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erl_time_sup.c
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erl_time_sup.c
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/*
* %CopyrightBegin%
*
* Copyright Ericsson AB 1999-2022. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* %CopyrightEnd%
*/
/*
* Support routines for the time
*/
/* #define ERTS_TIME_CORRECTION_PRINT */
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include "sys.h"
#include "erl_vm.h"
#include "global.h"
#define ERTS_WANT_TIMER_WHEEL_API
#include "erl_time.h"
#include "erl_driver.h"
#include "erl_nif.h"
#include "erl_proc_sig_queue.h"
static erts_mtx_t erts_get_time_mtx;
/* used by erts_runtime_elapsed_both */
typedef struct {
erts_mtx_t mtx;
ErtsMonotonicTime user;
ErtsMonotonicTime sys;
} ErtsRunTimePrevData;
static union {
ErtsRunTimePrevData data;
char align__[ERTS_ALC_CACHE_LINE_ALIGN_SIZE(sizeof(ErtsRunTimePrevData))];
} runtime_prev erts_align_attribute(ERTS_CACHE_LINE_SIZE);
static union {
erts_atomic64_t time;
char align__[ERTS_ALC_CACHE_LINE_ALIGN_SIZE(sizeof(erts_atomic64_t))];
} wall_clock_prev erts_align_attribute(ERTS_CACHE_LINE_SIZE);
static union {
erts_atomic64_t time;
char align__[ERTS_ALC_CACHE_LINE_ALIGN_SIZE(sizeof(erts_atomic64_t))];
} now_prev erts_align_attribute(ERTS_CACHE_LINE_SIZE);
static ErtsMonitor *time_offset_monitors = NULL;
static Uint no_time_offset_monitors = 0;
#ifdef DEBUG
static int time_sup_initialized = 0;
#endif
#define ERTS_MONOTONIC_TIME_KILO \
((ErtsMonotonicTime) 1000)
#define ERTS_MONOTONIC_TIME_MEGA \
(ERTS_MONOTONIC_TIME_KILO*ERTS_MONOTONIC_TIME_KILO)
#define ERTS_MONOTONIC_TIME_GIGA \
(ERTS_MONOTONIC_TIME_MEGA*ERTS_MONOTONIC_TIME_KILO)
#define ERTS_MONOTONIC_TIME_TERA \
(ERTS_MONOTONIC_TIME_GIGA*ERTS_MONOTONIC_TIME_KILO)
static void init_time_napi(void);
static void
schedule_send_time_offset_changed_notifications(ErtsMonotonicTime new_offset);
struct time_sup_read_only__ {
ErtsMonotonicTime (*get_time)(void);
int correction;
ErtsTimeWarpMode warp_mode;
#ifdef ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT
ErtsMonotonicTime moffset;
int os_corrected_monotonic_time;
int os_monotonic_time_disable;
char *os_monotonic_time_func;
char *os_monotonic_time_clock_id;
int os_monotonic_time_locked;
Uint64 os_monotonic_time_resolution;
Uint64 os_monotonic_time_extended;
#endif
char *os_system_time_func;
char *os_system_time_clock_id;
int os_system_time_locked;
Uint64 os_system_time_resolution;
Uint64 os_system_time_extended;
struct {
ErtsMonotonicTime large_diff;
ErtsMonotonicTime small_diff;
} adj;
struct {
ErtsMonotonicTime error;
ErtsMonotonicTime resolution;
int intervals;
int use_avg;
} drift_adj;
};
typedef struct {
ErtsMonotonicTime drift; /* Correction for os monotonic drift */
ErtsMonotonicTime error; /* Correction for error between system times */
} ErtsMonotonicCorrection;
typedef struct {
ErtsMonotonicTime erl_mtime;
ErtsMonotonicTime os_mtime;
ErtsMonotonicCorrection correction;
} ErtsMonotonicCorrectionInstance;
#define ERTS_MAX_DRIFT_INTERVALS 50
typedef struct {
struct {
struct {
ErtsMonotonicTime sys;
ErtsMonotonicTime mon;
} diff;
struct {
ErtsMonotonicTime sys;
ErtsMonotonicTime mon;
} time;
} intervals[ERTS_MAX_DRIFT_INTERVALS];
struct {
ErtsMonotonicTime sys;
ErtsMonotonicTime mon;
} acc;
int ix;
int dirty_counter;
} ErtsMonotonicDriftData;
typedef struct {
