X-Git-Url: https://git.octo.it/?a=blobdiff_plain;f=diff-delta.c;h=b7190ea47a9c249b108fe5b590e18ba7c27f4176;hb=c436eb8cf1efa3fe2c70100ae0cbc48f0feaf5af;hp=0730b24df8fe679d16e1cd03d066b4d7f33e73cd;hpb=2b8d9347aa1a11f1ac13591f89ca9f984d467c77;p=git.git

diff --git a/diff-delta.c b/diff-delta.c
index 0730b24d..b7190ea4 100644
--- a/diff-delta.c
+++ b/diff-delta.c
@@ -88,22 +88,35 @@ static struct index ** delta_index(const unsigned char *buf,
 
 	/*
 	 * Now make sure none of the hash buckets has more entries than
-	 * we're willing to test.  Otherwise we short-circuit the entry
-	 * list uniformly to still preserve a good repartition across
-	 * the reference buffer.
+	 * we're willing to test.  Otherwise we cull the entry list to
+	 * limit identical three byte prefixes to still preserve a good
+	 * repartition across the reference buffer.
 	 */
 	for (i = 0; i < hsize; i++) {
+		struct index **list, *bucket, *remaining;
+		int cnt;
 		if (hash_count[i] < hlimit)
 			continue;
-		entry = hash[i];
-		do {
-			struct index *keep = entry;
-			int skip = hash_count[i] / hlimit / 2;
-			do {
-				entry = entry->next;
-			} while(--skip && entry);
-			keep->next = entry;
-		} while(entry);
+
+		bucket = NULL;
+		list = &bucket;
+		remaining = hash[i];
+		cnt = 0;
+		while (cnt < hlimit && remaining) {
+			struct index *this = remaining, *that;
+			remaining = remaining->next;
+			for (that = bucket; that; that = that->next) {
+				if (!memcmp(that->ptr, this->ptr, 3))
+					break;
+			}
+			if (that)
+				continue; /* discard */
+			cnt++;
+			*list = this;
+			list = &(this->next);
+			this->next = NULL;
+		}
+		hash[i] = bucket;
 	}
 	free(hash_count);