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import operator
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from .. import _core
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from .._highlevel_generic import StapledStream
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from .. import _util
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from ..abc import SendStream, ReceiveStream
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################################################################
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# In-memory streams - Unbounded buffer version
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################################################################
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class _UnboundedByteQueue:
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def __init__(self):
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self._data = bytearray()
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self._closed = False
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self._lot = _core.ParkingLot()
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self._fetch_lock = _util.ConflictDetector(
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"another task is already fetching data"
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)
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# This object treats "close" as being like closing the send side of a
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# channel: so after close(), calling put() raises ClosedResourceError, and
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# calling the get() variants drains the buffer and then returns an empty
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# bytearray.
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def close(self):
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self._closed = True
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self._lot.unpark_all()
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def close_and_wipe(self):
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self._data = bytearray()
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self.close()
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def put(self, data):
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if self._closed:
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raise _core.ClosedResourceError("virtual connection closed")
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self._data += data
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self._lot.unpark_all()
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def _check_max_bytes(self, max_bytes):
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if max_bytes is None:
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return
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max_bytes = operator.index(max_bytes)
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if max_bytes < 1:
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raise ValueError("max_bytes must be >= 1")
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def _get_impl(self, max_bytes):
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assert self._closed or self._data
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if max_bytes is None:
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max_bytes = len(self._data)
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if self._data:
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chunk = self._data[:max_bytes]
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del self._data[:max_bytes]
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assert chunk
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return chunk
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else:
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return bytearray()
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def get_nowait(self, max_bytes=None):
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with self._fetch_lock:
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self._check_max_bytes(max_bytes)
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if not self._closed and not self._data:
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raise _core.WouldBlock
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return self._get_impl(max_bytes)
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async def get(self, max_bytes=None):
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with self._fetch_lock:
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self._check_max_bytes(max_bytes)
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if not self._closed and not self._data:
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await self._lot.park()
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else:
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await _core.checkpoint()
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return self._get_impl(max_bytes)
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class MemorySendStream(SendStream, metaclass=_util.Final):
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"""An in-memory :class:`~trio.abc.SendStream`.
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Args:
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send_all_hook: An async function, or None. Called from
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:meth:`send_all`. Can do whatever you like.
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wait_send_all_might_not_block_hook: An async function, or None. Called
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from :meth:`wait_send_all_might_not_block`. Can do whatever you
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like.
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close_hook: A synchronous function, or None. Called from :meth:`close`
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and :meth:`aclose`. Can do whatever you like.
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.. attribute:: send_all_hook
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wait_send_all_might_not_block_hook
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close_hook
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All of these hooks are also exposed as attributes on the object, and
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you can change them at any time.
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"""
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def __init__(
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self,
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send_all_hook=None,
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wait_send_all_might_not_block_hook=None,
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close_hook=None,
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):
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self._conflict_detector = _util.ConflictDetector(
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"another task is using this stream"
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)
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self._outgoing = _UnboundedByteQueue()
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self.send_all_hook = send_all_hook
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self.wait_send_all_might_not_block_hook = wait_send_all_might_not_block_hook
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self.close_hook = close_hook
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async def send_all(self, data):
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"""Places the given data into the object's internal buffer, and then
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calls the :attr:`send_all_hook` (if any).
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"""
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# Execute two checkpoints so we have more of a chance to detect
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# buggy user code that calls this twice at the same time.
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with self._conflict_detector:
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await _core.checkpoint()
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await _core.checkpoint()
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self._outgoing.put(data)
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if self.send_all_hook is not None:
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await self.send_all_hook()
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async def wait_send_all_might_not_block(self):
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"""Calls the :attr:`wait_send_all_might_not_block_hook` (if any), and
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then returns immediately.
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"""
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# Execute two checkpoints so we have more of a chance to detect
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# buggy user code that calls this twice at the same time.
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with self._conflict_detector:
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await _core.checkpoint()
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await _core.checkpoint()
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# check for being closed:
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self._outgoing.put(b"")
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if self.wait_send_all_might_not_block_hook is not None:
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await self.wait_send_all_might_not_block_hook()
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def close(self):
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"""Marks this stream as closed, and then calls the :attr:`close_hook`
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(if any).
