Merge branch 'mh/ref-store'

The ref-store abstraction was introduced to the refs API so that we
can plug in different backends to store references.

* mh/ref-store: (38 commits)
  refs: implement iteration over only per-worktree refs
  refs: make lock generic
  refs: add method to rename refs
  refs: add methods to init refs db
  refs: make delete_refs() virtual
  refs: add method for initial ref transaction commit
  refs: add methods for reflog
  refs: add method iterator_begin
  files_ref_iterator_begin(): take a ref_store argument
  split_symref_update(): add a files_ref_store argument
  lock_ref_sha1_basic(): add a files_ref_store argument
  lock_ref_for_update(): add a files_ref_store argument
  commit_ref_update(): add a files_ref_store argument
  lock_raw_ref(): add a files_ref_store argument
  repack_without_refs(): add a files_ref_store argument
  refs: make peel_ref() virtual
  refs: make create_symref() virtual
  refs: make pack_refs() virtual
  refs: make verify_refname_available() virtual
  refs: make read_raw_ref() virtual
  ...

1 files changed, 299 insertions, 10 deletions

diff --git a/refs.c b/refs.c
index b4e7cac..113e3c8 100644
--- a/refs.c
+++ b/refs.c
@@ -10,6 +10,25 @@
 #include "tag.h"
 
 /*
+ * List of all available backends
+ */
+static struct ref_storage_be *refs_backends = &refs_be_files;
+
+static struct ref_storage_be *find_ref_storage_backend(const char *name)
+{
+	struct ref_storage_be *be;
+	for (be = refs_backends; be; be = be->next)
+		if (!strcmp(be->name, name))
+			return be;
+	return NULL;
+}
+
+int ref_storage_backend_exists(const char *name)
+{
+	return find_ref_storage_backend(name) != NULL;
+}
+
+/*
  * How to handle various characters in refnames:
  * 0: An acceptable character for refs
  * 1: End-of-component
@@ -1081,20 +1100,20 @@ const char *find_descendant_ref(const char *dirname,
 	return NULL;
 }
 
-int rename_ref_available(const char *oldname, const char *newname)
+int rename_ref_available(const char *old_refname, const char *new_refname)
 {
 	struct string_list skip = STRING_LIST_INIT_NODUP;
 	struct strbuf err = STRBUF_INIT;
-	int ret;
+	int ok;
 
-	string_list_insert(&skip, oldname);
-	ret = !verify_refname_available(newname, NULL, &skip, &err);
-	if (!ret)
+	string_list_insert(&skip, old_refname);
+	ok = !verify_refname_available(new_refname, NULL, &skip, &err);
+	if (!ok)
 		error("%s", err.buf);
 
 	string_list_clear(&skip, 0);
 	strbuf_release(&err);
-	return ret;
+	return ok;
 }
 
 int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
@@ -1132,9 +1151,13 @@ int head_ref(each_ref_fn fn, void *cb_data)
 static int do_for_each_ref(const char *submodule, const char *prefix,
 			   each_ref_fn fn, int trim, int flags, void *cb_data)
 {
+	struct ref_store *refs = get_ref_store(submodule);
 	struct ref_iterator *iter;
 
-	iter = files_ref_iterator_begin(submodule, prefix, flags);
+	if (!refs)
+		return 0;
+
+	iter = refs->be->iterator_begin(refs, prefix, flags);
 	iter = prefix_ref_iterator_begin(iter, prefix, trim);
 
 	return do_for_each_ref_iterator(iter, fn, cb_data);
@@ -1193,8 +1216,10 @@ int for_each_rawref(each_ref_fn fn, void *cb_data)
 }
 
 /* This function needs to return a meaningful errno on failure */
-const char *resolve_ref_unsafe(const char *refname, int resolve_flags,
-			       unsigned char *sha1, int *flags)
+static const char *resolve_ref_recursively(struct ref_store *refs,
+					   const char *refname,
+					   int resolve_flags,
+					   unsigned char *sha1, int *flags)
 {
 	static struct strbuf sb_refname = STRBUF_INIT;
 	int unused_flags;
@@ -1226,7 +1251,8 @@ const char *resolve_ref_unsafe(const char *refname, int resolve_flags,
 	for (symref_count = 0; symref_count < SYMREF_MAXDEPTH; symref_count++) {
 		unsigned int read_flags = 0;
 
