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[PATCH v3 2/8] Add a place for (not) sharing stuff between worktrees

From
Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Date
Oct 21, 2018, 08:08 UTC
Message-ID
<20181021080859.3203-3-pclouds@gmail.com>
In-Reply-To
<20181021080859.3203-1-pclouds@gmail.com>

When multiple worktrees are used, we need rules to determine if something belongs to one worktree or all of them. Instead of keeping adding rules when new stuff comes (*), have a generic rule:

- Inside $GIT_DIR, which is per-worktree by default, add
  $GIT_DIR/common which is always shared. New features that want to
  share stuff should put stuff under this directory.
- Inside refs/, which is shared by default except refs/bisect, add
  refs/worktree/ which is per-worktree. We may eventually move
  refs/bisect to this new location and remove the exception in refs
  code.
(*) And it may also include stuff from external commands which will
    have no way to modify common/per-worktree rules.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 Documentation/git-worktree.txt         | 19 ++++++++++++++-
 Documentation/gitrepository-layout.txt | 11 +++++++--
 path.c                                 |  2 ++
 refs.c                                 |  1 +
 refs/files-backend.c                   | 14 ++++++++---
 t/t0060-path-utils.sh                  |  2 ++
 t/t1415-worktree-refs.sh               | 33 ++++++++++++++++++++++++++
 7 files changed, 76 insertions(+), 6 deletions(-)
 create mode 100755 t/t1415-worktree-refs.sh
diff --git a/Documentation/git-worktree.txt b/Documentation/git-worktree.txt
index e2ee9fc21b..a50fbf8094 100644
--- a/Documentation/git-worktree.txt
+++ b/Documentation/git-worktree.txt
@@ -204,6 +204,22 @@ working trees, it can be used to identify worktrees. For example if
 you only have two working trees, at "/abc/def/ghi" and "/abc/def/ggg",
 then "ghi" or "def/ghi" is enough to point to the former working tree.
 
+REFS
+----
+In multiple working trees, some refs may be shared between all working
+trees, some refs are local. One example is HEAD is different for all
+working trees. This section is about the sharing rules.
+
+In general, all pseudo refs are per working tree and all refs starting
+with "refs/" are shared. Pseudo refs are ones like HEAD which are
+directly under GIT_DIR instead of inside GIT_DIR/refs. There are one
+exception to this: refs inside refs/bisect and refs/worktree is not
+shared.
+
+To access refs, it's best not to look inside GIT_DIR directly. Instead
+use commands such as linkgit:git-revparse[1] or linkgit:git-update-ref[1]
+which will handle refs correctly.
+
 DETAILS
 -------
 Each linked working tree has a private sub-directory in the repository's
@@ -228,7 +244,8 @@ linked working tree `git rev-parse --git-path HEAD` returns
 `/path/other/test-next/.git/HEAD` or `/path/main/.git/HEAD`) while `git
 rev-parse --git-path refs/heads/master` uses
 $GIT_COMMON_DIR and returns `/path/main/.git/refs/heads/master`,
-since refs are shared across all working trees.
+since refs are shared across all working trees, except refs/bisect and
+refs/worktree.
 
 See linkgit:gitrepository-layout[5] for more information. The rule of
 thumb is do not make any assumption about whether a path belongs to
diff --git a/Documentation/gitrepository-layout.txt b/Documentation/gitrepository-layout.txt
index e85148f05e..89b616e049 100644
--- a/Documentation/gitrepository-layout.txt
+++ b/Documentation/gitrepository-layout.txt
@@ -95,8 +95,10 @@ refs::
 	References are stored in subdirectories of this
 	directory.  The 'git prune' command knows to preserve
 	objects reachable from refs found in this directory and
-	its subdirectories. This directory is ignored if $GIT_COMMON_DIR
-	is set and "$GIT_COMMON_DIR/refs" will be used instead.
+	its subdirectories.
+	This directory is ignored (except refs/bisect and
+	refs/worktree) if $GIT_COMMON_DIR is set and
+	"$GIT_COMMON_DIR/refs" will be used instead.
 
 refs/heads/`name`::
 	records tip-of-the-tree commit objects of branch `name`
@@ -165,6 +167,11 @@ hooks::
 	each hook. This directory is ignored if $GIT_COMMON_DIR is set
 	and "$GIT_COMMON_DIR/hooks" will be used instead.
 
