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Copy pathitem_71.py
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executable file
·264 lines (203 loc) · 6.05 KB
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#!/usr/bin/env PYTHONHASHSEED=1234 python3
# Copyright 2014-2019 Brett Slatkin, Pearson Education Inc.
#
# 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)