Merge branch 'sb/object-store-replace'

The effort to pass the repository in-core structure throughout the
API continues.  This round deals with the code that implements the
refs/replace/ mechanism.

* sb/object-store-replace:
  replace-object: allow lookup_replace_object to handle arbitrary repositories
  replace-object: allow do_lookup_replace_object to handle arbitrary repositories
  replace-object: allow prepare_replace_object to handle arbitrary repositories
  refs: allow for_each_replace_ref to handle arbitrary repositories
  refs: store the main ref store inside the repository struct
  replace-object: add repository argument to lookup_replace_object
  replace-object: add repository argument to do_lookup_replace_object
  replace-object: add repository argument to prepare_replace_object
  refs: add repository argument to for_each_replace_ref
  refs: add repository argument to get_main_ref_store
  replace-object: check_replace_refs is safe in multi repo environment
  replace-object: eliminate replace objects prepared flag
  object-store: move lookup_replace_object to replace-object.h
  replace-object: move replace_map to object store
  replace_object: use oidmap

17 files changed, 134 insertions, 150 deletions

diff --git a/builtin/mktag.c b/builtin/mktag.c
index 9f5a50a8fd..82a6e86077 100644
--- a/builtin/mktag.c
+++ b/builtin/mktag.c
@@ -1,5 +1,6 @@
 #include "builtin.h"
 #include "tag.h"
+#include "replace-object.h"
 
 /*
  * A signature file has a very simple fixed format: four lines
@@ -24,7 +25,7 @@ static int verify_object(const struct object_id *oid, const char *expected_type)
 	enum object_type type;
 	unsigned long size;
 	void *buffer = read_object_file(oid, &type, &size);
-	const struct object_id *repl = lookup_replace_object(oid);
+	const struct object_id *repl = lookup_replace_object(the_repository, oid);
 
 	if (buffer) {
 		if (type == type_from_string(expected_type))
diff --git a/builtin/pack-refs.c b/builtin/pack-refs.c
index b106a392a4..f3353564f9 100644
--- a/builtin/pack-refs.c
+++ b/builtin/pack-refs.c
@@ -1,6 +1,7 @@
 #include "builtin.h"
 #include "parse-options.h"
 #include "refs.h"
+#include "repository.h"
 
 static char const * const pack_refs_usage[] = {
 	N_("git pack-refs [<options>]"),
@@ -17,5 +18,5 @@ int cmd_pack_refs(int argc, const char **argv, const char *prefix)
 	};
 	if (parse_options(argc, argv, prefix, opts, pack_refs_usage, 0))
 		usage_with_options(pack_refs_usage, opts);
-	return refs_pack_refs(get_main_ref_store(), flags);
+	return refs_pack_refs(get_main_ref_store(the_repository), flags);
 }
diff --git a/builtin/replace.c b/builtin/replace.c
index 935647be6b..237ea656cf 100644
--- a/builtin/replace.c
+++ b/builtin/replace.c
@@ -14,6 +14,8 @@
 #include "refs.h"
 #include "parse-options.h"
 #include "run-command.h"
+#include "object-store.h"
+#include "repository.h"
 #include "tag.h"
 
 static const char * const git_replace_usage[] = {
@@ -83,7 +85,7 @@ static int list_replace_refs(const char *pattern, const char *format)
 		    "valid formats are 'short', 'medium' and 'long'\n",
 		    format);
 
-	for_each_replace_ref(show_reference, (void *)&data);
+	for_each_replace_ref(the_repository, show_reference, (void *)&data);
 
 	return 0;
 }
diff --git a/cache.h b/cache.h
index 601a49c79f..0c1fb9fbcc 100644
--- a/cache.h
+++ b/cache.h
@@ -1193,25 +1193,6 @@ static inline void *read_object_file(const struct object_id *oid, enum object_ty
 	return read_object_file_extended(oid, type, size, 1);
 }
 
