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/*
* Copyright 2016 Garrett D'Amore <garrett@damore.org>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom
* the Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
/*
* This is more of a direct #include of a .c rather than .h file.
* But having it be a .h makes compiler rules work out properly. Do
* not include this more than once into your program, or you will
* get multiple symbols defined.
*/
/*
* POSIX clock stuff.
*/
#include <time.h>
#include <errno.h>
#include <string.h>
#ifndef NNG_USE_GETTIMEOFDAY
/*
* Use POSIX realtime stuff.
*/
uint64_t
nni_clock(void)
{
struct timespec ts;
uint64_t usec;
if (clock_gettime(NNG_USE_CLOCKID, &ts) != 0) {
/* This should never ever occur. */
nni_panic("clock_gettime failed: %s", strerror(errno));
}
usec = ts.tv_sec;
usec *= 1000000;
usec += (ts.tv_nsec / 1000);
return (usec);
}
void
nni_usleep(uint64_t usec)
{
struct timespec ts;
ts.tv_sec = usec / 1000000;
ts.tv_nsec = (usec % 1000000) * 1000;
/* Do this in a loop, so that interrupts don't actually wake us. */
while (ts.tv_sec || ts.tv_nsec) {
(void) nanosleep(&ts, &ts);
}
}
#else /* NNG_USE_GETTIMEOFDAY */
/*
* If you're here, its because you don't have a modern clock_gettime with
* monotonic clocks, or the necessary pthread_condattr_settclock(). In
* this case, you should be advised that *bad* things can happen if your
* system clock changes time while programs using this library are running.
* (Basically, timeouts can take longer or shorter, leading to either hangs
* or apparent spurious errors. Eventually it should all sort itself out,
* but if you change the clock by a large amount you might wonder what the
* heck is happening until it does.)
*/
#include <pthread.h>
#include <sys/time.h>
uint64_t
nni_clock(void)
{
uint64_t usec;
struct timeval tv;
if (gettimeofday(&tv, NULL) != 0) {
nni_panic("gettimeofday failed: %s", strerror(errno));
}
usec = tv.tv_sec;
usec *= 1000000;
usec += tv.tv_usec;
return (usec);
}
void
nni_usleep(uint64_t usec)
{
/*
* So probably there is no nanosleep. We could in theory use
* pthread condition variables, but that means doing memory
* allocation, or forcing the use of pthreads where the platform
* might be preferring the use of another threading package.
* Additionally, use of pthreads means that we cannot use
* relative times in a clock_settime safe manner.
* So we can use poll() instead, which is rather coarse, but
* pretty much guaranteed to work.
*/
struct pollfd pfd;
uint64_t now;
uint64_t expire;
/*
* Possibly we could pass NULL instead of pfd, but passing a valid
* pointer ensures that if the system dereferences the pointer it
* won't come back with EFAULT.
*/
pfd.fd = -1;
pfd.events = 0;
now = nni_clock();
expire = now + usec;
while (now < expire) {
/*
* In theory we could round up to a whole number of msec,
* but under the covers poll already does some rounding up,
* and the loop above guarantees that we will not bail out
* early. So this gives us a better chance to avoid adding
* nearly an extra unneeded millisecond to the wait.
*/
(void) poll(&pfd, 0, (int)((expire - now) / 1000));
now = nni_clock();
}
}
#endif /* NNG_USE_GETTIMEOFDAY */
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