-		if (read_raw_ref(refname, sha1, &sb_refname, &read_flags)) {
+		if (refs->be->read_raw_ref(refs, refname,
+					   sha1, &sb_refname, &read_flags)) {
 			*flags |= read_flags;
 			if (errno != ENOENT || (resolve_flags & RESOLVE_REF_READING))
 				return NULL;
@@ -1265,3 +1291,266 @@ const char *resolve_ref_unsafe(const char *refname, int resolve_flags,
 	errno = ELOOP;
 	return NULL;
 }
+
+/* backend functions */
+int refs_init_db(struct strbuf *err)
+{
+	struct ref_store *refs = get_ref_store(NULL);
+
+	return refs->be->init_db(refs, err);
+}
+
+const char *resolve_ref_unsafe(const char *refname, int resolve_flags,
+			       unsigned char *sha1, int *flags)
+{
+	return resolve_ref_recursively(get_ref_store(NULL), refname,
+				       resolve_flags, sha1, flags);
+}
+
+int resolve_gitlink_ref(const char *submodule, const char *refname,
+			unsigned char *sha1)
+{
+	size_t len = strlen(submodule);
+	struct ref_store *refs;
+	int flags;
+
+	while (len && submodule[len - 1] == '/')
+		len--;
+
+	if (!len)
+		return -1;
+
+	if (submodule[len]) {
+		/* We need to strip off one or more trailing slashes */
+		char *stripped = xmemdupz(submodule, len);
+
+		refs = get_ref_store(stripped);
+		free(stripped);
+	} else {
+		refs = get_ref_store(submodule);
+	}
+
+	if (!refs)
+		return -1;
+
+	if (!resolve_ref_recursively(refs, refname, 0, sha1, &flags) ||
+	    is_null_sha1(sha1))
+		return -1;
+	return 0;
+}
+
+/* A pointer to the ref_store for the main repository: */
+static struct ref_store *main_ref_store;
+
+/* A linked list of ref_stores for submodules: */
+static struct ref_store *submodule_ref_stores;
+
+void base_ref_store_init(struct ref_store *refs,
+			 const struct ref_storage_be *be,
+			 const char *submodule)
+{
+	refs->be = be;
+	if (!submodule) {
+		if (main_ref_store)
+			die("BUG: main_ref_store initialized twice");
+
+		refs->submodule = "";
+		refs->next = NULL;
+		main_ref_store = refs;
+	} else {
+		if (lookup_ref_store(submodule))
+			die("BUG: ref_store for submodule '%s' initialized twice",
+			    submodule);
+
+		refs->submodule = xstrdup(submodule);
+		refs->next = submodule_ref_stores;
+		submodule_ref_stores = refs;
+	}
+}
+
+struct ref_store *ref_store_init(const char *submodule)
+{
+	const char *be_name = "files";
+	struct ref_storage_be *be = find_ref_storage_backend(be_name);
+
+	if (!be)
+		die("BUG: reference backend %s is unknown", be_name);
+
+	if (!submodule || !*submodule)
+		return be->init(NULL);
+	else
+		return be->init(submodule);
+}
+
+struct ref_store *lookup_ref_store(const char *submodule)
+{
+	struct ref_store *refs;
+
+	if (!submodule || !*submodule)
+		return main_ref_store;
+
+	for (refs = submodule_ref_stores; refs; refs = refs->next) {
+		if (!strcmp(submodule, refs->submodule))
+			return refs;
+	}
+
+	return NULL;
+}
+
+struct ref_store *get_ref_store(const char *submodule)
+{
+	struct ref_store *refs;
+
+	if (!submodule || !*submodule) {
+		refs = lookup_ref_store(NULL);
+
+		if (!refs)
+			refs = ref_store_init(NULL);
+	} else {
+		refs = lookup_ref_store(submodule);
+
+		if (!refs) {
+			struct strbuf submodule_sb = STRBUF_INIT;
+
+			strbuf_addstr(&submodule_sb, submodule);
+			if (is_nonbare_repository_dir(&submodule_sb))
+				refs = ref_store_init(submodule);
+			strbuf_release(&submodule_sb);
+		}
+	}
+
+	return refs;
+}
+
+void assert_main_repository(struct ref_store *refs, const char *caller)
+{
