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/*
* General time-keeping code and variables
*
* Copyright 2000-2021 Willy Tarreau <w@1wt.eu>
*
* 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
* 2 of the License, or (at your option) any later version.
*
*/
#include <sys/time.h>
#include <signal.h>
#include <time.h>
#ifdef USE_THREAD
#include <pthread.h>
#endif
#include <haproxy/api.h>
#include <haproxy/activity.h>
#include <haproxy/clock.h>
#include <haproxy/signal-t.h>
#include <haproxy/time.h>
#include <haproxy/tinfo-t.h>
#include <haproxy/tools.h>
struct timeval start_date; /* the process's start date in wall-clock time */
struct timeval ready_date; /* date when the process was considered ready */
ullong start_time_ns; /* the process's start date in internal monotonic time (ns) */
volatile ullong _global_now_ns; /* locally stored common monotonic date between all threads, in ns (wraps every 585 yr) */
volatile ullong *global_now_ns; /* common monotonic date, may point to _global_now_ns or shared memory */
volatile uint _global_now_ms; /* locally stored common monotonic date in milliseconds (may wrap) */
volatile uint *global_now_ms; /* common monotonic date in milliseconds (may wrap), may point to _global_now_ms or shared memory */
/* when CLOCK_MONOTONIC is supported, the offset is applied from th_ctx->prev_mono_time instead */
THREAD_ALIGNED() static llong now_offset; /* global offset between system time and global time in ns */
THREAD_LOCAL ullong now_ns; /* internal monotonic date derived from real clock, in ns (wraps every 585 yr) */
THREAD_LOCAL uint now_ms; /* internal monotonic date in milliseconds (may wrap) */
THREAD_LOCAL struct timeval date; /* the real current date (wall-clock time) */
static THREAD_LOCAL ullong before_poll_mono_ns; /* system wide monotonic time when entering poll last */
static THREAD_LOCAL struct timeval before_poll; /* system date before calling poll() */
static THREAD_LOCAL struct timeval after_poll; /* system date after leaving poll() */
static THREAD_LOCAL unsigned int samp_time; /* total elapsed time over current sample */
static THREAD_LOCAL unsigned int idle_time; /* total idle time over current sample */
static THREAD_LOCAL unsigned int iso_time_sec; /* last iso time value for this thread */
static THREAD_LOCAL char iso_time_str[34]; /* ISO time representation of gettimeofday() */
#if defined(_POSIX_TIMERS) && (_POSIX_TIMERS > 0) && defined(_POSIX_THREAD_CPUTIME)
static clockid_t per_thread_clock_id[MAX_THREADS];
#endif
/* returns the system's monotonic time in nanoseconds if supported, otherwise zero */
uint64_t now_mono_time(void)
{
uint64_t ret = 0;
#if defined(_POSIX_TIMERS) && (_POSIX_TIMERS > 0) && defined(_POSIX_MONOTONIC_CLOCK)
struct timespec ts;
if (clock_gettime(CLOCK_MONOTONIC, &ts) == 0)
ret = ts.tv_sec * 1000000000ULL + ts.tv_nsec;
#endif
return ret;
}
/* Returns the system's monotonic time in nanoseconds.
* Uses the coarse clock source if supported (for fast but
* less precise queries with limited resource usage).
* Fallback to now_mono_time() if coarse source is not supported,
* which may itself return 0 if not supported either.
*/
uint64_t now_mono_time_fast(void)
{
#if defined(CLOCK_MONOTONIC_COARSE)
struct timespec ts;
if (clock_gettime(CLOCK_MONOTONIC_COARSE, &ts) == 0)
return (ts.tv_sec * 1000000000ULL + ts.tv_nsec);
#endif
/* fallback to regular mono time,
* returns 0 if not supported
*/
return now_mono_time();
}
/* returns the current thread's cumulated CPU time in nanoseconds if supported, otherwise zero */
uint64_t now_cpu_time(void)
{
uint64_t ret = 0;
#if defined(_POSIX_TIMERS) && (_POSIX_TIMERS > 0) && defined(_POSIX_THREAD_CPUTIME)
struct timespec ts;
if (clock_gettime(CLOCK_THREAD_CPUTIME_ID, &ts) == 0)
ret = ts.tv_sec * 1000000000ULL + ts.tv_nsec;
#endif
return ret;
}
/* Returns the current thread's cumulated CPU time in nanoseconds.
*
* thread_local timer is cached so that call is less precise but also less
* expensive if heavily used.
