call init_pack_revindex() lazily

This makes life much easier for next patch, as well as being more efficient
when the revindex is actually not used.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-pack-objects.c

@@ -1148,8 +1148,6 @@ static void get_object_details(void)
 		sorted_by_offset[i] = objects + i;
 	qsort(sorted_by_offset, nr_objects, sizeof(*sorted_by_offset), pack_offset_sort);
 
-	init_pack_revindex();
-
 	for (i = 0; i < nr_objects; i++)
 		check_object(sorted_by_offset[i]);
 

pack-check.c

@@ -107,7 +107,6 @@ static void show_pack_info(struct packed_git *p)
 
 	nr_objects = p->num_objects;
 	memset(chain_histogram, 0, sizeof(chain_histogram));
-	init_pack_revindex();
 
 	for (i = 0; i < nr_objects; i++) {
 		const unsigned char *sha1;

pack-revindex.c

@@ -40,7 +40,7 @@ static int pack_revindex_ix(struct packed_git *p)
 	return -1 - i;
 }
 
-void init_pack_revindex(void)
+static void init_pack_revindex(void)
 {
 	int num;
 	struct packed_git *p;
@@ -118,9 +118,11 @@ struct revindex_entry *find_pack_revindex(struct packed_git *p, off_t ofs)
 	struct pack_revindex *rix;
 	struct revindex_entry *revindex;
 
+	if (!pack_revindex_hashsz)
+		init_pack_revindex();
 	num = pack_revindex_ix(p);
 	if (num < 0)
-		die("internal error: pack revindex uninitialized");
+		die("internal error: pack revindex fubar");
 
 	rix = &pack_revindex[num];
 	if (!rix->revindex)

pack-revindex.h

@@ -6,7 +6,6 @@ struct revindex_entry {
 	unsigned int nr;
 };
 
-void init_pack_revindex(void);
 struct revindex_entry *find_pack_revindex(struct packed_git *p, off_t ofs);
 
 #endif