Add a place for (not) sharing stuff between worktrees

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>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/git-worktree.txt b/Documentation/git-worktree.txt
index e2ee9fc21b400b01b006d5460698f0229e23ff9f..a50fbf80948a481ed64cce1bd11dbf00f6eba76b 100644 (file)
--- 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 e85148f05eb79a968ad84bac6ce7a88289270c49..89b616e0491ed7ee760ae934311777f9eb833be7 100644 (file)
--- 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 34f0f98349a6eccd462614cdf143bb031ca348c8..bf4bb02a27be020efbd3afb560c40cba0ad84043 100644 (file)
--- 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 9f7268d5fe8c9ddfdf67b1533ae9cedc8ee25375..1bc4ed301bcb3068d2aab84333f1a7c50fa24821 100644 (file)
--- 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 16ef9325e0d9985c36fd525016340246caaa1af8..2dd77f9485ea19b1e850851be2c0a0ef9b342ace 100644 (file)
--- 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 cd74c0a4714680a935c7f52a09ffed2f0a5ebc11..c7b53e494ba43fdcff874a506468a4ecc0881a48 100755 (executable)
--- 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 (executable)
index 0000000..16c91be
--- /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