ErtsMonotonicCorrectionInstance prev;
ErtsMonotonicCorrectionInstance curr;
} ErtsMonotonicCorrectionInstances;
typedef struct {
ErtsMonotonicCorrectionInstances insts;
ErtsMonotonicDriftData drift;
ErtsMonotonicTime last_check;
int short_check_interval;
} ErtsMonotonicCorrectionData;
struct time_sup_infrequently_changed__ {
#ifdef ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT
struct {
erts_rwmtx_t rwmtx;
ErtsTWheelTimer timer;
ErtsMonotonicCorrectionData cdata;
} parmon;
ErtsMonotonicTime minit;
#endif
ErtsSystemTime sinit;
ErtsMonotonicTime not_corrected_moffset;
erts_atomic64_t offset;
ErtsMonotonicTime shadow_offset;
erts_atomic32_t preliminary_offset;
};
struct time_sup_frequently_changed__ {
ErtsMonotonicTime last_not_corrected_time;
};
static struct {
union {
struct time_sup_read_only__ o;
char align__[ERTS_ALC_CACHE_LINE_ALIGN_SIZE(sizeof(struct time_sup_read_only__))];
} r;
union {
struct time_sup_infrequently_changed__ c;
char align__[ERTS_ALC_CACHE_LINE_ALIGN_SIZE(sizeof(struct time_sup_infrequently_changed__))];
} inf;
union {
struct time_sup_frequently_changed__ c;
char align__[ERTS_ALC_CACHE_LINE_ALIGN_SIZE(sizeof(struct time_sup_frequently_changed__))];
} f;
} time_sup erts_align_attribute(ERTS_CACHE_LINE_SIZE);
ErtsTimeSupData erts_time_sup__ erts_align_attribute(ERTS_CACHE_LINE_SIZE);
static ERTS_INLINE void
init_time_offset(ErtsMonotonicTime offset)
{
erts_atomic64_init_nob(&time_sup.inf.c.offset, (erts_aint64_t) offset);
}
static ERTS_INLINE void
set_time_offset(ErtsMonotonicTime offset)
{
erts_atomic64_set_relb(&time_sup.inf.c.offset, (erts_aint64_t) offset);
}
static ERTS_INLINE ErtsMonotonicTime
get_time_offset(void)
{
return (ErtsMonotonicTime) erts_atomic64_read_acqb(&time_sup.inf.c.offset);
}
static ERTS_INLINE void
update_last_mtime(ErtsSchedulerData *esdp, ErtsMonotonicTime mtime)
{
if (!esdp)
esdp = erts_get_scheduler_data();
if (esdp) {
#if 1
if (mtime < esdp->last_monotonic_time)
erts_exit(ERTS_ABORT_EXIT,
"Monotonic time stepped backwards!\n"
"Previous time: %b64d\n"
"Current time: %b64d\n",
esdp->last_monotonic_time,
mtime);
#endif
ASSERT(mtime >= esdp->last_monotonic_time);
esdp->last_monotonic_time = mtime;
esdp->check_time_reds = 0;
}
}
#ifdef ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT
/*
* Time correction adjustments made due to
* error between Erlang system time and OS
* system time:
* - Large adjustment ~1%
* - Small adjustment ~0.05%
*/
#define ERTS_TCORR_ERR_UNIT 2048
#define ERTS_TCORR_ERR_LARGE_ADJ 20
#define ERTS_TCORR_ERR_SMALL_ADJ 1
#define ERTS_INIT_SHORT_INTERVAL_COUNTER 10
#define ERTS_LONG_TIME_CORRECTION_CHECK ERTS_SEC_TO_MONOTONIC(60)
#define ERTS_SHORT_TIME_CORRECTION_CHECK ERTS_SEC_TO_MONOTONIC(15)
#define ERTS_TIME_DRIFT_MAX_ADJ_DIFF ERTS_USEC_TO_MONOTONIC(50)
#define ERTS_TIME_DRIFT_MIN_ADJ_DIFF ERTS_USEC_TO_MONOTONIC(5)
/*
* Maximum drift of the OS monotonic clock expected.
*
* We use 1 milli second per second. If the monotonic
* clock drifts more than this we will fail to adjust for
* drift, and error correction will kick in instead.
* If it is larger than this, one could argue that the
* primitive is to poor to be used...
*/
#define ERTS_MAX_MONOTONIC_DRIFT ERTS_MSEC_TO_MONOTONIC(1)
/*
* We assume that precision is 32 times worse than the
* resolution. This is a wild guess, but there are no
* practical way to determine actual precision.
