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Implement time.monotonic() on Mac OS X #58312
Description
| BPO | 14104 |
|---|---|
| Nosy | @ronaldoussoren, @pitrou, @vstinner, @ned-deily |
| Files |
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 2012-03-12.23:27:28.933>
created_at = <Date 2012-02-23.23:09:14.831>
labels = ['library']
title = 'Implement time.monotonic() on Mac OS X'
updated_at = <Date 2012-03-12.23:29:14.621>
user = 'https://github.com/vstinner'bugs.python.org fields:
activity = <Date 2012-03-12.23:29:14.621>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2012-03-12.23:27:28.933>
closer = 'vstinner'
components = ['Library (Lib)']
creation = <Date 2012-02-23.23:09:14.831>
creator = 'vstinner'
dependencies = []
files = ['24798', '24804']
hgrepos = []
issue_num = 14104
keywords = ['patch']
message_count = 8.0
messages = ['154095', '155478', '155502', '155507', '155511', '155515', '155520', '155521']
nosy_count = 6.0
nosy_names = ['nicholas.riley', 'ronaldoussoren', 'pitrou', 'vstinner', 'ned.deily', 'python-dev']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'patch review'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue14104'
versions = ['Python 3.3']
Activity
vstinner commentedon Feb 23, 2012
time.monotonic() can use mach_absolute_time() on Mac OS X. mach_timebase_info() may be used to convert the result to a number of seconds. Examples:
https://github.com/ThomasHabets/monotonic_clock/blob/master/src/monotonic_mach.c
http://svn.boost.org/svn/boost/trunk/boost/chrono/detail/inlined/mac/chrono.hpp
(search steady_clock)
Another way is to use clock_get_time() with host_get_clock_service(SYSTEM_CLOCK). Example:
https://github.com/gavinbeatty/python-monotonic-time/blob/master/darwin.c
nicholasriley commentedon Mar 12, 2012
Attached is a patch which implements time.monotonic() using mach_absolute_time() / mach_timebase_info(). This was recommended by Apple in their technical Q&A 1398:
https://developer.apple.com/library/mac/#qa/qa1398/
vstinner commentedon Mar 12, 2012
Is it possible that mach_timebase_info() fails? No according to the Technical Q&A QA1398.
"time * timebase.numer" may overflow, you should maybe multiply using the double type to avoid the overflow.
nicholasriley commentedon Mar 12, 2012
timebase.numer and timebase.denom are always 1 in practice (see the "note" in the tech Q&A); I included them for completeness, but maybe it's just better to not bother?
vstinner commentedon Mar 12, 2012
In this case, you will not lose precision and it's safe to cast to double to multiply and divide ;-)
nicholasriley commentedon Mar 12, 2012
OK, you have a point :-) New patch attached.
python-dev commentedon Mar 12, 2012
New changeset 3c875719e46d by Victor Stinner in branch 'default':
Issue bpo-14104: Implement time.monotonic() on Mac OS X,
http://hg.python.org/cpython/rev/3c875719e46d
vstinner commentedon Mar 12, 2012
Path commited, thanks for the patch Nicholas!