POSIX clock_*()
for NodeJS 
Installation
npm install posix-clock
Examples
clock_getres()
var clock = require('posix-clock');
var clockResolution = clock.getres(clock.MONOTONIC);
console.log(
'Resolution of CLOCK_MONOTONIC: '
+ clockResolution.sec + ' sec and '
+ clockResolution.nsec + ' nanosec.'
, clockResolution
);
Resolution of CLOCK_MONOTONIC: 0 sec and 1 nanosec. { sec: 0, nsec: 1 }
clock_gettime()
var clock = require('posix-clock');
var clockTime = clock.gettime(clock.MONOTONIC);
console.log(
'Time from CLOCK_MONOTONIC: '
+ clockTime.sec + ' sec and '
+ clockTime.nsec + ' nanosec.'
, clockTime
);
Time from CLOCK_MONOTONIC: 15224 sec and 557776233 nanosec. { sec: 15224, nsec: 557776233 }
clock_nanosleep()
var clock = require('posix-clock');
// sleep until 13 Feb 2009 23:31:30 UTC (Unix Timestamp = 1234567890)
clock.nanosleep(
clock.REALTIME,
clock.TIMER_ABSTIME,
{
sec: 1234567890,
nsec: 0
}
);
// sleep at least 10 seconds and 123 nanoseconds
clock.nanosleep(
clock.REALTIME,
0,
{
sec: 10,
nsec: 123
}
);
API
Methods
gettime(clockId)
- the function retrieve the time from the specified clock clockId.
See man 2 clock_gettime for more details.
getres(clockId)
- the function return the resolution (precision) of the
specified clock clockId. The resolution of clocks depends on the implementation and cannot be
configured by a particular process.
See man 2 clock_getres for more details.
nanosleep(clockId, flags, sleepTime)
- high resolution sleep with specifiable clock.
If the flag TIMER_ABSTIME
is not set in the flags
argument, the nanosleep()
function shall cause the current thread to be suspended from execution until
either the time interval specified by the sleepTime
argument has elapsed,
or a signal is delivered to the calling thread and its action is to invoke a
signal-catching function, or the process is terminated.
The clock used to measure the time shall be the clock specified by clockId.
See man 2 clock_nanosleep for more details.
On non-linux OS only nanosleep(REALTIME, 0, {...})
is supported.
Clocks
REALTIME
- system-wide clock that measures real (i.e., wall-clock) time.
This clock is affected by discontinuous jumps in
the system time (e.g., if the system administrator
manually changes the clock), and by the incremental adjustments
performed by adjtime(3) and NTP.
MONOTONIC
- clock that cannot be set and represents monotonic time since some
unspecified starting point. This clock is not affected by discontinuous
jumps in the system time (e.g., if the system administrator
manually changes the clock), but is affected by the incremental adjustments
performed by adjtime(3) and NTP.
Linux-specific
PROCESS_CPUTIME_ID
- since Linux 2.6.12.
High-resolution per-process timer from the CPU.
THREAD_CPUTIME_ID
- since Linux 2.6.12.
Thread-specific CPU-time clock.
REALTIME_COARSE
- since Linux 2.6.32; Linux-specific.
A faster but less precise version of REALTIME
.
Use when you need very fast, but not fine-grained timestamps.
MONOTONIC_COARSE
- since Linux 2.6.32; Linux-specific.
A faster but less precise version of MONOTONIC
.
Use when you need very fast, but not fine-grained timestamps.
MONOTONIC_RAW
- since Linux 2.6.28; Linux-specific.
Similar to MONOTONIC
, but provides access to a raw hardware-based time
that is not subject to NTP adjustments or the incremental adjustments
performed by adjtime(3).
BOOTTIME
- since Linux 2.6.39; Linux-specific
Identical to MONOTONIC
, except it also includes
any time that the system is suspended. This allows applications to get
a suspend-aware monotonic clock without having to deal with
the complications of REALTIME
, which may have discontinuities
if the time is changed using settimeofday(2).
FreeBSD-specific
REALTIME_FAST
- analog of REALTIME
but do not perform a full time
counter query, so their accuracy is one timer tick
REALTIME_PRECISE
- analog of REALTIME
but get the most exact value
as possible, at the expense of execution time
MONOTONIC_FAST
- analog of MONOTONIC
but do not perform a full time
counter query, so their accuracy is one timer tick
MONOTONIC_PRECISE
- analog of MONOTONIC
but get the most exact value
as possible, at the expense of execution time
UPTIME
- which starts at zero when the kernel boots and increments
monotonically in SI seconds while the machine is running
UPTIME_FAST
- analog of UPTIME
but do not perform a full time
counter query, so their accuracy is one timer tick
UPTIME_PRECISE
- analog of UPTIME
but get the most exact value
as possible, at the expense of execution time
SECOND
- returns the current second without performing a full
time counter query, using in-kernel cached value of current second.
PROF
- for time that increments when the CPU is running in user or kernel mode