-/*
- * This internal function is only declared here for the benefit of
- * lookup_replace_object().  Please do not call it directly.
- */
-extern const struct object_id *do_lookup_replace_object(const struct object_id *oid);
-
-/*
- * If object sha1 should be replaced, return the replacement object's
- * name (replaced recursively, if necessary).  The return value is
- * either sha1 or a pointer to a permanently-allocated value.  When
- * object replacement is suppressed, always return sha1.
- */
-static inline const struct object_id *lookup_replace_object(const struct object_id *oid)
-{
-	if (!check_replace_refs)
-		return oid;
-	return do_lookup_replace_object(oid);
-}
-
 /* Read and unpack an object file into memory, write memory to an object file */
 extern int oid_object_info(const struct object_id *, unsigned long *);
 
diff --git a/environment.c b/environment.c
index 80542e2b4f..f4dd45eb3d 100644
--- a/environment.c
+++ b/environment.c
@@ -51,7 +51,7 @@ const char *editor_program;
 const char *askpass_program;
 const char *excludes_file;
 enum auto_crlf auto_crlf = AUTO_CRLF_FALSE;
-int check_replace_refs = 1;
+int check_replace_refs = 1; /* NEEDSWORK: rename to read_replace_refs */
 char *git_replace_ref_base;
 enum eol core_eol = EOL_UNSET;
 int global_conv_flags_eol = CONV_EOL_RNDTRP_WARN;
diff --git a/object-store.h b/object-store.h
index fef33f345f..1ff862c7f9 100644
--- a/object-store.h
+++ b/object-store.h
@@ -1,6 +1,8 @@
 #ifndef OBJECT_STORE_H
 #define OBJECT_STORE_H
 
+#include "oidmap.h"
+
 struct alternate_object_database {
 	struct alternate_object_database *next;
 
@@ -94,6 +96,12 @@ struct raw_object_store {
 	struct alternate_object_database **alt_odb_tail;
 
 	/*
+	 * Objects that should be substituted by other objects
+	 * (see git-replace(1)).
+	 */
+	struct oidmap *replace_map;
+
+	/*
 	 * private data
 	 *
 	 * should only be accessed directly by packfile.c
diff --git a/object.c b/object.c
index a0a756f24f..66cffaf6e5 100644
--- a/object.c
+++ b/object.c
@@ -1,5 +1,6 @@
 #include "cache.h"
 #include "object.h"
+#include "replace-object.h"
 #include "blob.h"
 #include "tree.h"
 #include "commit.h"
@@ -246,7 +247,7 @@ struct object *parse_object(const struct object_id *oid)
 	unsigned long size;
 	enum object_type type;
 	int eaten;
-	const struct object_id *repl = lookup_replace_object(oid);
+	const struct object_id *repl = lookup_replace_object(the_repository, oid);
 	void *buffer;
 	struct object *obj;
 
diff --git a/refs.c b/refs.c
index 10f69da2b8..64aadd14c9 100644
--- a/refs.c
+++ b/refs.c
@@ -14,6 +14,7 @@
 #include "submodule.h"
 #include "worktree.h"
 #include "argv-array.h"
+#include "repository.h"
 
 /*
  * List of all available backends
@@ -207,7 +208,7 @@ char *refs_resolve_refdup(struct ref_store *refs,
 char *resolve_refdup(const char *refname, int resolve_flags,
 		     struct object_id *oid, int *flags)
 {
-	return refs_resolve_refdup(get_main_ref_store(),
+	return refs_resolve_refdup(get_main_ref_store(the_repository),
 				   refname, resolve_flags,
 				   oid, flags);
 }
@@ -229,7 +230,7 @@ int refs_read_ref_full(struct ref_store *refs, const char *refname,
 
 int read_ref_full(const char *refname, int resolve_flags, struct object_id *oid, int *flags)
 {
-	return refs_read_ref_full(get_main_ref_store(), refname,
+	return refs_read_ref_full(get_main_ref_store(the_repository), refname,
 				  resolve_flags, oid, flags);
 }
 
@@ -376,7 +377,7 @@ int refs_for_each_tag_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
 
 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 {
-	return refs_for_each_tag_ref(get_main_ref_store(), fn, cb_data);
+	return refs_for_each_tag_ref(get_main_ref_store(the_repository), fn, cb_data);
 }
 
 int refs_for_each_branch_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
@@ -386,7 +387,7 @@ int refs_for_each_branch_ref(struct ref_store *refs, each_ref_fn fn, void *cb_da
 
