Merge branch 'mh/submodule-hash'

Code and design clean-up for the refs API.

* mh/submodule-hash:
  read_loose_refs(): read refs using resolve_ref_recursively()
  files_ref_store::submodule: use NULL for the main repository
  base_ref_store_init(): remove submodule argument
  refs: push the submodule attribute down
  refs: store submodule ref stores in a hashmap
  register_ref_store(): new function
  refs: remove some unnecessary handling of submodule == ""
  refs: make some ref_store lookup functions private
  refs: reorder some function definitions

1 files changed, 81 insertions, 40 deletions

diff --git a/refs.c b/refs.c
index cd36b64ed93..81b64b4ed51 100644
--- a/refs.c
+++ b/refs.c
@@ -3,6 +3,7 @@
  */
 
 #include "cache.h"
+#include "hashmap.h"
 #include "lockfile.h"
 #include "refs.h"
 #include "refs/refs-internal.h"
@@ -1234,10 +1235,10 @@ int for_each_rawref(each_ref_fn fn, void *cb_data)
 }
 
 /* This function needs to return a meaningful errno on failure */
-static const char *resolve_ref_recursively(struct ref_store *refs,
-					   const char *refname,
-					   int resolve_flags,
-					   unsigned char *sha1, int *flags)
+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;
@@ -1357,62 +1358,102 @@ int resolve_gitlink_ref(const char *submodule, const char *refname,
 	return 0;
 }
 
+struct submodule_hash_entry
+{
+	struct hashmap_entry ent; /* must be the first member! */
+
+	struct ref_store *refs;
+
+	/* NUL-terminated name of submodule: */
+	char submodule[FLEX_ARRAY];
+};
+
+static int submodule_hash_cmp(const void *entry, const void *entry_or_key,
+			      const void *keydata)
+{
+	const struct submodule_hash_entry *e1 = entry, *e2 = entry_or_key;
+	const char *submodule = keydata ? keydata : e2->submodule;
+
+	return strcmp(e1->submodule, submodule);
+}
+
+static struct submodule_hash_entry *alloc_submodule_hash_entry(
+		const char *submodule, struct ref_store *refs)
+{
+	struct submodule_hash_entry *entry;
+
+	FLEX_ALLOC_STR(entry, submodule, submodule);
+	hashmap_entry_init(entry, strhash(submodule));
+	entry->refs = refs;
+	return entry;
+}
+
 /* 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;
+/* A hashmap of ref_stores, stored by submodule name: */
+static struct hashmap submodule_ref_stores;
 
-void base_ref_store_init(struct ref_store *refs,
-			 const struct ref_storage_be *be,
-			 const char *submodule)
+/*
+ * Return the ref_store instance for the specified submodule (or the
+ * main repository if submodule is NULL). If that ref_store hasn't
+ * been initialized yet, return NULL.
+ */
+static struct ref_store *lookup_ref_store(const char *submodule)
+{
+	struct submodule_hash_entry *entry;
+
+	if (!submodule)
+		return main_ref_store;
+
+	if (!submodule_ref_stores.tablesize)
+		/* It's initialized on demand in register_ref_store(). */
+		return NULL;
+
+	entry = hashmap_get_from_hash(&submodule_ref_stores,
+				      strhash(submodule), submodule);
+	return entry ? entry->refs : NULL;
+}
+
+/*
+ * Register the specified ref_store to be the one that should be used
+ * for submodule (or the main repository if submodule is NULL). It is
+ * a fatal error to call this function twice for the same submodule.
+ */
+static void register_ref_store(struct ref_store *refs, 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))
+		if (!submodule_ref_stores.tablesize)
+			hashmap_init(&submodule_ref_stores, submodule_hash_cmp, 0);
+
+		if (hashmap_put(&submodule_ref_stores,
+				alloc_submodule_hash_entry(submodule, refs)))
 			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)
+/*
+ * Create, record, and return a ref_store instance for the specified
+ * submodule (or the main repository if submodule is NULL).
+ */
+static 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);
+	struct ref_store *refs;
 
 	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;
+	refs = be->init(submodule);
+	register_ref_store(refs, submodule);
+	return refs;
 }
 
 struct ref_store *get_ref_store(const char *submodule)
@@ -1440,10 +1481,10 @@ struct ref_store *get_ref_store(const char *submodule)
 	return refs;
 }
 
-void assert_main_repository(struct ref_store *refs, const char *caller)
+void base_ref_store_init(struct ref_store *refs,
+			 const struct ref_storage_be *be)
 {
-	if (*refs->submodule)
-		die("BUG: %s called for a submodule", caller);
+	refs->be = be;
 }
 
 /* backend functions */