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VILLASnode/lib/task.c

203 lines
4.3 KiB
C

/** Run tasks periodically.
*
* @author Steffen Vogel <stvogel@eonerc.rwth-aachen.de>
* @copyright 2017-2018, Institute for Automation of Complex Power Systems, EONERC
* @license GNU General Public License (version 3)
*
* VILLASnode
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*********************************************************************************/
#include <unistd.h>
#include <time.h>
#include <errno.h>
#include <villas/utils.h>
#include <villas/task.h>
#include <villas/timing.h>
#if PERIODIC_TASK_IMPL == TIMERFD
#include <sys/timerfd.h>
#elif PERIODIC_TASK_IMPL == RDTSC
#include <villas/tsc.h>
#endif
int task_init(struct task *t, double rate, int clock)
{
int ret;
t->clock = clock;
#if PERIODIC_TASK_IMPL == TIMERFD
t->fd = timerfd_create(t->clock, 0);
if (t->fd < 0)
return -1;
#elif PERIODIC_TASK_IMPL == RDTSC
ret = tsc_init(&t->tsc);
if (ret)
return ret;
#endif
ret = task_set_rate(t, rate);
if (ret)
return ret;
return 0;
}
int task_set_timeout(struct task *t, double to)
{
struct timespec now;
clock_gettime(t->clock, &now);
struct timespec timeout = time_from_double(to);
struct timespec next = time_add(&now, &timeout);
return task_set_next(t, &next);
}
int task_set_next(struct task *t, struct timespec *next)
{
#if PERIODIC_TASK_IMPL == RDTSC
#else
t->next = *next;
#if PERIODIC_TASK_IMPL == TIMERFD
int ret;
struct itimerspec its = {
.it_interval = (struct timespec) { 0, 0 },
.it_value = t->next
};
ret = timerfd_settime(t->fd, TFD_TIMER_ABSTIME, &its, NULL);
if (ret)
return ret;
#endif
#endif
return 0;
}
int task_set_rate(struct task *t, double rate)
{
#if PERIODIC_TASK_IMPL == RDTSC
t->period = tsc_rate_to_cycles(&t->tsc, rate);
t->next = tsc_now(&t->tsc) + t->period;
#else
/* A rate of 0 will disarm the timer */
t->period = rate ? time_from_double(1.0 / rate) : (struct timespec) { 0, 0 };
#if PERIODIC_TASK_IMPL == CLOCK_NANOSLEEP || PERIODIC_TASK_IMPL == NANOSLEEP
struct timespec now, next;
clock_gettime(t->clock, &now);
next = time_add(&now, &t->period);
return task_set_next(t, &next);
#elif PERIODIC_TASK_IMPL == TIMERFD
int ret;
struct itimerspec its = {
.it_interval = t->period,
.it_value = t->period
};
ret = timerfd_settime(t->fd, 0, &its, NULL);
if (ret)
return ret;
#endif
#endif
return 0;
}
int task_destroy(struct task *t)
{
#if PERIODIC_TASK_IMPL == TIMERFD
return close(t->fd);
#endif
return 0;
}
uint64_t task_wait(struct task *t)
{
uint64_t runs;
#if PERIODIC_TASK_IMPL == CLOCK_NANOSLEEP || PERIODIC_TASK_IMPL == NANOSLEEP
int ret;
struct timespec now;
ret = clock_gettime(t->clock, &now);
if (ret)
return ret;
for (runs = 0; time_cmp(&t->next, &now) < 0; runs++)
t->next = time_add(&t->next, &t->period);
#if PERIODIC_TASK_IMPL == CLOCK_NANOSLEEP
do {
ret = clock_nanosleep(t->clock, TIMER_ABSTIME, &t->next, NULL);
} while (ret == EINTR);
#elif PERIODIC_TASK_IMPL == NANOSLEEP
struct timespec req, rem = time_diff(&now, &t->next);
do {
req = rem;
ret = nanosleep(&req, &rem);
} while (ret < 0 && errno == EINTR);
#endif
if (ret)
return 0;
ret = clock_gettime(t->clock, &now);
if (ret)
return ret;
for (; time_cmp(&t->next, &now) < 0; runs++)
t->next = time_add(&t->next, &t->period);
#elif PERIODIC_TASK_IMPL == TIMERFD
int ret;
ret = read(t->fd, &runs, sizeof(runs));
if (ret < 0)
return 0;
#elif PERIODIC_TASK_IMPL == RDTSC
uint64_t now;
do {
now = tsc_now(&t->tsc);
} while (now < t->next);
for (runs = 0; t->next < now; runs++)
t->next += t->period;
#else
#error "Invalid period task implementation"
#endif
return runs;
}
int task_fd(struct task *t)
{
#if PERIODIC_TASK_IMPL == TIMERFD
return t->fd;
#else
return -1;
#endif
}