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More efficiently check if any non-stdin fds are in the call to select on Windows

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This commit is contained in:
dmiller
2022-09-23 21:42:00 +00:00
parent 8dbefeba86
commit ed19887f41
1 changed files with 29 additions and 16 deletions
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45
nbase/nbase_misc.c
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@@ -358,28 +358,46 @@ int fselect(int s, fd_set *rmaster, fd_set *wmaster, fd_set *emaster, struct tim
#ifdef WIN32
static int stdin_thread_started = 0;
int fds_ready = 0;
int iter = -1, i;
int iter = -1;
int do_select = 0;
struct timeval stv;
fd_set rset, wset, eset;
int r_stdin = rmaster != NULL && checked_fd_isset(STDIN_FILENO, rmaster);
int e_stdin = emaster != NULL && checked_fd_isset(STDIN_FILENO, emaster);
int r_stdin = 0;
int e_stdin = 0;
int stdin_ready = 0;
/* Figure out whether there are any FDs in the sets, as @$@!$# Windows
returns WSAINVAL (10022) if you call a select() with no FDs, even though
the Linux man page says that doing so is a good, reasonably portable way
to sleep with subsecond precision. Sigh. */
for(i = s; i > STDIN_FILENO; i--) {
if ((rmaster != NULL && checked_fd_isset(i, rmaster))
|| (wmaster != NULL && checked_fd_isset(i, wmaster))
|| (emaster != NULL && checked_fd_isset(i, emaster)))
break;
s--;
if (rmaster != NULL) {
/* If stdin is requested, clear it and remember it. */
if (checked_fd_isset(STDIN_FILENO, rmaster)) {
r_stdin = 1;
checked_fd_clr(STDIN_FILENO, rmaster);
}
/* If any are left, we'll do a select. Otherwise, it's a sleep. */
do_select = do_select || rmaster->fd_count;
}
/* Same thing with exceptions */
if (emaster != NULL) {
if (checked_fd_isset(STDIN_FILENO, emaster)) {
e_stdin = 1;
checked_fd_clr(STDIN_FILENO, emaster);
}
do_select = do_select || emaster->fd_count;
}
/* stdin can't be written to, so ignore it. */
if (wmaster != NULL) {
assert(!checked_fd_isset(STDIN_FILENO, wmaster));
do_select = do_select || wmaster->fd_count;
}
/* Handle the case where stdin is not in scope. */
if (!(r_stdin || e_stdin)) {
if (s > 0) {
if (do_select) {
/* Do a normal select. */
return select(s, rmaster, wmaster, emaster, tv);
} else {
@@ -412,11 +430,6 @@ int fselect(int s, fd_set *rmaster, fd_set *wmaster, fd_set *emaster, struct tim
stdin_thread_started = 1;
}
if (r_stdin)
checked_fd_clr(STDIN_FILENO, rmaster);
if (e_stdin)
checked_fd_clr(STDIN_FILENO, emaster);
if (tv) {
int usecs = (tv->tv_sec * 1000000) + tv->tv_usec;
@@ -449,7 +462,7 @@ int fselect(int s, fd_set *rmaster, fd_set *wmaster, fd_set *emaster, struct tim
fds_ready = 0;
/* selecting on anything other than stdin? */
if (s > 1)
if (do_select)
fds_ready = select(s, &rset, &wset, &eset, &stv);
else
usleep(stv.tv_sec * 1000000UL + stv.tv_usec);