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from __future__ import annotations
from collections import OrderedDict, deque
from dataclasses import dataclass, field
from types import TracebackType
from typing import Generic, NamedTuple, TypeVar
from .. import (
BrokenResourceError,
ClosedResourceError,
EndOfStream,
WouldBlock,
)
from ..abc import Event, ObjectReceiveStream, ObjectSendStream
from ..lowlevel import checkpoint
T_Item = TypeVar("T_Item")
T_co = TypeVar("T_co", covariant=True)
T_contra = TypeVar("T_contra", contravariant=True)
class MemoryObjectStreamStatistics(NamedTuple):
current_buffer_used: int #: number of items stored in the buffer
#: maximum number of items that can be stored on this stream (or :data:`math.inf`)
max_buffer_size: float
open_send_streams: int #: number of unclosed clones of the send stream
open_receive_streams: int #: number of unclosed clones of the receive stream
#: number of tasks blocked on :meth:`MemoryObjectSendStream.send`
tasks_waiting_send: int
#: number of tasks blocked on :meth:`MemoryObjectReceiveStream.receive`
tasks_waiting_receive: int
@dataclass(eq=False)
class MemoryObjectStreamState(Generic[T_Item]):
max_buffer_size: float = field()
buffer: deque[T_Item] = field(init=False, default_factory=deque)
open_send_channels: int = field(init=False, default=0)
open_receive_channels: int = field(init=False, default=0)
waiting_receivers: OrderedDict[Event, list[T_Item]] = field(
init=False, default_factory=OrderedDict
)
waiting_senders: OrderedDict[Event, T_Item] = field(
init=False, default_factory=OrderedDict
)
def statistics(self) -> MemoryObjectStreamStatistics:
return MemoryObjectStreamStatistics(
len(self.buffer),
self.max_buffer_size,
self.open_send_channels,
self.open_receive_channels,
len(self.waiting_senders),
len(self.waiting_receivers),
)
@dataclass(eq=False)
class MemoryObjectReceiveStream(Generic[T_co], ObjectReceiveStream[T_co]):
_state: MemoryObjectStreamState[T_co]
_closed: bool = field(init=False, default=False)
def __post_init__(self) -> None:
self._state.open_receive_channels += 1
def receive_nowait(self) -> T_co:
"""
Receive the next item if it can be done without waiting.
:return: the received item
:raises ~anyio.ClosedResourceError: if this send stream has been closed
:raises ~anyio.EndOfStream: if the buffer is empty and this stream has been
closed from the sending end
:raises ~anyio.WouldBlock: if there are no items in the buffer and no tasks
waiting to send
"""
if self._closed:
raise ClosedResourceError
if self._state.waiting_senders:
# Get the item from the next sender
send_event, item = self._state.waiting_senders.popitem(last=False)
self._state.buffer.append(item)
send_event.set()
if self._state.buffer:
return self._state.buffer.popleft()
elif not self._state.open_send_channels:
raise EndOfStream
raise WouldBlock
async def receive(self) -> T_co:
await checkpoint()
try:
return self.receive_nowait()
except WouldBlock:
# Add ourselves in the queue
receive_event = Event()
container: list[T_co] = []
self._state.waiting_receivers[receive_event] = container
try:
await receive_event.wait()
finally:
self._state.waiting_receivers.pop(receive_event, None)
if container:
return container[0]
else:
raise EndOfStream
def clone(self) -> MemoryObjectReceiveStream[T_co]:
"""
Create a clone of this receive stream.
Each clone can be closed separately. Only when all clones have been closed will
the receiving end of the memory stream be considered closed by the sending ends.
:return: the cloned stream
"""
if self._closed:
raise ClosedResourceError
return MemoryObjectReceiveStream(_state=self._state)
def close(self) -> None:
"""
Close the stream.
This works the exact same way as :meth:`aclose`, but is provided as a special
case for the benefit of synchronous callbacks.
"""
if not self._closed:
self._closed = True
self._state.open_receive_channels -= 1
if self._state.open_receive_channels == 0:
send_events = list(self._state.waiting_senders.keys())
for event in send_events:
event.set()
async def aclose(self) -> None:
self.close()
def statistics(self) -> MemoryObjectStreamStatistics:
"""
Return statistics about the current state of this stream.
.. versionadded:: 3.0
"""
return self._state.statistics()
def __enter__(self) -> MemoryObjectReceiveStream[T_co]:
return self
def __exit__(
self,
exc_type: type[BaseException] | None,
exc_val: BaseException | None,
exc_tb: TracebackType | None,
) -> None:
self.close()
@dataclass(eq=False)
class MemoryObjectSendStream(Generic[T_contra], ObjectSendStream[T_contra]):
_state: MemoryObjectStreamState[T_contra]
_closed: bool = field(init=False, default=False)
def __post_init__(self) -> None:
self._state.open_send_channels += 1
def send_nowait(self, item: T_contra) -> None:
"""
Send an item immediately if it can be done without waiting.
:param item: the item to send
:raises ~anyio.ClosedResourceError: if this send stream has been closed
:raises ~anyio.BrokenResourceError: if the stream has been closed from the
receiving end
:raises ~anyio.WouldBlock: if the buffer is full and there are no tasks waiting
to receive
"""
if self._closed:
raise ClosedResourceError
if not self._state.open_receive_channels:
raise BrokenResourceError
if self._state.waiting_receivers:
receive_event, container = self._state.waiting_receivers.popitem(last=False)
container.append(item)
receive_event.set()
elif len(self._state.buffer) < self._state.max_buffer_size:
self._state.buffer.append(item)
else:
raise WouldBlock
async def send(self, item: T_contra) -> None:
"""
Send an item to the stream.
If the buffer is full, this method blocks until there is again room in the
buffer or the item can be sent directly to a receiver.
:param item: the item to send
:raises ~anyio.ClosedResourceError: if this send stream has been closed
:raises ~anyio.BrokenResourceError: if the stream has been closed from the
receiving end
"""
await checkpoint()
try:
self.send_nowait(item)
except WouldBlock:
# Wait until there's someone on the receiving end
send_event = Event()
self._state.waiting_senders[send_event] = item
try:
await send_event.wait()
except BaseException:
self._state.waiting_senders.pop(send_event, None)
raise
if self._state.waiting_senders.pop(send_event, None):
raise BrokenResourceError from None
def clone(self) -> MemoryObjectSendStream[T_contra]:
"""
Create a clone of this send stream.
Each clone can be closed separately. Only when all clones have been closed will
the sending end of the memory stream be considered closed by the receiving ends.
:return: the cloned stream
"""
if self._closed:
raise ClosedResourceError
return MemoryObjectSendStream(_state=self._state)
def close(self) -> None:
"""
Close the stream.
This works the exact same way as :meth:`aclose`, but is provided as a special
case for the benefit of synchronous callbacks.
"""
if not self._closed:
self._closed = True
self._state.open_send_channels -= 1
if self._state.open_send_channels == 0:
receive_events = list(self._state.waiting_receivers.keys())
self._state.waiting_receivers.clear()
for event in receive_events:
event.set()
async def aclose(self) -> None:
self.close()
def statistics(self) -> MemoryObjectStreamStatistics:
"""
Return statistics about the current state of this stream.
.. versionadded:: 3.0
"""
return self._state.statistics()
def __enter__(self) -> MemoryObjectSendStream[T_contra]:
return self
def __exit__(
self,
exc_type: type[BaseException] | None,
exc_val: BaseException | None,
exc_tb: TracebackType | None,
) -> None:
self.close()
|
