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[JS + docs] improve std/monotimes module (#17103)

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flywind 2021-02-22 04:09:25 -06:00 • committed by GitHub
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2 changed files with 49 additions and 43 deletions
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82
lib/std/monotimes.nim
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@ -8,34 +8,38 @@
# #
##[ ##[
The ``std/monotimes`` module implements monotonic timestamps. A monotonic The `std/monotimes` module implements monotonic timestamps. A monotonic
timestamp represents the time that has passed since some system defined timestamp represents the time that has passed since some system defined
point in time. The monotonic timestamps are guaranteed to always increase, point in time. The monotonic timestamps are guaranteed to always increase,
meaning that that the following is guaranteed to work: meaning that that the following is guaranteed to work:
.. code-block:: nim
let a = getMonoTime()
# ... do some work
let b = getMonoTime()
assert a <= b
This is not guaranteed for the `times.Time` type! This means that the
`MonoTime` should be used when measuring durations of time with
high precision.
However, since `MonoTime` represents the time that has passed since some
unknown time origin, it cannot be converted to a human readable timestamp.
If this is required, the `times.Time` type should be used instead.
The `MonoTime` type stores the timestamp in nanosecond resolution, but note
that the actual supported time resolution differs for different systems.
See also
========
* `times module <times.html>`_
]## ]##
import times runnableExamples:
import std/os
let a = getMonoTime()
sleep(10)
let b = getMonoTime()
assert a < b
##[
This is not guaranteed for the `times.Time` type! This means that the
`MonoTime` should be used when measuring durations of time with
high precision.
However, since `MonoTime` represents the time that has passed since some
unknown time origin, it cannot be converted to a human readable timestamp.
If this is required, the `times.Time` type should be used instead.
The `MonoTime` type stores the timestamp in nanosecond resolution, but note
that the actual supported time resolution differs for different systems.
See also
========
* `times module <times.html>`_
]##
import std/times
type type
MonoTime* = object ## Represents a monotonic timestamp. MonoTime* = object ## Represents a monotonic timestamp.
@ -53,18 +57,16 @@ when defined(macosx):
when defined(js): when defined(js):
proc getJsTicks: float = proc getJsTicks: float =
## Returns ticks in the unit seconds ## Returns ticks in the unit seconds.
when defined(nodejs):
{.emit: """ {.emit: """
var isNode = typeof module !== 'undefined' && module.exports let process = require('process');
let time = process.hrtime();
if (isNode) { `result` = time[0] + time[1] / 1000000000;
var process = require('process');
var time = process.hrtime()
return time[0] + time[1] / 1000000000;
} else {
return window.performance.now() / 1000;
}
""".} """.}
else:
proc jsNow(): float {.importjs: "window.performance.now()".}
result = jsNow() / 1000
# Workaround for #6752. # Workaround for #6752.
{.push overflowChecks: off.} {.push overflowChecks: off.}
@ -75,7 +77,7 @@ when defined(js):
{.pop.} {.pop.}
elif defined(posix) and not defined(osx): elif defined(posix) and not defined(osx):
import posix import std/posix
elif defined(windows): elif defined(windows):
proc QueryPerformanceCounter(res: var uint64) {. proc QueryPerformanceCounter(res: var uint64) {.
@ -84,11 +86,11 @@ elif defined(windows):
importc: "QueryPerformanceFrequency", stdcall, dynlib: "kernel32".} importc: "QueryPerformanceFrequency", stdcall, dynlib: "kernel32".}
proc getMonoTime*(): MonoTime {.tags: [TimeEffect].} = proc getMonoTime*(): MonoTime {.tags: [TimeEffect].} =
## Get the current `MonoTime` timestamp. ## Returns the current `MonoTime` timestamp.
## ##
## When compiled with the JS backend and executed in a browser, ## When compiled with the JS backend and executed in a browser,
## this proc calls `window.performance.now()`, which is not supported by ## this proc calls `window.performance.now()`.
## older browsers. See [MDN](https://developer.mozilla.org/en-US/docs/Web/API/Performance/now) ## See [MDN](https://developer.mozilla.org/en-US/docs/Web/API/Performance/now)
## for more information. ## for more information.
when defined(js): when defined(js):
let ticks = getJsTicks() let ticks = getJsTicks()

6
tests/stdlib/tmonotimes.nim
View file

@ -1,4 +1,8 @@
import std/monotimes, times discard """
targets: "c js"
"""
import std/[monotimes, times]
let d = initDuration(nanoseconds = 10) let d = initDuration(nanoseconds = 10)
let t1 = getMonoTime() let t1 = getMonoTime()