[PATCH 04/15] replace-object: eliminate replace objects prepared flag

[Stefan Beller]

Make the oidmap a pointer.

That way we eliminate the need for the global boolean
variable 'replace_object_prepared' as we can put this information
into the pointer being NULL or not.

Another advantage of this is that we would more quickly catch
code that tries to access replace-map without initializing it.

This also allows the '#include "oidmap.h"' introduced in a previous
patch to be replaced by the forward declaration of 'struct oidmap;'.
Keeping the type opaque discourages circumventing accessor functions;
not dragging in other headers avoids some compile time overhead.

One disadvantage of this is change is performance as we need to
pay the overhead for a malloc. The alternative of moving the
global variable into the object store is less modular code.

Helped-by: René Scharfe <l....@web.de>
Helped-by: Junio C Hamano <gits...@pobox.com>
Signed-off-by: Stefan Beller <sbel...@google.com>
---
 object-store.h   |  2 +-
 replace_object.c | 16 +++++++++-------
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/object-store.h b/object-store.h
index c04b4c95eb..1ff862c7f9 100644
--- a/object-store.h
+++ b/object-store.h
@@ -99,7 +99,7 @@ struct raw_object_store {
         * Objects that should be substituted by other objects
         * (see git-replace(1)).
         */
-       struct oidmap replace_map;
+       struct oidmap *replace_map;
 
        /*
         * private data
diff --git a/replace_object.c b/replace_object.c
index afbdf2df25..953fa9cc40 100644
--- a/replace_object.c
+++ b/replace_object.c
@@ -25,7 +25,7 @@ static int register_replace_ref(const char *refname,
        oidcpy(&repl_obj->replacement, oid);
 
        /* Register new object */
-       if (oidmap_put(&the_repository->objects->replace_map, repl_obj))
+       if (oidmap_put(the_repository->objects->replace_map, repl_obj))
                die("duplicate replace ref: %s", refname);
 
        return 0;
@@ -33,14 +33,16 @@ static int register_replace_ref(const char *refname,
 
 static void prepare_replace_object(void)
 {
-       static int replace_object_prepared;
-
-       if (replace_object_prepared)
+       if (the_repository->objects->replace_map)
                return;
 
+       the_repository->objects->replace_map =
+               xmalloc(sizeof(*the_repository->objects->replace_map));
+       oidmap_init(the_repository->objects->replace_map, 0);
+
        for_each_replace_ref(register_replace_ref, NULL);
-       replace_object_prepared = 1;
-       if (!the_repository->objects->replace_map.map.tablesize)
+
+       if (!the_repository->objects->replace_map->map.tablesize)
                check_replace_refs = 0;
 }
 
@@ -64,7 +66,7 @@ const struct object_id *do_lookup_replace_object(const struct 
object_id *oid)
        /* Try to recursively replace the object */
        while (depth-- > 0) {
                struct replace_object *repl_obj =
-                       oidmap_get(&the_repository->objects->replace_map, cur);
+                       oidmap_get(the_repository->objects->replace_map, cur);
                if (!repl_obj)
                        return cur;
                cur = &repl_obj->replacement;
-- 
2.17.0.484.g0c8726318c-goog