* We use the mono time as a cache expiration hint since now_cpu_time() is
* known to be much more expensive than now_mono_time_fast() on systems
* supporting the COARSE clock source.
*
* Returns 0 if either now_mono_time_fast() or now_cpu_time() are not
* supported.
*/
uint64_t now_cpu_time_fast(void)
{
static THREAD_LOCAL uint64_t mono_cache = 0;
static THREAD_LOCAL uint64_t cpu_cache = 0;
uint64_t mono_cur;
mono_cur = now_mono_time_fast();
if (unlikely(mono_cur != mono_cache)) {
/* global mono clock was updated: local cache is outdated */
cpu_cache = now_cpu_time();
mono_cache = mono_cur;
}
return cpu_cache;
}
/* returns another thread's cumulated CPU time in nanoseconds if supported, otherwise zero */
uint64_t now_cpu_time_thread(int thr)
{
uint64_t ret = 0;
#if defined(_POSIX_TIMERS) && (_POSIX_TIMERS > 0) && defined(_POSIX_THREAD_CPUTIME)
struct timespec ts;
if (clock_gettime(per_thread_clock_id[thr], &ts) == 0)
ret = ts.tv_sec * 1000000000ULL + ts.tv_nsec;
#endif
return ret;
}
/* set the clock source for the local thread */
void clock_set_local_source(void)
{
#if defined(_POSIX_TIMERS) && (_POSIX_TIMERS > 0) && defined(_POSIX_THREAD_CPUTIME) && (_POSIX_THREAD_CPUTIME >= 0)
#ifdef USE_THREAD
pthread_getcpuclockid(pthread_self(), &per_thread_clock_id[tid]);
#else
per_thread_clock_id[tid] = CLOCK_THREAD_CPUTIME_ID;
#endif
#endif
}
/* registers a timer <tmr> of type timer_t delivering signal <sig> with value
* <val>. It tries on the current thread's clock ID first and falls back to
* CLOCK_REALTIME. Returns non-zero on success, 1 on failure.
*/
int clock_setup_signal_timer(void *tmr, int sig, int val)
{
int ret = 0;
#if defined(USE_RT) && (_POSIX_TIMERS > 0) && defined(_POSIX_THREAD_CPUTIME)
struct sigevent sev = { };
timer_t *timer = tmr;
sigset_t set;
/* unblock the WDTSIG signal we intend to use */
sigemptyset(&set);
sigaddset(&set, WDTSIG);
ha_sigmask(SIG_UNBLOCK, &set, NULL);
/* this timer will signal WDTSIG when it fires, with tid in the si_int
* field (important since any thread will receive the signal).
*/
sev.sigev_notify = SIGEV_SIGNAL;
sev.sigev_signo = sig;
sev.sigev_value.sival_int = val;
if (timer_create(per_thread_clock_id[tid], &sev, timer) != -1 ||
timer_create(CLOCK_REALTIME, &sev, timer) != -1)
ret = 1;
#endif
return ret;
}
/* clock_update_date: sets <date> to system time, and sets <now_ns> to something
* as close as possible to real time, following a monotonic function. The main
* principle consists in detecting backwards and forwards time jumps and adjust
* an offset to correct them. This function should be called once after each
* poll, and never farther apart than MAX_DELAY_MS*2. The poll's timeout should
* be passed in <max_wait>, and the return value in <interrupted> (a non-zero
* value means that we have not expired the timeout).
*
* clock_init_process_date() must have been called once first, and
* clock_init_thread_date() must also have been called once for each thread.
*
* An offset is used to adjust the current time (date), to figure a monotonic
* local time (now_ns). The offset is not critical, as it is only updated after
* a clock jump is detected. From this point all threads will apply it to their
* locally measured time, and will then agree around a common monotonic
* global_now_ns value that serves to further refine their local time. Both
* now_ns and global_now_ns are 64-bit integers counting nanoseconds since a
* vague reference (it starts roughly 20s before the next wrap-around of the
* millisecond counter after boot). The offset is also an integral number of
* nanoseconds, but it's signed so that the clock can be adjusted in the two
* directions.
*/
void clock_update_local_date(int max_wait, int interrupted)
{
struct timeval min_deadline, max_deadline;
llong ofs = HA_ATOMIC_LOAD(&now_offset);
llong date_ns;
gettimeofday(&date, NULL);
th_ctx->curr_mono_time = now_mono_time();
date_ns = th_ctx->curr_mono_time;
if (date_ns) {
/* no need to go through complex calculations, we have
* monotonic time. The offset will never change.
