git/diff-tree-helper.c
Junio C Hamano b46f0b6dfd Optimize diff-cache -p --cached
This patch optimizes "diff-cache -p --cached" by avoiding to
inflate blobs into temporary files when the blob recorded in the
cache matches the corresponding file in the work tree.  The file
in the work tree is passed as the comparison source in such a
case instead.

This optimization kicks in only when we have already read the
cache this optimization and this is deliberate.  Especially,
diff-tree does not use this code, because changes are contained
in small number of files relative to the project size most of
the time, and reading cache is so expensive for a large project
that the cost of reading it outweighs the savings by not
inflating blobs.

Also this patch cleans up the structure passed from diff clients
by removing one unused structure member.

Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-05-04 01:45:24 -07:00

143 lines
2.8 KiB
C

/*
* Copyright (C) 2005 Junio C Hamano
*/
#include "cache.h"
#include "strbuf.h"
#include "diff.h"
static int matches_pathspec(const char *name, const char **spec, int cnt)
{
int i;
int namelen = strlen(name);
for (i = 0; i < cnt; i++) {
int speclen = strlen(spec[i]);
if (! strncmp(spec[i], name, speclen) &&
speclen <= namelen &&
(name[speclen] == 0 ||
name[speclen] == '/'))
return 1;
}
return 0;
}
static int parse_oneside_change(const char *cp, struct diff_spec *one,
char *path)
{
int ch;
one->file_valid = one->sha1_valid = 1;
one->mode = 0;
while ((ch = *cp) && '0' <= ch && ch <= '7') {
one->mode = (one->mode << 3) | (ch - '0');
cp++;
}
if (strncmp(cp, "\tblob\t", 6))
return -1;
cp += 6;
if (get_sha1_hex(cp, one->blob_sha1))
return -1;
cp += 40;
if (*cp++ != '\t')
return -1;
strcpy(path, cp);
return 0;
}
static int parse_diff_tree_output(const char *buf,
const char **spec, int cnt, int reverse)
{
struct diff_spec old, new;
char path[PATH_MAX];
const char *cp = buf;
int ch;
switch (*cp++) {
case 'U':
if (!cnt || matches_pathspec(cp + 1, spec, cnt))
diff_unmerge(cp + 1);
return 0;
case '+':
old.file_valid = 0;
parse_oneside_change(cp, &new, path);
break;
case '-':
new.file_valid = 0;
parse_oneside_change(cp, &old, path);
break;
case '*':
old.file_valid = old.sha1_valid =
new.file_valid = new.sha1_valid = 1;
old.mode = new.mode = 0;
while ((ch = *cp) && ('0' <= ch && ch <= '7')) {
old.mode = (old.mode << 3) | (ch - '0');
cp++;
}
if (strncmp(cp, "->", 2))
return -1;
cp += 2;
while ((ch = *cp) && ('0' <= ch && ch <= '7')) {
new.mode = (new.mode << 3) | (ch - '0');
cp++;
}
if (strncmp(cp, "\tblob\t", 6))
return -1;
cp += 6;
if (get_sha1_hex(cp, old.blob_sha1))
return -1;
cp += 40;
if (strncmp(cp, "->", 2))
return -1;
cp += 2;
if (get_sha1_hex(cp, new.blob_sha1))
return -1;
cp += 40;
if (*cp++ != '\t')
return -1;
strcpy(path, cp);
break;
default:
return -1;
}
if (!cnt || matches_pathspec(path, spec, cnt)) {
if (reverse)
run_external_diff(path, &new, &old);
else
run_external_diff(path, &old, &new);
}
return 0;
}
static const char *diff_tree_helper_usage =
"diff-tree-helper [-R] [-z] paths...";
int main(int ac, const char **av) {
struct strbuf sb;
int reverse = 0;
int line_termination = '\n';
strbuf_init(&sb);
while (1 < ac && av[1][0] == '-') {
if (av[1][1] == 'R')
reverse = 1;
else if (av[1][1] == 'z')
line_termination = 0;
else
usage(diff_tree_helper_usage);
ac--; av++;
}
/* the remaining parameters are paths patterns */
while (1) {
int status;
read_line(&sb, stdin, line_termination);
if (sb.eof)
break;
status = parse_diff_tree_output(sb.buf, av+1, ac-1, reverse);
if (status)
fprintf(stderr, "cannot parse %s\n", sb.buf);
}
return 0;
}