 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 {
-	return refs_for_each_branch_ref(get_main_ref_store(), fn, cb_data);
+	return refs_for_each_branch_ref(get_main_ref_store(the_repository), fn, cb_data);
 }
 
 int refs_for_each_remote_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
@@ -396,7 +397,7 @@ int refs_for_each_remote_ref(struct ref_store *refs, each_ref_fn fn, void *cb_da
 
 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 {
-	return refs_for_each_remote_ref(get_main_ref_store(), fn, cb_data);
+	return refs_for_each_remote_ref(get_main_ref_store(the_repository), fn, cb_data);
 }
 
 int head_ref_namespaced(each_ref_fn fn, void *cb_data)
@@ -744,7 +745,7 @@ int refs_delete_ref(struct ref_store *refs, const char *msg,
 	struct strbuf err = STRBUF_INIT;
 
 	if (ref_type(refname) == REF_TYPE_PSEUDOREF) {
-		assert(refs == get_main_ref_store());
+		assert(refs == get_main_ref_store(the_repository));
 		return delete_pseudoref(refname, old_oid);
 	}
 
@@ -766,7 +767,7 @@ int refs_delete_ref(struct ref_store *refs, const char *msg,
 int delete_ref(const char *msg, const char *refname,
 	       const struct object_id *old_oid, unsigned int flags)
 {
-	return refs_delete_ref(get_main_ref_store(), msg, refname,
+	return refs_delete_ref(get_main_ref_store(the_repository), msg, refname,
 			       old_oid, flags);
 }
 
@@ -942,7 +943,7 @@ struct ref_transaction *ref_store_transaction_begin(struct ref_store *refs,
 
 struct ref_transaction *ref_transaction_begin(struct strbuf *err)
 {
-	return ref_store_transaction_begin(get_main_ref_store(), err);
+	return ref_store_transaction_begin(get_main_ref_store(the_repository), err);
 }
 
 void ref_transaction_free(struct ref_transaction *transaction)
@@ -1074,7 +1075,7 @@ int refs_update_ref(struct ref_store *refs, const char *msg,
 	int ret = 0;
 
 	if (ref_type(refname) == REF_TYPE_PSEUDOREF) {
-		assert(refs == get_main_ref_store());
+		assert(refs == get_main_ref_store(the_repository));
 		ret = write_pseudoref(refname, new_oid, old_oid, &err);
 	} else {
 		t = ref_store_transaction_begin(refs, &err);
@@ -1113,7 +1114,7 @@ int update_ref(const char *msg, const char *refname,
 	       const struct object_id *old_oid,
 	       unsigned int flags, enum action_on_err onerr)
 {
-	return refs_update_ref(get_main_ref_store(), msg, refname, new_oid,
+	return refs_update_ref(get_main_ref_store(the_repository), msg, refname, new_oid,
 			       old_oid, flags, onerr);
 }
 
@@ -1334,7 +1335,7 @@ int refs_head_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
 
 int head_ref(each_ref_fn fn, void *cb_data)
 {
-	return refs_head_ref(get_main_ref_store(), fn, cb_data);
+	return refs_head_ref(get_main_ref_store(the_repository), fn, cb_data);
 }
 
 struct ref_iterator *refs_ref_iterator_begin(
@@ -1393,7 +1394,7 @@ int refs_for_each_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
 
 int for_each_ref(each_ref_fn fn, void *cb_data)
 {
-	return refs_for_each_ref(get_main_ref_store(), fn, cb_data);
+	return refs_for_each_ref(get_main_ref_store(the_repository), fn, cb_data);
 }
 
 int refs_for_each_ref_in(struct ref_store *refs, const char *prefix,
@@ -1404,7 +1405,7 @@ int refs_for_each_ref_in(struct ref_store *refs, const char *prefix,
 
 int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
 {
-	return refs_for_each_ref_in(get_main_ref_store(), prefix, fn, cb_data);
+	return refs_for_each_ref_in(get_main_ref_store(the_repository), prefix, fn, cb_data);
 }
 
 int for_each_fullref_in(const char *prefix, each_ref_fn fn, void *cb_data, unsigned int broken)
@@ -1413,7 +1414,7 @@ int for_each_fullref_in(const char *prefix, each_ref_fn fn, void *cb_data, unsig
 
 	if (broken)
 		flag = DO_FOR_EACH_INCLUDE_BROKEN;
-	return do_for_each_ref(get_main_ref_store(),
+	return do_for_each_ref(get_main_ref_store(the_repository),
 			       prefix, fn, 0, flag, cb_data);
 }
 
