[PATCH 02/10] revision: learn '--no-kept-objects'

From: Taylor Blau <me@ttaylorr.com>
To: git@vger.kernel.org
Cc: peff@peff.net, dstolee@microsoft.com
Subject: [PATCH 02/10] revision: learn '--no-kept-objects'
Date: Tue, 19 Jan 2021 18:24:05 -0500	[thread overview]
Message-ID: <4184529648abe7451b5c7b772493df8c067cec82.1611098616.git.me@ttaylorr.com> (raw)
In-Reply-To: <cover.1611098616.git.me@ttaylorr.com>

Some callers want to perform a reachability traversal that terminates
when an object is found in a kept pack. The closest existing option is
'--honor-pack-keep', but this isn't quite what we want. Instead of
halting the traversal midway through, a full traversal is always
performed, and the results are only trimmed afterwords.

Besides needing to introduce a new flag (since culling results
post-facto can be different than halting the traversal as it's
happening), there is an additional wrinkle handling the distinction
in-core and on-disk kept packs. That is: what kinds of kept pack should
stop the traversal?

Introduce '--no-kept-objects[=<on-disk|in-core>]' to specify which kinds
of kept packs, if any, should stop a traversal. This can be useful for
callers that want to perform a reachability analysis, but want to leave
certain packs alone (for e.g., when doing a geometric repack that has
some "large" packs it wants to leave alone).

Signed-off-by: Taylor Blau <me@ttaylorr.com>
---
 Documentation/rev-list-options.txt |  7 +++
 list-objects.c                     |  7 +++
 revision.c                         | 15 +++++++
 revision.h                         |  4 ++
 t/t6114-keep-packs.sh              | 69 ++++++++++++++++++++++++++++++
 5 files changed, 102 insertions(+)
 create mode 100755 t/t6114-keep-packs.sh

diff --git a/Documentation/rev-list-options.txt b/Documentation/rev-list-options.txt
index 002379056a..817419d552 100644
--- a/Documentation/rev-list-options.txt
+++ b/Documentation/rev-list-options.txt
@@ -856,6 +856,13 @@ ifdef::git-rev-list[]
 	Only useful with `--objects`; print the object IDs that are not
 	in packs.
 
+--no-kept-objects[=<kind>]::
+	Halts the traversal as soon as an object in a kept pack is
+	found. If `<kind>` is `on-disk`, only packs with a corresponding
+	`*.keep` file are ignored. If `<kind>` is `in-core`, only packs
+	with their in-core kept state set are ignored. Otherwise, both
+	kinds of kept packs are ignored.
+
 --object-names::
 	Only useful with `--objects`; print the names of the object IDs
 	that are found. This is the default behavior.
diff --git a/list-objects.c b/list-objects.c
index e19589baa0..b06c3bfeba 100644
--- a/list-objects.c
+++ b/list-objects.c
@@ -338,6 +338,13 @@ static void traverse_trees_and_blobs(struct traversal_context *ctx,
 			ctx->show_object(obj, name, ctx->show_data);
 			continue;
 		}
+		if (ctx->revs->no_kept_objects) {
+			struct pack_entry e;
+			if (find_kept_pack_entry(ctx->revs->repo, &obj->oid,
+						 ctx->revs->keep_pack_cache_flags,
+						 &e))
+				continue;
+		}
 		if (!path)
 			path = "";
 		if (obj->type == OBJ_TREE) {
diff --git a/revision.c b/revision.c
index 1bb590ece7..ff1ea77224 100644
--- a/revision.c
+++ b/revision.c
@@ -2334,6 +2334,16 @@ static int handle_revision_opt(struct rev_info *revs, int argc, const char **arg
 		revs->unpacked = 1;
 	} else if (starts_with(arg, "--unpacked=")) {
 		die(_("--unpacked=<packfile> no longer supported"));
+	} else if (!strcmp(arg, "--no-kept-objects")) {
+		revs->no_kept_objects = 1;
+		revs->keep_pack_cache_flags |= IN_CORE_KEEP_PACKS;
+		revs->keep_pack_cache_flags |= ON_DISK_KEEP_PACKS;
+	} else if (skip_prefix(arg, "--no-kept-objects=", &optarg)) {
+		revs->no_kept_objects = 1;
+		if (!strcmp(optarg, "in-core"))
+			revs->keep_pack_cache_flags |= IN_CORE_KEEP_PACKS;
+		if (!strcmp(optarg, "on-disk"))
+			revs->keep_pack_cache_flags |= ON_DISK_KEEP_PACKS;
 	} else if (!strcmp(arg, "-r")) {
 		revs->diff = 1;
 		revs->diffopt.flags.recursive = 1;
@@ -3822,6 +3832,11 @@ enum commit_action get_commit_action(struct rev_info *revs, struct commit *commi
 		return commit_ignore;
 	if (revs->unpacked && has_object_pack(&commit->object.oid))
 		return commit_ignore;
+	if (revs->no_kept_objects) {
+		if (has_object_kept_pack(&commit->object.oid,
+					 revs->keep_pack_cache_flags))
+			return commit_ignore;
+	}
 	if (commit->object.flags & UNINTERESTING)
 		return commit_ignore;
 	if (revs->line_level_traverse && !want_ancestry(revs)) {
diff --git a/revision.h b/revision.h
index 086ff10280..15d0e6aee5 100644
--- a/revision.h
+++ b/revision.h
@@ -148,6 +148,7 @@ struct rev_info {
 			edge_hint_aggressive:1,
 			limited:1,
 			unpacked:1,
+			no_kept_objects:1,
 			boundary:2,
 			count:1,
 			left_right:1,
@@ -312,6 +313,9 @@ struct rev_info {
 	 * This is loaded from the commit-graph being used.
 	 */
 	struct bloom_filter_settings *bloom_filter_settings;
+
+	/* misc. flags related to '--no-kept-objects' */
+	unsigned keep_pack_cache_flags;
 };
 
