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aiofile-3.8.1
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مشاهده بیشترتوضیحات
Asynchronous file operations.
| ویژگی | مقدار |
|---|---|
| سیستم عامل | - |
| نام فایل | aiofile-3.8.1 |
| نام | aiofile |
| نسخه کتابخانه | 3.8.1 |
| نگهدارنده | [] |
| ایمیل نگهدارنده | [] |
| نویسنده | Dmitry Orlov <me@mosquito.su> |
| ایمیل نویسنده | me@mosquito.su |
| آدرس صفحه اصلی | http://github.com/mosquito/aiofile |
| آدرس اینترنتی | https://pypi.org/project/aiofile/ |
| مجوز | Apache 2 |
AIOFile
=======
.. image:: https://github.com/mosquito/aiofile/workflows/tox/badge.svg
:target: https://github.com/mosquito/aiofile/actions?query=branch%3Amaster
:alt: Github Actions
.. image:: https://img.shields.io/pypi/v/aiofile.svg
:target: https://pypi.python.org/pypi/aiofile/
:alt: Latest Version
.. image:: https://img.shields.io/pypi/wheel/aiofile.svg
:target: https://pypi.python.org/pypi/aiofile/
.. image:: https://img.shields.io/pypi/pyversions/aiofile.svg
:target: https://pypi.python.org/pypi/aiofile/
.. image:: https://img.shields.io/pypi/l/aiofile.svg
:target: https://pypi.python.org/pypi/aiofile/
Real asynchronous file operations with asyncio support.
Status
------
Development - Stable
Features
--------
* Since version 2.0.0 using `caio`_, is contain linux libaio and two
thread-based implementations (c-based and pure-python).
* AIOFile has no internal pointer. You should pass ``offset`` and
``chunk_size`` for each operation or use helpers (Reader or Writer).
The simples way is use ``async_open`` for create object with
file-like interface.
* For Linux using implementation based on `libaio`_.
* For POSIX (MacOS X and optional Linux) using implementation
using on `threadpool`_.
* Otherwise using pure-python thread-based implementation.
* Implementation chooses automatically depending on system compatibility.
.. _caio: https://pypi.org/project/caio
.. _libaio: https://pagure.io/libaio
.. _threadpool: https://github.com/mbrossard/threadpool/
Limitations
-----------
* Linux native AIO implementation not able to open special files.
Asynchronous operations against special fs like ``/proc/`` ``/sys/`` not
supported by the kernel. It's not a `aiofile`s or `caio` issue.
To In this cases, you might switch to thread-based implementations
(see troubleshooting_ section).
However, when used on supported file systems, the linux implementation has a
smaller overhead and preferred but it's not a silver bullet.
Code examples
-------------
All code examples requires python 3.6+.
High-level API
++++++++++++++
``async_open`` helper
~~~~~~~~~~~~~~~~~~~~~
Helper mimics to python python file-like objects, it's returns file like
object with similar but async methods.
Supported methods:
* ``async def read(length = -1)`` - reading chunk from file, when length is
``-1`` will be read file to the end.
* ``async def write(data)`` - write chunk to file
* ``def seek(offset)`` - set file pointer position
* ``def tell()`` - returns current file pointer position
* ``async def readline(size=-1, newline="\n")`` - read chunks until
newline or EOF. Since version 3.7.0 ``__aiter__`` returns ``LineReader``.
This method suboptimal for small lines because doesn't reuse read buffer.
When you want to read file by lines please avoid to use ``async_open``
use ``LineReader`` instead.
* ``def __aiter__() -> LineReader`` - iterator over lines.
* ``def iter_chunked(chunk_size: int = 32768) -> Reader`` - iterator over
chunks.
