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item_077.py
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executable file
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#!/usr/bin/env PYTHONHASHSEED=1234 python3
# Copyright 2014-2024 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.
### 책 예제에 맞는 환경 설정을 시작함
import random
random.seed(1234)
import logging
from pprint import pprint
from sys import stdout as STDOUT
# 모든 출력을 임시 디렉터리로 보냄
import atexit
import gc
import io
import os
import tempfile
TEST_DIR = tempfile.TemporaryDirectory()
atexit.register(TEST_DIR.cleanup)
# 윈도우에서 프로세스가 제대로 종료되도록 함
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)
### 책 예제에 맞는 환경설정 끝
print("아이템 77")
print("Example 1")
class NoNewData(Exception):
pass
def readline(handle):
offset = handle.tell()
handle.seek(0, 2)
length = handle.tell()
if length == offset:
raise NoNewData
handle.seek(offset, 0)
return handle.readline()
print("Example 2")
import time
def tail_file(handle, interval, write_func):
while not handle.closed:
try:
line = readline(handle)
except NoNewData:
time.sleep(interval)
else:
write_func(line)
print("Example 3")
from threading import Lock, Thread
def run_threads(handles, interval, output_path):
with open(output_path, "wb") as output:
lock = Lock()
def write(data):
with lock:
output.write(data)
threads = []
for handle in handles:
args = (handle, interval, write)
thread = Thread(target=tail_file, args=args)
thread.start()
threads.append(thread)
for thread in threads:
thread.join()
print("Example 4")
# 핸들에 쓰는 라이터를 시뮬레이션하는 전체 코드
import collections
import os
import random
import string
from tempfile import TemporaryDirectory
def write_random_data(path, write_count, interval):
with open(path, "wb") as f:
for i in range(write_count):
time.sleep(random.random() * interval)
letters = random.choices(string.ascii_lowercase, k=10)
data = f'{path}-{i:02}-{"".join(letters)}\n'
f.write(data.encode())
f.flush()
def start_write_threads(directory, file_count):
paths = []
for i in range(file_count):
path = os.path.join(directory, str(i))
with open(path, "w"):
# 읽기 스레드를 폴링할 때 파일이 경로상에 존재하게 함
pass
paths.append(path)
args = (path, 10, 0.1)
thread = Thread(target=write_random_data, args=args)
thread.start()
return paths
def close_all(handles):
time.sleep(1)
for handle in handles:
handle.close()
def setup():
tmpdir = TemporaryDirectory()
input_paths = start_write_threads(tmpdir.name, 5)
handles = []
for path in input_paths:
handle = open(path, "rb")
handles.append(handle)
Thread(target=close_all, args=(handles,)).start()
output_path = os.path.join(tmpdir.name, "merged")
return tmpdir, input_paths, handles, output_path
print("Example 5")
def confirm_merge(input_paths, output_path):
found = collections.defaultdict(list)
with open(output_path, "rb") as f:
for line in f:
for path in input_paths:
if line.find(path.encode()) == 0:
found[path].append(line)
expected = collections.defaultdict(list)
for path in input_paths:
with open(path, "rb") as f:
expected[path].extend(f.readlines())
for key, expected_lines in expected.items():
found_lines = found[key]
assert (
expected_lines == found_lines
), f"{expected_lines!r} == {found_lines!r}"
input_paths = ...
handles = ...
output_path = ...
tmpdir, input_paths, handles, output_path = setup()
run_threads(handles, 0.1, output_path)
confirm_merge(input_paths, output_path)
tmpdir.cleanup()
print("Example 6")
import asyncio
# TODO: 더이상 아래 조치가 필요하지 않은지 검증해봐야 함
#
# 윈도우에서 ProactorEventLoop를 스레드 내부에서 생성할 수 없다.
# 시그널 핸들러를 등록하려고 하기 때문이다.
# 다음은 SelectorEventLoop 정책을 사용하는 대안이다.
# 참조: https://bugs.python.org/issue33792
# policy = asyncio.get_event_loop_policy()
# policy._loop_factory = asyncio.SelectorEventLoop
async def run_tasks_mixed(handles, interval, output_path):
loop = asyncio.get_event_loop()
output = await loop.run_in_executor(None, open, output_path, "wb")
try:
async def write_async(data):
await loop.run_in_executor(None, output.write, data)
def write(data):
coro = write_async(data)
future = asyncio.run_coroutine_threadsafe(coro, loop)
future.result()
tasks = []
for handle in handles:
task = loop.run_in_executor(
None, tail_file, handle, interval, write
)
tasks.append(task)
await asyncio.gather(*tasks)
finally:
await loop.run_in_executor(None, output.close)
print("Example 7")
input_paths = ...
handles = ...
output_path = ...
tmpdir, input_paths, handles, output_path = setup()
asyncio.run(run_tasks_mixed(handles, 0.1, output_path))
confirm_merge(input_paths, output_path)
tmpdir.cleanup()
print("Example 8")
async def tail_async(handle, interval, write_func):
loop = asyncio.get_event_loop()
while not handle.closed:
try:
line = await loop.run_in_executor(None, readline, handle)
except NoNewData:
await asyncio.sleep(interval)
else:
await write_func(line)
print("Example 9")
async def run_tasks(handles, interval, output_path):
loop = asyncio.get_event_loop()
output = await loop.run_in_executor(None, open, output_path, "wb")
try:
async def write_async(data):
await loop.run_in_executor(None, output.write, data)
async with asyncio.TaskGroup() as group:
for handle in handles:
group.create_task(
tail_async(handle, interval, write_async)
)
finally:
await loop.run_in_executor(None, output.close)
print("Example 10")
input_paths = ...
handles = ...
output_path = ...
tmpdir, input_paths, handles, output_path = setup()
asyncio.run(run_tasks(handles, 0.1, output_path))
confirm_merge(input_paths, output_path)
tmpdir.cleanup()
print("Example 11")
def tail_file(handle, interval, write_func):
loop = asyncio.new_event_loop()
asyncio.set_event_loop(loop)
async def write_async(data):
await loop.run_in_executor(None, write_func, data)
coro = tail_async(handle, interval, write_async)
loop.run_until_complete(coro)
print("Example 12")
input_paths = ...
handles = ...
output_path = ...
tmpdir, input_paths, handles, output_path = setup()
run_threads(handles, 0.1, output_path)
confirm_merge(input_paths, output_path)
tmpdir.cleanup()