*/
goto done;
}
/* compute the minimum and maximum local date we may have reached based
* on our past date and the associated timeout. There are three possible
* extremities:
* - the new date cannot be older than before_poll
* - if not interrupted, the new date cannot be older than
* before_poll+max_wait
* - in any case the new date cannot be newer than
* before_poll+max_wait+some margin (100ms used here).
* In case of violation, we'll ignore the current date and instead
* restart from the last date we knew.
*/
_tv_ms_add(&min_deadline, &before_poll, max_wait);
_tv_ms_add(&max_deadline, &before_poll, max_wait + 100);
date_ns = tv_to_ns(&date);
if (unlikely(__tv_islt(&date, &before_poll) || // big jump backwards
(!interrupted && __tv_islt(&date, &min_deadline)) || // small jump backwards
date_ns + ofs >= now_ns + ms_to_ns(max_wait + 100)|| // offset changed by another thread
__tv_islt(&max_deadline, &date))) { // big jump forwards
if (!interrupted)
now_ns += ms_to_ns(max_wait);
/* consider the most recent known date */
now_ns = MAX(now_ns, HA_ATOMIC_LOAD(global_now_ns));
/* this event is rare, but it requires proper handling because if
* we just left now_ns where it was, the date will not be updated
* by clock_update_global_date().
*/
HA_ATOMIC_STORE(&now_offset, now_ns - date_ns);
} else {
done:
/* The date is still within expectations. Let's apply the
* now_offset to the system date. Note: ofs if made of two
* independent signed ints.
*/
now_ns = date_ns + ofs;
}
now_ms = ns_to_ms(now_ns);
/* correct for TICK_ETNERITY (0) */
if (unlikely(now_ms == TICK_ETERNITY))
now_ms++;
}
void clock_update_global_date()
{
ullong old_now_ns;
uint old_now_ms;
int now_ns_changed = 0;
/* now that we have bounded the local time, let's check if it's
* realistic regarding the global date, which only moves forward,
* otherwise catch up.
*/
old_now_ns = _HA_ATOMIC_LOAD(global_now_ns);
old_now_ms = _HA_ATOMIC_LOAD(global_now_ms);
do {
if (now_ns < old_now_ns) {
now_ns_changed = 1;
now_ns = old_now_ns;
}
/* now <now_ns> is expected to be the most accurate date,
* equal to <global_now_ns> or newer. Updating the global
* date too often causes extreme contention and is not
* needed: it's only used to help threads run at the
* same date in case of local drift, and the global date,
* which changes, is only used by freq counters (a choice
* which is debatable by the way since it changes under us).
* Tests have seen that the contention can be reduced from
* 37% in this function to almost 0% when keeping clocks
* synchronized no better than 32 microseconds, so that's
* what we're doing here.
*/
now_ms = ns_to_ms(now_ns);
/* correct for TICK_ETNERITY (0) */
if (unlikely(now_ms == TICK_ETERNITY))
now_ms++;
if (!((now_ns ^ old_now_ns) & ~0x7FFFULL)) {
if (now_ns_changed)
goto end;
return;
}
/* let's try to update the global_now_ns (both in nanoseconds
* and ms forms) or loop again.
*/
} while ((!_HA_ATOMIC_CAS(global_now_ns, &old_now_ns, now_ns) ||
(now_ms != old_now_ms && !_HA_ATOMIC_CAS(global_now_ms, &old_now_ms, now_ms))) &&
__ha_cpu_relax());
end:
if (!th_ctx->curr_mono_time) {
/* Only update the offset when monotonic time is not available.
* <now_ns> and <now_ms> are now updated to the last value of
* global_now_ns and global_now_ms, which were also monotonically
* updated. We can compute the latest offset, we don't care who writes
* it last, the variations will not break the monotonic property.
