From 4a6067cda51b592871144eb050d4673db9ad5103 Mon Sep 17 00:00:00 2001
From: Stefan Beller <sbeller@google.com>
Date: Mon, 20 Aug 2018 18:24:16 +0000
Subject: refs.c: migrate internal ref iteration to pass thru repository
 argument

In 60ce76d3581 (refs: add repository argument to for_each_replace_ref,
2018-04-11) and 0d296c57aec (refs: allow for_each_replace_ref to handle
arbitrary repositories, 2018-04-11), for_each_replace_ref learned how
to iterate over refs by a given arbitrary repository.
New attempts in the object store conversion have shown that it is useful
to have the repository handle available that the refs iteration is
currently iterating over.

To achieve this goal we will need to add a repository argument to
each_ref_fn in refs.h. However as many callers rely on the signature
such a patch would be too large.

So convert the internals of the ref subsystem first to pass through a
repository argument without exposing the change to the user. Assume
the_repository for the passed through repository, although it is not
used anywhere yet.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 refs.c               | 39 +++++++++++++++++++++++++++++++++++++--
 refs.h               | 10 ++++++++++
 refs/iterator.c      |  6 +++---
 refs/refs-internal.h |  5 +++--
 4 files changed, 53 insertions(+), 7 deletions(-)

diff --git a/refs.c b/refs.c
index 457fb78057..7cd76f72d2 100644
--- a/refs.c
+++ b/refs.c
@@ -1386,17 +1386,50 @@ struct ref_iterator *refs_ref_iterator_begin(
  * non-zero value, stop the iteration and return that value;
  * otherwise, return 0.
  */
+static int do_for_each_repo_ref(struct repository *r, const char *prefix,
+				each_repo_ref_fn fn, int trim, int flags,
+				void *cb_data)
+{
+	struct ref_iterator *iter;
+	struct ref_store *refs = get_main_ref_store(r);
+
+	if (!refs)
+		return 0;
+
+	iter = refs_ref_iterator_begin(refs, prefix, trim, flags);
+
+	return do_for_each_repo_ref_iterator(r, iter, fn, cb_data);
+}
+
+struct do_for_each_ref_help {
+	each_ref_fn *fn;
+	void *cb_data;
+};
+
+static int do_for_each_ref_helper(struct repository *r,
+				  const char *refname,
+				  const struct object_id *oid,
+				  int flags,
+				  void *cb_data)
+{
+	struct do_for_each_ref_help *hp = cb_data;
+
+	return hp->fn(refname, oid, flags, hp->cb_data);
+}
+
 static int do_for_each_ref(struct ref_store *refs, const char *prefix,
 			   each_ref_fn fn, int trim, int flags, void *cb_data)
 {
 	struct ref_iterator *iter;
+	struct do_for_each_ref_help hp = { fn, cb_data };
 
 	if (!refs)
 		return 0;
 
 	iter = refs_ref_iterator_begin(refs, prefix, trim, flags);
 
-	return do_for_each_ref_iterator(iter, fn, cb_data);
+	return do_for_each_repo_ref_iterator(the_repository, iter,
+					do_for_each_ref_helper, &hp);
 }
 
 int refs_for_each_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
@@ -2025,10 +2058,12 @@ cleanup:
 int refs_for_each_reflog(struct ref_store *refs, each_ref_fn fn, void *cb_data)
 {
 	struct ref_iterator *iter;
+	struct do_for_each_ref_help hp = { fn, cb_data };
 
 	iter = refs->be->reflog_iterator_begin(refs);
 
-	return do_for_each_ref_iterator(iter, fn, cb_data);
+	return do_for_each_repo_ref_iterator(the_repository, iter,
+					     do_for_each_ref_helper, &hp);
 }
 
 int for_each_reflog(each_ref_fn fn, void *cb_data)
diff --git a/refs.h b/refs.h
index cc2fb4c68c..80eec8bbc6 100644
--- a/refs.h
+++ b/refs.h
@@ -274,6 +274,16 @@ struct ref_transaction;
 typedef int each_ref_fn(const char *refname,
 			const struct object_id *oid, int flags, void *cb_data);
 
