clock_gettime: Add new identifier CLOCK_UPTIME_RAW for Darwin

[rfrail3]

BPO	35702
Nosy	@ronaldoussoren, @vstinner, @ned-deily, @tirkarthi, @nanjekyejoannah, @rfrail3
PRs	bpo-35702: Add new identifier CLOCK_UPTIME_RAW for Darwin #11503 bpo-35702: Add new identifier CLOCK_UPTIME_RAW for Darwin #11503 bpo-35702: Add new identifier CLOCK_UPTIME_RAW for Darwin #11503

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2019-01-10.16:58:35.670>
created_at = <Date 2019-01-10.07:43:37.268>
labels = ['OS-mac', 'type-feature', '3.8']
title = 'clock_gettime: Add new identifier CLOCK_UPTIME_RAW for Darwin'
updated_at = <Date 2019-01-10.18:01:48.090>
user = 'https://github.com/rfrail3'

bugs.python.org fields:

activity = <Date 2019-01-10.18:01:48.090>
actor = 'rfrail3'
assignee = 'none'
closed = True
closed_date = <Date 2019-01-10.16:58:35.670>
closer = 'vstinner'
components = ['macOS']
creation = <Date 2019-01-10.07:43:37.268>
creator = 'rfrail3'
dependencies = []
files = []
hgrepos = []
issue_num = 35702
keywords = ['patch', 'patch', 'patch']
message_count = 6.0
messages = ['333366', '333376', '333381', '333406', '333407', '333413']
nosy_count = 6.0
nosy_names = ['ronaldoussoren', 'vstinner', 'ned.deily', 'xtreak', 'nanjekyejoannah', 'rfrail3']
pr_nums = ['11503', '11503', '11503']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue35702'
versions = ['Python 3.8']

[rfrail3]

Finally since the release of OSX 10.12 the equivalent from the FreeBSD and OpenBSD "CLOCK_UPTIME" is available on Darwin under the name "CLOCK_UPTIME_RAW":

CLOCK_UPTIME FreeBSD [1]:
Starts at zero when the kernel boots and increments monotonically in SI seconds while the machine is running.

CLOCK_UPTIME OpenBSD [2]:
Time whose absolute value is the time the system has been running and not suspended, providing accurate uptime measurement, both absolute and interval

CLOCK_UPTIME_RAW Darwin [3]:
Clock that increments monotonically, tracking the time since an arbitrary point, unaffected by frequency or time adjustments and not increment while the system is asleep.

It would be useful to have it available on time module [4] for this platform.

As the behaviour is equivalent, maybe it can be assigned to the existing time.CLOCK_UPTIME funtion.

Thanks,

[1] - https://www.freebsd.org/cgi/man.cgi?query=clock_gettime
[2] - https://man.openbsd.org/clock_gettime.2
[3] - http://www.manpagez.com/man/3/clock_gettime_nsec_np/
[4] - https://docs.python.org/3/library/time.htm

[nanjekyejoannah]

I am working on this.

[vstinner]

As the behaviour is equivalent, maybe it can be assigned to the existing time.CLOCK_UPTIME funtion.

Nah, in Python we map directly to OS constant and don't try to be smart. It's up to the user of these constants to make their own choice.

Use Python functions for portable behavior: time.monotonic(), time.perf_counter(), etc.

[vstinner]

New changeset 572168a by Victor Stinner (Joannah Nanjekye) in branch 'master':
bpo-35702: Add new identifier time.CLOCK_UPTIME_RAW for macOS 10.12 (GH-11503)
572168a

[vstinner]

Joannah Nanjekye added time.CLOCK_UPTIME_RAW to the master branch (future Python 3.8). We don't add feature to stable versions (like 3.7), so I close the issue.

Thanks Ricardo Fraile for the report, I wasn't aware of this clock ;-)

Note: Until Python 3.8 is released, you can easily hardcode the constant in your application. Such constant rarely change.

[rfrail3]

Impressive response time, thanks team!