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| Current File : //opt/rh/rh-python35/root/usr/lib64/python3.5/asyncio/streams.py |
"""Stream-related things."""
__all__ = ['StreamReader', 'StreamWriter', 'StreamReaderProtocol',
'open_connection', 'start_server',
'IncompleteReadError',
]
import socket
if hasattr(socket, 'AF_UNIX'):
__all__.extend(['open_unix_connection', 'start_unix_server'])
from . import coroutines
from . import compat
from . import events
from . import futures
from . import protocols
from .coroutines import coroutine
from .log import logger
_DEFAULT_LIMIT = 2**16
class IncompleteReadError(EOFError):
"""
Incomplete read error. Attributes:
- partial: read bytes string before the end of stream was reached
- expected: total number of expected bytes
"""
def __init__(self, partial, expected):
EOFError.__init__(self, "%s bytes read on a total of %s expected bytes"
% (len(partial), expected))
self.partial = partial
self.expected = expected
@coroutine
def open_connection(host=None, port=None, *,
loop=None, limit=_DEFAULT_LIMIT, **kwds):
"""A wrapper for create_connection() returning a (reader, writer) pair.
The reader returned is a StreamReader instance; the writer is a
StreamWriter instance.
The arguments are all the usual arguments to create_connection()
except protocol_factory; most common are positional host and port,
with various optional keyword arguments following.
Additional optional keyword arguments are loop (to set the event loop
instance to use) and limit (to set the buffer limit passed to the
StreamReader).
(If you want to customize the StreamReader and/or
StreamReaderProtocol classes, just copy the code -- there's
really nothing special here except some convenience.)
"""
if loop is None:
loop = events.get_event_loop()
reader = StreamReader(limit=limit, loop=loop)
protocol = StreamReaderProtocol(reader, loop=loop)
transport, _ = yield from loop.create_connection(
lambda: protocol, host, port, **kwds)
writer = StreamWriter(transport, protocol, reader, loop)
return reader, writer
@coroutine
def start_server(client_connected_cb, host=None, port=None, *,
loop=None, limit=_DEFAULT_LIMIT, **kwds):
"""Start a socket server, call back for each client connected.
The first parameter, `client_connected_cb`, takes two parameters:
client_reader, client_writer. client_reader is a StreamReader
object, while client_writer is a StreamWriter object. This
parameter can either be a plain callback function or a coroutine;
if it is a coroutine, it will be automatically converted into a
Task.
The rest of the arguments are all the usual arguments to
loop.create_server() except protocol_factory; most common are
positional host and port, with various optional keyword arguments
following. The return value is the same as loop.create_server().
Additional optional keyword arguments are loop (to set the event loop
instance to use) and limit (to set the buffer limit passed to the
StreamReader).
The return value is the same as loop.create_server(), i.e. a
Server object which can be used to stop the service.
"""
if loop is None:
loop = events.get_event_loop()
def factory():
reader = StreamReader(limit=limit, loop=loop)
protocol = StreamReaderProtocol(reader, client_connected_cb,
loop=loop)
return protocol
return (yield from loop.create_server(factory, host, port, **kwds))
if hasattr(socket, 'AF_UNIX'):
# UNIX Domain Sockets are supported on this platform
@coroutine
def open_unix_connection(path=None, *,
loop=None, limit=_DEFAULT_LIMIT, **kwds):
"""Similar to `open_connection` but works with UNIX Domain Sockets."""
if loop is None:
loop = events.get_event_loop()
reader = StreamReader(limit=limit, loop=loop)
protocol = StreamReaderProtocol(reader, loop=loop)
transport, _ = yield from loop.create_unix_connection(
lambda: protocol, path, **kwds)
writer = StreamWriter(transport, protocol, reader, loop)
return reader, writer
@coroutine
def start_unix_server(client_connected_cb, path=None, *,
loop=None, limit=_DEFAULT_LIMIT, **kwds):
"""Similar to `start_server` but works with UNIX Domain Sockets."""
if loop is None:
loop = events.get_event_loop()
def factory():
reader = StreamReader(limit=limit, loop=loop)
protocol = StreamReaderProtocol(reader, client_connected_cb,
loop=loop)
return protocol
return (yield from loop.create_unix_server(factory, path, **kwds))
class FlowControlMixin(protocols.Protocol):
"""Reusable flow control logic for StreamWriter.drain().
This implements the protocol methods pause_writing(),
resume_reading() and connection_lost(). If the subclass overrides
these it must call the super methods.
StreamWriter.drain() must wait for _drain_helper() coroutine.