* ``.file`` property contains AIOFile object
Basic example:
.. code-block:: python
:name: test_basic
import asyncio
from pathlib import Path
from tempfile import gettempdir
from aiofile import async_open
tmp_filename = Path(gettempdir()) / "hello.txt"
async def main():
async with async_open(tmp_filename, 'w+') as afp:
await afp.write("Hello ")
await afp.write("world")
afp.seek(0)
print(await afp.read())
await afp.write("Hello from\nasync world")
print(await afp.readline())
print(await afp.readline())
loop = asyncio.get_event_loop()
loop.run_until_complete(main())
Example witout context manager:
.. code-block:: python
:name: test_no_context_manager
import asyncio
import atexit
import os
from tempfile import mktemp
from aiofile import async_open
TMP_NAME = mktemp()
atexit.register(os.unlink, TMP_NAME)
async def main():
afp = await async_open(TMP_NAME, "w")
await afp.write("Hello")
await afp.close()
asyncio.run(main())
assert open(TMP_NAME, "r").read() == "Hello"
Concatenate example program (``cat``):
.. code-block:: python
import asyncio
import sys
from argparse import ArgumentParser
from pathlib import Path
from aiofile import async_open
parser = ArgumentParser(
description="Read files line by line using asynchronous io API"
)
parser.add_argument("file_name", nargs="+", type=Path)
async def main(arguments):
for src in arguments.file_name:
async with async_open(src, "r") as afp:
async for line in afp:
sys.stdout.write(line)
asyncio.run(main(parser.parse_args()))
Copy file example program (``cp``):
.. code-block:: python
import asyncio
from argparse import ArgumentParser
from pathlib import Path
from aiofile import async_open
parser = ArgumentParser(
description="Copying files using asynchronous io API"
)
parser.add_argument("source", type=Path)
parser.add_argument("dest", type=Path)
parser.add_argument("--chunk-size", type=int, default=65535)
async def main(arguments):
async with async_open(arguments.source, "rb") as src, \
async_open(arguments.dest, "wb") as dest:
async for chunk in src.iter_chunked(arguments.chunk_size):
await dest.write(chunk)
asyncio.run(main(parser.parse_args()))
Example with opening already opened file pointer:
.. code-block:: python
:name: test_opened
import asyncio
from typing import IO, Any
from aiofile import async_open
async def main(fp: IO[Any]):
async with async_open(fp) as afp:
await afp.write("Hello from\nasync world")
print(await afp.readline())
with open("test.txt", "w+") as fp:
asyncio.run(main(fp))
Linux native aio doesn't support reading and writing special files
(e.g. procfs/sysfs/unix pipes/etc.) so you can perform operations with
this files using compatible context object.
.. code-block:: python
import asyncio
from aiofile import async_open
from caio import thread_aio_asyncio
from contextlib import AsyncExitStack
async def main():
async with AsyncExitStack() as stack:
# Custom context should be reused
ctx = await stack.enter_async_context(
thread_aio_asyncio.AsyncioContext()
)
# Open special file with custom context
src = await stack.enter_async_context(
async_open("/proc/cpuinfo", "r", context=ctx)
)
# Open regular file with default context
dest = await stack.enter_async_context(
async_open("/tmp/cpuinfo", "w")
)
# Copying file content line by line
async for line in src:
await dest.write(line)
asyncio.run(main())
``Reader`` and ``Writer``
~~~~~~~~~~~~~~~~~~~~~~~~~
When you want to read or write file linearly following example
might be helpful.
.. code-block:: python
import asyncio
from aiofile import AIOFile, Reader, Writer
async def main():
async with AIOFile("/tmp/hello.txt", 'w+') as afp:
writer = Writer(afp)
reader = Reader(afp, chunk_size=8)
await writer("Hello")
await writer(" ")
await writer("World")
await afp.fsync()
async for chunk in reader:
print(chunk)
loop = asyncio.get_event_loop()
loop.run_until_complete(main())
``LineReader`` - read file line by line
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LineReader is a helper that is very effective when you want to read a file
linearly and line by line.
It contains a buffer and will read the fragments of the file chunk by
chunk into the buffer, where it will try to find lines.
The default chunk size is 4KB.
.. code-block:: python
import asyncio
from aiofile import AIOFile, LineReader, Writer
async def main():
async with AIOFile("/tmp/hello.txt", 'w+') as afp:
writer = Writer(afp)
await writer("Hello")
await writer(" ")
await writer("World")
await writer("\n")
await writer("\n")
await writer("From async world")
await afp.fsync()
async for line in LineReader(afp):
print(line)
loop = asyncio.get_event_loop()
loop.run_until_complete(main())
When you want to read file by lines please avoid to use ``async_open``
use ``LineReader`` instead.
Low-level API
+++++++++++++
Following API is just little bit sugared ``caio`` API.
