mirror of
https://github.com/python/cpython.git
synced 2025-07-09 20:35:26 +00:00
7462b64911
This changes the main documentation, doc strings, source code comments, and a couple error messages in the test suite. In some cases the word was removed or edited some other way to fix the grammar.
528 lines
17 KiB
Python
528 lines
17 KiB
Python
"""Stream-related things."""
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__all__ = ['StreamReader', 'StreamWriter', 'StreamReaderProtocol',
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'open_connection', 'start_server',
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'IncompleteReadError',
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]
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import socket
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if hasattr(socket, 'AF_UNIX'):
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__all__.extend(['open_unix_connection', 'start_unix_server'])
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from . import coroutines
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from . import compat
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from . import events
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from . import futures
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from . import protocols
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from .coroutines import coroutine
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from .log import logger
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_DEFAULT_LIMIT = 2**16
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class IncompleteReadError(EOFError):
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"""
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Incomplete read error. Attributes:
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- partial: read bytes string before the end of stream was reached
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- expected: total number of expected bytes
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"""
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def __init__(self, partial, expected):
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EOFError.__init__(self, "%s bytes read on a total of %s expected bytes"
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% (len(partial), expected))
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self.partial = partial
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self.expected = expected
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@coroutine
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def open_connection(host=None, port=None, *,
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loop=None, limit=_DEFAULT_LIMIT, **kwds):
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"""A wrapper for create_connection() returning a (reader, writer) pair.
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The reader returned is a StreamReader instance; the writer is a
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StreamWriter instance.
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The arguments are all the usual arguments to create_connection()
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except protocol_factory; most common are positional host and port,
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with various optional keyword arguments following.
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Additional optional keyword arguments are loop (to set the event loop
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instance to use) and limit (to set the buffer limit passed to the
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StreamReader).
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(If you want to customize the StreamReader and/or
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StreamReaderProtocol classes, just copy the code -- there's
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really nothing special here except some convenience.)
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"""
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if loop is None:
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loop = events.get_event_loop()
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reader = StreamReader(limit=limit, loop=loop)
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protocol = StreamReaderProtocol(reader, loop=loop)
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transport, _ = yield from loop.create_connection(
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lambda: protocol, host, port, **kwds)
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writer = StreamWriter(transport, protocol, reader, loop)
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return reader, writer
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@coroutine
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def start_server(client_connected_cb, host=None, port=None, *,
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loop=None, limit=_DEFAULT_LIMIT, **kwds):
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"""Start a socket server, call back for each client connected.
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The first parameter, `client_connected_cb`, takes two parameters:
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client_reader, client_writer. client_reader is a StreamReader
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object, while client_writer is a StreamWriter object. This
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parameter can either be a plain callback function or a coroutine;
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if it is a coroutine, it will be automatically converted into a
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Task.
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The rest of the arguments are all the usual arguments to
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loop.create_server() except protocol_factory; most common are
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positional host and port, with various optional keyword arguments
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following. The return value is the same as loop.create_server().
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Additional optional keyword arguments are loop (to set the event loop
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instance to use) and limit (to set the buffer limit passed to the
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StreamReader).
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The return value is the same as loop.create_server(), i.e. a
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Server object which can be used to stop the service.
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"""
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if loop is None:
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loop = events.get_event_loop()
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def factory():
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reader = StreamReader(limit=limit, loop=loop)
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protocol = StreamReaderProtocol(reader, client_connected_cb,
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loop=loop)
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return protocol
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return (yield from loop.create_server(factory, host, port, **kwds))
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if hasattr(socket, 'AF_UNIX'):
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# UNIX Domain Sockets are supported on this platform
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@coroutine
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def open_unix_connection(path=None, *,
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loop=None, limit=_DEFAULT_LIMIT, **kwds):
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"""Similar to `open_connection` but works with UNIX Domain Sockets."""
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if loop is None:
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loop = events.get_event_loop()
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reader = StreamReader(limit=limit, loop=loop)
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protocol = StreamReaderProtocol(reader, loop=loop)
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transport, _ = yield from loop.create_unix_connection(
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lambda: protocol, path, **kwds)
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writer = StreamWriter(transport, protocol, reader, loop)
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return reader, writer
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@coroutine
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def start_unix_server(client_connected_cb, path=None, *,
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loop=None, limit=_DEFAULT_LIMIT, **kwds):
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"""Similar to `start_server` but works with UNIX Domain Sockets."""
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if loop is None:
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loop = events.get_event_loop()
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def factory():
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reader = StreamReader(limit=limit, loop=loop)
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protocol = StreamReaderProtocol(reader, client_connected_cb,
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loop=loop)
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return protocol
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return (yield from loop.create_unix_server(factory, path, **kwds))
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class FlowControlMixin(protocols.Protocol):
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"""Reusable flow control logic for StreamWriter.drain().
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This implements the protocol methods pause_writing(),
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resume_reading() and connection_lost(). If the subclass overrides
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these it must call the super methods.
