This document discusses how Magento handles timezones across different stores. It explains that Magento converts times from UTC to the admin store timezone. It also discusses how PHP and Linux systems represent and work with dates, times, and timezones internally. Finally, it provides some links for further reading on time and timezone standards.

1. What will happen when
we stop adjusting clocks?
Maciej Harbuz
X-Coding IT Studio
Date and time in Magento
with multistore

2. Today, we’re going to present how
Magento handle different timezones
in different stores.

3. How long takes a day
● daylight
● star day
● moon day
General

4. General
3
1
2

5. 1967r.
czas trwania 9 192 631 770 okresów fali świetlnej promieniowania odpowiadającego przejściu między
dwoma poziomami struktury nadsubtelnej stanu podstawowego atomu cezu 133 Cs
Leap second
23:59:59
23:59:60
00:00:00
General

6. 360° / 24h = 15 °/h
There are 38 different time zones
UTC-09:30 UTC+05:45 UTC+14:00
General

8. 00:00
00:00
12:00
12:00
23:59
23:59
06:33
05:33
19:20
18:20
summer
winter
Wrocław
Sevilla
08:13 20:44

9. Magento (1)

10. Magento (2)
Timezone change per website/store affects datetime in admin panel because that
isn’t saved persistent within order

11. Magento (3)
//convert time from UTC to admin store timezone
//we assume that all schedules in configuration (crontab.xml
and DB tables) are in admin store timezone
$time = $this->timezoneConverter->date($time)
->format('Y-m-d H:i');

12. Magento (4)
Magento doesn’t use NOW() from MySQL, but do use
CURRENT_TIMESTAMP in schema.xml’s
Keep in sync app time with db time
In CronJob, within module Sales, Magento uses
CURRENT_TIMESTAMP to clean up overdue orders

13. Magento (5)
MagentoFrameworkStdlib
namespace MagentoEavModelEntityAttributeBackendTime;
class Created
public function beforeSave($object)
{...
$object->setData(
$attributeCode,
gmdate(MagentoFrameworkStdlibDateTime::DATETIME_PHP_FORM
AT)
...}

14. PHP (1)
In directory ext/date
● php_date.c -> gmdate definition uses mostly timelib_time struct
● timelib.c
typedef struct _timelib_time {
timelib_sll y, m, d; /* Year, Month, Day */
timelib_sll h, i, s; /* Hour, mInute, Second */
timelib_sll us; /* Microseconds */
int z; /* UTC offset in seconds*/
timelib_sll sse; /* Seconds since epoch*/
...

15. PHP (2)
...
unsigned int have_time, have_date, have_zone,
have_relative, have_weeknr_day;
unsigned int sse_uptodate; /* !0 if the sse member
is up to date with the date/time members */
unsigned int tim_uptodate; /* !0 if the date/time
members are up to date with the sse member */
unsigned int is_localtime; /* 1 if the current
struct represents localtime, 0 if it is in GMT */
...

16. PHP (3)
...
unsigned int zone_type;
/* 1 time offset,
* 3 TimeZone identifier,
* 2 TimeZone abbreviation */
} timelib_time;

17. PHP (4)
/* {{{ proto int time(void)
Return current UNIX timestamp */
PHP_FUNCTION(time)
{
RETURN_LONG((zend_long)time(NULL));
}
/* }}} */

18. Update for PHP
...
Release 2018g - 2018-10-26 22:22:45 -0700
Briefly:
Morocco switches to permanent +01 on 2018-10-27.
Changes to future timestamps
Morocco switches from +00/+01 to permanent +01 effective
2018-10-27,
so its clocks will not fall back on 2018-10-28 as
previously scheduled.
(Thanks to Mohamed Essedik Najd and Brian Inglis.)
...

19. C (1)
time()
seconds from 00:00:00 on January 1, 1970
03:14:07 UTC on January 19, 2038
CLOCKS_PER_SEC

20. Ubuntu (1)
● date
● timedatectl
Local time: Mon 2018-12-03 20:06:58 CET
Universal time: Mon 2018-12-03 19:06:58 UTC
RTC time: Mon 2018-12-03 19:06:58
Time zone: Europe/Berlin (CET, +0100)
NTP enabled: yes
NTP synchronized: yes
RTC in local TZ: no
...

21. Ubuntu (2)
...
DST active: no
Last DST change: DST ended at
Sun 2018-10-28 02:59:59 CEST
Sun 2018-10-28 02:00:00 CET
Next DST change: DST begins (the clock jumps one hour
forward) at
Sun 2019-03-31 01:59:59 CET
Sun 2019-03-31 03:00:00 CEST

22. Ubuntu (3)
Network Time Protocol
STRATUM 0-15
4 s - 17 min (avg: 64 s)

23. Discussion

24. ● https://www.iana.org/time-zones
● https://www.youtube.com/watch?v=-5wpm-gesOY - MUST SEE
● https://www.youtube.com/watch?v=Wd2EEResjQU
● https://www.youtube.com/watch?v=0j74jcxSunY
● https://docs.magento.com
● http://www.open-std.org/JTC1/sc22/wg14/www/docs/n1256.pdf
Bibliography