Simple code timer for Python. Requires Python 3.2+

timeit.py

# The MIT License (MIT)
#
# Copyright (c) 2017 Gareth Watts
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
'''A simple wall-clock code timer.'''

from functools import wraps
import time
import threading

class timeit(dict):
    '''Report time taken for a piece of code to execute.

    This can be used either as a context manager, or as a decorator.

    Examples:

        @timeit('mytimer')
        def timethis():
            time.sleep(1)

        def myfunc():
            with timeit('mytimer'):
                time.sleep(1)

    The string output by timeit can be changed by supplying a fmt keyword
    to __init__.  Additionally, the object returned by the context manager can be
    treated as a dictionary, and entries assigned to it can be referenced in the
    format string, eg. to include result information:

    with timeit('make_request', fmt=timeit.fmt+' result={result}') as timer:
        result = make_http_call('http://example.com')
        timer['result'] = result

    # outputs something like:
    # timeit name='make_request' id=2 runtime=0.1s result=42

    Each invocation of the timer generates a new id, higher than the last.  There
    may be gaps in numbering.  it is thread safe.

    Args:
        name (str): Name to assign to this timer.  Displayed in formatted output
        fmt (str, optional): Override the default format string
    '''

    __id__ = 0
    __lck__ = threading.Lock()
    __cache__ = threading.local()

    #: string: Default format string used to print timer output
    fmt = "timeit name={name!r} id={id} runtime={runtime:.2}s"

    @classmethod
    def __next_id__(cls):
        with cls.__lck__:
            cls.__id__ += 1
            return cls.__id__

    def __init__(self, name, fmt=None, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self._start = None
        self.id = self.__next_id__()
        self.name = name
        if fmt:
            self.fmt = fmt
        ins = getattr(self.__cache__, name, None)
        if ins is None:
            setattr(self.__cache__, name, [])

    def __getitem__(self, key):
        if key == "id":
            return self.id
        if key == 'name':
            return self.name
        return super().__getitem__(key)

    def __enter__(self):
        getattr(self.__cache__, self.name).append(self)
        self._start = time.time()
        return self

    def __exit__(self, exc_type, exc_val, exc_tb):
        self['runtime'] = time.time() - self._start
        getattr(self.__cache__, self.name).pop()
        self.emit(self.fmt.format_map(self))

    def __call__(self, fn):
        @wraps(fn)
        def wrapper(*args, **kwargs):
            with type(self)(self.name, self.fmt, self) as t:
                return fn(*args, **kwargs)
        return wrapper

    def emit(self, msg):
        '''Emits the timer message; subclass and override to direct output elsewhere.'''
        print(msg)

    @classmethod
    def byname(cls, name):
        '''Byname returns the innermost timeit active instance with the given name.'''
        return getattr(cls.__cache__, name)[-1]

    @classmethod
    def set(cls, name, **kwargs):
        '''Set updates the innermost named timeout instance with the supplied values.

        This is useful when used with a timeit decorated function to pass
        data to format variables as it behaves correctly with recursive functions.
        '''
        cls.byname(name).update(kwargs)



if __name__ == '__main__':

    # Use it as a decorator
    @timeit('dectest')
    def go(arg1):
        print('running...', arg1)
        time.sleep(0.2)

    go("one")
    go("two")


    # Or as a context manager, with optional format override
    with timeit("withtest", fmt="Test {id} took {runtime} seconds"):
        print("running...")
        time.sleep(0.3)

    # or add your own information to it to print
    with timeit('another test', fmt=timeit.fmt+' result={result}') as t:
        time.sleep(0.15)
        t['result'] = "42"


    # supply custom args to the decorator for use in the fmt string,
    # use it recurisvely and update each recursive instance with values specific
    # to the call
    @timeit('factorial', fmt='factorial n={n} returned result={result} after {runtime}')
    def factorial(n):
        time.sleep(0.1 * n)
        if n > 1:
            result = n * factorial(n-1)
        else:
            result = 1
        timeit.set('factorial', n=n, result=result)
        return result

    print(factorial(5))