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pacman/query.c : -Qo optimization.

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I didn't understand why realpath was called on every files of every filelist
in query_fileowner :
ppath = resolve_path(path);

It turns out this is needed for the diverted files. For example, cddb_get
installs /usr/lib/perl5/site_perl/5.8.8/CDDB_get.pm which actually ends in
/usr/lib/perl5/site_perl/current/CDDB_get.pm .

And for making pacman -Qo /usr/lib/perl5/site_perl/current/CDDB_get.pm ,
realpath has to be called on both the target, and the file in the filelist.

However, realpath is costly, and calling it on every single file resulted
in a poor -Qo performance. Worst case :
pacman -Qo /lib/libz.so.1  0.35s user 1.51s system 99% cpu 1.864 total

So I did a little optimization to avoid calling realpath as much as
possible: first compare the basename of each file.

Result:
src/pacman/pacman -Qo /lib/libz.so.1  0.24s user 0.05s system 99% cpu 0.298
total

Obviously, the difference will be even bigger at the first run (no fs
cache), though it's quite scary on my system : 1.7s vs 40s previously.

Signed-off-by: Chantry Xavier <shiningxc@gmail.com>
Signed-off-by: Dan McGee <dan@archlinux.org>
This commit is contained in:
Chantry Xavier 2007-11-25 16:13:56 -06:00 committed by Dan McGee
parent 11133da587
commit d683033d3e
1 changed files with 8 additions and 0 deletions
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8
src/pacman/query.c
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@ -71,6 +71,7 @@ static int query_fileowner(alpm_list_t *targets)
for(t = targets; t; t = alpm_list_next(t)) {
int found = 0;
char *filename = alpm_list_getdata(t);
char *bname;
char *rpath;
struct stat buf;
alpm_list_t *i, *j;
@ -88,6 +89,8 @@ static int query_fileowner(alpm_list_t *targets)
continue;
}
bname = mbasename(filename);
if(!(rpath = resolve_path(filename))) {
fprintf(stderr, _("error: cannot determine real path for '%s': %s\n"),
filename, strerror(errno));
@ -103,6 +106,11 @@ static int query_fileowner(alpm_list_t *targets)
snprintf(path, PATH_MAX, "%s%s",
alpm_option_get_root(), (const char *)alpm_list_getdata(j));
/* avoid the costly resolve_path usage if the basenames don't match */
if(strcmp(mbasename(path), bname) != 0) {
continue;
}
ppath = resolve_path(path);
if(ppath && strcmp(ppath, rpath) == 0) {