*/
#define ERTS_ASSUMED_PRECISION_DROP 32
#define ERTS_MIN_MONOTONIC_DRIFT_MEASUREMENT \
(ERTS_SHORT_TIME_CORRECTION_CHECK - 2*ERTS_MAX_MONOTONIC_DRIFT)
static ERTS_INLINE ErtsMonotonicTime
calc_corrected_erl_mtime(ErtsMonotonicTime os_mtime,
ErtsMonotonicCorrectionInstance *cip,
ErtsMonotonicTime *os_mdiff_p,
int os_drift_corrected)
{
ErtsMonotonicTime erl_mtime, diff = os_mtime - cip->os_mtime;
ERTS_TIME_ASSERT(diff >= 0);
if (!os_drift_corrected)
diff += (cip->correction.drift*diff)/ERTS_MONOTONIC_TIME_UNIT;
erl_mtime = cip->erl_mtime;
erl_mtime += diff;
erl_mtime += cip->correction.error*(diff/ERTS_TCORR_ERR_UNIT);
if (os_mdiff_p)
*os_mdiff_p = diff;
return erl_mtime;
}
static ERTS_INLINE ErtsMonotonicTime
read_corrected_time(int os_drift_corrected)
{
ErtsMonotonicTime os_mtime;
ErtsMonotonicCorrectionInstance ci;
erts_rwmtx_rlock(&time_sup.inf.c.parmon.rwmtx);
os_mtime = erts_os_monotonic_time();
if (os_mtime >= time_sup.inf.c.parmon.cdata.insts.curr.os_mtime)
ci = time_sup.inf.c.parmon.cdata.insts.curr;
else {
if (os_mtime < time_sup.inf.c.parmon.cdata.insts.prev.os_mtime)
erts_exit(ERTS_ABORT_EXIT,
"OS monotonic time stepped backwards\n");
ci = time_sup.inf.c.parmon.cdata.insts.prev;
}
erts_rwmtx_runlock(&time_sup.inf.c.parmon.rwmtx);
return calc_corrected_erl_mtime(os_mtime, &ci, NULL,
os_drift_corrected);
}
static ErtsMonotonicTime get_os_drift_corrected_time(void)
{
return read_corrected_time(!0);
}
static ErtsMonotonicTime get_corrected_time(void)
{
return read_corrected_time(0);
}
#ifdef ERTS_TIME_CORRECTION_PRINT
static ERTS_INLINE void
print_correction(int change,
ErtsMonotonicTime sdiff,
ErtsMonotonicTime old_ecorr,
ErtsMonotonicTime old_dcorr,
ErtsMonotonicTime new_ecorr,
ErtsMonotonicTime new_dcorr,
Uint tmo)
{
ErtsMonotonicTime usec_sdiff;
if (sdiff < 0)
usec_sdiff = -1*ERTS_MONOTONIC_TO_USEC(-1*sdiff);
else
usec_sdiff = ERTS_MONOTONIC_TO_USEC(sdiff);
if (!change)
erts_fprintf(stderr,
"sdiff = %b64d usec : [ec=%b64d ppm, dc=%b64d ppb] : "
"tmo = %bpu msec\r\n",
usec_sdiff,
(1000000*old_ecorr) / ERTS_TCORR_ERR_UNIT,
(1000000000*old_dcorr) / ERTS_MONOTONIC_TIME_UNIT,
tmo);
else
erts_fprintf(stderr,
"sdiff = %b64d usec : [ec=%b64d ppm, dc=%b64d ppb] "
"-> [ec=%b64d ppm, dc=%b64d ppb] : tmo = %bpu msec\r\n",
usec_sdiff,
(1000000*old_ecorr) / ERTS_TCORR_ERR_UNIT,
(1000000000*old_dcorr) / ERTS_MONOTONIC_TIME_UNIT,
(1000000*new_ecorr) / ERTS_TCORR_ERR_UNIT,
(1000000000*new_dcorr) / ERTS_MONOTONIC_TIME_UNIT,
tmo);
}
#endif
static ERTS_INLINE ErtsMonotonicTime
get_timeout_pos(ErtsMonotonicTime now, ErtsMonotonicTime tmo)
{
ErtsMonotonicTime tpos;
tpos = ERTS_MONOTONIC_TO_CLKTCKS(now - 1);
tpos += ERTS_MSEC_TO_CLKTCKS(tmo);
tpos += 1;
return tpos;
}
static void
check_time_correction(void *vesdp)
{
int init_drift_adj = !vesdp;
ErtsSchedulerData *esdp = (ErtsSchedulerData *) vesdp;
ErtsMonotonicCorrection new_correction;
ErtsMonotonicCorrectionInstance ci;
ErtsMonotonicTime mdiff, sdiff, os_mtime, erl_mtime, os_stime,
erl_stime, time_offset, timeout_pos;
Uint timeout;
int os_drift_corrected = time_sup.r.o.os_corrected_monotonic_time;
int set_new_correction = 0, begin_short_intervals = 0;
erts_rwmtx_rlock(&time_sup.inf.c.parmon.rwmtx);
erts_os_times(&os_mtime, &os_stime);
ci = time_sup.inf.c.parmon.cdata.insts.curr;
erts_rwmtx_runlock(&time_sup.inf.c.parmon.rwmtx);
if (os_mtime < ci.os_mtime)
erts_exit(ERTS_ABORT_EXIT,
"OS monotonic time stepped backwards\n");
