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Database read optimizations

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Hard to believe there was still more room to improve on this, but I
found an easily correctable oversight tonight. Our databases (both sync
and local) contain many blank lines, and we were not moving onto the
next line right away in these cases; instead we would proceed through
our strcmp() conditional checks as normal.

Some local numbers follow to show the effects of this patch:

Sync `-Ss foobarbaz`:
71,709 blank lines skipped early
~1,505,889 strcmp() calls avoided (21 per line)
~15% speed improvement (.210 --> .179 sec)

Local `-Qs foobarbaz`:
6,823 blank lines skipped early
115,991 strcmp() calls avoided (17 per line)
~6% speed improvement (.080 -> .071 sec)

Signed-off-by: Dan McGee <dan@archlinux.org>
This commit is contained in:
Dan McGee 2011-08-28 22:20:41 -05:00
parent 040083b97f
commit b221af660d
2 changed files with 11 additions and 2 deletions
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8
lib/libalpm/be_local.c
View file

@ -580,7 +580,13 @@ static int local_db_read(alpm_pkg_t *info, alpm_dbinfrq_t inforeq)
goto error;
}
while(!feof(fp)) {
READ_NEXT();
if(fgets(line, sizeof(line), fp) == NULL && !feof(fp)) {
goto error;
}
if(_alpm_strip_newline(line) == 0) {
/* length of stripped line was zero */
continue;
}
if(strcmp(line, "%NAME%") == 0) {
READ_NEXT();
if(strcmp(line, info->name) != 0) {

5
lib/libalpm/be_sync.c
View file

@ -526,7 +526,10 @@ static int sync_db_read(alpm_db_t *db, struct archive *archive,
int ret;
while((ret = _alpm_archive_fgets(archive, &buf)) == ARCHIVE_OK) {
char *line = buf.line;
_alpm_strip_newline(line);
if(_alpm_strip_newline(line) == 0) {
/* length of stripped line was zero */
continue;
}
if(strcmp(line, "%NAME%") == 0) {
READ_NEXT();