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"""Event loop implementation that uses the `asyncio` standard module. |
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The `asyncio` module was added to python standard library on 3.4, and it |
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provides a pure python implementation of an event loop library. It is used |
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as a fallback in case pyuv is not available(on python implementations other |
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than CPython). |
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Earlier python versions are supported through the `trollius` package, which |
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is a backport of `asyncio` that works on Python 2.6+. |
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""" |
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from __future__ import absolute_import |
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import os |
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import sys |
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from collections import deque |
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try: |
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# For python 3.4+, use the standard library module |
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import asyncio |
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except (ImportError, SyntaxError): |
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# Fallback to trollius |
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import trollius as asyncio |
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from .base import BaseEventLoop |
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loop_cls = asyncio.SelectorEventLoop |
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if os.name == 'nt': |
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# On windows use ProactorEventLoop which support pipes and is backed by the |
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# more powerful IOCP facility |
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loop_cls = asyncio.ProactorEventLoop |
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class AsyncioEventLoop(BaseEventLoop, asyncio.Protocol, |
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asyncio.SubprocessProtocol): |
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"""`BaseEventLoop` subclass that uses `asyncio` as a backend.""" |
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def connection_made(self, transport): |
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"""Used to signal `asyncio.Protocol` of a successful connection.""" |
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self._transport = transport |
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self._raw_transport = transport |
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if isinstance(transport, asyncio.SubprocessTransport): |
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self._transport = transport.get_pipe_transport(0) |
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def connection_lost(self, exc): |
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"""Used to signal `asyncio.Protocol` of a lost connection.""" |
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self._on_error(exc.args[0] if exc else 'EOF') |
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def data_received(self, data): |
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"""Used to signal `asyncio.Protocol` of incoming data.""" |
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if self._on_data: |
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self._on_data(data) |
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return |
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self._queued_data.append(data) |
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def pipe_connection_lost(self, fd, exc): |
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"""Used to signal `asyncio.SubprocessProtocol` of a lost connection.""" |
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self._on_error(exc.args[0] if exc else 'EOF') |
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def pipe_data_received(self, fd, data): |
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"""Used to signal `asyncio.SubprocessProtocol` of incoming data.""" |
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if fd == 2: # stderr fd number |
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self._on_stderr(data) |
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elif self._on_data: |
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self._on_data(data) |
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else: |
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self._queued_data.append(data) |
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def process_exited(self): |
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"""Used to signal `asyncio.SubprocessProtocol` when the child exits.""" |
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self._on_error('EOF') |
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def _init(self): |
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self._loop = loop_cls() |
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self._queued_data = deque() |
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self._fact = lambda: self |
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self._raw_transport = None |
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def _connect_tcp(self, address, port): |
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coroutine = self._loop.create_connection(self._fact, address, port) |
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self._loop.run_until_complete(coroutine) |
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def _connect_socket(self, path): |
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if os.name == 'nt': |
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coroutine = self._loop.create_pipe_connection(self._fact, path) |
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else: |
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coroutine = self._loop.create_unix_connection(self._fact, path) |
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self._loop.run_until_complete(coroutine) |
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def _connect_stdio(self): |
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coroutine = self._loop.connect_read_pipe(self._fact, sys.stdin) |
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self._loop.run_until_complete(coroutine) |
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coroutine = self._loop.connect_write_pipe(self._fact, sys.stdout) |
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self._loop.run_until_complete(coroutine) |
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def _connect_child(self, argv): |
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self._child_watcher = asyncio.get_child_watcher() |
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self._child_watcher.attach_loop(self._loop) |
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coroutine = self._loop.subprocess_exec(self._fact, *argv) |
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self._loop.run_until_complete(coroutine) |
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def _start_reading(self): |
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pass |
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def _send(self, data): |
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self._transport.write(data) |
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def _run(self): |
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while self._queued_data: |
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self._on_data(self._queued_data.popleft()) |
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self._loop.run_forever() |
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def _stop(self): |
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self._loop.stop() |
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def _close(self): |
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if self._raw_transport is not None: |
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self._raw_transport.close() |
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self._loop.close() |
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def _threadsafe_call(self, fn): |
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self._loop.call_soon_threadsafe(fn) |
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def _setup_signals(self, signals): |
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if os.name == 'nt': |
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# add_signal_handler is not supported in win32 |
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self._signals = [] |
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return |
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self._signals = list(signals) |
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for signum in self._signals: |
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self._loop.add_signal_handler(signum, self._on_signal, signum) |
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def _teardown_signals(self): |
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for signum in self._signals: |
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self._loop.remove_signal_handler(signum) |
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This can be caused by one of the following:
1. Missing Dependencies
This error could indicate a configuration issue of Pylint. Make sure that your libraries are available by adding the necessary commands.
2. Missing __init__.py files
This error could also result from missing
__init__.py
files in your module folders. Make sure that you place one file in each sub-folder.