[PATCH v2 1/5] refs: introduce get_worktree_ref_store()

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

files-backend at this point is still aware of the per-repo/worktree
separation in refs, so it can handle a linked worktree.

Note: accessing a worktree of a submodule remains unaddressed. Perhaps
after get_worktrees() can access submodule (or rather a new function
get_submodule_worktrees(), that lists worktrees of a submodule), we can
update this function to work with submodules as well.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 refs.c | 27 +++++++++++++++++++++++++++
 refs.h |  2 ++
 2 files changed, 29 insertions(+)

diff --git a/refs.c b/refs.c
index e7206a420..ba4d9420c 100644
--- a/refs.c
+++ b/refs.c
@@ -10,6 +10,7 @@
 #include "object.h"
 #include "tag.h"
 #include "submodule.h"
+#include "worktree.h"
 
 /*
  * List of all available backends
@@ -1486,6 +1487,32 @@ struct ref_store *get_submodule_ref_store(const char *submodule)
 	return refs;
 }
 
+struct ref_store *get_worktree_ref_store(const struct worktree *wt)
+{
+	struct ref_store *refs;
+
+	if (wt->is_current)
+		return get_main_ref_store();
+
+	/*
+	 * We share the same hash map with submodules for
+	 * now. submodule paths are always relative (to topdir) while
+	 * worktree paths are always absolute. No chance of conflict.
+	 */
+	refs = lookup_submodule_ref_store(wt->path);
+	if (refs)
+		return refs;
+
+	if (wt->id)
+		refs = ref_store_init(git_common_path("worktrees/%s", wt->id));
+	else
+		refs = ref_store_init(get_git_common_dir());
+
+	if (refs)
+		register_submodule_ref_store(refs, wt->path);
+	return refs;
+}
+
 void base_ref_store_init(struct ref_store *refs,
 			 const struct ref_storage_be *be)
 {
diff --git a/refs.h b/refs.h
index 1287ba59c..464cc384a 100644
--- a/refs.h
+++ b/refs.h
@@ -565,5 +565,7 @@ struct ref_store *get_main_ref_store(void);
  * submodule==NULL.
  */
 struct ref_store *get_submodule_ref_store(const char *submodule);
+struct worktree;
+struct ref_store *get_worktree_ref_store(const struct worktree *wt);
 
 #endif /* REFS_H */
-- 
2.11.0.157.gd943d85