+/*
+ * The same as each_ref_fn, but also with a repository argument that
+ * contains the repository associated with the callback.
+ */
+typedef int each_repo_ref_fn(struct repository *r,
+			     const char *refname,
+			     const struct object_id *oid,
+			     int flags,
+			     void *cb_data);
+
 /*
  * The following functions invoke the specified callback function for
  * each reference indicated.  If the function ever returns a nonzero
diff --git a/refs/iterator.c b/refs/iterator.c
index 2ac91ac340..629e00a122 100644
--- a/refs/iterator.c
+++ b/refs/iterator.c
@@ -407,15 +407,15 @@ struct ref_iterator *prefix_ref_iterator_begin(struct ref_iterator *iter0,
 
 struct ref_iterator *current_ref_iter = NULL;
 
-int do_for_each_ref_iterator(struct ref_iterator *iter,
-			     each_ref_fn fn, void *cb_data)
+int do_for_each_repo_ref_iterator(struct repository *r, struct ref_iterator *iter,
+				  each_repo_ref_fn fn, void *cb_data)
 {
 	int retval = 0, ok;
 	struct ref_iterator *old_ref_iter = current_ref_iter;
 
 	current_ref_iter = iter;
 	while ((ok = ref_iterator_advance(iter)) == ITER_OK) {
-		retval = fn(iter->refname, iter->oid, iter->flags, cb_data);
+		retval = fn(r, iter->refname, iter->oid, iter->flags, cb_data);
 		if (retval) {
 			/*
 			 * If ref_iterator_abort() returns ITER_ERROR,
diff --git a/refs/refs-internal.h b/refs/refs-internal.h
index 04425d6d1e..89d7dd49cd 100644
--- a/refs/refs-internal.h
+++ b/refs/refs-internal.h
@@ -474,8 +474,9 @@ extern struct ref_iterator *current_ref_iter;
  * adapter between the callback style of reference iteration and the
  * iterator style.
  */
-int do_for_each_ref_iterator(struct ref_iterator *iter,
-			     each_ref_fn fn, void *cb_data);
+int do_for_each_repo_ref_iterator(struct repository *r,
+				  struct ref_iterator *iter,
+				  each_repo_ref_fn fn, void *cb_data);
 
 /*
  * Only include per-worktree refs in a do_for_each_ref*() iteration.
-- 
cgit v1.2.3


From 212e0f7efe163d062dcd393a0788cf3f93544a6e Mon Sep 17 00:00:00 2001
From: Stefan Beller <sbeller@google.com>
Date: Mon, 20 Aug 2018 18:24:19 +0000
Subject: refs.c: upgrade for_each_replace_ref to be a each_repo_ref_fn
 callback

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/replace.c | 8 ++++----
 refs.c            | 9 ++++-----
 refs.h            | 2 +-
 replace-object.c  | 5 +++--
 4 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/builtin/replace.c b/builtin/replace.c
index e997a562f0..b5861a0ee9 100644
--- a/builtin/replace.c
+++ b/builtin/replace.c
@@ -39,7 +39,8 @@ struct show_data {
 	enum replace_format format;
 };
 
-static int show_reference(const char *refname, const struct object_id *oid,
+static int show_reference(struct repository *r, const char *refname,
+			  const struct object_id *oid,
 			  int flag, void *cb_data)
 {
 	struct show_data *data = cb_data;
@@ -56,9 +57,8 @@ static int show_reference(const char *refname, const struct object_id *oid,
 			if (get_oid(refname, &object))
 				return error("Failed to resolve '%s' as a valid ref.", refname);
 
