effectivepython/example_code/item_71.py at master · sharc007/effectivepython · GitHub

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#!/usr/bin/env PYTHONHASHSEED=1234 python3

# Licensed under the Apache License, Version 2.0 (the "License");

# you may not use this file except in compliance with the License.

# You may obtain a copy of the License at

# http://www.apache.org/licenses/LICENSE-2.0

# Unless required by applicable law or agreed to in writing, software

# distributed under the License is distributed on an "AS IS" BASIS,

# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

# See the License for the specific language governing permissions and

# limitations under the License.

# Reproduce book environment

import random

random.seed(1234)

import logging

from pprint import pprint

from sys import stdout as STDOUT

# Write all output to a temporary directory

import atexit

import gc

import io

import os

import tempfile

TEST_DIR = tempfile.TemporaryDirectory()

atexit.register(TEST_DIR.cleanup)

# Make sure Windows processes exit cleanly

OLD_CWD = os.getcwd()

atexit.register(lambda: os.chdir(OLD_CWD))

os.chdir(TEST_DIR.name)

def close_open_files():

everything = gc.get_objects()

for obj in everything:

if isinstance(obj, io.IOBase):

obj.close()

atexit.register(close_open_files)

# Example 1

class Email:

def __init__(self, sender, receiver, message):

self.sender = sender

self.receiver = receiver

self.message = message

# Example 2

def get_emails():

yield Email('foo@example.com', 'bar@example.com', 'hello1')

yield Email('baz@example.com', 'banana@example.com', 'hello2')

yield None

yield Email('meep@example.com', 'butter@example.com', 'hello3')

yield Email('stuff@example.com', 'avocado@example.com', 'hello4')

yield None

yield Email('thingy@example.com', 'orange@example.com', 'hello5')

yield Email('roger@example.com', 'bob@example.com', 'hello6')

yield None

yield Email('peanut@example.com', 'alice@example.com', 'hello7')

yield None

EMAIL_IT = get_emails()

class NoEmailError(Exception):

pass

def try_receive_email():

# Returns an Email instance or raises NoEmailError

try:

email = next(EMAIL_IT)

except StopIteration:

email = None

if not email:

raise NoEmailError

print(f'Produced email: {email.message}')

return email

# Example 3

def produce_emails(queue):

while True:

try:

email = try_receive_email()

except NoEmailError:

return

else:

queue.append(email) # Producer

# Example 4

def consume_one_email(queue):

if not queue:

return

email = queue.pop(0) # Consumer

# Index the message for long-term archival

print(f'Consumed email: {email.message}')

# Example 5

def loop(queue, keep_running):

while keep_running():

produce_emails(queue)

consume_one_email(queue)

def make_test_end():

count=list(range(10))

def func():

if count:

count.pop()

return True

return False

return func

def my_end_func():

pass

my_end_func = make_test_end()

loop([], my_end_func)

# Example 6

import timeit

def print_results(count, tests):

avg_iteration = sum(tests) / len(tests)

print(f'Count {count:>5,} takes {avg_iteration:.6f}s')

return count, avg_iteration

def list_append_benchmark(count):

def run(queue):

for i in range(count):

queue.append(i)

tests = timeit.repeat(

setup='queue = []',

stmt='run(queue)',

globals=locals(),

repeat=1000,

number=1)

return print_results(count, tests)

# Example 7

def print_delta(before, after):

before_count, before_time = before

after_count, after_time = after

growth = 1 + (after_count - before_count) / before_count

slowdown = 1 + (after_time - before_time) / before_time

print(f'{growth:>4.1f}x data size, {slowdown:>4.1f}x time')

baseline = list_append_benchmark(500)

for count in (1_000, 2_000, 3_000, 4_000, 5_000):

print()

comparison = list_append_benchmark(count)

print_delta(baseline, comparison)

# Example 8

def list_pop_benchmark(count):

def prepare():

return list(range(count))

def run(queue):

while queue:

queue.pop(0)

tests = timeit.repeat(

setup='queue = prepare()',

stmt='run(queue)',

globals=locals(),

repeat=1000,

number=1)

return print_results(count, tests)

# Example 9

baseline = list_pop_benchmark(500)

for count in (1_000, 2_000, 3_000, 4_000, 5_000):

print()

comparison = list_pop_benchmark(count)

print_delta(baseline, comparison)

# Example 10

import collections

def consume_one_email(queue):

if not queue:

return

email = queue.popleft() # Consumer

# Process the email message

print(f'Consumed email: {email.message}')

def my_end_func():

pass

my_end_func = make_test_end()

EMAIL_IT = get_emails()

loop(collections.deque(), my_end_func)

# Example 11

def deque_append_benchmark(count):

def prepare():

return collections.deque()

def run(queue):

for i in range(count):

queue.append(i)

tests = timeit.repeat(

setup='queue = prepare()',

stmt='run(queue)',

globals=locals(),

repeat=1000,

number=1)

return print_results(count, tests)

baseline = deque_append_benchmark(500)

for count in (1_000, 2_000, 3_000, 4_000, 5_000):

print()

comparison = deque_append_benchmark(count)

print_delta(baseline, comparison)

# Example 12

def dequeue_popleft_benchmark(count):

def prepare():

return collections.deque(range(count))

def run(queue):

while queue:

queue.popleft()

tests = timeit.repeat(

setup='queue = prepare()',

stmt='run(queue)',

globals=locals(),

repeat=1000,

number=1)

return print_results(count, tests)

baseline = dequeue_popleft_benchmark(500)

for count in (1_000, 2_000, 3_000, 4_000, 5_000):

print()

comparison = dequeue_popleft_benchmark(count)

print_delta(baseline, comparison)

effectivepython/example_code/item_71.py at master · sharc007/effectivepython · GitHub

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