+common::
+	When multiple working trees are used, most of files in
+	$GIT_DIR are per-worktree with a few known exceptions. All
+	files under 'common' however will be shared between all
+	working trees.
 
 index::
 	The current index file for the repository.  It is
diff --git a/path.c b/path.c
index 34f0f98349..bf4bb02a27 100644
--- a/path.c
+++ b/path.c
@@ -108,6 +108,7 @@ struct common_dir {
 
 static struct common_dir common_list[] = {
 	{ 0, 1, 0, "branches" },
+	{ 0, 1, 0, "common" },
 	{ 0, 1, 0, "hooks" },
 	{ 0, 1, 0, "info" },
 	{ 0, 0, 1, "info/sparse-checkout" },
@@ -118,6 +119,7 @@ static struct common_dir common_list[] = {
 	{ 0, 1, 0, "objects" },
 	{ 0, 1, 0, "refs" },
 	{ 0, 1, 1, "refs/bisect" },
+	{ 0, 1, 1, "refs/worktree" },
 	{ 0, 1, 0, "remotes" },
 	{ 0, 1, 0, "worktrees" },
 	{ 0, 1, 0, "rr-cache" },
diff --git a/refs.c b/refs.c
index f07c775b50..67daf0918e 100644
--- a/refs.c
+++ b/refs.c
@@ -624,6 +624,7 @@ int dwim_log(const char *str, int len, struct object_id *oid, char **log)
 static int is_per_worktree_ref(const char *refname)
 {
 	return !strcmp(refname, "HEAD") ||
+		starts_with(refname, "refs/worktree/") ||
 		starts_with(refname, "refs/bisect/") ||
 		starts_with(refname, "refs/rewritten/");
 }
diff --git a/refs/files-backend.c b/refs/files-backend.c
index 16ef9325e0..2dd77f9485 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -269,9 +269,9 @@ static void loose_fill_ref_dir(struct ref_store *ref_store,
 	closedir(d);
 
 	/*
-	 * Manually add refs/bisect, which, being per-worktree, might
-	 * not appear in the directory listing for refs/ in the main
-	 * repo.
+	 * Manually add refs/bisect and refs/worktree, which, being
+	 * per-worktree, might not appear in the directory listing for
+	 * refs/ in the main repo.
 	 */
 	if (!strcmp(dirname, "refs/")) {
 		int pos = search_ref_dir(dir, "refs/bisect/", 12);
@@ -281,6 +281,14 @@ static void loose_fill_ref_dir(struct ref_store *ref_store,
 					dir->cache, "refs/bisect/", 12, 1);
 			add_entry_to_dir(dir, child_entry);
 		}
+
+		pos = search_ref_dir(dir, "refs/worktree/", 11);
+
+		if (pos < 0) {
+			struct ref_entry *child_entry = create_dir_entry(
+					dir->cache, "refs/worktree/", 11, 1);
+			add_entry_to_dir(dir, child_entry);
+		}
 	}
 }
 
diff --git a/t/t0060-path-utils.sh b/t/t0060-path-utils.sh
index cd74c0a471..c7b53e494b 100755
--- a/t/t0060-path-utils.sh
+++ b/t/t0060-path-utils.sh
@@ -306,6 +306,8 @@ test_git_path GIT_COMMON_DIR=bar hooks/me                 bar/hooks/me
 test_git_path GIT_COMMON_DIR=bar config                   bar/config
 test_git_path GIT_COMMON_DIR=bar packed-refs              bar/packed-refs
 test_git_path GIT_COMMON_DIR=bar shallow                  bar/shallow
+test_git_path GIT_COMMON_DIR=bar common                   bar/common
+test_git_path GIT_COMMON_DIR=bar common/file              bar/common/file
 
 # In the tests below, $(pwd) must be used because it is a native path on
 # Windows and avoids MSYS's path mangling (which simplifies "foo/../bar" and
diff --git a/t/t1415-worktree-refs.sh b/t/t1415-worktree-refs.sh
new file mode 100755
index 0000000000..16c91bef57
--- /dev/null
+++ b/t/t1415-worktree-refs.sh
@@ -0,0 +1,33 @@
+#!/bin/sh
+
+test_description='per-worktree refs'
+
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	test_commit initial &&
+	test_commit wt1 &&
+	test_commit wt2 &&
+	git worktree add wt1 wt1 &&
+	git worktree add wt2 wt2 &&
+	git checkout initial &&
+	git update-ref refs/worktree/foo HEAD &&
+	git -C wt1 update-ref refs/worktree/foo HEAD &&
+	git -C wt2 update-ref refs/worktree/foo HEAD
+'
+
+test_expect_success 'refs/worktree must not be packed' '
+	git pack-refs --all &&
+	test_path_is_missing .git/refs/tags/wt1 &&
+	test_path_is_file .git/refs/worktree/foo &&
+	test_path_is_file .git/worktrees/wt1/refs/worktree/foo &&
+	test_path_is_file .git/worktrees/wt2/refs/worktree/foo
+'
+
+test_expect_success 'refs/worktree are per-worktree' '
+	test_cmp_rev worktree/foo initial &&
+	( cd wt1 && test_cmp_rev worktree/foo wt1 ) &&
+	( cd wt2 && test_cmp_rev worktree/foo wt2 )
+'
+
+test_done