-			obj_type = oid_object_info(the_repository, &object,
-						   NULL);
-			repl_type = oid_object_info(the_repository, oid, NULL);
+			obj_type = oid_object_info(r, &object, NULL);
+			repl_type = oid_object_info(r, oid, NULL);
 
 			printf("%s (%s) -> %s (%s)\n", refname, type_name(obj_type),
 			       oid_to_hex(oid), type_name(repl_type));
diff --git a/refs.c b/refs.c
index 7cd76f72d2..c5a5f727e8 100644
--- a/refs.c
+++ b/refs.c
@@ -1474,12 +1474,11 @@ int refs_for_each_fullref_in(struct ref_store *refs, const char *prefix,
 	return do_for_each_ref(refs, prefix, fn, 0, flag, cb_data);
 }
 
-int for_each_replace_ref(struct repository *r, each_ref_fn fn, void *cb_data)
+int for_each_replace_ref(struct repository *r, each_repo_ref_fn fn, void *cb_data)
 {
-	return do_for_each_ref(get_main_ref_store(r),
-			       git_replace_ref_base, fn,
-			       strlen(git_replace_ref_base),
-			       DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
+	return do_for_each_repo_ref(r, git_replace_ref_base, fn,
+				    strlen(git_replace_ref_base),
+				    DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
 }
 
 int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
diff --git a/refs.h b/refs.h
index 80eec8bbc6..a0a18223a1 100644
--- a/refs.h
+++ b/refs.h
@@ -317,7 +317,7 @@ int for_each_fullref_in(const char *prefix, each_ref_fn fn, void *cb_data,
 int for_each_tag_ref(each_ref_fn fn, void *cb_data);
 int for_each_branch_ref(each_ref_fn fn, void *cb_data);
 int for_each_remote_ref(each_ref_fn fn, void *cb_data);
-int for_each_replace_ref(struct repository *r, each_ref_fn fn, void *cb_data);
+int for_each_replace_ref(struct repository *r, each_repo_ref_fn fn, void *cb_data);
 int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data);
 int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
 			 const char *prefix, void *cb_data);
diff --git a/replace-object.c b/replace-object.c
index 4162df6324..3c17864eb7 100644
--- a/replace-object.c
+++ b/replace-object.c
@@ -6,7 +6,8 @@
 #include "repository.h"
 #include "commit.h"
 
-static int register_replace_ref(const char *refname,
+static int register_replace_ref(struct repository *r,
+				const char *refname,
 				const struct object_id *oid,
 				int flag, void *cb_data)
 {
@@ -25,7 +26,7 @@ static int register_replace_ref(const char *refname,
 	oidcpy(&repl_obj->replacement, oid);
 
 	/* Register new object */
-	if (oidmap_put(the_repository->objects->replace_map, repl_obj))
+	if (oidmap_put(r->objects->replace_map, repl_obj))
 		die("duplicate replace ref: %s", refname);
 
 	return 0;
-- 
cgit v1.2.3


From 950c62bda208790e223230a73ce6c19ae8f9177b Mon Sep 17 00:00:00 2001
From: Derrick Stolee <dstolee@microsoft.com>
Date: Mon, 20 Aug 2018 18:24:21 +0000
Subject: commit-graph: update design document

As it exists right now, the commit-graph feature may provide
inconsistent results when combined with commit grafts, replace objects,
and shallow clones. Update the design document to discuss why these
interactions are difficult to reconcile and how we will avoid errors by
preventing updates to and reads from the commit-graph file when these
other features exist.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/technical/commit-graph.txt | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/Documentation/technical/commit-graph.txt b/Documentation/technical/commit-graph.txt
index c664acbd76..001395e950 100644
--- a/Documentation/technical/commit-graph.txt
+++ b/Documentation/technical/commit-graph.txt
@@ -112,12 +112,24 @@ Design Details
 - The file format includes parameters for the object ID hash function,
   so a future change of hash algorithm does not require a change in format.
 