 int ref_excluded(struct string_list *, const char *path);
diff --git a/t/t6114-keep-packs.sh b/t/t6114-keep-packs.sh
new file mode 100755
index 0000000000..9239d8aa46
--- /dev/null
+++ b/t/t6114-keep-packs.sh
@@ -0,0 +1,69 @@
+#!/bin/sh
+
+test_description='rev-list with .keep packs'
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	test_commit loose &&
+	test_commit packed &&
+	test_commit kept &&
+
+	KEPT_PACK=$(git pack-objects --revs .git/objects/pack/pack <<-EOF
+	refs/tags/kept
+	^refs/tags/packed
+	EOF
+	) &&
+	MISC_PACK=$(git pack-objects --revs .git/objects/pack/pack <<-EOF
+	refs/tags/packed
+	^refs/tags/loose
+	EOF
+	) &&
+
+	touch .git/objects/pack/pack-$KEPT_PACK.keep
+'
+
+rev_list_objects () {
+	git rev-list "$@" >out &&
+	sort out
+}
+
+idx_objects () {
+	git show-index <$1 >expect-idx &&
+	cut -d" " -f2 <expect-idx | sort
+}
+
+test_expect_success '--no-kept-objects excludes trees and blobs in .keep packs' '
+	rev_list_objects --objects --all --no-object-names >kept &&
+	rev_list_objects --objects --all --no-object-names --no-kept-objects >no-kept &&
+
+	idx_objects .git/objects/pack/pack-$KEPT_PACK.idx >expect &&
+	comm -3 kept no-kept >actual &&
+
+	test_cmp expect actual
+'
+
+test_expect_success '--no-kept-objects excludes kept non-MIDX object' '
+	test_config core.multiPackIndex true &&
+
+	# Create a pack with just the commit object in pack, and do not mark it
+	# as kept (even though it appears in $KEPT_PACK, which does have a .keep
+	# file).
+	MIDX_PACK=$(git pack-objects .git/objects/pack/pack <<-EOF
+	$(git rev-parse kept)
+	EOF
+	) &&
+
+	# Write a MIDX containing all packs, but use the version of the commit
+	# at "kept" in a non-kept pack by touching $MIDX_PACK.
+	touch .git/objects/pack/pack-$MIDX_PACK.pack &&
+	git multi-pack-index write &&
+
+	rev_list_objects --objects --no-object-names --no-kept-objects HEAD >actual &&
+	(
+		idx_objects .git/objects/pack/pack-$MISC_PACK.idx &&
+		git rev-list --objects --no-object-names refs/tags/loose
+	) | sort >expect &&
+	test_cmp expect actual
+'
+
+test_done
-- 
2.30.0.138.g6d7191ea01