@@ -1428,9 +1429,9 @@ int refs_for_each_fullref_in(struct ref_store *refs, const char *prefix,
 	return do_for_each_ref(refs, prefix, fn, 0, flag, cb_data);
 }
 
-int for_each_replace_ref(each_ref_fn fn, void *cb_data)
+int for_each_replace_ref(struct repository *r, each_ref_fn fn, void *cb_data)
 {
-	return do_for_each_ref(get_main_ref_store(),
+	return do_for_each_ref(get_main_ref_store(r),
 			       git_replace_ref_base, fn,
 			       strlen(git_replace_ref_base),
 			       DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
@@ -1441,7 +1442,7 @@ int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
 	struct strbuf buf = STRBUF_INIT;
 	int ret;
 	strbuf_addf(&buf, "%srefs/", get_git_namespace());
-	ret = do_for_each_ref(get_main_ref_store(),
+	ret = do_for_each_ref(get_main_ref_store(the_repository),
 			      buf.buf, fn, 0, 0, cb_data);
 	strbuf_release(&buf);
 	return ret;
@@ -1455,7 +1456,7 @@ int refs_for_each_rawref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
 
 int for_each_rawref(each_ref_fn fn, void *cb_data)
 {
-	return refs_for_each_rawref(get_main_ref_store(), fn, cb_data);
+	return refs_for_each_rawref(get_main_ref_store(the_repository), fn, cb_data);
 }
 
 int refs_read_raw_ref(struct ref_store *ref_store,
@@ -1561,7 +1562,7 @@ const char *refs_resolve_ref_unsafe(struct ref_store *refs,
 /* backend functions */
 int refs_init_db(struct strbuf *err)
 {
-	struct ref_store *refs = get_main_ref_store();
+	struct ref_store *refs = get_main_ref_store(the_repository);
 
 	return refs->be->init_db(refs, err);
 }
@@ -1569,7 +1570,7 @@ int refs_init_db(struct strbuf *err)
 const char *resolve_ref_unsafe(const char *refname, int resolve_flags,
 			       struct object_id *oid, int *flags)
 {
-	return refs_resolve_ref_unsafe(get_main_ref_store(), refname,
+	return refs_resolve_ref_unsafe(get_main_ref_store(the_repository), refname,
 				       resolve_flags, oid, flags);
 }
 
@@ -1621,9 +1622,6 @@ static struct ref_store_hash_entry *alloc_ref_store_hash_entry(
 	return entry;
 }
 
-/* A pointer to the ref_store for the main repository: */
-static struct ref_store *main_ref_store;
-
 /* A hashmap of ref_stores, stored by submodule name: */
 static struct hashmap submodule_ref_stores;
 
@@ -1665,13 +1663,13 @@ static struct ref_store *ref_store_init(const char *gitdir,
 	return refs;
 }
 
-struct ref_store *get_main_ref_store(void)
+struct ref_store *get_main_ref_store(struct repository *r)
 {
-	if (main_ref_store)
-		return main_ref_store;
+	if (r->refs)
+		return r->refs;
 
-	main_ref_store = ref_store_init(get_git_dir(), REF_STORE_ALL_CAPS);
-	return main_ref_store;
+	r->refs = ref_store_init(r->gitdir, REF_STORE_ALL_CAPS);
+	return r->refs;
 }
 
 /*
@@ -1740,7 +1738,7 @@ struct ref_store *get_worktree_ref_store(const struct worktree *wt)
 	const char *id;
 
 	if (wt->is_current)
-		return get_main_ref_store();
+		return get_main_ref_store(the_repository);
 
 	id = wt->id ? wt->id : "/";
 	refs = lookup_ref_store_map(&worktree_ref_stores, id);
@@ -1796,7 +1794,7 @@ int refs_peel_ref(struct ref_store *refs, const char *refname,
 
 int peel_ref(const char *refname, struct object_id *oid)
 {
-	return refs_peel_ref(get_main_ref_store(), refname, oid);
+	return refs_peel_ref(get_main_ref_store(the_repository), refname, oid);
 }
 
 int refs_create_symref(struct ref_store *refs,
@@ -1812,7 +1810,7 @@ int refs_create_symref(struct ref_store *refs,
 int create_symref(const char *ref_target, const char *refs_heads_master,
 		  const char *logmsg)
 {
-	return refs_create_symref(get_main_ref_store(), ref_target,
+	return refs_create_symref(get_main_ref_store(the_repository), ref_target,
 				  refs_heads_master, logmsg);
 }
 