+- Commit grafts and replace objects can change the shape of the commit
+  history. The latter can also be enabled/disabled on the fly using
+  `--no-replace-objects`. This leads to difficultly storing both possible
+  interpretations of a commit id, especially when computing generation
+  numbers. The commit-graph will not be read or written when
+  replace-objects or grafts are present.
+
+- Shallow clones create grafts of commits by dropping their parents. This
+  leads the commit-graph to think those commits have generation number 1.
+  If and when those commits are made unshallow, those generation numbers
+  become invalid. Since shallow clones are intended to restrict the commit
+  history to a very small set of commits, the commit-graph feature is less
+  helpful for these clones, anyway. The commit-graph will not be read or
+  written when shallow commits are present.
+
 Future Work
 -----------
 
-- The commit graph feature currently does not honor commit grafts. This can
-  be remedied by duplicating or refactoring the current graft logic.
-
 - After computing and storing generation numbers, we must make graph
   walks aware of generation numbers to gain the performance benefits they
   enable. This will mostly be accomplished by swapping a commit-date-ordered
-- 
cgit v1.2.3


From b7758963424e238b9152f0c9991325ff7fdffff1 Mon Sep 17 00:00:00 2001
From: Derrick Stolee <dstolee@microsoft.com>
Date: Mon, 20 Aug 2018 18:24:24 +0000
Subject: test-repository: properly init repo

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 t/helper/test-repository.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/t/helper/test-repository.c b/t/helper/test-repository.c
index 2762ca6562..6a84a53efb 100644
--- a/t/helper/test-repository.c
+++ b/t/helper/test-repository.c
@@ -15,7 +15,10 @@ static void test_parse_commit_in_graph(const char *gitdir, const char *worktree,
 	struct commit *c;
 	struct commit_list *parent;
 
-	repo_init(&r, gitdir, worktree);
+	setup_git_env(gitdir);
+
+	if (repo_init(&r, gitdir, worktree))
+		die("Couldn't init repo");
 
 	c = lookup_commit(&r, commit_oid);
 
@@ -38,7 +41,10 @@ static void test_get_commit_tree_in_graph(const char *gitdir,
 	struct commit *c;
 	struct tree *tree;
 
-	repo_init(&r, gitdir, worktree);
+	setup_git_env(gitdir);
+
+	if (repo_init(&r, gitdir, worktree))
+		die("Couldn't init repo");
 
 	c = lookup_commit(&r, commit_oid);
 
-- 
cgit v1.2.3


From d6538246d3d4edbfbc9b0af6a2aa38552d35f7f1 Mon Sep 17 00:00:00 2001
From: Derrick Stolee <dstolee@microsoft.com>
Date: Mon, 20 Aug 2018 18:24:27 +0000
Subject: commit-graph: not compatible with replace objects

Create new method commit_graph_compatible(r) to check if a given
repository r is compatible with the commit-graph feature. Fill the
method with a check to see if replace-objects exist. Test this
interaction succeeds, including ignoring an existing commit-graph and
failing to write a new commit-graph. However, we do ensure that
we write a new commit-graph by setting read_replace_refs to 0, thereby
ignoring the replace refs.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/commit-graph.c  |  4 ++++
 commit-graph.c          | 21 +++++++++++++++++++++
 replace-object.c        |  2 +-
 replace-object.h        |  2 ++
 t/t5318-commit-graph.sh | 22 ++++++++++++++++++++++
 5 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/builtin/commit-graph.c b/builtin/commit-graph.c
index 0bf0c48657..da737df321 100644
--- a/builtin/commit-graph.c
+++ b/builtin/commit-graph.c
@@ -120,6 +120,8 @@ static int graph_read(int argc, const char **argv)
 	return 0;
 }
 
+extern int read_replace_refs;
+
 static int graph_write(int argc, const char **argv)
 {
 	struct string_list *pack_indexes = NULL;
@@ -150,6 +152,8 @@ static int graph_write(int argc, const char **argv)
 	if (!opts.obj_dir)
 		opts.obj_dir = get_object_directory();
 
+	read_replace_refs = 0;
+
 	if (opts.reachable) {
 		write_commit_graph_reachable(opts.obj_dir, opts.append);
 		return 0;
diff --git a/commit-graph.c b/commit-graph.c
index b0a55ad128..2c01fa433f 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -13,6 +13,8 @@
 #include "commit-graph.h"
 #include "object-store.h"
 #include "alloc.h"
+#include "hashmap.h"
+#include "replace-object.h"
 