erl_mtime = calc_corrected_erl_mtime(os_mtime, &ci, &mdiff,
os_drift_corrected);
time_offset = get_time_offset();
erl_stime = erl_mtime + time_offset;
sdiff = erl_stime - os_stime;
if (time_sup.inf.c.shadow_offset) {
ERTS_TIME_ASSERT(time_sup.r.o.warp_mode == ERTS_SINGLE_TIME_WARP_MODE);
if (erts_atomic32_read_nob(&time_sup.inf.c.preliminary_offset))
sdiff += time_sup.inf.c.shadow_offset;
else
time_sup.inf.c.shadow_offset = 0;
}
new_correction = ci.correction;
if (time_sup.r.o.warp_mode == ERTS_MULTI_TIME_WARP_MODE
&& (sdiff < -2*time_sup.r.o.adj.small_diff
|| 2*time_sup.r.o.adj.small_diff < sdiff)) {
/* System time diff exeeded limits; change time offset... */
time_offset -= sdiff;
sdiff = 0;
set_time_offset(time_offset);
schedule_send_time_offset_changed_notifications(time_offset);
begin_short_intervals = 1;
if (ci.correction.error != 0) {
set_new_correction = 1;
new_correction.error = 0;
}
}
else if ((time_sup.r.o.warp_mode == ERTS_SINGLE_TIME_WARP_MODE
&& erts_atomic32_read_nob(&time_sup.inf.c.preliminary_offset))
&& (sdiff < -2*time_sup.r.o.adj.small_diff
|| 2*time_sup.r.o.adj.small_diff < sdiff)) {
/*
* System time diff exeeded limits; change shadow offset
* and let OS system time leap away from Erlang system
* time.
*/
time_sup.inf.c.shadow_offset -= sdiff;
sdiff = 0;
begin_short_intervals = 1;
if (ci.correction.error != 0) {
set_new_correction = 1;
new_correction.error = 0;
}
}
else if (ci.correction.error == 0) {
if (sdiff < -time_sup.r.o.adj.small_diff) {
set_new_correction = 1;
if (sdiff < -time_sup.r.o.adj.large_diff)
new_correction.error = ERTS_TCORR_ERR_LARGE_ADJ;
else
new_correction.error = ERTS_TCORR_ERR_SMALL_ADJ;
}
else if (sdiff > time_sup.r.o.adj.small_diff) {
set_new_correction = 1;
if (sdiff > time_sup.r.o.adj.large_diff)
new_correction.error = -ERTS_TCORR_ERR_LARGE_ADJ;
else
new_correction.error = -ERTS_TCORR_ERR_SMALL_ADJ;
}
}
else if (ci.correction.error > 0) {
if (sdiff < 0) {
if (ci.correction.error != ERTS_TCORR_ERR_LARGE_ADJ
&& sdiff < -time_sup.r.o.adj.large_diff) {
new_correction.error = ERTS_TCORR_ERR_LARGE_ADJ;
set_new_correction = 1;
}
}
else if (sdiff > time_sup.r.o.adj.small_diff) {
set_new_correction = 1;
if (sdiff > time_sup.r.o.adj.large_diff)
new_correction.error = -ERTS_TCORR_ERR_LARGE_ADJ;
else
new_correction.error = -ERTS_TCORR_ERR_SMALL_ADJ;
}
else {
set_new_correction = 1;
new_correction.error = 0;
}
}
else /* if (ci.correction.error < 0) */ {
if (0 < sdiff) {
if (ci.correction.error != -ERTS_TCORR_ERR_LARGE_ADJ
&& time_sup.r.o.adj.large_diff < sdiff) {
new_correction.error = -ERTS_TCORR_ERR_LARGE_ADJ;
set_new_correction = 1;
}
}
else if (sdiff < -time_sup.r.o.adj.small_diff) {
set_new_correction = 1;
if (sdiff < -time_sup.r.o.adj.large_diff)
new_correction.error = ERTS_TCORR_ERR_LARGE_ADJ;
else
new_correction.error = ERTS_TCORR_ERR_SMALL_ADJ;
}
else {
set_new_correction = 1;
new_correction.error = 0;
}
}
if (!os_drift_corrected) {
ErtsMonotonicDriftData *ddp = &time_sup.inf.c.parmon.cdata.drift;
int ix = ddp->ix;
ErtsMonotonicTime mtime_diff, old_os_mtime;
old_os_mtime = ddp->intervals[ix].time.mon;
mtime_diff = os_mtime - old_os_mtime;
if ((mtime_diff >= ERTS_MIN_MONOTONIC_DRIFT_MEASUREMENT)
| init_drift_adj) {
ErtsMonotonicTime drift_adj, drift_adj_diff, old_os_stime,
smtime_diff, stime_diff, mtime_acc, stime_acc,
avg_drift_adj, max_drift;
old_os_stime = ddp->intervals[ix].time.sys;
mtime_acc = ddp->acc.mon;