"""
def __init__(self, loop=None):
if loop is None:
self._loop = events.get_event_loop()
else:
self._loop = loop
self._paused = False
self._drain_waiter = None
self._connection_lost = False
def pause_writing(self):
assert not self._paused
self._paused = True
if self._loop.get_debug():
logger.debug("%r pauses writing", self)
def resume_writing(self):
assert self._paused
self._paused = False
if self._loop.get_debug():
logger.debug("%r resumes writing", self)
waiter = self._drain_waiter
if waiter is not None:
self._drain_waiter = None
if not waiter.done():
waiter.set_result(None)
def connection_lost(self, exc):
self._connection_lost = True
# Wake up the writer if currently paused.
if not self._paused:
return
waiter = self._drain_waiter
if waiter is None:
return
self._drain_waiter = None
if waiter.done():
return
if exc is None:
waiter.set_result(None)
else:
waiter.set_exception(exc)
@coroutine
def _drain_helper(self):
if self._connection_lost:
raise ConnectionResetError('Connection lost')
if not self._paused:
return
waiter = self._drain_waiter
assert waiter is None or waiter.cancelled()
waiter = futures.Future(loop=self._loop)
self._drain_waiter = waiter
yield from waiter
class StreamReaderProtocol(FlowControlMixin, protocols.Protocol):
"""Helper class to adapt between Protocol and StreamReader.
(This is a helper class instead of making StreamReader itself a
Protocol subclass, because the StreamReader has other potential
uses, and to prevent the user of the StreamReader to accidentally
call inappropriate methods of the protocol.)
"""
def __init__(self, stream_reader, client_connected_cb=None, loop=None):
super().__init__(loop=loop)
self._stream_reader = stream_reader
self._stream_writer = None
self._client_connected_cb = client_connected_cb
def connection_made(self, transport):
self._stream_reader.set_transport(transport)
if self._client_connected_cb is not None:
self._stream_writer = StreamWriter(transport, self,
self._stream_reader,
self._loop)
res = self._client_connected_cb(self._stream_reader,
self._stream_writer)
if coroutines.iscoroutine(res):
self._loop.create_task(res)
def connection_lost(self, exc):
if exc is None:
self._stream_reader.feed_eof()
else:
self._stream_reader.set_exception(exc)
super().connection_lost(exc)
def data_received(self, data):
self._stream_reader.feed_data(data)
def eof_received(self):
self._stream_reader.feed_eof()
return True
class StreamWriter:
"""Wraps a Transport.
This exposes write(), writelines(), [can_]write_eof(),
get_extra_info() and close(). It adds drain() which returns an
optional Future on which you can wait for flow control. It also
adds a transport property which references the Transport
directly.
"""
def __init__(self, transport, protocol, reader, loop):
self._transport = transport
self._protocol = protocol
# drain() expects that the reader has an exception() method
assert reader is None or isinstance(reader, StreamReader)
self._reader = reader
self._loop = loop
def __repr__(self):
info = [self.__class__.__name__, 'transport=%r' % self._transport]
if self._reader is not None:
info.append('reader=%r' % self._reader)
return '<%s>' % ' '.join(info)
@property
def transport(self):
return self._transport
def write(self, data):
self._transport.write(data)
def writelines(self, data):
self._transport.writelines(data)
def write_eof(self):
return self._transport.write_eof()
def can_write_eof(self):
return self._transport.can_write_eof()
def close(self):
return self._transport.close()
def get_extra_info(self, name, default=None):
return self._transport.get_extra_info(name, default)
@coroutine
def drain(self):
"""Flush the write buffer.
The intended use is to write
w.write(data)
yield from w.drain()
"""
if self._reader is not None:
exc = self._reader.exception()
if exc is not None:
raise exc
if self._transport is not None:
if self._transport.is_closing():
# Yield to the event loop so connection_lost() may be
# called. Without this, _drain_helper() would return
# immediately, and code that calls
# write(...); yield from drain()
# in a loop would never call connection_lost(), so it
# would not see an error when the socket is closed.
yield
yield from self._protocol._drain_helper()
class StreamReader:
def __init__(self, limit=_DEFAULT_LIMIT, loop=None):
# The line length limit is a security feature;
# it also doubles as half the buffer limit.
self._limit = limit
if loop is None:
self._loop = events.get_event_loop()
else:
self._loop = loop
self._buffer = bytearray()
self._eof = False # Whether we're done.