-- 
2.19.1.647.g708186aaf9
Previous: Nguyễn Thái Ngọc DuyNext: Junio C Hamano
Message 45 of 60 in “fix per-worktree ref iteration in fsck/reflog expire”
  1. 0/8 fix per-worktree ref iteration in fsck/reflog expireNguyễn Thái Ngọc Duy, Sep 22, 2018
  2. 1/8 refs.c: indent with tabs, not spacesNguyễn Thái Ngọc Duy, Sep 22, 2018
  3. 2/8 Add a place for (not) sharing stuff between worktreesNguyễn Thái Ngọc Duy, Sep 22, 2018
  4. Eric SunshineSep 23, 2018
  5. Stefan BellerSep 25, 2018
  6. Duy NguyenSep 25, 2018
  7. Stefan BellerSep 25, 2018
  8. Duy NguyenSep 25, 2018
  9. Stefan BellerSep 25, 2018
  10. 3/8 refs: new ref types to make per-worktree refs visible to all worktreesNguyễn Thái Ngọc Duy, Sep 22, 2018
  11. Eric SunshineSep 23, 2018
  12. Duy NguyenSep 23, 2018
  13. Stefan BellerSep 25, 2018
  14. Duy NguyenSep 25, 2018
  15. Stefan BellerSep 25, 2018
  16. Junio C HamanoSep 25, 2018
  17. Duy NguyenSep 29, 2018
  18. Junio C HamanoOct 6, 2018
  19. 4/8 revision.c: correct a parameter nameNguyễn Thái Ngọc Duy, Sep 22, 2018
  20. 5/8 revision.c: better error reporting on ref from different worktreesNguyễn Thái Ngọc Duy, Sep 22, 2018
  21. Eric SunshineSep 23, 2018
  22. Duy NguyenSep 23, 2018
  23. 7/8 fsck: check HEAD and reflog from other worktreesNguyễn Thái Ngọc Duy, Sep 22, 2018
  24. Eric SunshineSep 23, 2018
  25. Duy NguyenSep 29, 2018
  26. 8/8 reflog expire: cover reflog from all worktreesNguyễn Thái Ngọc Duy, Sep 22, 2018
  27. 6/8 fsck: Move fsck_head_link() to get_default_heads() to avoid some globalsNguyễn Thái Ngọc Duy, Sep 22, 2018
  28. 0/8 fix per-worktree ref iteration in fsck/reflog expireNguyễn Thái Ngọc Duy, Sep 29, 2018
  29. 2/8 Add a place for (not) sharing stuff between worktreesNguyễn Thái Ngọc Duy, Sep 29, 2018
  30. 1/8 refs.c: indent with tabs, not spacesNguyễn Thái Ngọc Duy, Sep 29, 2018
  31. 3/8 refs: new ref types to make per-worktree refs visible to all worktreesNguyễn Thái Ngọc Duy, Sep 29, 2018
  32. Eric SunshineSep 30, 2018
  33. Junio C HamanoOct 7, 2018
  34. 4/8 revision.c: correct a parameter nameNguyễn Thái Ngọc Duy, Sep 29, 2018
  35. 5/8 revision.c: better error reporting on ref from different worktreesNguyễn Thái Ngọc Duy, Sep 29, 2018
  36. Eric SunshineSep 30, 2018
  37. 7/8 fsck: check HEAD and reflog from other worktreesNguyễn Thái Ngọc Duy, Sep 29, 2018
  38. 6/8 fsck: Move fsck_head_link() to get_default_heads() to avoid some globalsNguyễn Thái Ngọc Duy, Sep 29, 2018
  39. 8/8 reflog expire: cover reflog from all worktreesNguyễn Thái Ngọc Duy, Sep 29, 2018
  40. Eric SunshineSep 30, 2018
  41. Duy NguyenOct 2, 2018
  42. Eric SunshineOct 3, 2018
  43. 0/8 fix per-worktree ref iteration in fsck/reflog expireNguyễn Thái Ngọc Duy, Oct 21, 2018
  44. 1/8 refs.c: indent with tabs, not spacesNguyễn Thái Ngọc Duy, Oct 21, 2018
  45. 2/8 Add a place for (not) sharing stuff between worktreesNguyễn Thái Ngọc Duy, Oct 21, 2018
  46. Junio C HamanoOct 22, 2018
  47. Duy NguyenOct 29, 2018
  48. SZEDER GáborOct 22, 2018
  49. 3/8 refs: new ref types to make per-worktree refs visible to all worktreesNguyễn Thái Ngọc Duy, Oct 21, 2018
  50. Ævar Arnfjörð BjarmasonNov 24, 2018
  51. Junio C HamanoNov 25, 2018
  52. files-backend.c: fix build error on SolarisNguyễn Thái Ngọc Duy, Nov 25, 2018
  53. Carlo ArenasNov 25, 2018
  54. Duy NguyenNov 25, 2018
  55. Junio C HamanoNov 26, 2018
  56. 4/8 revision.c: correct a parameter nameNguyễn Thái Ngọc Duy, Oct 21, 2018
  57. 5/8 revision.c: better error reporting on ref from different worktreesNguyễn Thái Ngọc Duy, Oct 21, 2018
  58. 6/8 fsck: Move fsck_head_link() to get_default_heads() to avoid some globalsNguyễn Thái Ngọc Duy, Oct 21, 2018
  59. 7/8 fsck: check HEAD and reflog from other worktreesNguyễn Thái Ngọc Duy, Oct 21, 2018
  60. 8/8 reflog expire: cover reflog from all worktreesNguyễn Thái Ngọc Duy, Oct 21, 2018

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