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