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StreamWriter.drain() must wait for _drain_helper() coroutine.
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"""
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def __init__(self, loop=None):
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if loop is None:
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self._loop = events.get_event_loop()
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else:
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self._loop = loop
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self._paused = False
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self._drain_waiter = None
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self._connection_lost = False
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def pause_writing(self):
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assert not self._paused
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self._paused = True
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if self._loop.get_debug():
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logger.debug("%r pauses writing", self)
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def resume_writing(self):
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assert self._paused
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self._paused = False
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if self._loop.get_debug():
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logger.debug("%r resumes writing", self)
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waiter = self._drain_waiter
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if waiter is not None:
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self._drain_waiter = None
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if not waiter.done():
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waiter.set_result(None)
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def connection_lost(self, exc):
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self._connection_lost = True
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# Wake up the writer if currently paused.
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if not self._paused:
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return
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waiter = self._drain_waiter
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if waiter is None:
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return
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self._drain_waiter = None
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if waiter.done():
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return
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if exc is None:
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waiter.set_result(None)
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else:
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waiter.set_exception(exc)
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@coroutine
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def _drain_helper(self):
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if self._connection_lost:
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raise ConnectionResetError('Connection lost')
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if not self._paused:
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return
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waiter = self._drain_waiter
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assert waiter is None or waiter.cancelled()
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waiter = futures.Future(loop=self._loop)
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self._drain_waiter = waiter
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yield from waiter
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class StreamReaderProtocol(FlowControlMixin, protocols.Protocol):
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"""Helper class to adapt between Protocol and StreamReader.
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(This is a helper class instead of making StreamReader itself a
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Protocol subclass, because the StreamReader has other potential
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uses, and to prevent the user of the StreamReader to accidentally
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call inappropriate methods of the protocol.)
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"""
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def __init__(self, stream_reader, client_connected_cb=None, loop=None):
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super().__init__(loop=loop)
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self._stream_reader = stream_reader
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self._stream_writer = None
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self._client_connected_cb = client_connected_cb
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def connection_made(self, transport):
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self._stream_reader.set_transport(transport)
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if self._client_connected_cb is not None:
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self._stream_writer = StreamWriter(transport, self,
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self._stream_reader,
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self._loop)
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res = self._client_connected_cb(self._stream_reader,
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self._stream_writer)
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if coroutines.iscoroutine(res):
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self._loop.create_task(res)
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def connection_lost(self, exc):
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if exc is None:
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self._stream_reader.feed_eof()
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else:
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self._stream_reader.set_exception(exc)
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super().connection_lost(exc)
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def data_received(self, data):
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self._stream_reader.feed_data(data)
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def eof_received(self):
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self._stream_reader.feed_eof()
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return True
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class StreamWriter:
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"""Wraps a Transport.
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This exposes write(), writelines(), [can_]write_eof(),
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get_extra_info() and close(). It adds drain() which returns an
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optional Future on which you can wait for flow control. It also
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adds a transport property which references the Transport
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directly.
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"""
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def __init__(self, transport, protocol, reader, loop):
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self._transport = transport
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self._protocol = protocol
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# drain() expects that the reader has an exception() method
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assert reader is None or isinstance(reader, StreamReader)
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self._reader = reader
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self._loop = loop
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def __repr__(self):
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info = [self.__class__.__name__, 'transport=%r' % self._transport]
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if self._reader is not None:
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info.append('reader=%r' % self._reader)
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return '<%s>' % ' '.join(info)
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@property
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def transport(self):
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return self._transport
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def write(self, data):
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self._transport.write(data)
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def writelines(self, data):
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self._transport.writelines(data)
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def write_eof(self):
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return self._transport.write_eof()
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def can_write_eof(self):
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return self._transport.can_write_eof()
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def close(self):
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return self._transport.close()
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def get_extra_info(self, name, default=None):
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return self._transport.get_extra_info(name, default)
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@coroutine
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def drain(self):
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"""Flush the write buffer.
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The intended use is to write
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w.write(data)
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yield from w.drain()
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"""
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if self._reader is not None:
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exc = self._reader.exception()
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if exc is not None:
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raise exc
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if self._transport is not None:
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if self._transport._closing:
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# Yield to the event loop so connection_lost() may be
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# called. Without this, _drain_helper() would return
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# immediately, and code that calls
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# write(...); yield from drain()
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# in a loop would never call connection_lost(), so it
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# would not see an error when the socket is closed.
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yield
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yield from self._protocol._drain_helper()
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class StreamReader:
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def __init__(self, limit=_DEFAULT_LIMIT, loop=None):
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# The line length limit is a security feature;
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# it also doubles as half the buffer limit.
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self._limit = limit
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if loop is None:
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self._loop = events.get_event_loop()
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else:
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self._loop = loop
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self._buffer = bytearray()
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self._eof = False # Whether we're done.
