simple_timer.py

"""
Simple timer class. Example usage:

t = Timer()
for url in ('http://www.google.com/', 'http://www.yahoo.com/'):
    t.start('fetch url')
    content = urllib.urlopen(url).read()
    t.stop('fetch url')
    t.start('reorder bytes')
    bytes = list(content)
    bytes.sort()
    t.stop('reorder bytes')

t.print_summary()

fetch url: 2 calls, avg = 0.557923, min = 0.547084, max = 0.568763, sum = 1.115847
reorder bytes: 2 calls, avg = 0.028007, min = 0.003244, max = 0.052770, sum = 0.056014

"""

import time

class Timer(object):
    def __init__(self):
        self.in_flight = {}
        self.results = {}
    
    def start(self, name):
        assert name not in self.in_flight,\
            "Can't start a '%s' timer if one is already running" % name
        self.in_flight[name] = time.time()
    
    def stop(self, name):
        assert name in self.in_flight,\
            "Can't stop a '%s' timer without starting it first" % name
        duration = time.time() - self.in_flight[name]
        del self.in_flight[name]
        self.results.setdefault(name, []).append(duration)
    
    def summary(self, name):
        results = self.results.get(name, [])
        s = '%s: %d calls, avg = %.6f, min = %.6f, max = %.6f, sum = %.6f' % (
            name, len(results), sum(results) / len(results),
            min(results), max(results), sum(results)
        )
        return s
    
    def print_summary(self):
        for key in self.results:
            print self.summary(key)