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"""
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# XXX should this cancel any pending calls to the send_all_hook and
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# wait_send_all_might_not_block_hook? Those are the only places where
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# send_all and wait_send_all_might_not_block can be blocked.
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#
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# The way we set things up, send_all_hook is memory_stream_pump, and
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# wait_send_all_might_not_block_hook is unset. memory_stream_pump is
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# synchronous. So normally, send_all and wait_send_all_might_not_block
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# cannot block at all.
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self._outgoing.close()
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if self.close_hook is not None:
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self.close_hook()
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async def aclose(self):
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"""Same as :meth:`close`, but async."""
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self.close()
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await _core.checkpoint()
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async def get_data(self, max_bytes=None):
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"""Retrieves data from the internal buffer, blocking if necessary.
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Args:
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max_bytes (int or None): The maximum amount of data to
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retrieve. None (the default) means to retrieve all the data
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that's present (but still blocks until at least one byte is
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available).
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Returns:
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If this stream has been closed, an empty bytearray. Otherwise, the
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requested data.
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"""
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return await self._outgoing.get(max_bytes)
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def get_data_nowait(self, max_bytes=None):
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"""Retrieves data from the internal buffer, but doesn't block.
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See :meth:`get_data` for details.
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Raises:
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trio.WouldBlock: if no data is available to retrieve.
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"""
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return self._outgoing.get_nowait(max_bytes)
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class MemoryReceiveStream(ReceiveStream, metaclass=_util.Final):
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"""An in-memory :class:`~trio.abc.ReceiveStream`.
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Args:
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receive_some_hook: An async function, or None. Called from
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:meth:`receive_some`. Can do whatever you like.
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close_hook: A synchronous function, or None. Called from :meth:`close`
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and :meth:`aclose`. Can do whatever you like.
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.. attribute:: receive_some_hook
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close_hook
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Both hooks are also exposed as attributes on the object, and you can
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change them at any time.
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"""
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def __init__(self, receive_some_hook=None, close_hook=None):
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self._conflict_detector = _util.ConflictDetector(
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"another task is using this stream"
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)
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self._incoming = _UnboundedByteQueue()
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self._closed = False
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self.receive_some_hook = receive_some_hook
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self.close_hook = close_hook
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async def receive_some(self, max_bytes=None):
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"""Calls the :attr:`receive_some_hook` (if any), and then retrieves
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data from the internal buffer, blocking if necessary.
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"""
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# Execute two checkpoints so we have more of a chance to detect
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# buggy user code that calls this twice at the same time.
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with self._conflict_detector:
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await _core.checkpoint()
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await _core.checkpoint()
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if self._closed:
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raise _core.ClosedResourceError
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if self.receive_some_hook is not None:
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await self.receive_some_hook()
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# self._incoming's closure state tracks whether we got an EOF.
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# self._closed tracks whether we, ourselves, are closed.
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# self.close() sends an EOF to wake us up and sets self._closed,
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# so after we wake up we have to check self._closed again.
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data = await self._incoming.get(max_bytes)
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if self._closed:
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raise _core.ClosedResourceError
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return data
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def close(self):
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"""Discards any pending data from the internal buffer, and marks this
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stream as closed.
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"""
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self._closed = True
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self._incoming.close_and_wipe()
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if self.close_hook is not None:
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self.close_hook()
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async def aclose(self):
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"""Same as :meth:`close`, but async."""
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self.close()
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await _core.checkpoint()
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def put_data(self, data):
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"""Appends the given data to the internal buffer."""
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self._incoming.put(data)
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def put_eof(self):
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"""Adds an end-of-file marker to the internal buffer."""
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self._incoming.close()
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def memory_stream_pump(memory_send_stream, memory_receive_stream, *, max_bytes=None):
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"""Take data out of the given :class:`MemorySendStream`'s internal buffer,
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and put it into the given :class:`MemoryReceiveStream`'s internal buffer.
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Args:
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memory_send_stream (MemorySendStream): The stream to get data from.
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memory_receive_stream (MemoryReceiveStream): The stream to put data into.
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max_bytes (int or None): The maximum amount of data to transfer in this
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call, or None to transfer all available data.
