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PEP 418: Cleanup the glossary 

* <nanosecond> and <clock_monotonic> are not terms of the glossary
 * remove the useless definition of duration
 * monotonic: reading a monotonic clock is not slower than other clock
This commit is contained in:
Victor Stinner 2012-04-28 10:59:31 +02:00
parent 7cbdcfa301
commit 92e2f078f0
1 changed files with 3 additions and 14 deletions
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17
pep-0418.txt
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@ -610,14 +610,14 @@ Glossary
:Clock: :Clock:
An instrument for measuring time. Different clocks have different An instrument for measuring time. Different clocks have different
characteristics; for example, a clock with <nanosecond> characteristics; for example, a clock with nanosecond
<precision> may start to <drift> after a few minutes, while a less <precision> may start to <drift> after a few minutes, while a less
precise clock remained accurate for days. This PEP is primarily precise clock remained accurate for days. This PEP is primarily
concerned with clocks which use a unit of seconds. concerned with clocks which use a unit of seconds.
:Counter: :Counter:
A clock which increments each time a certain event occurs. A A clock which increments each time a certain event occurs. A
counter is <strictly monotonic>, but not <clock_monotonic>. It can counter is strictly monotonic, but not a monotonic clock. It can
be used to generate a unique (and ordered) timestamp, but these be used to generate a unique (and ordered) timestamp, but these
timestamps cannot be mapped to <civil time>; tick creation may well timestamps cannot be mapped to <civil time>; tick creation may well
be bursty, with several advances in the same millisecond followed be bursty, with several advances in the same millisecond followed
@ -630,12 +630,6 @@ Glossary
when profiling, but they do not map directly to user response time, when profiling, but they do not map directly to user response time,
nor are they directly comparable to (real time) seconds. nor are they directly comparable to (real time) seconds.
:Duration:
Elapsed time. The difference between the starting and ending
times. A defined <epoch> creates an implicit (and usually large)
duration. More precision can generally be provided for a
relatively small <duration>.
:Drift: :Drift:
The accumulated error against "true" time, as defined externally to The accumulated error against "true" time, as defined externally to
the system. Drift may be due to imprecision, or to a difference the system. Drift may be due to imprecision, or to a difference
@ -657,12 +651,7 @@ Glossary
Moving in at most one direction; for clocks, that direction is Moving in at most one direction; for clocks, that direction is
forward. The <clock> should also be <steady>, and should be forward. The <clock> should also be <steady>, and should be
convertible to a unit of seconds. The tradeoffs often include lack convertible to a unit of seconds. The tradeoffs often include lack
of a defined <epoch> or mapping to <Civil Time>, and being more of a defined <epoch> or mapping to <Civil Time>.
expensive (in <latency>, power usage, or <duration> spent within
calls to the clock itself) to use. For example, the clock may
represent (a constant multiplied by) ticks of a specific quartz
timer on a specific CPU core, and calls would therefore require
synchronization between cores.
:Precision: :Precision:
The amount of deviation among measurements of the same physical The amount of deviation among measurements of the same physical