How do I get monotonic time durations in python?

Question

I want to log how long something takes in real walltime. Currently I\'m doing this:

startTime = time.time()
someSQLOrSomething()
print \"That took %.3f secon         


        

Answer 1

That function is simple enough that you can use ctypes to access it:

#!/usr/bin/env python

__all__ = ["monotonic_time"]

import ctypes, os

CLOCK_MONOTONIC_RAW = 4 # see 

class timespec(ctypes.Structure):
    _fields_ = [
        ('tv_sec', ctypes.c_long),
        ('tv_nsec', ctypes.c_long)
    ]

librt = ctypes.CDLL('librt.so.1', use_errno=True)
clock_gettime = librt.clock_gettime
clock_gettime.argtypes = [ctypes.c_int, ctypes.POINTER(timespec)]

def monotonic_time():
    t = timespec()
    if clock_gettime(CLOCK_MONOTONIC_RAW , ctypes.pointer(t)) != 0:
        errno_ = ctypes.get_errno()
        raise OSError(errno_, os.strerror(errno_))
    return t.tv_sec + t.tv_nsec * 1e-9

if __name__ == "__main__":
    print monotonic_time()