse1 >pattern2
+'
+
+test_expect_success 'verify blob count in normal packfile' '
+	git -C r3 ls-files -s sparse1 sparse2 dir1/sparse1 dir1/sparse2 \
+		| awk -f print_2.awk \
+		| sort >expected &&
+	git -C r3 pack-objects --rev --stdout >all.pack <<-EOF &&
+	HEAD
+	EOF
+	git -C r3 index-pack ../all.pack &&
+	git -C r3 verify-pack -v ../all.pack \
+		| grep blob \
+		| awk -f print_1.awk \
+		| sort >observed &&
+	test_cmp observed expected
+'
+
+test_expect_success 'verify sparse:path=pattern1' '
+	git -C r3 ls-files -s dir1/sparse1 dir1/sparse2 \
+		| awk -f print_2.awk \
+		| sort >expected &&
+	git -C r3 pack-objects --rev --stdout --filter=sparse:path=../pattern1 >filter.pack <<-EOF &&
+	HEAD
+	EOF
+	git -C r3 index-pack ../filter.pack &&
+	git -C r3 verify-pack -v ../filter.pack \
+		| grep blob \
+		| awk -f print_1.awk \
+		| sort >observed &&
+	test_cmp observed expected
+'
+
+test_expect_success 'verify normal and sparse:path=pattern1 packfiles have same commits/trees' '
+	git -C r3 verify-pack -v ../all.pack \
+		| grep -E "commit|tree" \
+		| awk -f print_1.awk \
+		| sort >expected &&
+	git -C r3 verify-pack -v ../filter.pack \
+		| grep -E "commit|tree" \
+		| awk -f print_1.awk \
+		| sort >observed &&
+	test_cmp observed expected
+'
+
+test_expect_success 'verify sparse:path=pattern2' '
+	git -C r3 ls-files -s sparse1 dir1/sparse1 \
+		| awk -f print_2.awk \
+		| sort >expected &&
+	git -C r3 pack-objects --rev --stdout --filter=sparse:path=../pattern2 >filter.pack <<-EOF &&
+	HEAD
+	EOF
+	git -C r3 index-pack ../filter.pack &&
+	git -C r3 verify-pack -v ../filter.pack \
+		| grep blob \
+		| awk -f print_1.awk \
+		| sort >observed &&
+	test_cmp observed expected
+'
+
+test_expect_success 'verify normal and sparse:path=pattern2 packfiles have same commits/trees' '
+	git -C r3 verify-pack -v ../all.pack \
+		| grep -E "commit|tree" \
+		| awk -f print_1.awk \
+		| sort >expected &&
+	git -C r3 verify-pack -v ../filter.pack \
+		| grep -E "commit|tree" \
+		| awk -f print_1.awk \
+		| sort >observed &&
+	test_cmp observed expected
+'
+
+# Test sparse:oid=<oid-ish> filter.
+# Like sparse:path, but we get the sparse-checkout specification from
+# a blob rather than a file on disk.
+
+test_expect_success 'setup r4' '
+	git init r4 &&
+	mkdir r4/dir1 &&
+	for n in sparse1 sparse2
+	do
+		echo "This is file: $n" > r4/$n
+		git -C r4 add $n
+		echo "This is file: dir1/$n" > r4/dir1/$n
+		git -C r4 add dir1/$n
+	done &&
+	echo dir1/ >r4/pattern &&
+	git -C r4 add pattern &&
+	git -C r4 commit -m "pattern"
+'
+
+test_expect_success 'verify blob count in normal packfile' '
+	git -C r4 ls-files -s pattern sparse1 sparse2 dir1/sparse1 dir1/sparse2 \
+		| awk -f print_2.awk \
+		| sort >expected &&
+	git -C r4 pack-objects --rev --stdout >all.pack <<-EOF &&
+	HEAD
+	EOF
+	git -C r4 index-pack ../all.pack &&
+	git -C r4 verify-pack -v ../all.pack \
+		| grep blob \
+		| awk -f print_1.awk \
+		| sort >observed &&
+	test_cmp observed expected
+'
+
+test_expect_success 'verify sparse:oid=OID' '
+	git -C r4 ls-files -s dir1/sparse1 dir1/sparse2 \
+		| awk -f print_2.awk \
+		| sort >expected &&
+	oid=$(git -C r4 ls-files -s pattern | awk -f print_2.awk) &&
+	git -C r4 pack-objects --rev --stdout --filter=sparse:oid=$oid >filter.pack <<-EOF &&
+	HEAD
+	EOF
+	git -C r4 index-pack ../filter.pack &&
+	git -C r4 verify-pack -v ../filter.pack \
+		| grep blob \
+		| awk -f print_1.awk \
+		| sort >observed &&
+	test_cmp observed expected
+'
+
+test_expect_success 'verify sparse:oid=oid-ish' '
+	git -C r4 ls-files -s dir1/sparse1 dir1/sparse2 \
+		| awk -f print_2.awk \
+		| sort >expected &&
+	git -C r4 pack-objects --rev --stdout --filter=sparse:oid=master:pattern >filter.pack <<-EOF &&
+	HEAD
+	EOF
+	git -C r4 index-pack ../filter.pack &&
+	git -C r4 verify-pack -v ../filter.pack \
+		| grep blob \
+		| awk -f print_1.awk \
+		| sort >observed &&
+	test_cmp observed expected
+'
+
+# Delete some loose objects and use pack-objects, but WITHOUT any filtering.
+# This models previously omitted objects that we did not receive.
+
+test_expect_success 'setup r1 - delete loose blobs' '
+	git -C r1 ls-files -s file.1 file.2 file.3 file.4 file.5 \
+		| awk -f print_2.awk \
+		| sort >expected &&
+	for id in `cat expected | sed "s|..|&/|"`
+	do
+		rm r1/.git/objects/$id
+	done
+'
+
+test_expect_success 'verify pack-objects fails w/ missing objects' '
+	test_must_fail git -C r1 pack-objects --rev --stdout >miss.pack <<-EOF
+	HEAD
+	EOF
+'
+
+test_expect_success 'verify pack-objects fails w/ --missing=error' '
+	test_must_fail git -C r1 pack-objects --rev --stdout --missing=error >miss.pack <<-EOF
+	HEAD
+	EOF
+'
+
+test_expect_success 'verify pack-objects w/ --missing=allow-any' '
+	git -C r1 pack-objects --rev --stdout --missing=allow-any >miss.pack <<-EOF
+	HEAD
+	EOF
+'
+
+test_done