Write and Read
~~~~~~~~~~~~~~
.. code-block:: python
import asyncio
from aiofile import AIOFile
async def main():
async with AIOFile("/tmp/hello.txt", 'w+') as afp:
await afp.write("Hello ")
await afp.write("world", offset=7)
await afp.fsync()
print(await afp.read())
loop = asyncio.get_event_loop()
loop.run_until_complete(main())
Read file line by line
~~~~~~~~~~~~~~~~~~~~~~
.. code-block:: python
import asyncio
from aiofile import AIOFile, LineReader, Writer
async def main():
async with AIOFile("/tmp/hello.txt", 'w') as afp:
writer = Writer(afp)
for i in range(10):
await writer("%d Hello World\n" % i)
await writer("Tail-less string")
async with AIOFile("/tmp/hello.txt", 'r') as afp:
async for line in LineReader(afp):
print(line[:-1])
loop = asyncio.get_event_loop()
loop.run_until_complete(main())
More examples
-------------
Useful examples with ``aiofile``
Async CSV Dict Reader
+++++++++++++++++++++
.. code-block:: python
import asyncio
import io
from csv import DictReader
from aiofile import AIOFile, LineReader
class AsyncDictReader:
def __init__(self, afp, **kwargs):
self.buffer = io.BytesIO()
self.file_reader = LineReader(
afp, line_sep=kwargs.pop('line_sep', '\n'),
chunk_size=kwargs.pop('chunk_size', 4096),
offset=kwargs.pop('offset', 0),
)
self.reader = DictReader(
io.TextIOWrapper(
self.buffer,
encoding=kwargs.pop('encoding', 'utf-8'),
errors=kwargs.pop('errors', 'replace'),
), **kwargs,
)
self.line_num = 0
def __aiter__(self):
return self
async def __anext__(self):
if self.line_num == 0:
header = await self.file_reader.readline()
self.buffer.write(header)
line = await self.file_reader.readline()
if not line:
raise StopAsyncIteration
self.buffer.write(line)
self.buffer.seek(0)
try:
result = next(self.reader)
except StopIteration as e:
raise StopAsyncIteration from e
self.buffer.seek(0)
self.buffer.truncate(0)
self.line_num = self.reader.line_num
return result
async def main():
async with AIOFile('sample.csv', 'rb') as afp:
async for item in AsyncDictReader(afp):
print(item)
loop = asyncio.new_event_loop()
asyncio.set_event_loop(loop)
try:
loop.run_until_complete(main())
finally:
# Shutting down and closing file descriptors after interrupt
loop.run_until_complete(loop.shutdown_asyncgens())
loop.close()
.. _troubleshooting:
Troubleshooting
---------------
The caio ``linux`` implementation works normal for modern linux kernel versions
and file systems. So you may have problems specific for your environment.
It's not a bug and might be resolved some ways:
1. Upgrade the kernel
2. Use compatible file system
3. Use threads based or pure python implementation.
The caio since version 0.7.0 contains some ways to do this.
1. In runtime use the environment variable ``CAIO_IMPL`` with
possible values:
* ``linux`` - use native linux kernels aio mechanism
* ``thread`` - use thread based implementation written in C
* ``python`` - use pure python implementation
2. File ``default_implementation`` located near ``__init__.py`` in caio
installation path. It's useful for distros package maintainers. This file
might contains comments (lines starts with ``#`` symbol) and the first line
should be one of ``linux`` ``thread`` or ``python``.
3. You might manually manage contexts:
.. code-block:: python
import asyncio
from aiofile import async_open
from caio import linux_aio, thread_aio
async def main():
linux_ctx = linux_aio.Context()
threads_ctx = thread_aio.Context()
async with async_open("/tmp/test.txt", "a", context=linux_ctx) as afp:
await afp.write("Hello")
async with async_open("/tmp/test.txt", "a", context=threads_ctx) as afp:
print(await afp.read())
asyncio.run(main())
زبان مورد نیاز
| مقدار | نام |
|---|---|
| >=3.7, <4 | Python |
نحوه نصب
نصب پکیج whl aiofile-3.8.1:
pip install aiofile-3.8.1.whl
نصب پکیج tar.gz aiofile-3.8.1:
pip install aiofile-3.8.1.tar.gz