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117 lines
4.3 KiB
117 lines
4.3 KiB
3 years ago
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from dataclasses import dataclass, field
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from typing import Any, Callable, Mapping
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from .. import ClosedResourceError, DelimiterNotFound, EndOfStream, IncompleteRead
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from ..abc import AnyByteReceiveStream, ByteReceiveStream
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@dataclass(eq=False)
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class BufferedByteReceiveStream(ByteReceiveStream):
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"""
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Wraps any bytes-based receive stream and uses a buffer to provide sophisticated receiving
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capabilities in the form of a byte stream.
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"""
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receive_stream: AnyByteReceiveStream
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_buffer: bytearray = field(init=False, default_factory=bytearray)
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_closed: bool = field(init=False, default=False)
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async def aclose(self) -> None:
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await self.receive_stream.aclose()
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self._closed = True
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@property
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def buffer(self) -> bytes:
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"""The bytes currently in the buffer."""
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return bytes(self._buffer)
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@property
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def extra_attributes(self) -> Mapping[Any, Callable[[], Any]]:
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return self.receive_stream.extra_attributes
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async def receive(self, max_bytes: int = 65536) -> bytes:
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if self._closed:
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raise ClosedResourceError
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if self._buffer:
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chunk = bytes(self._buffer[:max_bytes])
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del self._buffer[:max_bytes]
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return chunk
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elif isinstance(self.receive_stream, ByteReceiveStream):
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return await self.receive_stream.receive(max_bytes)
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else:
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# With a bytes-oriented object stream, we need to handle any surplus bytes we get from
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# the receive() call
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chunk = await self.receive_stream.receive()
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if len(chunk) > max_bytes:
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# Save the surplus bytes in the buffer
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self._buffer.extend(chunk[max_bytes:])
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return chunk[:max_bytes]
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else:
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return chunk
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async def receive_exactly(self, nbytes: int) -> bytes:
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"""
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Read exactly the given amount of bytes from the stream.
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:param nbytes: the number of bytes to read
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:return: the bytes read
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:raises ~anyio.IncompleteRead: if the stream was closed before the requested
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amount of bytes could be read from the stream
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"""
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while True:
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remaining = nbytes - len(self._buffer)
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if remaining <= 0:
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retval = self._buffer[:nbytes]
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del self._buffer[:nbytes]
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return bytes(retval)
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try:
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if isinstance(self.receive_stream, ByteReceiveStream):
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chunk = await self.receive_stream.receive(remaining)
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else:
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chunk = await self.receive_stream.receive()
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except EndOfStream as exc:
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raise IncompleteRead from exc
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self._buffer.extend(chunk)
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async def receive_until(self, delimiter: bytes, max_bytes: int) -> bytes:
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"""
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Read from the stream until the delimiter is found or max_bytes have been read.
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:param delimiter: the marker to look for in the stream
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:param max_bytes: maximum number of bytes that will be read before raising
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:exc:`~anyio.DelimiterNotFound`
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:return: the bytes read (not including the delimiter)
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:raises ~anyio.IncompleteRead: if the stream was closed before the delimiter
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was found
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:raises ~anyio.DelimiterNotFound: if the delimiter is not found within the
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bytes read up to the maximum allowed
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"""
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delimiter_size = len(delimiter)
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offset = 0
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while True:
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# Check if the delimiter can be found in the current buffer
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index = self._buffer.find(delimiter, offset)
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if index >= 0:
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found = self._buffer[:index]
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del self._buffer[:index + len(delimiter):]
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return bytes(found)
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# Check if the buffer is already at or over the limit
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if len(self._buffer) >= max_bytes:
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raise DelimiterNotFound(max_bytes)
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# Read more data into the buffer from the socket
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try:
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data = await self.receive_stream.receive()
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except EndOfStream as exc:
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raise IncompleteRead from exc
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# Move the offset forward and add the new data to the buffer
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offset = max(len(self._buffer) - delimiter_size + 1, 0)
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self._buffer.extend(data)
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