runtime/dyninst/timer.c - systemtap

Data types defined

Functions defined

Macros defined

Source code

/* -*- linux-c -*-
* Dyninst Timer Functions
* Copyright (C) 2012 Red Hat Inc.
*
* This file is part of systemtap, and is free software.  You can
* redistribute it and/or modify it under the terms of the GNU General
* Public License (GPL); either version 2, or (at your option) any
* later version.
*/

#ifndef _STAPDYN_TIMER_C_
‌#define _STAPDYN_TIMER_C_

#include <signal.h>
#include <time.h>

#ifndef NSEC_PER_SEC
‌#define NSEC_PER_SEC 1000000000L
#endif

‌struct stap_hrtimer_probe {
    struct sigevent sigev;
    timer_t timer_id;
    struct itimerspec its;
    const struct stap_probe * const probe;
    int64_t intrv;
    int64_t rnd;
};

‌static void _stp_hrtimer_init(void)
{
    return;
}

static int
‌_stp_hrtimer_start(struct stap_hrtimer_probe *shp)
{
    /* Specify a timer with the correct initial value (possibly
     * randomized a bit).
     *
     * If this isn't a randomized timer probe, go ahead and set
     * up the repeating interval values.
     *
     * The probe's interval is in nanoseconds,
     * but in a int64_t. So, break it down into seconds and
     * (leftover) nanoseconds so it will fit in a 'struct
     * timespec'.
     */

    if (shp->rnd == 0) {
        shp->its.it_value.tv_sec = (shp->its.it_interval.tv_sec    \
                        = shp->intrv / NSEC_PER_SEC);
        shp->its.it_value.tv_nsec = (shp->its.it_interval.tv_nsec \
                         = shp->intrv % NSEC_PER_SEC);
    }
    else {
        int64_t i = shp->intrv + _stp_random_u(shp->rnd);
        shp->its.it_value.tv_sec = i / NSEC_PER_SEC;
        shp->its.it_value.tv_nsec = i % NSEC_PER_SEC;
    }
    return timer_settime(shp->timer_id, 0, &shp->its, NULL);
}

static int
‌_stp_hrtimer_create(struct stap_hrtimer_probe *shp, void (*function)(sigval_t))
{
    int rc;

    /* Create the timer. */
    shp->sigev.sigev_notify = SIGEV_THREAD;
    shp->sigev.sigev_value.sival_ptr = shp;
    shp->sigev.sigev_notify_function = function;
    shp->sigev.sigev_notify_attributes = NULL;
    return timer_create(CLOCK_MONOTONIC, &shp->sigev, &shp->timer_id);
}

‌static void _stp_hrtimer_update(struct stap_hrtimer_probe *shp)
{
    int64_t i = shp->intrv;

    /* The timer only needs updating if this is a randomized timer
     * probe */
    if (shp->rnd == 0)
        return;

    /* The probe's interval is in nanoseconds, but in a
     * int64_t. So, break it down into seconds and (leftover)
     * nanoseconds.
     */
    i += _stp_random_u(shp->rnd);
    shp->its.it_value.tv_sec = i / NSEC_PER_SEC;
    shp->its.it_value.tv_nsec = i % NSEC_PER_SEC;
    timer_settime(shp->timer_id, 0, &shp->its, NULL);
}

‌static void _stp_hrtimer_cancel(struct stap_hrtimer_probe *shp)
{
    shp->its.it_value.tv_sec = 0;
    shp->its.it_value.tv_nsec = 0;
    timer_settime(shp->timer_id, 0, &shp->its, NULL);
}

‌static void _stp_hrtimer_delete(struct stap_hrtimer_probe *shp)
{
    (void) timer_delete(shp->timer_id);
}

#endif /* _STAPDYN_TIMER_C_ */