[PATCH 1/4] pack v4: avoid strlen() in tree_entry_prefix

* [PATCH 1/4] pack v4: avoid strlen() in tree_entry_prefix
@ 2013-09-12 10:38 Nguyễn Thái Ngọc Duy
  2013-09-12 10:38 ` [PATCH 2/4] pack v4: add v4_size to struct delta_base_cache_entry Nguyễn Thái Ngọc Duy
                   ` (3 more replies)
  0 siblings, 4 replies; 12+ messages in thread
From: Nguyễn Thái Ngọc Duy @ 2013-09-12 10:38 UTC (permalink / raw)
  To: git; +Cc: Nicolas Pitre, Nguyễn Thái Ngọc Duy

We do know the length of the path name of an tree entry from the tree
dictionary. On an unoptimized build, this cuts down "git rev-list
--objects v1.8.4"'s time from 6.2s to 5.8s. This difference is less on
optimized builds.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 packv4-parse.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/packv4-parse.c b/packv4-parse.c
index c00a014..ae3e6a5 100644
--- a/packv4-parse.c
+++ b/packv4-parse.c
@@ -50,15 +50,17 @@ struct packv4_dict *pv4_create_dict(const unsigned char *data, int dict_size)
 		return NULL;
 	}
 
-	dict = xmalloc(sizeof(*dict) + nb_entries * sizeof(dict->offsets[0]));
+	dict = xmalloc(sizeof(*dict) +
+		       (nb_entries + 1) * sizeof(dict->offsets[0]));
 	dict->data = data;
 	dict->nb_entries = nb_entries;
 
+	dict->offsets[0] = 0;
 	cp = data;
 	for (i = 0; i < nb_entries; i++) {
-		dict->offsets[i] = cp - data;
 		cp += 2;
 		cp += strlen((const char *)cp) + 1;
+		dict->offsets[i + 1] = cp - data;
 	}
 
 	return dict;
@@ -163,7 +165,8 @@ static void load_path_dict(struct packed_git *p)
 	p->path_dict = paths;
 }
 
-const unsigned char *get_pathref(struct packed_git *p, unsigned int index)
+const unsigned char *get_pathref(struct packed_git *p, unsigned int index,
+				 int *len)
 {
 	if (!p->path_dict)
 		load_path_dict(p);
@@ -172,6 +175,9 @@ const unsigned char *get_pathref(struct packed_git *p, unsigned int index)
 		error("%s: index overflow", __func__);
 		return NULL;
 	}
+	if (len)
+		*len = p->path_dict->offsets[index + 1] -
+			p->path_dict->offsets[index];
 	return p->path_dict->data + p->path_dict->offsets[index];
 }
 
@@ -373,9 +379,9 @@ static int copy_canonical_tree_entries(struct packed_git *p, off_t offset,
 }
 
 static int tree_entry_prefix(unsigned char *buf, unsigned long size,
-			     const unsigned char *path, unsigned mode)
+			     const unsigned char *path, int path_len,
+			     unsigned mode)
 {
-	int path_len = strlen((const char *)path) + 1;
 	int mode_len = 0;
 	int len;
 	unsigned char mode_buf[8];
@@ -463,14 +469,15 @@ static int decode_entries(struct packed_git *p, struct pack_window **w_curs,
 			 */
 			const unsigned char *path, *sha1;
 			unsigned mode;
-			int len;
+			int len, pathlen;
 
-			path = get_pathref(p, what >> 1);
+			path = get_pathref(p, what >> 1, &pathlen);
 			sha1 = get_sha1ref(p, &scp);
 			if (!path || !sha1)
 				return -1;
 			mode = (path[0] << 8) | path[1];
-			len = tree_entry_prefix(*dstp, *sizep, path + 2, mode);
+			len = tree_entry_prefix(*dstp, *sizep,
+						path + 2, pathlen - 2, mode);
 			if (!len || len + 20 > *sizep)
 				return -1;
 			hashcpy(*dstp + len, sha1);
-- 
1.8.2.83.gc99314b

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