*/
HA_ATOMIC_STORE(&now_offset, now_ns - tv_to_ns(&date));
}
else if (global_now_ns != &_global_now_ns) {
/*
* or global_now_ns is shared with other processes: this results
* in the now_offset requiring to self-adjust so that it is consistent
* with now_offset used by other processes, as we may have learned from
* a new global_now_ns that was used in pair with a different offset from
* ours
*/
HA_ATOMIC_STORE(&now_offset, now_ns - th_ctx->curr_mono_time);
}
}
/* must be called once at boot to initialize some global variables */
void clock_init_process_date(void)
{
now_offset = 0;
before_poll_mono_ns = now_mono_time(); // 0 if not supported
th_ctx->prev_mono_time = th_ctx->curr_mono_time = before_poll_mono_ns;
gettimeofday(&date, NULL);
after_poll = before_poll = date;
_global_now_ns = th_ctx->curr_mono_time;
if (!_global_now_ns) // CLOCK_MONOTONIC not supported
_global_now_ns = tv_to_ns(&date);
now_ns = _global_now_ns;
_global_now_ms = ns_to_ms(now_ns);
/* force time to wrap 20s after boot: we first compute the time offset
* that once applied to the wall-clock date will make the local time
* wrap in 5 seconds. This offset is applied to the process-wide time,
* and will be used to recompute the local time, both of which will
* match and continue from this shifted date.
*/
now_offset = sec_to_ns((uint)((uint)(-_global_now_ms) / 1000U - BOOT_TIME_WRAP_SEC));
_global_now_ns += now_offset;
now_ns = _global_now_ns;
now_ms = ns_to_ms(now_ns);
/* correct for TICK_ETNERITY (0) */
if (now_ms == TICK_ETERNITY)
now_ms++;
_global_now_ms = now_ms;
/* for now global_now_ms points to the process-local _global_now_ms */
global_now_ms = &_global_now_ms;
/* same goes for global_ns_ns */
global_now_ns = &_global_now_ns;
th_ctx->idle_pct = 100;
clock_update_date(0, 1);
}
void clock_adjust_now_offset(void)
{
/* Only update the offset when monotonic time is not available. */
if (th_ctx->curr_mono_time)
return;
HA_ATOMIC_STORE(&now_offset, now_ns - tv_to_ns(&date));
}
void clock_set_now_offset(llong ofs)
{
HA_ATOMIC_STORE(&now_offset, ofs);
}
llong clock_get_now_offset(void)
{
return HA_ATOMIC_LOAD(&now_offset);
}
/* must be called once per thread to initialize their thread-local variables.
* Note that other threads might also be initializing and running in parallel.
*/
void clock_init_thread_date(void)
{
gettimeofday(&date, NULL);
after_poll = before_poll = date;
now_ns = _HA_ATOMIC_LOAD(global_now_ns);
th_ctx->idle_pct = 100;
th_ctx->prev_cpu_time = now_cpu_time();
th_ctx->prev_mono_time = now_mono_time();
th_ctx->curr_mono_time = th_ctx->prev_mono_time;
before_poll_mono_ns = th_ctx->curr_mono_time;
clock_update_date(0, 1);
}
/* report the average CPU idle percentage over all running threads, between 0 and 100 */
uint clock_report_idle(void)
{
uint total = 0;
uint rthr = 0;
uint thr;
for (thr = 0; thr < MAX_THREADS; thr++) {
if (!ha_thread_info[thr].tg ||
!(ha_thread_info[thr].tg->threads_enabled & ha_thread_info[thr].ltid_bit))
continue;
total += HA_ATOMIC_LOAD(&ha_thread_ctx[thr].idle_pct);
rthr++;
}
return rthr ? total / rthr : 0;
}
/* Update the idle time value twice a second, to be called after
* clock_update_date() when called after poll(), and currently called only by
* clock_leaving_poll() below. It relies on <before_poll> to be updated to
* the system time before calling poll().
*/
static inline void clock_measure_idle(void)
{
/* Let's compute the idle to work ratio. We worked between after_poll
* and before_poll, and slept between before_poll and date. The idle_pct
* is updated at most twice every second. Note that the current second
* rarely changes so we avoid a multiply when not needed.
*/
int delta;
if (before_poll_mono_ns) {
/* CLOCK_MONOTONIC in use, use it and convert it to microseconds */
idle_time += (th_ctx->curr_mono_time - before_poll_mono_ns) / 1000ull;
samp_time += (th_ctx->curr_mono_time - th_ctx->prev_mono_time) / 1000ull;
} else {
/* CLOCK_MONOTONIC not used */
if ((delta = date.tv_sec - before_poll.tv_sec))
delta *= 1000000;
idle_time += delta + (date.tv_usec - before_poll.tv_usec);
if ((delta = date.tv_sec - after_poll.tv_sec))
delta *= 1000000;
samp_time += delta + (date.tv_usec - after_poll.tv_usec);
after_poll.tv_sec = date.tv_sec; after_poll.tv_usec = date.tv_usec;
}
if (samp_time < 500000)
return;
HA_ATOMIC_STORE(&th_ctx->idle_pct, (100ULL * idle_time + samp_time / 2) / samp_time);
idle_time = samp_time = 0;
}
/* Collect date and time information after leaving poll(). <timeout> must be
* set to the maximum sleep time passed to poll (in milliseconds), and
* <interrupted> must be zero if the poller reached the timeout or non-zero
* otherwise, which generally is provided by the poller's return value.