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Returns:
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True if it successfully transferred some data, or False if there was no
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data to transfer.
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This is used to implement :func:`memory_stream_one_way_pair` and
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:func:`memory_stream_pair`; see the latter's docstring for an example
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of how you might use it yourself.
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"""
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try:
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data = memory_send_stream.get_data_nowait(max_bytes)
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except _core.WouldBlock:
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return False
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try:
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if not data:
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memory_receive_stream.put_eof()
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else:
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memory_receive_stream.put_data(data)
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except _core.ClosedResourceError:
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raise _core.BrokenResourceError("MemoryReceiveStream was closed")
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return True
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def memory_stream_one_way_pair():
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"""Create a connected, pure-Python, unidirectional stream with infinite
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buffering and flexible configuration options.
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You can think of this as being a no-operating-system-involved
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Trio-streamsified version of :func:`os.pipe` (except that :func:`os.pipe`
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returns the streams in the wrong order – we follow the superior convention
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that data flows from left to right).
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Returns:
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A tuple (:class:`MemorySendStream`, :class:`MemoryReceiveStream`), where
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the :class:`MemorySendStream` has its hooks set up so that it calls
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:func:`memory_stream_pump` from its
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:attr:`~MemorySendStream.send_all_hook` and
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:attr:`~MemorySendStream.close_hook`.
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The end result is that data automatically flows from the
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:class:`MemorySendStream` to the :class:`MemoryReceiveStream`. But you're
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also free to rearrange things however you like. For example, you can
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temporarily set the :attr:`~MemorySendStream.send_all_hook` to None if you
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want to simulate a stall in data transmission. Or see
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:func:`memory_stream_pair` for a more elaborate example.
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"""
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send_stream = MemorySendStream()
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recv_stream = MemoryReceiveStream()
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def pump_from_send_stream_to_recv_stream():
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memory_stream_pump(send_stream, recv_stream)
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async def async_pump_from_send_stream_to_recv_stream():
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pump_from_send_stream_to_recv_stream()
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send_stream.send_all_hook = async_pump_from_send_stream_to_recv_stream
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send_stream.close_hook = pump_from_send_stream_to_recv_stream
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return send_stream, recv_stream
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def _make_stapled_pair(one_way_pair):
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pipe1_send, pipe1_recv = one_way_pair()
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pipe2_send, pipe2_recv = one_way_pair()
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stream1 = StapledStream(pipe1_send, pipe2_recv)
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stream2 = StapledStream(pipe2_send, pipe1_recv)
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return stream1, stream2
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def memory_stream_pair():
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"""Create a connected, pure-Python, bidirectional stream with infinite
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buffering and flexible configuration options.
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This is a convenience function that creates two one-way streams using
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:func:`memory_stream_one_way_pair`, and then uses
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:class:`~trio.StapledStream` to combine them into a single bidirectional
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stream.
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This is like a no-operating-system-involved, Trio-streamsified version of
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:func:`socket.socketpair`.
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Returns:
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A pair of :class:`~trio.StapledStream` objects that are connected so
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that data automatically flows from one to the other in both directions.
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After creating a stream pair, you can send data back and forth, which is
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enough for simple tests::
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left, right = memory_stream_pair()
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await left.send_all(b"123")
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assert await right.receive_some() == b"123"
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await right.send_all(b"456")
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assert await left.receive_some() == b"456"
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But if you read the docs for :class:`~trio.StapledStream` and
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:func:`memory_stream_one_way_pair`, you'll see that all the pieces
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involved in wiring this up are public APIs, so you can adjust to suit the
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requirements of your tests. For example, here's how to tweak a stream so
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that data flowing from left to right trickles in one byte at a time (but
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data flowing from right to left proceeds at full speed)::
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left, right = memory_stream_pair()
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async def trickle():
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# left is a StapledStream, and left.send_stream is a MemorySendStream
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# right is a StapledStream, and right.recv_stream is a MemoryReceiveStream
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while memory_stream_pump(left.send_stream, right.recv_stream, max_bytes=1):
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# Pause between each byte
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await trio.sleep(1)
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# Normally this send_all_hook calls memory_stream_pump directly without
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# passing in a max_bytes. We replace it with our custom version:
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left.send_stream.send_all_hook = trickle
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And here's a simple test using our modified stream objects::
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async def sender():
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await left.send_all(b"12345")
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await left.send_eof()
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async def receiver():
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async for data in right:
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print(data)
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async with trio.open_nursery() as nursery:
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nursery.start_soon(sender)
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nursery.start_soon(receiver)
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By default, this will print ``b"12345"`` and then immediately exit; with
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our trickle stream it instead sleeps 1 second, then prints ``b"1"``, then
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sleeps 1 second, then prints ``b"2"``, etc.
