From:   Stefan Beller <sbeller@google.com>
To:     sbeller@google.com
Cc:     git@vger.kernel.org, jonathantanmy@google.com, l.s.r@web.de,
        pclouds@gmail.com, sandals@crustytoothpaste.net,
        sunshine@sunshineco.com
Subject: [PATCH 01/15] replace_object: use oidmap
Date:   Wed, 11 Apr 2018 17:21:04 -0700
Message-Id: <20180412002118.102976-2-sbeller@google.com>
In-Reply-To: <20180412002118.102976-1-sbeller@google.com>
References: <20180409224533.17764-1-sbeller@google.com>
 <20180412002118.102976-1-sbeller@google.com>
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From: René Scharfe <l.s.r@web.de>

Load the replace objects into an oidmap to allow for easy lookups in
constant time.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Stefan Beller <sbeller@google.com>
---
 replace_object.c | 76 ++++++++++--------------------------------------
 1 file changed, 16 insertions(+), 60 deletions(-)

diff --git a/replace_object.c b/replace_object.c
index 336357394d..a757a5ebf2 100644
--- a/replace_object.c
+++ b/replace_object.c
@@ -1,54 +1,14 @@
 #include "cache.h"
-#include "sha1-lookup.h"
+#include "oidmap.h"
 #include "refs.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 replace_object {
+	struct oidmap_entry 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 struct oidmap replace_map = OIDMAP_INIT;
 
 static int register_replace_ref(const char *refname,
 				const struct object_id *oid,
@@ -59,7 +19,7 @@ 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;
@@ -69,7 +29,7 @@ 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(&replace_map, repl_obj))
 		die("duplicate replace ref: %s", refname);
 
 	return 0;
@@ -84,7 +44,7 @@ static void prepare_replace_object(void)
 
 	for_each_replace_ref(register_replace_ref, NULL);
 	replace_object_prepared = 1;
-	if (!replace_object_nr)
+	if (!replace_map.map.tablesize)
 		check_replace_refs = 0;
 }
 
@@ -100,21 +60,17 @@ static void prepare_replace_object(void)
  */
 const struct object_id *do_lookup_replace_object(const struct object_id *oid)
 {
-	int pos, depth = MAXREPLACEDEPTH;
+	int depth = MAXREPLACEDEPTH;
 	const struct object_id *cur = oid;
 
 	prepare_replace_object();
 
 	/* 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(&replace_map, cur);
+		if (!repl_obj)
+			return cur;
+		cur = &repl_obj->replacement;
+	}
+	die("replace depth too high for object %s", oid_to_hex(oid));
 }
-- 
2.17.0.484.g0c8726318c-goog