+	if (*refs->submodule)
+		die("BUG: %s called for a submodule", caller);
+}
+
+/* backend functions */
+int pack_refs(unsigned int flags)
+{
+	struct ref_store *refs = get_ref_store(NULL);
+
+	return refs->be->pack_refs(refs, flags);
+}
+
+int peel_ref(const char *refname, unsigned char *sha1)
+{
+	struct ref_store *refs = get_ref_store(NULL);
+
+	return refs->be->peel_ref(refs, refname, sha1);
+}
+
+int create_symref(const char *ref_target, const char *refs_heads_master,
+		  const char *logmsg)
+{
+	struct ref_store *refs = get_ref_store(NULL);
+
+	return refs->be->create_symref(refs, ref_target, refs_heads_master,
+				       logmsg);
+}
+
+int ref_transaction_commit(struct ref_transaction *transaction,
+			   struct strbuf *err)
+{
+	struct ref_store *refs = get_ref_store(NULL);
+
+	return refs->be->transaction_commit(refs, transaction, err);
+}
+
+int verify_refname_available(const char *refname,
+			     const struct string_list *extra,
+			     const struct string_list *skip,
+			     struct strbuf *err)
+{
+	struct ref_store *refs = get_ref_store(NULL);
+
+	return refs->be->verify_refname_available(refs, refname, extra, skip, err);
+}
+
+int for_each_reflog(each_ref_fn fn, void *cb_data)
+{
+	struct ref_store *refs = get_ref_store(NULL);
+	struct ref_iterator *iter;
+
+	iter = refs->be->reflog_iterator_begin(refs);
+
+	return do_for_each_ref_iterator(iter, fn, cb_data);
+}
+
+int for_each_reflog_ent_reverse(const char *refname, each_reflog_ent_fn fn,
+				void *cb_data)
+{
+	struct ref_store *refs = get_ref_store(NULL);
+
+	return refs->be->for_each_reflog_ent_reverse(refs, refname,
+						     fn, cb_data);
+}
+
+int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn,
+			void *cb_data)
+{
+	struct ref_store *refs = get_ref_store(NULL);
+
+	return refs->be->for_each_reflog_ent(refs, refname, fn, cb_data);
+}
+
+int reflog_exists(const char *refname)
+{
+	struct ref_store *refs = get_ref_store(NULL);
+
+	return refs->be->reflog_exists(refs, refname);
+}
+
+int safe_create_reflog(const char *refname, int force_create,
+		       struct strbuf *err)
+{
+	struct ref_store *refs = get_ref_store(NULL);
+
+	return refs->be->create_reflog(refs, refname, force_create, err);
+}
+
+int delete_reflog(const char *refname)
+{
+	struct ref_store *refs = get_ref_store(NULL);
+
+	return refs->be->delete_reflog(refs, refname);
+}
+
+int reflog_expire(const char *refname, const unsigned char *sha1,
+		  unsigned int flags,
+		  reflog_expiry_prepare_fn prepare_fn,
+		  reflog_expiry_should_prune_fn should_prune_fn,
+		  reflog_expiry_cleanup_fn cleanup_fn,
+		  void *policy_cb_data)
+{
+	struct ref_store *refs = get_ref_store(NULL);
+
+	return refs->be->reflog_expire(refs, refname, sha1, flags,
+				       prepare_fn, should_prune_fn,
+				       cleanup_fn, policy_cb_data);
+}
+
+int initial_ref_transaction_commit(struct ref_transaction *transaction,
+				   struct strbuf *err)
+{
+	struct ref_store *refs = get_ref_store(NULL);
+
+	return refs->be->initial_transaction_commit(refs, transaction, err);
+}
+
+int delete_refs(struct string_list *refnames, unsigned int flags)
+{
+	struct ref_store *refs = get_ref_store(NULL);
+
+	return refs->be->delete_refs(refs, refnames, flags);
+}
+
+int rename_ref(const char *oldref, const char *newref, const char *logmsg)
+{
+	struct ref_store *refs = get_ref_store(NULL);
+
+	return refs->be->rename_ref(refs, oldref, newref, logmsg);
+}