@@ -2020,7 +2018,7 @@ int refs_for_each_reflog(struct ref_store *refs, each_ref_fn fn, void *cb_data)
 
 int for_each_reflog(each_ref_fn fn, void *cb_data)
 {
-	return refs_for_each_reflog(get_main_ref_store(), fn, cb_data);
+	return refs_for_each_reflog(get_main_ref_store(the_repository), fn, cb_data);
 }
 
 int refs_for_each_reflog_ent_reverse(struct ref_store *refs,
@@ -2035,7 +2033,7 @@ int refs_for_each_reflog_ent_reverse(struct ref_store *refs,
 int for_each_reflog_ent_reverse(const char *refname, each_reflog_ent_fn fn,
 				void *cb_data)
 {
-	return refs_for_each_reflog_ent_reverse(get_main_ref_store(),
+	return refs_for_each_reflog_ent_reverse(get_main_ref_store(the_repository),
 						refname, fn, cb_data);
 }
 
@@ -2048,7 +2046,7 @@ int refs_for_each_reflog_ent(struct ref_store *refs, const char *refname,
 int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn,
 			void *cb_data)
 {
-	return refs_for_each_reflog_ent(get_main_ref_store(), refname,
+	return refs_for_each_reflog_ent(get_main_ref_store(the_repository), refname,
 					fn, cb_data);
 }
 
@@ -2059,7 +2057,7 @@ int refs_reflog_exists(struct ref_store *refs, const char *refname)
 
 int reflog_exists(const char *refname)
 {
-	return refs_reflog_exists(get_main_ref_store(), refname);
+	return refs_reflog_exists(get_main_ref_store(the_repository), refname);
 }
 
 int refs_create_reflog(struct ref_store *refs, const char *refname,
@@ -2071,7 +2069,7 @@ int refs_create_reflog(struct ref_store *refs, const char *refname,
 int safe_create_reflog(const char *refname, int force_create,
 		       struct strbuf *err)
 {
-	return refs_create_reflog(get_main_ref_store(), refname,
+	return refs_create_reflog(get_main_ref_store(the_repository), refname,
 				  force_create, err);
 }
 
@@ -2082,7 +2080,7 @@ int refs_delete_reflog(struct ref_store *refs, const char *refname)
 
 int delete_reflog(const char *refname)
 {
-	return refs_delete_reflog(get_main_ref_store(), refname);
+	return refs_delete_reflog(get_main_ref_store(the_repository), refname);
 }
 
 int refs_reflog_expire(struct ref_store *refs,
@@ -2105,7 +2103,7 @@ int reflog_expire(const char *refname, const struct object_id *oid,
 		  reflog_expiry_cleanup_fn cleanup_fn,
 		  void *policy_cb_data)
 {
-	return refs_reflog_expire(get_main_ref_store(),
+	return refs_reflog_expire(get_main_ref_store(the_repository),
 				  refname, oid, flags,
 				  prepare_fn, should_prune_fn,
 				  cleanup_fn, policy_cb_data);
@@ -2128,7 +2126,7 @@ int refs_delete_refs(struct ref_store *refs, const char *msg,
 int delete_refs(const char *msg, struct string_list *refnames,
 		unsigned int flags)
 {
-	return refs_delete_refs(get_main_ref_store(), msg, refnames, flags);
+	return refs_delete_refs(get_main_ref_store(the_repository), msg, refnames, flags);
 }
 
 int refs_rename_ref(struct ref_store *refs, const char *oldref,
@@ -2139,7 +2137,7 @@ int refs_rename_ref(struct ref_store *refs, const char *oldref,
 
