busybox/libbb/bb_do_delay.c
Denys Vlasenko 030fe31760 libbb: make msleep() result in only one syscall instead of looping
function                                             old     new   delta
msleep                                                45      52      +7

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2020-12-11 16:48:47 +01:00

68 lines
1.5 KiB
C

/* vi: set sw=4 ts=4: */
/*
* Busybox utility routines.
*
* Copyright (C) 2005 by Tito Ragusa <tito-wolit@tiscali.it>
*
* Licensed under GPLv2, see file LICENSE in this source tree.
*/
#include "libbb.h"
/* void FAST_FUNC bb_do_delay(unsigned seconds) { ... } - no users yet */
#ifndef LOGIN_FAIL_DELAY
#define LOGIN_FAIL_DELAY 3
#endif
void FAST_FUNC pause_after_failed_login(void)
{
#if 0 /* over-engineered madness */
time_t end, diff;
end = time(NULL) + LOGIN_FAIL_DELAY;
diff = LOGIN_FAIL_DELAY;
do {
sleep(diff);
diff = end - time(NULL);
} while (diff > 0);
#else
sleep(LOGIN_FAIL_DELAY);
#endif
}
void FAST_FUNC sleep1(void)
{
sleep(1);
}
void FAST_FUNC msleep(unsigned ms)
{
#if 0
/* 1. usleep(n) is not guaranteed by standards to accept n >= 1000000
* 2. multiplication in usleep(ms * 1000) can overflow if ms > 4294967
* (sleep of ~71.5 minutes)
* Let's play safe and loop:
*/
while (ms > 500) {
usleep(500000);
ms -= 500;
}
usleep(ms * 1000);
#else
//usleep is often implemented as a call to nanosleep.
//Simply do the same to implement msleep.
//it's marginally larger, but wakes your CPU less often:
//function old new delta
//msleep 45 52 +7
struct timespec ts;
ts.tv_sec = ms / 1000;
ts.tv_nsec = (ms % 1000) * 1000000;
/*
* If a signal has non-default handler, nanosleep returns early.
* Our version of msleep doesn't return early
* if interrupted by such signals:
*/
while (nanosleep(&ts, &ts) != 0)
continue;
#endif
}