Timer

Timer#

The code in this notebook helps with measuring time.

Prerequisites

  • This notebook needs some understanding on advanced concepts in Python, notably

    • classes

    • the Python with statement

    • measuring time

Synopsis#

To use the code provided in this chapter, write

>>> from fuzzingbook.Timer import <identifier>

and then make use of the following features.

Note: The examples in this section only work after the rest of the cells have been executed.

with Timer() as t:
    some_long_running_function()
t.elapsed_time()

0.030869709007674828

Measuring Time#

The class Timer allows measuring the elapsed time during some code execution.

import bookutils.setup

import time

def clock() -> float:
    """
    Return the number of fractional seconds elapsed since some point of reference.
    """
    return time.perf_counter()

from types import TracebackType

class Timer:
    def __init__(self) -> None:
        """Constructor"""
        self.start_time = clock()
        self.end_time = None

    def __enter__(self) -> Any:
        """Begin of `with` block"""
        self.start_time = clock()
        self.end_time = None
        return self

    def __exit__(self, exc_type: Type, exc_value: BaseException,
                 tb: TracebackType) -> None:
        """End of `with` block"""
        self.end_time = clock()  # type: ignore

    def elapsed_time(self) -> float:
        """Return elapsed time in seconds"""
        if self.end_time is None:
            # still running
            return clock() - self.start_time
        else:
            return self.end_time - self.start_time  # type: ignore

Here’s an example:

def some_long_running_function() -> None:
    i = 1000000
    while i > 0:
        i -= 1

print("Stopping total time:")
with Timer() as t:
    some_long_running_function()
print(t.elapsed_time())

Stopping total time:
0.03015562499058433

print("Stopping time in between:")
with Timer() as t:
    for i in range(10):
        some_long_running_function()
        print(t.elapsed_time())

Stopping time in between:
0.0305006249982398
0.0604882909974549
0.09118766599567607
0.12214049999602139
0.15291795798111707
0.18302566598867998

0.21359354100422934
0.2463232500012964
0.2783738329890184

0.3103841659903992

That’s it, folks – enjoy!

Lessons Learned#

  • With the Timer class, it is very easy to measure elapsed time.

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