[Python-checkins] peps: PEP 418: Mention the Technical Q&A QA1398 for mach_absolute_time()

[victor.stinner]

http://hg.python.org/peps/rev/05bfb02e57db
changeset:   4161:05bfb02e57db
user:        Victor Stinner <victor.stinner at gmail.com>
date:        Wed Mar 28 02:59:01 2012 +0200
summary:
  PEP 418: Mention the Technical Q&A QA1398 for mach_absolute_time()

files:
  pep-0418.txt |  23 +++++++++++++----------
  1 files changed, 13 insertions(+), 10 deletions(-)


diff --git a/pep-0418.txt b/pep-0418.txt
--- a/pep-0418.txt
+++ b/pep-0418.txt
@@ -137,7 +137,7 @@
 
 It is available on all platforms and cannot fail.
 
-Pseudo-code [#pseudo]_: ::
+Pseudo-code::
 
     def hires():
         if hires.use_monotonic:
@@ -158,11 +158,15 @@
 mach_absolute_time
 ^^^^^^^^^^^^^^^^^^
 
-Mac OS X provides a monotonic clock: mach_absolute_time(). mach_timebase_info()
-provides a fraction to convert the clock value to a number of nanoseconds.
+Mac OS X provides a monotonic clock: mach_absolute_time(). It is based on
+absolute elapsed time delta since system boot. It is not adjusted and cannot be
+set.
 
-According to the documentation, mach_timebase_info() is always equals to one
-and does never fail, even if the function may fail according to its prototype.
+mach_timebase_info() gives a fraction to convert the clock value to a number of
+nanoseconds. According to the documentation (`Technical Q&A QA1398
+<https://developer.apple.com/library/mac/#qa/qa1398/>`_), mach_timebase_info()
+is always equals to one and does never fail, even if the function may fail
+according to its prototype.
 
 mach_absolute_time() has a resolution of 1 nanosecond.
 
@@ -189,7 +193,7 @@
 clock_getres() gives the clock resolution. It is 1 nanosecond on Linux.
 
 .. note::
-   clock_gettime() requires to link the program with the realtime ("rt") library.
+   clock_gettime() requires to link the program to the rt (real-time) library.
 
 QueryPerformanceCounter
 ^^^^^^^^^^^^^^^^^^^^^^^
@@ -197,7 +201,6 @@
 High-resolution performance counter. It is monotonic.
 QueryPerformanceFrequency() gives its frequency.
 
-
 On Windows XP, QueryPerformanceFrequency() is the processor frequency and
 QueryPerformanceCounter() is the TSC of the current processor. Windows XP
 had a bug (see `KB896256 <http://support.microsoft.com/?id=896256>`_): on a
@@ -315,9 +318,9 @@
 One function with a flag: time.monotonic(strict=False)
 ----------------------------------------------------------
 
- * time.monotonic(strict=False) falls back to another clock if no monotonic clock
-   is not available or does not work, but it does never fail.
- * time.monotonic(strict=True) raises OSError if monotonic clock fails or
+ * time.monotonic(strict=False) falls back to the system clock if no monotonic
+   clock is available or if the monotonic clock failed.
+ * time.monotonic(strict=True) raises OSError if monotonic clock fails and
    NotImplementedError if the system does not provide a monotonic clock
 
 "A keyword argument that gets passed as a constant in the caller is usually

-- 
Repository URL: http://hg.python.org/peps