 #define GRAPH_SIGNATURE 0x43475048 /* "CGPH" */
 #define GRAPH_CHUNKID_OIDFANOUT 0x4f494446 /* "OIDF" */
@@ -56,6 +58,19 @@ static struct commit_graph *alloc_commit_graph(void)
 	return g;
 }
 
+extern int read_replace_refs;
+
+static int commit_graph_compatible(struct repository *r)
+{
+	if (read_replace_refs) {
+		prepare_replace_object(r);
+		if (hashmap_get_size(&r->objects->replace_map->map))
+			return 0;
+	}
+
+	return 1;
+}
+
 struct commit_graph *load_commit_graph_one(const char *graph_file)
 {
 	void *graph_map;
@@ -223,6 +238,9 @@ static int prepare_commit_graph(struct repository *r)
 		 */
 		return 0;
 
+	if (!commit_graph_compatible(r))
+		return 0;
+
 	obj_dir = r->objects->objectdir;
 	prepare_commit_graph_one(r, obj_dir);
 	prepare_alt_odb(r);
@@ -693,6 +711,9 @@ void write_commit_graph(const char *obj_dir,
 	int num_extra_edges;
 	struct commit_list *parent;
 
+	if (!commit_graph_compatible(the_repository))
+		return;
+
 	oids.nr = 0;
 	oids.alloc = approximate_object_count() / 4;
 
diff --git a/replace-object.c b/replace-object.c
index 3c17864eb7..9821f1477e 100644
--- a/replace-object.c
+++ b/replace-object.c
@@ -32,7 +32,7 @@ static int register_replace_ref(struct repository *r,
 	return 0;
 }
 
-static void prepare_replace_object(struct repository *r)
+void prepare_replace_object(struct repository *r)
 {
 	if (r->objects->replace_map)
 		return;
diff --git a/replace-object.h b/replace-object.h
index 9345e105dd..16528df942 100644
--- a/replace-object.h
+++ b/replace-object.h
@@ -10,6 +10,8 @@ struct replace_object {
 	struct object_id replacement;
 };
 
+void prepare_replace_object(struct repository *r);
+
 /*
  * This internal function is only declared here for the benefit of
  * lookup_replace_object().  Please do not call it directly.
diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh
index 4f17d7701e..e0c3c60f66 100755
--- a/t/t5318-commit-graph.sh
+++ b/t/t5318-commit-graph.sh
@@ -259,6 +259,28 @@ test_expect_success 'check that gc computes commit-graph' '
 	test_cmp commit-graph-after-gc $objdir/info/commit-graph
 '
 
+test_expect_success 'replace-objects invalidates commit-graph' '
+	cd "$TRASH_DIRECTORY" &&
+	test_when_finished rm -rf replace &&
+	git clone full replace &&
+	(
+		cd replace &&
+		git commit-graph write --reachable &&
+		test_path_is_file .git/objects/info/commit-graph &&
+		git replace HEAD~1 HEAD~2 &&
+		git -c core.commitGraph=false log >expect &&
+		git -c core.commitGraph=true log >actual &&
+		test_cmp expect actual &&
+		git commit-graph write --reachable &&
+		git -c core.commitGraph=false --no-replace-objects log >expect &&
+		git -c core.commitGraph=true --no-replace-objects log >actual &&
+		test_cmp expect actual &&
+		rm -rf .git/objects/info/commit-graph &&
+		git commit-graph write --reachable &&
+		test_path_is_file .git/objects/info/commit-graph
+	)
+'
+
 # the verify tests below expect the commit-graph to contain
 # exactly the commits reachable from the commits/8 branch.
 # If the file changes the set of commits in the list, then the
-- 
cgit v1.2.3


From 20fd6d57996e33c30b6bb030329523d0116f15ec Mon Sep 17 00:00:00 2001
From: Derrick Stolee <dstolee@microsoft.com>
Date: Mon, 20 Aug 2018 18:24:30 +0000
Subject: commit-graph: not compatible with grafts

Augment commit_graph_compatible(r) to return false when the given
repository r has commit grafts or is a shallow clone. Test that in these
situations we ignore existing commit-graph files and we do not write new
commit-graph files.