 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
 {
-	return refs_rename_ref(get_main_ref_store(), oldref, newref, logmsg);
+	return refs_rename_ref(get_main_ref_store(the_repository), oldref, newref, logmsg);
 }
 
 int refs_copy_existing_ref(struct ref_store *refs, const char *oldref,
@@ -2150,5 +2148,5 @@ int refs_copy_existing_ref(struct ref_store *refs, const char *oldref,
 
 int copy_existing_ref(const char *oldref, const char *newref, const char *logmsg)
 {
-	return refs_copy_existing_ref(get_main_ref_store(), oldref, newref, logmsg);
+	return refs_copy_existing_ref(get_main_ref_store(the_repository), oldref, newref, logmsg);
 }
diff --git a/refs.h b/refs.h
index 93b6dce944..cc2fb4c68c 100644
--- a/refs.h
+++ b/refs.h
@@ -307,7 +307,7 @@ int for_each_fullref_in(const char *prefix, each_ref_fn fn, void *cb_data,
 int for_each_tag_ref(each_ref_fn fn, void *cb_data);
 int for_each_branch_ref(each_ref_fn fn, void *cb_data);
 int for_each_remote_ref(each_ref_fn fn, void *cb_data);
-int for_each_replace_ref(each_ref_fn fn, void *cb_data);
+int for_each_replace_ref(struct repository *r, each_ref_fn fn, void *cb_data);
 int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data);
 int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
 			 const char *prefix, void *cb_data);
@@ -765,7 +765,7 @@ int reflog_expire(const char *refname, const struct object_id *oid,
 
 int ref_storage_backend_exists(const char *name);
 
-struct ref_store *get_main_ref_store(void);
+struct ref_store *get_main_ref_store(struct repository *r);
 /*
  * Return the ref_store instance for the specified submodule. For the
  * main repository, use submodule==NULL; such a call cannot fail. For
diff --git a/refs/files-backend.c b/refs/files-backend.c
index a92a2aa821..49d8f67bf1 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -62,10 +62,6 @@ struct ref_lock {
 	struct object_id old_oid;
 };
 
-/*
- * Future: need to be in "struct repository"
- * when doing a full libification.
- */
 struct files_ref_store {
 	struct ref_store base;
 	unsigned int store_flags;
diff --git a/replace-object.c b/replace-object.c
index 336357394d..246b98cd4f 100644
--- a/replace-object.c
+++ b/replace-object.c
@@ -1,55 +1,11 @@
 #include "cache.h"
-#include "sha1-lookup.h"
+#include "oidmap.h"
+#include "object-store.h"
+#include "replace-object.h"
 #include "refs.h"
+#include "repository.h"
 #include "commit.h"
 
-/*
- * An array of replacements.  The array is kept sorted by the original
- * sha1.
- */
-static struct replace_object {
-	struct object_id original;
-	struct object_id replacement;
-} **replace_object;
-
-static int replace_object_alloc, replace_object_nr;
-
-static const unsigned char *replace_sha1_access(size_t index, void *table)
-{
-	struct replace_object **replace = table;
-	return replace[index]->original.hash;
-}
-
-static int replace_object_pos(const unsigned char *sha1)
-{
-	return sha1_pos(sha1, replace_object, replace_object_nr,
-			replace_sha1_access);
-}
-
-static int register_replace_object(struct replace_object *replace,
-				   int ignore_dups)
-{
-	int pos = replace_object_pos(replace->original.hash);
-
-	if (0 <= pos) {
-		if (ignore_dups)
-			free(replace);
-		else {
-			free(replace_object[pos]);
-			replace_object[pos] = replace;
-		}
-		return 1;
-	}
-	pos = -pos - 1;
-	ALLOC_GROW(replace_object, replace_object_nr + 1, replace_object_alloc);
-	replace_object_nr++;
-	if (pos < replace_object_nr)
-		MOVE_ARRAY(replace_object + pos + 1, replace_object + pos,
-			   replace_object_nr - pos - 1);
-	replace_object[pos] = replace;
-	return 0;
-}
-
 static int register_replace_ref(const char *refname,
 				const struct object_id *oid,
 				int flag, void *cb_data)
@@ -59,7 +15,7 @@ static int register_replace_ref(const char *refname,
 	const char *hash = slash ? slash + 1 : refname;
 	struct replace_object *repl_obj = xmalloc(sizeof(*repl_obj));
 