stime_acc = ddp->acc.sys;
avg_drift_adj = (((stime_acc - mtime_acc)
* ERTS_MONOTONIC_TIME_UNIT)
/ mtime_acc);
mtime_diff = os_mtime - old_os_mtime;
stime_diff = os_stime - old_os_stime;
smtime_diff = stime_diff - mtime_diff;
ix++;
if (ix >= time_sup.r.o.drift_adj.intervals)
ix = 0;
mtime_acc -= ddp->intervals[ix].diff.mon;
mtime_acc += mtime_diff;
stime_acc -= ddp->intervals[ix].diff.sys;
stime_acc += stime_diff;
ddp->intervals[ix].diff.mon = mtime_diff;
ddp->intervals[ix].diff.sys = stime_diff;
ddp->intervals[ix].time.mon = os_mtime;
ddp->intervals[ix].time.sys = os_stime;
ddp->ix = ix;
ddp->acc.mon = mtime_acc;
ddp->acc.sys = stime_acc;
max_drift = ERTS_MAX_MONOTONIC_DRIFT;
max_drift *= ERTS_MONOTONIC_TO_SEC(mtime_diff);
if (smtime_diff > time_sup.r.o.drift_adj.error + max_drift
|| smtime_diff < -1*time_sup.r.o.drift_adj.error - max_drift) {
dirty_intervals:
/*
* We had a leap in system time. Mark array as
* dirty to ensure that dirty values are rotated
* out before we use it again...
*/
ddp->dirty_counter = time_sup.r.o.drift_adj.intervals;
begin_short_intervals = 1;
}
else if (ddp->dirty_counter > 0) {
if (init_drift_adj) {
new_correction.drift = ((smtime_diff
* ERTS_MONOTONIC_TIME_UNIT)
/ mtime_diff);
set_new_correction = 1;
}
ddp->dirty_counter--;
}
else {
if (ddp->dirty_counter == 0) {
/* Force set new drift correction... */
set_new_correction = 1;
ddp->dirty_counter--;
}
if (time_sup.r.o.drift_adj.use_avg)
drift_adj = (((stime_acc - mtime_acc)
* ERTS_MONOTONIC_TIME_UNIT)
/ mtime_acc);
else
drift_adj = ((smtime_diff
* ERTS_MONOTONIC_TIME_UNIT)
/ mtime_diff);
drift_adj_diff = avg_drift_adj - drift_adj;
if (drift_adj_diff < -ERTS_TIME_DRIFT_MAX_ADJ_DIFF
|| ERTS_TIME_DRIFT_MAX_ADJ_DIFF < drift_adj_diff)
goto dirty_intervals;
drift_adj_diff = drift_adj - new_correction.drift;
if (drift_adj_diff) {
if (drift_adj_diff > ERTS_TIME_DRIFT_MAX_ADJ_DIFF)
drift_adj_diff = ERTS_TIME_DRIFT_MAX_ADJ_DIFF;
else if (drift_adj_diff < -ERTS_TIME_DRIFT_MAX_ADJ_DIFF)
drift_adj_diff = -ERTS_TIME_DRIFT_MAX_ADJ_DIFF;
new_correction.drift += drift_adj_diff;
if (drift_adj_diff < -ERTS_TIME_DRIFT_MIN_ADJ_DIFF
|| ERTS_TIME_DRIFT_MIN_ADJ_DIFF < drift_adj_diff) {
set_new_correction = 1;
}
}
}
}
}
begin_short_intervals |= set_new_correction;
if (begin_short_intervals) {
time_sup.inf.c.parmon.cdata.short_check_interval
= ERTS_INIT_SHORT_INTERVAL_COUNTER;
}
else if ((os_mtime - time_sup.inf.c.parmon.cdata.last_check
>= ERTS_SHORT_TIME_CORRECTION_CHECK - ERTS_MONOTONIC_TIME_UNIT)
&& time_sup.inf.c.parmon.cdata.short_check_interval > 0) {
time_sup.inf.c.parmon.cdata.short_check_interval--;
}
time_sup.inf.c.parmon.cdata.last_check = os_mtime;
if (new_correction.error == 0)
timeout = ERTS_MONOTONIC_TO_MSEC(ERTS_LONG_TIME_CORRECTION_CHECK);
else {
ErtsMonotonicTime ecorr = new_correction.error;
ErtsMonotonicTime abs_sdiff;
abs_sdiff = (sdiff < 0) ? -1*sdiff : sdiff;
if (ecorr < 0)
ecorr = -1*ecorr;
if (abs_sdiff > ecorr*(ERTS_LONG_TIME_CORRECTION_CHECK/ERTS_TCORR_ERR_UNIT))
timeout = ERTS_MONOTONIC_TO_MSEC(ERTS_LONG_TIME_CORRECTION_CHECK);
else {
timeout = ERTS_MONOTONIC_TO_MSEC((ERTS_TCORR_ERR_UNIT*abs_sdiff)/ecorr);
if (timeout < 10)
timeout = 10;
}
}
if (timeout > ERTS_MONOTONIC_TO_MSEC(ERTS_SHORT_TIME_CORRECTION_CHECK)
&& (time_sup.inf.c.parmon.cdata.short_check_interval
|| time_sup.inf.c.parmon.cdata.drift.dirty_counter >= 0)) {
timeout = ERTS_MONOTONIC_TO_MSEC(ERTS_SHORT_TIME_CORRECTION_CHECK);