Helped-by: Jakub Narebski <jnareb@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 commit-graph.c          |  6 ++++++
 commit.c                |  2 +-
 commit.h                |  1 +
 t/t5318-commit-graph.sh | 38 ++++++++++++++++++++++++++++++++++++++
 4 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/commit-graph.c b/commit-graph.c
index 2c01fa433f..c4eaedf4e5 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -68,6 +68,12 @@ static int commit_graph_compatible(struct repository *r)
 			return 0;
 	}
 
+	prepare_commit_graft(r);
+	if (r->parsed_objects && r->parsed_objects->grafts_nr)
+		return 0;
+	if (is_repository_shallow(r))
+		return 0;
+
 	return 1;
 }
 
diff --git a/commit.c b/commit.c
index 30d1af2b20..ef9a2cbb23 100644
--- a/commit.c
+++ b/commit.c
@@ -209,7 +209,7 @@ static int read_graft_file(struct repository *r, const char *graft_file)
 	return 0;
 }
 
-static void prepare_commit_graft(struct repository *r)
+void prepare_commit_graft(struct repository *r)
 {
 	char *graft_file;
 
diff --git a/commit.h b/commit.h
index da0db36eba..5459e279fe 100644
--- a/commit.h
+++ b/commit.h
@@ -202,6 +202,7 @@ typedef int (*each_commit_graft_fn)(const struct commit_graft *, void *);
 
 struct commit_graft *read_graft_line(struct strbuf *line);
 int register_commit_graft(struct repository *r, struct commit_graft *, int);
+void prepare_commit_graft(struct repository *r);
 struct commit_graft *lookup_commit_graft(struct repository *r, const struct object_id *oid);
 
 extern struct commit_list *get_merge_bases(struct commit *rev1, struct commit *rev2);
diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh
index e0c3c60f66..6aee861f78 100755
--- a/t/t5318-commit-graph.sh
+++ b/t/t5318-commit-graph.sh
@@ -281,6 +281,44 @@ test_expect_success 'replace-objects invalidates commit-graph' '
 	)
 '
 
+test_expect_success 'commit grafts invalidate commit-graph' '
+	cd "$TRASH_DIRECTORY" &&
+	test_when_finished rm -rf graft &&
+	git clone full graft &&
+	(
+		cd graft &&
+		git commit-graph write --reachable &&
+		test_path_is_file .git/objects/info/commit-graph &&
+		H1=$(git rev-parse --verify HEAD~1) &&
+		H3=$(git rev-parse --verify HEAD~3) &&
+		echo "$H1 $H3" >.git/info/grafts &&
+		git -c core.commitGraph=false log >expect &&
+		git -c core.commitGraph=true log >actual &&
+		test_cmp expect actual &&
+		git commit-graph write --reachable &&
+		git -c core.commitGraph=false --no-replace-objects log >expect &&
+		git -c core.commitGraph=true --no-replace-objects log >actual &&
+		test_cmp expect actual &&
+		rm -rf .git/objects/info/commit-graph &&
+		git commit-graph write --reachable &&
+		test_path_is_missing .git/objects/info/commit-graph
+	)
+'
+
+test_expect_success 'replace-objects invalidates commit-graph' '
+	cd "$TRASH_DIRECTORY" &&
+	test_when_finished rm -rf shallow &&
+	git clone --depth 2 "file://$TRASH_DIRECTORY/full" shallow &&
+	(
+		cd shallow &&
+		git commit-graph write --reachable &&
+		test_path_is_missing .git/objects/info/commit-graph &&
+		git fetch origin --unshallow &&
+		git commit-graph write --reachable &&
+		test_path_is_file .git/objects/info/commit-graph
+	)
+'
+
 # the verify tests below expect the commit-graph to contain
 # exactly the commits reachable from the commits/8 branch.
 # If the file changes the set of commits in the list, then the
-- 
cgit v1.2.3


