path: root/libnetdata/clocks/clocks.c

// SPDX-License-Identifier: GPL-3.0-or-later

#include "../libnetdata.h"

// defaults are for compatibility
// call clocks_init() once, to optimize these default settings
static clockid_t clock_boottime_to_use = CLOCK_MONOTONIC;
static clockid_t clock_monotonic_to_use = CLOCK_MONOTONIC;

usec_t clock_monotonic_resolution = 1000;
usec_t clock_realtime_resolution = 1000;

#ifndef HAVE_CLOCK_GETTIME
inline int clock_gettime(clockid_t clk_id __maybe_unused, struct timespec *ts) {
    struct timeval tv;
    if(unlikely(gettimeofday(&tv, NULL) == -1)) {
        error("gettimeofday() failed.");
        return -1;
    }
    ts->tv_sec = tv.tv_sec;
    ts->tv_nsec = (long)((tv.tv_usec % USEC_PER_SEC) * NSEC_PER_USEC);
    return 0;
}
#endif

// Similar to CLOCK_MONOTONIC, but provides access to a raw hardware-based time that is not subject to NTP adjustments
// or the incremental adjustments performed by adjtime(3).  This clock does not count time that the system is suspended

static void test_clock_monotonic_raw(void) {
#ifdef CLOCK_MONOTONIC_RAW
    struct timespec ts;
    if(clock_gettime(CLOCK_MONOTONIC_RAW, &ts) == -1 && errno == EINVAL)
        clock_monotonic_to_use = CLOCK_MONOTONIC;
    else
        clock_monotonic_to_use = CLOCK_MONOTONIC_RAW;
#else
    clock_monotonic_to_use = CLOCK_MONOTONIC;
#endif
}

// When running a binary with CLOCK_BOOTTIME defined on a system with a linux kernel older than Linux 2.6.39 the
// clock_gettime(2) system call fails with EINVAL. In that case it must fall-back to CLOCK_MONOTONIC.

static void test_clock_boottime(void) {
    struct timespec ts;
    if(clock_gettime(CLOCK_BOOTTIME, &ts) == -1 && errno == EINVAL)
        clock_boottime_to_use = clock_monotonic_to_use;
    else
        clock_boottime_to_use = CLOCK_BOOTTIME;
}

static usec_t get_clock_resolution(clockid_t clock) {
    struct timespec ts;
    clock_getres(clock, &ts);
    return ts.tv_sec * USEC_PER_SEC + ts.tv_nsec * NSEC_PER_USEC;
}

// perform any initializations required for clocks

void clocks_init(void) {
    // monotonic raw has to be tested before boottime
    test_clock_monotonic_raw();

    // boottime has to be tested after monotonic coarse
    test_clock_boottime();

    clock_monotonic_resolution = get_clock_resolution(clock_monotonic_to_use);
    clock_realtime_resolution = get_clock_resolution(CLOCK_REALTIME);

    // if for any reason these are zero, netdata will crash
    // since we use them as modulo to calculations
    if(!clock_realtime_resolution)
        clock_realtime_resolution = 1000;

    if(!clock_monotonic_resolution)
        clock_monotonic_resolution = 1000;
}

inline time_t now_sec(clockid_t clk_id) {
    struct timespec ts;
    if(unlikely(clock_gettime(clk_id, &ts) == -1)) {
        error("clock_gettime(%d, &timespec) failed.", clk_id);
        return 0;
    }
    return ts.tv_sec;
}

inline usec_t now_usec(clockid_t clk_id) {
    struct timespec ts;
    if(unlikely(clock_gettime(clk_id, &ts) == -1)) {
        error("clock_gettime(%d, &timespec) failed.", clk_id);
        return 0;
    }
    return (usec_t)ts.tv_sec * USEC_PER_SEC + (ts.tv_nsec % NSEC_PER_SEC) / NSEC_PER_USEC;
}

inline int now_timeval(clockid_t clk_id, struct timeval *tv) {
    struct timespec ts;