}
timeout_pos = get_timeout_pos(erl_mtime, timeout);
#ifdef ERTS_TIME_CORRECTION_PRINT
print_correction(set_new_correction,
sdiff,
ci.correction.error,
ci.correction.drift,
new_correction.error,
new_correction.drift,
timeout);
#endif
if (set_new_correction) {
erts_rwmtx_rwlock(&time_sup.inf.c.parmon.rwmtx);
os_mtime = erts_os_monotonic_time();
/* Save previous correction instance */
time_sup.inf.c.parmon.cdata.insts.prev = ci;
/*
* Current correction instance begin when
* OS monotonic time has increased two units.
*/
os_mtime += 2;
/*
* Erlang monotonic time corresponding to
* next OS monotonic time using previous
* correction.
*/
erl_mtime = calc_corrected_erl_mtime(os_mtime, &ci, NULL,
os_drift_corrected);
/*
* Save new current correction instance.
*/
time_sup.inf.c.parmon.cdata.insts.curr.erl_mtime = erl_mtime;
time_sup.inf.c.parmon.cdata.insts.curr.os_mtime = os_mtime;
time_sup.inf.c.parmon.cdata.insts.curr.correction = new_correction;
erts_rwmtx_rwunlock(&time_sup.inf.c.parmon.rwmtx);
}
if (!esdp)
esdp = erts_get_scheduler_data();
erts_twheel_set_timer(esdp->timer_wheel,
&time_sup.inf.c.parmon.timer,
check_time_correction,
(void *) esdp,
timeout_pos);
}
static ErtsMonotonicTime get_os_corrected_time(void)
{
ASSERT(time_sup.r.o.warp_mode == ERTS_MULTI_TIME_WARP_MODE);
return erts_os_monotonic_time() + time_sup.r.o.moffset;
}
static void
check_time_offset(void *vesdp)
{
ErtsSchedulerData *esdp = (ErtsSchedulerData *) vesdp;
ErtsMonotonicTime sdiff, os_mtime, erl_mtime, os_stime,
erl_stime, time_offset, timeout, timeout_pos;
ASSERT(time_sup.r.o.warp_mode == ERTS_MULTI_TIME_WARP_MODE);
erts_os_times(&os_mtime, &os_stime);
erl_mtime = os_mtime + time_sup.r.o.moffset;
time_offset = get_time_offset();
erl_stime = erl_mtime + time_offset;
sdiff = erl_stime - os_stime;
if ((sdiff < -2*time_sup.r.o.adj.small_diff
|| 2*time_sup.r.o.adj.small_diff < sdiff)) {
/* System time diff exeeded limits; change time offset... */
#ifdef ERTS_TIME_CORRECTION_PRINT
erts_fprintf(stderr, "sdiff = %b64d nsec -> 0 nsec\n",
ERTS_MONOTONIC_TO_NSEC(sdiff));
#endif
time_offset -= sdiff;
sdiff = 0;
set_time_offset(time_offset);
schedule_send_time_offset_changed_notifications(time_offset);
}
#ifdef ERTS_TIME_CORRECTION_PRINT
else erts_fprintf(stderr, "sdiff = %b64d nsec\n",
ERTS_MONOTONIC_TO_NSEC(sdiff));
#endif
timeout = ERTS_MONOTONIC_TO_MSEC(ERTS_LONG_TIME_CORRECTION_CHECK);
timeout_pos = get_timeout_pos(erl_mtime, timeout);
erts_twheel_set_timer(esdp->timer_wheel,
&time_sup.inf.c.parmon.timer,
check_time_offset,
vesdp,
timeout_pos);
}
static void
init_check_time_correction(void *vesdp)
{
ErtsMonotonicDriftData *ddp;
ErtsMonotonicTime old_mtime, old_stime, mtime, stime, mtime_diff,
stime_diff, smtime_diff, max_drift;
int ix;
ddp = &time_sup.inf.c.parmon.cdata.drift;
ix = ddp->ix;
old_mtime = ddp->intervals[0].time.mon;
old_stime = ddp->intervals[0].time.sys;
erts_os_times(&mtime, &stime);
mtime_diff = mtime - old_mtime;
stime_diff = stime - old_stime;
smtime_diff = stime_diff - mtime_diff;
max_drift = ERTS_MAX_MONOTONIC_DRIFT;
max_drift *= ERTS_MONOTONIC_TO_SEC(mtime_diff);
if (smtime_diff > time_sup.r.o.drift_adj.error + max_drift
|| smtime_diff < -1*time_sup.r.o.drift_adj.error - max_drift) {
/* Had a system time leap... pretend no drift... */
stime_diff = mtime_diff;
}
/*
* We use old time values in order to trigger
* a drift adjustment, and repeat this interval
* in all slots...