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Pro-tip: you can insert sleep calls (like in our example above) to
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manipulate the flow of data across tasks... and then use
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:class:`MockClock` and its :attr:`~MockClock.autojump_threshold`
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functionality to keep your test suite running quickly.
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If you want to stress test a protocol implementation, one nice trick is to
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use the :mod:`random` module (preferably with a fixed seed) to move random
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numbers of bytes at a time, and insert random sleeps in between them. You
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can also set up a custom :attr:`~MemoryReceiveStream.receive_some_hook` if
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you want to manipulate things on the receiving side, and not just the
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sending side.
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"""
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return _make_stapled_pair(memory_stream_one_way_pair)
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################################################################
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# In-memory streams - Lockstep version
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################################################################
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class _LockstepByteQueue:
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def __init__(self):
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self._data = bytearray()
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self._sender_closed = False
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|
|
self._receiver_closed = False
|
|
|
self._receiver_waiting = False
|
|
|
self._waiters = _core.ParkingLot()
|
|
|
self._send_conflict_detector = _util.ConflictDetector(
|
|
|
"another task is already sending"
|
|
|
)
|
|
|
self._receive_conflict_detector = _util.ConflictDetector(
|
|
|
"another task is already receiving"
|
|
|
)
|
|
|
|
|
|
def _something_happened(self):
|
|
|
self._waiters.unpark_all()
|
|
|
|
|
|
# Always wakes up when one side is closed, because everyone always reacts
|
|
|
# to that.
|
|
|
async def _wait_for(self, fn):
|
|
|
while True:
|
|
|
if fn():
|
|
|
break
|
|
|
if self._sender_closed or self._receiver_closed:
|
|
|
break
|
|
|
await self._waiters.park()
|
|
|
await _core.checkpoint()
|
|
|
|
|
|
def close_sender(self):
|
|
|
self._sender_closed = True
|
|
|
self._something_happened()
|
|
|
|
|
|
def close_receiver(self):
|
|
|
self._receiver_closed = True
|
|
|
self._something_happened()
|
|
|
|
|
|
async def send_all(self, data):
|
|
|
with self._send_conflict_detector:
|
|
|
if self._sender_closed:
|
|
|
raise _core.ClosedResourceError
|
|
|
if self._receiver_closed:
|
|
|
raise _core.BrokenResourceError
|
|
|
assert not self._data
|
|
|
self._data += data
|
|
|
self._something_happened()
|
|
|
await self._wait_for(lambda: not self._data)
|
|
|
if self._sender_closed:
|
|
|
raise _core.ClosedResourceError
|
|
|
if self._data and self._receiver_closed:
|
|
|
raise _core.BrokenResourceError
|
|
|
|
|
|
async def wait_send_all_might_not_block(self):
|
|
|
with self._send_conflict_detector:
|
|
|
if self._sender_closed:
|
|
|
raise _core.ClosedResourceError
|
|
|
if self._receiver_closed:
|
|
|
await _core.checkpoint()
|
|
|
return
|
|
|
await self._wait_for(lambda: self._receiver_waiting)
|
|
|
if self._sender_closed:
|
|
|
raise _core.ClosedResourceError
|
|
|
|
|
|
async def receive_some(self, max_bytes=None):
|
|
|
with self._receive_conflict_detector:
|
|
|
# Argument validation
|
|
|
if max_bytes is not None:
|
|
|
max_bytes = operator.index(max_bytes)
|
|
|
if max_bytes < 1:
|
|
|
raise ValueError("max_bytes must be >= 1")
|
|
|
# State validation
|
|
|
if self._receiver_closed:
|
|
|
raise _core.ClosedResourceError
|
|
|
# Wake wait_send_all_might_not_block and wait for data
|
|
|
self._receiver_waiting = True
|
|
|
self._something_happened()
|
|
|
try:
|
|
|
await self._wait_for(lambda: self._data)
|
|
|
finally:
|
|
|
self._receiver_waiting = False
|
|
|
if self._receiver_closed:
|
|
|
raise _core.ClosedResourceError
|
|
|
# Get data, possibly waking send_all
|
|
|
if self._data:
|
|
|
# Neat trick: if max_bytes is None, then obj[:max_bytes] is
|
|
|
# the same as obj[:].
|
|
|
got = self._data[:max_bytes]
|
|
|
del self._data[:max_bytes]
|
|
|
self._something_happened()
|
|
|
return got
|
|
|
else:
|
|
|
assert self._sender_closed
|
|
|
return b""
|
|
|
|
|
|
|
|
|
class _LockstepSendStream(SendStream):
|
|
|
def __init__(self, lbq):
|
|
|
self._lbq = lbq
|
|
|
|
|
|
def close(self):
|
|
|
self._lbq.close_sender()
|
|
|
|
|
|
async def aclose(self):
|
|
|
self.close()
|
|
|
await _core.checkpoint()
|
|
|
|
|
|
async def send_all(self, data):
|
|
|
await self._lbq.send_all(data)
|
|
|
|
|
|
async def wait_send_all_might_not_block(self):
|
|
|
await self._lbq.wait_send_all_might_not_block()
|
|
|
|
|
|
|
|
|
class _LockstepReceiveStream(ReceiveStream):
|
|
|
def __init__(self, lbq):
|
|
|
self._lbq = lbq
|
|
|
|
|
|
def close(self):
|
|
|
self._lbq.close_receiver()
|
|
|
|
|
|
async def aclose(self):
|
|
|
self.close()
|
|
|
await _core.checkpoint()
|
|
|
|
|
|
async def receive_some(self, max_bytes=None):
|
|
|
return await self._lbq.receive_some(max_bytes)
|
|
|
|
|
|
|
|
|
def lockstep_stream_one_way_pair():
|
|
|
"""Create a connected, pure Python, unidirectional stream where data flows
|
|
|
in lockstep.
|
|
|
|
|
|
Returns:
|
|
|
A tuple
|
|
|
(:class:`~trio.abc.SendStream`, :class:`~trio.abc.ReceiveStream`).
|
|
|
|
|
|
This stream has *absolutely no* buffering. Each call to
|
|
|
:meth:`~trio.abc.SendStream.send_all` will block until all the given data
|
|
|
has been returned by a call to
|
|
|
:meth:`~trio.abc.ReceiveStream.receive_some`.
|
|
|
|
|
|
This can be useful for testing flow control mechanisms in an extreme case,
|
|
|
or for setting up "clogged" streams to use with
|
|
|
:func:`check_one_way_stream` and friends.
|
|
|
|
|
|
In addition to fulfilling the :class:`~trio.abc.SendStream` and
|
|
|
:class:`~trio.abc.ReceiveStream` interfaces, the return objects
|
|
|
also have a synchronous ``close`` method.
|
|
|
|
|
|
"""
|
|
|
|
|
|
lbq = _LockstepByteQueue()
|
|
|
return _LockstepSendStream(lbq), _LockstepReceiveStream(lbq)
|
|
|
|
|
|
|
|
|
def lockstep_stream_pair():
|
|
|
"""Create a connected, pure-Python, bidirectional stream where data flows
|
|
|
in lockstep.
|
|
|
|
|
|
Returns:
|
|
|
A tuple (:class:`~trio.StapledStream`, :class:`~trio.StapledStream`).
|
|
|
|
|
|
This is a convenience function that creates two one-way streams using
|
|
|
:func:`lockstep_stream_one_way_pair`, and then uses
|
|
|
:class:`~trio.StapledStream` to combine them into a single bidirectional
|
|
|
stream.
|
|
|
|
|
|
"""
|
|
|
return _make_stapled_pair(lockstep_stream_one_way_pair)
|