git/tree-walk.c
Linus Torvalds 4651ece854 Switch over tree descriptors to contain a pre-parsed entry
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@linux-foundation.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2007-03-21 11:15:26 -07:00

210 lines
4.3 KiB
C

#include "cache.h"
#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)
{
unsigned long size = 0;
void *buf = NULL;
if (sha1) {
buf = read_object_with_reference(sha1, tree_type, &size, NULL);
if (!buf)
die("unable to read tree %s", sha1_to_hex(sha1));
}
init_tree_desc(desc, buf, size);
return buf;
}
static int entry_compare(struct name_entry *a, struct name_entry *b)
{
return base_name_compare(
a->path, tree_entry_len(a->path, a->sha1), a->mode,
b->path, tree_entry_len(b->path, b->sha1), b->mode);
}
static void entry_clear(struct name_entry *a)
{
memset(a, 0, sizeof(*a));
}
static void entry_extract(struct tree_desc *t, struct name_entry *a)
{
*a = t->entry;
}
void update_tree_entry(struct tree_desc *desc)
{
const void *buf = desc->buffer;
const unsigned char *end = desc->entry.sha1 + 20;
unsigned long size = desc->size;
unsigned long len = end - (const unsigned char *)buf;
if (size < len)
die("corrupt tree file");
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)
{
if (!desc->size)
return 0;
*entry = desc->entry;
update_tree_entry(desc);
return 1;
}
void traverse_trees(int n, struct tree_desc *t, const char *base, traverse_callback_t callback)
{
struct name_entry *entry = xmalloc(n*sizeof(*entry));
for (;;) {
unsigned long mask = 0;
int i, last;
last = -1;
for (i = 0; i < n; i++) {
if (!t[i].size)
continue;
entry_extract(t+i, entry+i);
if (last >= 0) {
int cmp = entry_compare(entry+i, entry+last);
/*
* Is the new name bigger than the old one?
* Ignore it
*/
if (cmp > 0)
continue;
/*
* Is the new name smaller than the old one?
* Ignore all old ones
*/
if (cmp < 0)
mask = 0;
}
mask |= 1ul << i;
last = i;
}
if (!mask)
break;
/*
* Update the tree entries we've walked, and clear
* all the unused name-entries.
*/
for (i = 0; i < n; i++) {
if (mask & (1ul << i)) {
update_tree_entry(t+i);
continue;
}
entry_clear(entry + i);
}
callback(n, mask, entry, base);
}
free(entry);
}
static int find_tree_entry(struct tree_desc *t, const char *name, unsigned char *result, unsigned *mode)
{
int namelen = strlen(name);
while (t->size) {
const char *entry;
const unsigned char *sha1;
int entrylen, cmp;
sha1 = tree_entry_extract(t, &entry, mode);
update_tree_entry(t);
entrylen = tree_entry_len(entry, sha1);
if (entrylen > namelen)
continue;
cmp = memcmp(name, entry, entrylen);
if (cmp > 0)
continue;
if (cmp < 0)
break;
if (entrylen == namelen) {
hashcpy(result, sha1);
return 0;
}
if (name[entrylen] != '/')
continue;
if (!S_ISDIR(*mode))
break;
if (++entrylen == namelen) {
hashcpy(result, sha1);
return 0;
}
return get_tree_entry(sha1, name + entrylen, result, mode);
}
return -1;
}
int get_tree_entry(const unsigned char *tree_sha1, const char *name, unsigned char *sha1, unsigned *mode)
{
int retval;
void *tree;
unsigned long size;
struct tree_desc t;
unsigned char root[20];
tree = read_object_with_reference(tree_sha1, tree_type, &size, root);
if (!tree)
return -1;
if (name[0] == '\0') {
hashcpy(sha1, root);
return 0;
}
init_tree_desc(&t, tree, size);
retval = find_tree_entry(&t, name, sha1, mode);
free(tree);
return retval;
}