*/
for (ix = 0; ix < time_sup.r.o.drift_adj.intervals; ix++) {
ddp->intervals[ix].diff.mon = mtime_diff;
ddp->intervals[ix].diff.sys = stime_diff;
ddp->intervals[ix].time.mon = old_mtime;
ddp->intervals[ix].time.sys = old_stime;
}
ddp->acc.sys = stime_diff*time_sup.r.o.drift_adj.intervals;
ddp->acc.mon = mtime_diff*time_sup.r.o.drift_adj.intervals;
ddp->ix = 0;
ddp->dirty_counter = time_sup.r.o.drift_adj.intervals;
check_time_correction(vesdp);
}
static ErtsMonotonicTime
finalize_corrected_time_offset(ErtsSystemTime *stimep)
{
ErtsMonotonicTime os_mtime;
ErtsMonotonicCorrectionInstance ci;
int os_drift_corrected = time_sup.r.o.os_corrected_monotonic_time;
erts_rwmtx_rlock(&time_sup.inf.c.parmon.rwmtx);
erts_os_times(&os_mtime, stimep);
ci = time_sup.inf.c.parmon.cdata.insts.curr;
erts_rwmtx_runlock(&time_sup.inf.c.parmon.rwmtx);
if (os_mtime < ci.os_mtime)
erts_exit(ERTS_ABORT_EXIT,
"OS monotonic time stepped backwards\n");
return calc_corrected_erl_mtime(os_mtime, &ci, NULL,
os_drift_corrected);
}
static void
late_init_time_correction(ErtsSchedulerData *esdp)
{
int quick_init_drift_adj;
void (*check_func)(void *);
ErtsMonotonicTime timeout, timeout_pos;
quick_init_drift_adj =
ERTS_MONOTONIC_TO_USEC(time_sup.r.o.drift_adj.error) == 0;
if (quick_init_drift_adj)
timeout = ERTS_MONOTONIC_TO_MSEC(ERTS_SHORT_TIME_CORRECTION_CHECK/10);
else
timeout = ERTS_MONOTONIC_TO_MSEC(ERTS_SHORT_TIME_CORRECTION_CHECK);
if (!time_sup.r.o.os_corrected_monotonic_time)
check_func = init_check_time_correction;
else if (time_sup.r.o.get_time == get_os_corrected_time) {
quick_init_drift_adj = 0;
check_func = check_time_offset;
}
else
check_func = check_time_correction;
timeout_pos = get_timeout_pos(erts_get_monotonic_time(esdp),
timeout);
erts_twheel_init_timer(&time_sup.inf.c.parmon.timer);
erts_twheel_set_timer(esdp->timer_wheel,
&time_sup.inf.c.parmon.timer,
check_func,
(quick_init_drift_adj
? NULL
: esdp),
timeout_pos);
}
#endif /* ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT */
static ErtsMonotonicTime get_not_corrected_time(void)
{
ErtsMonotonicTime stime, mtime;
erts_mtx_lock(&erts_get_time_mtx);
stime = erts_os_system_time();
mtime = stime - time_sup.inf.c.not_corrected_moffset;
if (mtime >= time_sup.f.c.last_not_corrected_time)
time_sup.f.c.last_not_corrected_time = mtime;
else {
mtime = time_sup.f.c.last_not_corrected_time;
if (time_sup.r.o.warp_mode == ERTS_MULTI_TIME_WARP_MODE) {
ErtsMonotonicTime new_offset = stime - mtime;
new_offset = ERTS_MONOTONIC_TO_USEC(new_offset);
new_offset = ERTS_USEC_TO_MONOTONIC(new_offset);
if (time_sup.inf.c.not_corrected_moffset != new_offset) {
time_sup.inf.c.not_corrected_moffset = new_offset;
set_time_offset(new_offset);
schedule_send_time_offset_changed_notifications(new_offset);
}
}
}
ASSERT(stime == mtime + time_sup.inf.c.not_corrected_moffset);
erts_mtx_unlock(&erts_get_time_mtx);
return mtime;
}
int erts_check_time_adj_support(int time_correction,
ErtsTimeWarpMode time_warp_mode)
{
if (!time_correction)
return 1;
/* User wants time correction */
