On Tue, Nov 24, 2015 at 9:28 AM, Eric Covener <cove...@gmail.com> wrote:
> On Tue, Nov 24, 2015 at 10:21 AM, Jim Jagielski <j...@jagunet.com> wrote:
> > For these types of paths, where we use a switch/case against
> > the 1st char of the token, the real reason why we used that
> > impl was to avoid the (expected) expensive string comparison.
>
> Maybe naively, I thought we were saving some potential function
> call overhead here rather than some strcasecmp overhead.
>
In part, but also in this specific case;
while (token) {
***
A switch here short circuits three function calls;
if (!ap_casecmpstrn(token, "no-cache", 8)) {
if (token[8] == '=') {
cc->no_cache_header = 1;
}
else if (!token[8]) {
cc->no_cache = 1;
}
}
else if (!ap_casecmpstr(token, "no-store")) {
cc->no_store = 1;
}
else if (!ap_casecmpstr(token, "no-transform")) {
cc->no_transform = 1;
}
***
A switch here short circuits four function calls;
else if (!ap_casecmpstrn(token, "max-age", 7)) {
if (token[7] == '='
&& !apr_strtoff(&offt, token + 8, &endp, 10)
&& endp > token + 8 && !*endp) {
cc->max_age = 1;
cc->max_age_value = offt;
}
}
else if (!ap_casecmpstr(token, "must-revalidate")) {
cc->must_revalidate = 1;
}
else if (!ap_casecmpstrn(token, "max-stale", 9)) {
if (token[9] == '='
&& !apr_strtoff(&offt, token + 10, &endp, 10)
&& endp > token + 10 && !*endp) {
cc->max_stale = 1;
cc->max_stale_value = offt;
}
else if (!token[9]) {
cc->max_stale = 1;
cc->max_stale_value = -1;
}
}
else if (!ap_casecmpstrn(token, "min-fresh", 9)) {
if (token[9] == '='
&& !apr_strtoff(&offt, token + 10, &endp, 10)
&& endp > token + 10 && !*endp) {
cc->min_fresh = 1;
cc->min_fresh_value = offt;
}
}
***
Plus the overhead if each function call itself, it is still sensible to
narrow out
several groups of tokens (could even use if s[0]=='n' s[1]=='o' tests)
Does it make sense to expose the ap_tolower_ascii() function? We could
call it ap_tolower_plaintext() or something else to distinguish that it
isn't
lowercasing extended characters? Or is the case 'N': case 'n': syntax
easier to follow?