    if(unlikely(clock_gettime(clk_id, &ts) == -1)) {
        error("clock_gettime(%d, &timespec) failed.", clk_id);
        tv->tv_sec = 0;
        tv->tv_usec = 0;
        return -1;
    }

    tv->tv_sec = ts.tv_sec;
    tv->tv_usec = (suseconds_t)((ts.tv_nsec % NSEC_PER_SEC) / NSEC_PER_USEC);
    return 0;
}

inline time_t now_realtime_sec(void) {
    return now_sec(CLOCK_REALTIME);
}

inline usec_t now_realtime_usec(void) {
    return now_usec(CLOCK_REALTIME);
}

inline int now_realtime_timeval(struct timeval *tv) {
    return now_timeval(CLOCK_REALTIME, tv);
}

inline time_t now_monotonic_sec(void) {
    return now_sec(clock_monotonic_to_use);
}

inline usec_t now_monotonic_usec(void) {
    return now_usec(clock_monotonic_to_use);
}

inline int now_monotonic_timeval(struct timeval *tv) {
    return now_timeval(clock_monotonic_to_use, tv);
}

inline time_t now_monotonic_high_precision_sec(void) {
    return now_sec(CLOCK_MONOTONIC);
}

inline usec_t now_monotonic_high_precision_usec(void) {
    return now_usec(CLOCK_MONOTONIC);
}

inline int now_monotonic_high_precision_timeval(struct timeval *tv) {
    return now_timeval(CLOCK_MONOTONIC, tv);
}

inline time_t now_boottime_sec(void) {
    return now_sec(clock_boottime_to_use);
}

inline usec_t now_boottime_usec(void) {
    return now_usec(clock_boottime_to_use);
}

inline int now_boottime_timeval(struct timeval *tv) {
    return now_timeval(clock_boottime_to_use, tv);
}

inline usec_t timeval_usec(struct timeval *tv) {
    return (usec_t)tv->tv_sec * USEC_PER_SEC + (tv->tv_usec % USEC_PER_SEC);
}

inline msec_t timeval_msec(struct timeval *tv) {
    return (msec_t)tv->tv_sec * MSEC_PER_SEC + ((tv->tv_usec % USEC_PER_SEC) / MSEC_PER_SEC);
}

inline susec_t dt_usec_signed(struct timeval *now, struct timeval *old) {
    usec_t ts1 = timeval_usec(now);
    usec_t ts2 = timeval_usec(old);

    if(likely(ts1 >= ts2)) return (susec_t)(ts1 - ts2);
    return -((susec_t)(ts2 - ts1));
}

inline usec_t dt_usec(struct timeval *now, struct timeval *old) {
    usec_t ts1 = timeval_usec(now);
    usec_t ts2 = timeval_usec(old);
    return (ts1 > ts2) ? (ts1 - ts2) : (ts2 - ts1);
}

#ifdef __linux__
void sleep_to_absolute_time(usec_t usec) {
    static int einval_printed = 0, enotsup_printed = 0, eunknown_printed = 0;
    clockid_t clock = CLOCK_REALTIME;

    struct timespec req = {
        .tv_sec = (time_t)(usec / USEC_PER_SEC),
        .tv_nsec = (suseconds_t)((usec % USEC_PER_SEC) * NSEC_PER_USEC)
    };

    errno = 0;
    int ret = 0;
    while( (ret = clock_nanosleep(clock, TIMER_ABSTIME, &req, NULL)) != 0 ) {
        if(ret == EINTR) {
            errno = 0;
            continue;
        }
        else {
            if (ret == EINVAL) {
                if (!einval_printed) {
                    einval_printed++;
                    error(
                        "Invalid time given to clock_nanosleep(): clockid = %d, tv_sec = %lld, tv_nsec = %ld",
                        clock,
                        (long long)req.tv_sec,
                        req.tv_nsec);
                }
            } else if (<