#ifdef ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT
return !time_sup.r.o.os_monotonic_time_disable;
#else
return 0;
#endif
}
int
erts_has_time_correction(void)
{
return time_sup.r.o.correction;
}
void erts_init_sys_time_sup(void)
{
ErtsSysInitTimeResult sys_init_time_res
= ERTS_SYS_INIT_TIME_RESULT_INITER;
sys_init_time(&sys_init_time_res);
erts_time_sup__.r.o.monotonic_time_unit
= sys_init_time_res.os_monotonic_time_unit;
#ifndef SYS_CLOCK_RESOLUTION
erts_time_sup__.r.o.clktck_resolution
= sys_init_time_res.sys_clock_resolution;
erts_time_sup__.r.o.clktck_resolution *= 1000;
#endif
#ifdef ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT
time_sup.r.o.os_monotonic_time_disable
= !sys_init_time_res.have_os_monotonic_time;
time_sup.r.o.os_corrected_monotonic_time =
sys_init_time_res.have_corrected_os_monotonic_time;
time_sup.r.o.os_monotonic_time_func
= sys_init_time_res.os_monotonic_time_info.func;
time_sup.r.o.os_monotonic_time_clock_id
= sys_init_time_res.os_monotonic_time_info.clock_id;
time_sup.r.o.os_monotonic_time_locked
= sys_init_time_res.os_monotonic_time_info.locked_use;
time_sup.r.o.os_monotonic_time_resolution
= sys_init_time_res.os_monotonic_time_info.resolution;
time_sup.r.o.os_monotonic_time_extended
= sys_init_time_res.os_monotonic_time_info.extended;
#endif
time_sup.r.o.os_system_time_func
= sys_init_time_res.os_system_time_info.func;
time_sup.r.o.os_system_time_clock_id
= sys_init_time_res.os_system_time_info.clock_id;
time_sup.r.o.os_system_time_locked
= sys_init_time_res.os_system_time_info.locked_use;
time_sup.r.o.os_system_time_resolution
= sys_init_time_res.os_system_time_info.resolution;
}
int
erts_init_time_sup(int time_correction, ErtsTimeWarpMode time_warp_mode)
{
ErtsMonotonicTime resolution, ilength, intervals, short_isecs;
#if !ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT
ErtsMonotonicTime abs_native_offset, native_offset;
#endif
init_time_napi();
erts_hl_timer_init();
ASSERT(ERTS_MONOTONIC_TIME_MIN < ERTS_MONOTONIC_TIME_MAX);
erts_mtx_init(&erts_get_time_mtx, "get_time", NIL,
ERTS_LOCK_FLAGS_PROPERTY_STATIC | ERTS_LOCK_FLAGS_CATEGORY_GENERIC);
erts_mtx_init(&runtime_prev.data.mtx, "runtime", NIL,
ERTS_LOCK_FLAGS_PROPERTY_STATIC | ERTS_LOCK_FLAGS_CATEGORY_GENERIC);
runtime_prev.data.user = 0;
runtime_prev.data.sys = 0;
time_sup.r.o.correction = time_correction;
time_sup.r.o.warp_mode = time_warp_mode;
if (time_warp_mode == ERTS_SINGLE_TIME_WARP_MODE)
erts_atomic32_init_nob(&time_sup.inf.c.preliminary_offset, 1);
else
erts_atomic32_init_nob(&time_sup.inf.c.preliminary_offset, 0);
time_sup.inf.c.shadow_offset = 0;
#if !ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT
/*
* NOTE! erts_time_sup__.r.o.start *need* to be a multiple
* of ERTS_MONOTONIC_TIME_UNIT.
*/
#ifdef ARCH_32
erts_time_sup__.r.o.start = ((((ErtsMonotonicTime) 1) << 32)-1);
erts_time_sup__.r.o.start /= ERTS_MONOTONIC_TIME_UNIT;
erts_time_sup__.r.o.start *= ERTS_MONOTONIC_TIME_UNIT;
erts_time_sup__.r.o.start += ERTS_MONOTONIC_TIME_UNIT;