-	if (get_oid_hex(hash, &repl_obj->original)) {
+	if (get_oid_hex(hash, &repl_obj->original.oid)) {
 		free(repl_obj);
 		warning("bad replace ref name: %s", refname);
 		return 0;
@@ -69,23 +25,22 @@ static int register_replace_ref(const char *refname,
 	oidcpy(&repl_obj->replacement, oid);
 
 	/* Register new object */
-	if (register_replace_object(repl_obj, 1))
+	if (oidmap_put(the_repository->objects->replace_map, repl_obj))
 		die("duplicate replace ref: %s", refname);
 
 	return 0;
 }
 
-static void prepare_replace_object(void)
+static void prepare_replace_object(struct repository *r)
 {
-	static int replace_object_prepared;
-
-	if (replace_object_prepared)
+	if (r->objects->replace_map)
 		return;
 
-	for_each_replace_ref(register_replace_ref, NULL);
-	replace_object_prepared = 1;
-	if (!replace_object_nr)
-		check_replace_refs = 0;
+	r->objects->replace_map =
+		xmalloc(sizeof(*the_repository->objects->replace_map));
+	oidmap_init(r->objects->replace_map, 0);
+
+	for_each_replace_ref(r, register_replace_ref, NULL);
 }
 
 /* We allow "recursive" replacement. Only within reason, though */
@@ -98,23 +53,21 @@ static void prepare_replace_object(void)
  * permanently-allocated value.  This function always respects replace
  * references, regardless of the value of check_replace_refs.
  */
-const struct object_id *do_lookup_replace_object(const struct object_id *oid)
+const struct object_id *do_lookup_replace_object(struct repository *r,
+						 const struct object_id *oid)
 {
-	int pos, depth = MAXREPLACEDEPTH;
+	int depth = MAXREPLACEDEPTH;
 	const struct object_id *cur = oid;
 
-	prepare_replace_object();
+	prepare_replace_object(r);
 
 	/* Try to recursively replace the object */
-	do {
-		if (--depth < 0)
-			die("replace depth too high for object %s",
-			    oid_to_hex(oid));
-
-		pos = replace_object_pos(cur->hash);
-		if (0 <= pos)
-			cur = &replace_object[pos]->replacement;
-	} while (0 <= pos);
-
-	return cur;
+	while (depth-- > 0) {
+		struct replace_object *repl_obj =
+			oidmap_get(r->objects->replace_map, cur);
+		if (!repl_obj)
+			return cur;
+		cur = &repl_obj->replacement;
+	}
+	die("replace depth too high for object %s", oid_to_hex(oid));
 }
diff --git a/replace-object.h b/replace-object.h
new file mode 100644
index 0000000000..f996de3d62
--- /dev/null
+++ b/replace-object.h
@@ -0,0 +1,36 @@
+#ifndef REPLACE_OBJECT_H
+#define REPLACE_OBJECT_H
+
+#include "oidmap.h"
+#include "repository.h"
+#include "object-store.h"
+
+struct replace_object {
+	struct oidmap_entry original;
+	struct object_id replacement;
+};
+
+/*
+ * This internal function is only declared here for the benefit of
+ * lookup_replace_object().  Please do not call it directly.
+ */
+extern const struct object_id *do_lookup_replace_object(struct repository *r,
+							const struct object_id *oid);
+
+/*
+ * If object sha1 should be replaced, return the replacement object's
+ * name (replaced recursively, if necessary).  The return value is
+ * either sha1 or a pointer to a permanently-allocated value.  When
+ * object replacement is suppressed, always return sha1.
+ */
+static inline const struct object_id *lookup_replace_object(struct repository *r,
+							    const struct object_id *oid)
+{
+	if (!check_replace_refs ||
+	    (r->objects->replace_map &&
+	     r->objects->replace_map->map.tablesize == 0))
+		return oid;
+	return do_lookup_replace_object(r, oid);
+}
+
+#endif /* REPLACE_OBJECT_H */
diff --git a/repository.h b/repository.h
index 6041367f08..f2646f0c52 100644
--- a/repository.h
+++ b/repository.h
@@ -26,6 +26,9 @@ struct repository {
 	 */
 	struct raw_object_store *objects;
 