self._waiter = None # A future used by _wait_for_data()
self._exception = None
self._transport = None
self._paused = False
def __repr__(self):
info = ['StreamReader']
if self._buffer:
info.append('%d bytes' % len(self._buffer))
if self._eof:
info.append('eof')
if self._limit != _DEFAULT_LIMIT:
info.append('l=%d' % self._limit)
if self._waiter:
info.append('w=%r' % self._waiter)
if self._exception:
info.append('e=%r' % self._exception)
if self._transport:
info.append('t=%r' % self._transport)
if self._paused:
info.append('paused')
return '<%s>' % ' '.join(info)
def exception(self):
return self._exception
def set_exception(self, exc):
self._exception = exc
waiter = self._waiter
if waiter is not None:
self._waiter = None
if not waiter.cancelled():
waiter.set_exception(exc)
def _wakeup_waiter(self):
"""Wakeup read() or readline() function waiting for data or EOF."""
waiter = self._waiter
if waiter is not None:
self._waiter = None
if not waiter.cancelled():
waiter.set_result(None)
def set_transport(self, transport):
assert self._transport is None, 'Transport already set'
self._transport = transport
def _maybe_resume_transport(self):
if self._paused and len(self._buffer) <= self._limit:
self._paused = False
self._transport.resume_reading()
def feed_eof(self):
self._eof = True
self._wakeup_waiter()
def at_eof(self):
"""Return True if the buffer is empty and 'feed_eof' was called."""
return self._eof and not self._buffer
def feed_data(self, data):
assert not self._eof, 'feed_data after feed_eof'
if not data:
return
self._buffer.extend(data)
self._wakeup_waiter()
if (self._transport is not None and
not self._paused and
len(self._buffer) > 2*self._limit):
try:
self._transport.pause_reading()
except NotImplementedError:
# The transport can't be paused.
# We'll just have to buffer all data.
# Forget the transport so we don't keep trying.
self._transport = None
else:
self._paused = True
@coroutine
def _wait_for_data(self, func_name):
"""Wait until feed_data() or feed_eof() is called."""
# StreamReader uses a future to link the protocol feed_data() method
# to a read coroutine. Running two read coroutines at the same time
# would have an unexpected behaviour. It would not possible to know
# which coroutine would get the next data.
if self._waiter is not None:
raise RuntimeError('%s() called while another coroutine is '
'already waiting for incoming data' % func_name)
self._waiter = futures.Future(loop=self._loop)
try:
yield from self._waiter
finally:
self._waiter = None
@coroutine
def readline(self):
if self._exception is not None:
raise self._exception
line = bytearray()
not_enough = True
while not_enough:
while self._buffer and not_enough:
ichar = self._buffer.find(b'\n')
if ichar < 0:
line.extend(self._buffer)
self._buffer.clear()
else:
ichar += 1
line.extend(self._buffer[:ichar])
del self._buffer[:ichar]
not_enough = False
if len(line) > self._limit:
self._maybe_resume_transport()
raise ValueError('Line is too long')
if self._eof:
break
if not_enough:
yield from self._wait_for_data('readline')
self._maybe_resume_transport()
return bytes(line)
@coroutine
def read(self, n=-1):
if self._exception is not None:
raise self._exception
if not n:
return b''
if n < 0:
# This used to just loop creating a new waiter hoping to
# collect everything in self._buffer, but that would
# deadlock if the subprocess sends more than self.limit
# bytes. So just call self.read(self._limit) until EOF.
blocks = []
while True:
block = yield from self.read(self._limit)
if not block:
break
blocks.append(block)
return b''.join(blocks)
else:
if not self._buffer and not self._eof:
yield from self._wait_for_data('read')
if n < 0 or len(self._buffer) <= n:
data = bytes(self._buffer)
self._buffer.clear()
else:
# n > 0 and len(self._buffer) > n
data = bytes(self._buffer[:n])
del self._buffer[:n]
self._maybe_resume_transport()
return data
@coroutine
def readexactly(self, n):
if self._exception is not None:
raise self._exception
# There used to be "optimized" code here. It created its own
# Future and waited until self._buffer had at least the n
# bytes, then called read(n). Unfortunately, this could pause
# the transport if the argument was larger than the pause
# limit (which is twice self._limit). So now we just read()
# into a local buffer.
blocks = []
while n > 0:
block = yield from self.read(n)
if not block:
partial = b''.join(blocks)
raise IncompleteReadError(partial, len(partial) + n)
blocks.append(block)
n -= len(block)
return b''.join(blocks)
if compat.PY35:
@coroutine
def __aiter__(self):
return self
@coroutine
def __anext__(self):
val = yield from self.readline()
if val == b'':
raise StopAsyncIteration
return val