*/
void clock_leaving_poll(int timeout, int interrupted)
{
clock_measure_idle();
th_ctx->prev_cpu_time = now_cpu_time();
th_ctx->prev_mono_time = th_ctx->curr_mono_time;
}
/* Collect date and time information before calling poll(). This will be used
* to count the run time of the past loop and the sleep time of the next poll.
* It also compares the elapsed and cpu times during the activity period to
* estimate the amount of stolen time, which is reported if higher than half
* a millisecond.
*/
void clock_entering_poll(void)
{
uint64_t new_mono_time;
uint64_t new_cpu_time;
uint32_t run_time;
int64_t stolen;
new_cpu_time = now_cpu_time();
new_mono_time = now_mono_time();
/* the the time when we entere poll */
before_poll_mono_ns = new_mono_time;
/* The time might have jumped either backwards or forwards during tasks
* processing. It's easy to detect a backwards jump, but a forward jump
* needs a margin. Here the upper limit of 2 seconds corresponds to a
* large margin at which the watchdog would already trigger so it looks
* sufficient to avoid false positives most of the time. The goal here
* is to make sure that before_poll can be trusted when entering
* clock_update_local_date() so that we can detect and fix time jumps.
* All this will also make sure we don't report idle/run times that are
* too much wrong during such jumps.
*/
if (before_poll_mono_ns)
run_time = (before_poll_mono_ns - th_ctx->curr_mono_time) / 1000ull;
else {
gettimeofday(&before_poll, NULL);
if (unlikely(__tv_islt(&before_poll, &after_poll)))
before_poll = after_poll;
else if (unlikely(__tv_ms_elapsed(&after_poll, &before_poll) >= 2000))
tv_ms_add(&before_poll, &after_poll, 2000);
run_time = (before_poll.tv_sec - after_poll.tv_sec) * 1000000U + (before_poll.tv_usec - after_poll.tv_usec);
}
if (th_ctx->prev_cpu_time && th_ctx->prev_mono_time) {
new_cpu_time -= th_ctx->prev_cpu_time;
new_mono_time -= th_ctx->prev_mono_time;
stolen = new_mono_time - new_cpu_time;
if (unlikely(stolen >= 500000)) {
stolen /= 500000;
/* more than half a millisecond difference might
* indicate an undesired preemption.
*/
report_stolen_time(stolen);
}
}
/* update the average runtime */
activity_count_runtime(run_time);
}
/* returns the current date as returned by gettimeofday() in ISO+microsecond
* format. It uses a thread-local static variable that the reader can consume
* for as long as it wants until next call. Thus, do not call it from a signal
* handler. If <pad> is non-0, a trailing space will be added. It will always
* return exactly 32 or 33 characters (depending on padding) and will always be
* zero-terminated, thus it will always fit into a 34 bytes buffer.
* This also always include the local timezone (in +/-HH:mm format) .
*/
char *timeofday_as_iso_us(int pad)
{
struct timeval new_date;
struct tm tm;
const char *offset;
char c;
gettimeofday(&new_date, NULL);
if (new_date.tv_sec != iso_time_sec || !new_date.tv_sec) {
get_localtime(new_date.tv_sec, &tm);
offset = get_gmt_offset(new_date.tv_sec, &tm);
if (unlikely(strftime(iso_time_str, sizeof(iso_time_str), "%Y-%m-%dT%H:%M:%S.000000+00:00", &tm) != 32))
strlcpy2(iso_time_str, "YYYY-mm-ddTHH:MM:SS.000000-00:00", sizeof(iso_time_str)); // make the failure visible but respect format.
iso_time_str[26] = offset[0];
iso_time_str[27] = offset[1];
iso_time_str[28] = offset[2];
iso_time_str[30] = offset[3];
iso_time_str[31] = offset[4];
iso_time_sec = new_date.tv_sec;
}
/* utoa_pad adds a trailing 0 so we save the char for restore */
c = iso_time_str[26];
utoa_pad(new_date.tv_usec, iso_time_str + 20, 7);
iso_time_str[26] = c;
if (pad) {
iso_time_str[32] = ' ';
iso_time_str[33] = 0;
}
return iso_time_str;
}
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