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self._waiter = None # A future used by _wait_for_data()
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self._exception = None
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self._transport = None
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self._paused = False
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def __repr__(self):
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info = ['StreamReader']
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if self._buffer:
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info.append('%d bytes' % len(self._buffer))
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if self._eof:
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info.append('eof')
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if self._limit != _DEFAULT_LIMIT:
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info.append('l=%d' % self._limit)
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if self._waiter:
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info.append('w=%r' % self._waiter)
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if self._exception:
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info.append('e=%r' % self._exception)
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if self._transport:
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info.append('t=%r' % self._transport)
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if self._paused:
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info.append('paused')
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return '<%s>' % ' '.join(info)
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def exception(self):
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return self._exception
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def set_exception(self, exc):
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self._exception = exc
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waiter = self._waiter
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if waiter is not None:
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self._waiter = None
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if not waiter.cancelled():
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waiter.set_exception(exc)
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def _wakeup_waiter(self):
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"""Wakeup read() or readline() function waiting for data or EOF."""
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waiter = self._waiter
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if waiter is not None:
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self._waiter = None
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if not waiter.cancelled():
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waiter.set_result(None)
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def set_transport(self, transport):
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assert self._transport is None, 'Transport already set'
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self._transport = transport
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def _maybe_resume_transport(self):
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if self._paused and len(self._buffer) <= self._limit:
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self._paused = False
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self._transport.resume_reading()
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def feed_eof(self):
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self._eof = True
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self._wakeup_waiter()
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def at_eof(self):
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"""Return True if the buffer is empty and 'feed_eof' was called."""
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return self._eof and not self._buffer
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def feed_data(self, data):
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assert not self._eof, 'feed_data after feed_eof'
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if not data:
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return
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self._buffer.extend(data)
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self._wakeup_waiter()
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if (self._transport is not None and
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not self._paused and
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len(self._buffer) > 2*self._limit):
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try:
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self._transport.pause_reading()
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except NotImplementedError:
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# The transport can't be paused.
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# We'll just have to buffer all data.
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# Forget the transport so we don't keep trying.
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self._transport = None
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else:
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self._paused = True
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@coroutine
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def _wait_for_data(self, func_name):
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"""Wait until feed_data() or feed_eof() is called."""
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# StreamReader uses a future to link the protocol feed_data() method
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# to a read coroutine. Running two read coroutines at the same time
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# would have an unexpected behaviour. It would not possible to know
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# which coroutine would get the next data.
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if self._waiter is not None:
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raise RuntimeError('%s() called while another coroutine is '
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'already waiting for incoming data' % func_name)
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self._waiter = futures.Future(loop=self._loop)
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try:
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yield from self._waiter
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finally:
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self._waiter = None
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@coroutine
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def readline(self):
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if self._exception is not None:
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raise self._exception
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line = bytearray()
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not_enough = True
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while not_enough:
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while self._buffer and not_enough:
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ichar = self._buffer.find(b'\n')
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if ichar < 0:
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line.extend(self._buffer)
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self._buffer.clear()
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else:
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ichar += 1
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line.extend(self._buffer[:ichar])
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del self._buffer[:ichar]
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not_enough = False
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if len(line) > self._limit:
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self._maybe_resume_transport()
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raise ValueError('Line is too long')
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if self._eof:
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break
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if not_enough:
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yield from self._wait_for_data('readline')
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self._maybe_resume_transport()
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return bytes(line)
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@coroutine
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def read(self, n=-1):
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if self._exception is not None:
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raise self._exception
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if not n:
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return b''
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if n < 0:
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# This used to just loop creating a new waiter hoping to
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# collect everything in self._buffer, but that would
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# deadlock if the subprocess sends more than self.limit
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# bytes. So just call self.read(self._limit) until EOF.
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blocks = []
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while True:
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block = yield from self.read(self._limit)
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if not block:
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break
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blocks.append(block)
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return b''.join(blocks)
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else:
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if not self._buffer and not self._eof:
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yield from self._wait_for_data('read')
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if n < 0 or len(self._buffer) <= n:
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data = bytes(self._buffer)
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self._buffer.clear()
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else:
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# n > 0 and len(self._buffer) > n
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data = bytes(self._buffer[:n])
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del self._buffer[:n]
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self._maybe_resume_transport()
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return data
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@coroutine
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def readexactly(self, n):
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if self._exception is not None:
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raise self._exception
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# There used to be "optimized" code here. It created its own
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# Future and waited until self._buffer had at least the n
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# bytes, then called read(n). Unfortunately, this could pause
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# the transport if the argument was larger than the pause
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# limit (which is twice self._limit). So now we just read()
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# into a local buffer.
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blocks = []
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while n > 0:
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block = yield from self.read(n)
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if not block:
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partial = b''.join(blocks)
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raise IncompleteReadError(partial, len(partial) + n)
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blocks.append(block)
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n -= len(block)
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return b''.join(blocks)
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if compat.PY35:
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@coroutine
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def __aiter__(self):
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return self
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@coroutine
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def __anext__(self):
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val = yield from self.readline()
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if val == b'':
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raise StopAsyncIteration
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return val
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