From 5cef295f283e84351a104c66f949a53a56297aa7 Mon Sep 17 00:00:00 2001
From: Derrick Stolee <dstolee@microsoft.com>
Date: Mon, 20 Aug 2018 18:24:32 +0000
Subject: commit-graph: not compatible with uninitialized repo

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 commit-graph.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/commit-graph.c b/commit-graph.c
index c4eaedf4e5..cee2caab5c 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -62,6 +62,9 @@ extern int read_replace_refs;
 
 static int commit_graph_compatible(struct repository *r)
 {
+	if (!r->gitdir)
+		return 0;
+
 	if (read_replace_refs) {
 		prepare_replace_object(r);
 		if (hashmap_get_size(&r->objects->replace_map->map))
-- 
cgit v1.2.3


From 829a321569d8e8f2c582aef9f0c990df976ab842 Mon Sep 17 00:00:00 2001
From: Derrick Stolee <dstolee@microsoft.com>
Date: Mon, 20 Aug 2018 18:24:34 +0000
Subject: commit-graph: close_commit_graph before shallow walk

Call close_commit_graph() when about to start a rev-list walk that
includes shallow commits. This is necessary in code paths that "fake"
shallow commits for the sake of fetch. Specifically, test 351 in
t5500-fetch-pack.sh runs

	git fetch --shallow-exclude one origin

with a file-based transfer. When the "remote" has a commit-graph, we do
not prevent the commit-graph from being loaded, but then the commits are
intended to be dynamically transferred into shallow commits during
get_shallow_commits_by_rev_list(). By closing the commit-graph before
this call, we prevent this interaction.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 commit-graph.c | 8 ++++----
 commit-graph.h | 1 +
 upload-pack.c  | 2 ++
 3 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/commit-graph.c b/commit-graph.c
index cee2caab5c..4bd1a4abbf 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -260,10 +260,10 @@ static int prepare_commit_graph(struct repository *r)
 	return !!r->objects->commit_graph;
 }
 
-static void close_commit_graph(void)
+void close_commit_graph(struct repository *r)
 {
-	free_commit_graph(the_repository->objects->commit_graph);
-	the_repository->objects->commit_graph = NULL;
+	free_commit_graph(r->objects->commit_graph);
+	r->objects->commit_graph = NULL;
 }
 
 static int bsearch_graph(struct commit_graph *g, struct object_id *oid, uint32_t *pos)
@@ -875,7 +875,7 @@ void write_commit_graph(const char *obj_dir,
 	write_graph_chunk_data(f, GRAPH_OID_LEN, commits.list, commits.nr);
 	write_graph_chunk_large_edges(f, commits.list, commits.nr);
 
-	close_commit_graph();
+	close_commit_graph(the_repository);
 	finalize_hashfile(f, NULL, CSUM_HASH_IN_STREAM | CSUM_FSYNC);
 	commit_lock_file(&lk);
 
diff --git a/commit-graph.h b/commit-graph.h
index 76e098934a..13d736cdde 100644
--- a/commit-graph.h
+++ b/commit-graph.h
@@ -59,6 +59,7 @@ void write_commit_graph(const char *obj_dir,
 
 int verify_commit_graph(struct repository *r, struct commit_graph *g);
 
+void close_commit_graph(struct repository *);
 void free_commit_graph(struct commit_graph *);
 
 #endif
diff --git a/upload-pack.c b/upload-pack.c
index 82b393ec31..2ae9d9bb47 100644
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -24,6 +24,7 @@
 #include "quote.h"
 #include "upload-pack.h"
 #include "serve.h"
+#include "commit-graph.h"
 
 /* Remember to update object flag allocation in object.h */
 #define THEY_HAVE	(1u << 11)
@@ -740,6 +741,7 @@ static void deepen_by_rev_list(int ac, const char **av,
 {
 	struct commit_list *result;
 
+	close_commit_graph(the_repository);
 	result = get_shallow_commits_by_rev_list(ac, av, SHALLOW, NOT_SHALLOW);
 	send_shallow(result);
 	free_commit_list(result);
-- 
cgit v1.2.3