+	/* The store in which the refs are held. */
+	struct ref_store *refs;
+
 	/*
 	 * Path to the repository's graft file.
 	 * Cannot be NULL after initialization.
diff --git a/revision.c b/revision.c
index b42c836d7a..1cff11833e 100644
--- a/revision.c
+++ b/revision.c
@@ -6,6 +6,7 @@
 #include "diff.h"
 #include "refs.h"
 #include "revision.h"
+#include "repository.h"
 #include "graph.h"
 #include "grep.h"
 #include "reflog-walk.h"
@@ -1285,7 +1286,7 @@ void add_reflogs_to_pending(struct rev_info *revs, unsigned flags)
 
 	cb.all_revs = revs;
 	cb.all_flags = flags;
-	cb.refs = get_main_ref_store();
+	cb.refs = get_main_ref_store(the_repository);
 	for_each_reflog(handle_one_reflog, &cb);
 
 	if (!revs->single_worktree)
@@ -2176,7 +2177,7 @@ static int handle_revision_pseudo_opt(const char *submodule,
 			die("BUG: --single-worktree cannot be used together with submodule");
 		refs = get_submodule_ref_store(submodule);
 	} else
-		refs = get_main_ref_store();
+		refs = get_main_ref_store(the_repository);
 
 	/*
 	 * NOTE!
diff --git a/sha1-file.c b/sha1-file.c
index 77ccaab928..64a5bd7d87 100644
--- a/sha1-file.c
+++ b/sha1-file.c
@@ -23,6 +23,7 @@
 #include "sha1-lookup.h"
 #include "bulk-checkin.h"
 #include "repository.h"
+#include "replace-object.h"
 #include "streaming.h"
 #include "dir.h"
 #include "list.h"
@@ -1239,7 +1240,7 @@ int oid_object_info_extended(const struct object_id *oid, struct object_info *oi
 	int already_retried = 0;
 
 	if (flags & OBJECT_INFO_LOOKUP_REPLACE)
-		real = lookup_replace_object(oid);
+		real = lookup_replace_object(the_repository, oid);
 
 	if (is_null_oid(real))
 		return -1;
@@ -1383,8 +1384,8 @@ void *read_object_file_extended(const struct object_id *oid,
 	const struct packed_git *p;
 	const char *path;
 	struct stat st;
-	const struct object_id *repl = lookup_replace ? lookup_replace_object(oid)
-						      : oid;
+	const struct object_id *repl = lookup_replace ?
+		lookup_replace_object(the_repository, oid) : oid;
 
 	errno = 0;
 	data = read_object(repl->hash, type, size);
diff --git a/streaming.c b/streaming.c
index 7d55ba64c7..cce7b17ea7 100644
--- a/streaming.c
+++ b/streaming.c
@@ -5,6 +5,7 @@
 #include "streaming.h"
 #include "repository.h"
 #include "object-store.h"
+#include "replace-object.h"
 #include "packfile.h"
 
 enum input_source {
@@ -139,7 +140,7 @@ struct git_istream *open_istream(const struct object_id *oid,
 {
 	struct git_istream *st;
 	struct object_info oi = OBJECT_INFO_INIT;
-	const struct object_id *real = lookup_replace_object(oid);
+	const struct object_id *real = lookup_replace_object(the_repository, oid);
 	enum input_source src = istream_source(real, type, &oi);
 
 	if (src < 0)
diff --git a/t/helper/test-ref-store.c b/t/helper/test-ref-store.c
index 7c4f43746e..e9e0541276 100644
--- a/t/helper/test-ref-store.c
+++ b/t/helper/test-ref-store.c
@@ -3,6 +3,7 @@
 #include "refs.h"
 #include "worktree.h"
 #include "object-store.h"
+#include "repository.h"
 
 static const char *notnull(const char *arg, const char *name)
 {
@@ -23,7 +24,7 @@ static const char **get_store(const char **argv, struct ref_store **refs)
 	if (!argv[0]) {
 		die("ref store required");
 	} else if (!strcmp(argv[0], "main")) {
-		*refs = get_main_ref_store();
+		*refs = get_main_ref_store(the_repository);
 	} else if (skip_prefix(argv[0], "submodule:", &gitdir)) {
 		struct strbuf sb = STRBUF_INIT;
 		int ret;