This makes the tree descriptor contain a "struct name_entry" as part of
it, and it gets filled in so that it always contains a valid entry. On
some benchmarks, it improves performance by up to 15%.
That makes tree entry "extract" trivial, and means that we only actually
need to decode each tree entry just once: we decode the first one when
we initialize the tree descriptor, and each subsequent one when doing
"update_tree_entry()". In particular, this means that we don't need to
do strlen() both at extract time _and_ at update time.
Finally, it also allows more sharing of code (entry_extract(), that
wanted a "struct name_entry", just got totally trivial, along with the
"tree_entry()" function).
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
---
tree-walk.c | 101 +++++++++++++++++++++++++---------------------------------
tree-walk.h | 18 +++++++---
2 files changed, 57 insertions(+), 62 deletions(-)
diff --git a/tree-walk.c b/tree-walk.c
index c65492c..3cb757b 100644
--- a/tree-walk.c
+++ b/tree-walk.c
@@ -2,10 +2,42 @@
#include "tree-walk.h"
#include "tree.h"
+static const char *get_mode(const char *str, unsigned int *modep)
+{
+ unsigned char c;
+ unsigned int mode = 0;
+
+ while ((c = *str++) != ' ') {
+ if (c < '0' || c > '7')
+ return NULL;
+ mode = (mode << 3) + (c - '0');
+ }
+ *modep = mode;
+ return str;
+}
+
+static void decode_tree_entry(struct tree_desc *desc, const void *buf, unsigned long size)
+{
+ const char *path;
+ unsigned int mode, len;
+
+ path = get_mode(buf, &mode);
+ if (!path)
+ die("corrupt tree file");
+ len = strlen(path) + 1;
+
+ /* Initialize the descriptor entry */
+ desc->entry.path = path;
+ desc->entry.mode = mode;
+ desc->entry.sha1 = (const unsigned char *)(path + len);
+}
+
void init_tree_desc(struct tree_desc *desc, const void *buffer, unsigned long size)
{
desc->buffer = buffer;
desc->size = size;
+ if (size)
+ decode_tree_entry(desc, buffer, size);
}
void *fill_tree_descriptor(struct tree_desc *desc, const unsigned char *sha1)
@@ -36,78 +68,33 @@ static void entry_clear(struct name_entry *a)
static void entry_extract(struct tree_desc *t, struct name_entry *a)
{
- a->sha1 = tree_entry_extract(t, &a->path, &a->mode);
+ *a = t->entry;
}
void update_tree_entry(struct tree_desc *desc)
{
const void *buf = desc->buffer;
+ const void *end = desc->entry.sha1 + 20;
unsigned long size = desc->size;
- int len = strlen(buf) + 1 + 20;
+ unsigned long len = end - buf;
if (size < len)
die("corrupt tree file");
- desc->buffer = (char *) buf + len;
- desc->size = size - len;
-}
-
-static const char *get_mode(const char *str, unsigned int *modep)
-{
- unsigned char c;
- unsigned int mode = 0;
-
- while ((c = *str++) != ' ') {
- if (c < '0' || c > '7')
- return NULL;
- mode = (mode << 3) + (c - '0');
- }
- *modep = mode;
- return str;
-}
-
-const unsigned char *tree_entry_extract(struct tree_desc *desc, const char **pathp, unsigned int *modep)
-{
- const void *tree = desc->buffer;
- unsigned long size = desc->size;
- int len = strlen(tree)+1;
- const unsigned char *sha1 = (unsigned char *) tree + len;
- const char *path;
- unsigned int mode;
-
- path = get_mode(tree, &mode);
- if (!path || size < len + 20)
- die("corrupt tree file");
- *pathp = path;
- *modep = canon_mode(mode);
- return sha1;
+ buf = end;
+ size -= len;
+ desc->buffer = buf;
+ desc->size = size;
+ if (size)
+ decode_tree_entry(desc, buf, size);
}
int tree_entry(struct tree_desc *desc, struct name_entry *entry)
{
- const void *tree = desc->buffer;
- const char *path;
- unsigned long len, size = desc->size;
-
- if (!size)
+ if (!desc->size)
return 0;
- path = get_mode(tree, &entry->mode);
- if (!path)
- die("corrupt tree file");
-
- entry->path = path;
- len = strlen(path);
-
- path += len + 1;
- entry->sha1 = (const unsigned char *) path;
-
- path += 20;
- len = path - (char *) tree;
- if (len > size)
- die("corrupt tree file");
-
- desc->buffer = path;
- desc->size = size - len;
+ *entry = desc->entry;
+ update_tree_entry(desc);
return 1;
}
diff --git a/tree-walk.h b/tree-walk.h
index ca0c29f..43458cf 100644
--- a/tree-walk.h
+++ b/tree-walk.h
@@ -1,17 +1,25 @@
#ifndef TREE_WALK_H
#define TREE_WALK_H
-struct tree_desc {
- const void *buffer;
- unsigned int size;
-};
-
struct name_entry {
const unsigned char *sha1;
const char *path;
unsigned int mode;
};
+struct tree_desc {
+ const void *buffer;
+ struct name_entry entry;
+ unsigned int size;
+};
+
+static inline const unsigned char *tree_entry_extract(struct tree_desc *desc, const char **pathp, unsigned int *modep)
+{
+ *pathp = desc->entry.path;
+ *modep = canon_mode(desc->entry.mode);
+ return desc->entry.sha1;
+}
+
static inline int tree_entry_len(const char *name, const unsigned char *sha1)
{
return (char *)sha1 - (char *)name - 1;
--
1.5.1.rc1.13.g0872-dirty
-
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