Viewing file:  streams.py (20.35 KB) -rw-r--r--
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import asyncio
import collections
import warnings
from typing import Awaitable, Callable, Deque, Generic, List, Optional, Tuple, TypeVar
from .base_protocol import BaseProtocol
from .helpers import BaseTimerContext, set_exception, set_result
from .log import internal_logger
from .typedefs import Final
__all__ = (
"EMPTY_PAYLOAD",
"EofStream",
"StreamReader",
"DataQueue",
"FlowControlDataQueue",
)
_T = TypeVar("_T")
class EofStream(Exception):
"""eof stream indication."""
class AsyncStreamIterator(Generic[_T]):
def __init__(self, read_func: Callable[[], Awaitable[_T]]) -> None:
self.read_func = read_func
def __aiter__(self) -> "AsyncStreamIterator[_T]":
return self
async def __anext__(self) -> _T:
try:
rv = await self.read_func()
except EofStream:
raise StopAsyncIteration
if rv == b"":
raise StopAsyncIteration
return rv
class ChunkTupleAsyncStreamIterator:
def __init__(self, stream: "StreamReader") -> None:
self._stream = stream
def __aiter__(self) -> "ChunkTupleAsyncStreamIterator":
return self
async def __anext__(self) -> Tuple[bytes, bool]:
rv = await self._stream.readchunk()
if rv == (b"", False):
raise StopAsyncIteration
return rv
class AsyncStreamReaderMixin:
def __aiter__(self) -> AsyncStreamIterator[bytes]:
return AsyncStreamIterator(self.readline) # type: ignore[attr-defined]
def iter_chunked(self, n: int) -> AsyncStreamIterator[bytes]:
"""Returns an asynchronous iterator that yields chunks of size n.
Python-3.5 available for Python 3.5+ only
"""
return AsyncStreamIterator(
lambda: self.read(n) # type: ignore[attr-defined,no-any-return]
)
def iter_any(self) -> AsyncStreamIterator[bytes]:
"""Yield all available data as soon as it is received.
Python-3.5 available for Python 3.5+ only
"""
return AsyncStreamIterator(self.readany) # type: ignore[attr-defined]
def iter_chunks(self) -> ChunkTupleAsyncStreamIterator:
"""Yield chunks of data as they are received by the server.
The yielded objects are tuples
of (bytes, bool) as returned by the StreamReader.readchunk method.
Python-3.5 available for Python 3.5+ only
"""
return ChunkTupleAsyncStreamIterator(self) # type: ignore[arg-type]
class StreamReader(AsyncStreamReaderMixin):
"""An enhancement of asyncio.StreamReader.
Supports asynchronous iteration by line, chunk or as available::
async for line in reader:
...
async for chunk in reader.iter_chunked(1024):
...
async for slice in reader.iter_any():
...
"""
total_bytes = 0
def __init__(
self,
protocol: BaseProtocol,
limit: int,
*,
timer: Optional[BaseTimerContext] = None,
loop: Optional[asyncio.AbstractEventLoop] = None,
) -> None:
self._protocol = protocol
self._low_water = limit
self._high_water = limit * 2
if loop is None:
loop = asyncio.get_event_loop()
self._loop = loop
self._size = 0
self._cursor = 0
self._http_chunk_splits = None # type: Optional[List[int]]
self._buffer = collections.deque() # type: Deque[bytes]
self._buffer_offset = 0
self._eof = False
self._waiter = None # type: Optional[asyncio.Future[None]]
self._eof_waiter = None # type: Optional[asyncio.Future[None]]
self._exception = None # type: Optional[BaseException]
self._timer = timer
self._eof_callbacks = [] # type: List[Callable[[], None]]
def __repr__(self) -> str:
info = [self.__class__.__name__]
if self._size:
info.append("%d bytes" % self._size)
if self._eof:
info.append("eof")
if self._low_water != 2 ** 16: # default limit
info.append("low=%d high=%d" % (self._low_water, self._high_water))
if self._waiter:
info.append("w=%r" % self._waiter)
if self._exception:
info.append("e=%r" % self._exception)
return "<%s>" % " ".join(info)
def get_read_buffer_limits(self) -> Tuple[int, int]:
return (self._low_water, self._high_water)
def exception(self) -> Optional[BaseException]:
return self._exception
def set_exception(self, exc: BaseException) -> None:
self._exception = exc
self._eof_callbacks.clear()
waiter = self._waiter
if waiter is not None:
self._waiter = None
set_exception(waiter, exc)
waiter = self._eof_waiter
if waiter is not None:
self._eof_waiter = None
set_exception(waiter, exc)
def on_eof(self, callback: Callable[[], None]) -> None:
if self._eof:
try:
callback()
except Exception:
internal_logger.exception("Exception in eof callback")
else:
self._eof_callbacks.append(callback)
def feed_eof(self) -> None:
self._eof = True
waiter = self._waiter
if waiter is not None:
self._waiter = None
set_result(waiter, None)
waiter = self._eof_waiter
if waiter is not None:
self._eof_waiter = None
set_result(waiter, None)
for cb in self._eof_callbacks:
try:
cb()
except Exception:
internal_logger.exception("Exception in eof callback")
self._eof_callbacks.clear()
def is_eof(self) -> bool:
"""Return True if 'feed_eof' was called."""
return self._eof
def at_eof(self) -> bool:
"""Return True if the buffer is empty and 'feed_eof' was called."""
return self._eof and not self._buffer
async def wait_eof(self) -> None:
if self._eof:
return
assert self._eof_waiter is None
self._eof_waiter = self._loop.create_future()
try:
await self._eof_waiter
finally:
self._eof_waiter = None
def unread_data(self, data: bytes) -> None:
"""rollback reading some data from stream, inserting it to buffer head."""
warnings.warn(
"unread_data() is deprecated "
"and will be removed in future releases (#3260)",
DeprecationWarning,
stacklevel=2,
)
if not data:
return
if self._buffer_offset:
self._buffer[0] = self._buffer[0][self._buffer_offset :]
self._buffer_offset = 0
self._size += len(data)
self._cursor -= len(data)
self._buffer.appendleft(data)
self._eof_counter = 0
# TODO: size is ignored, remove the param later
def feed_data(self, data: bytes, size: int = 0) -> None:
assert not self._eof, "feed_data after feed_eof"
if not data:
return
self._size += len(data)
self._buffer.append(data)
self.total_bytes += len(data)
waiter = self._waiter
if waiter is not None:
self._waiter = None
set_result(waiter, None)
if self._size > self._high_water and not self._protocol._reading_paused:
self._protocol.pause_reading()
def begin_http_chunk_receiving(self) -> None:
if self._http_chunk_splits is None:
if self.total_bytes:
raise RuntimeError(
"Called begin_http_chunk_receiving when" "some data was already fed"
)
self._http_chunk_splits = []
def end_http_chunk_receiving(self) -> None:
if self._http_chunk_splits is None:
raise RuntimeError(
"Called end_chunk_receiving without calling "
"begin_chunk_receiving first"
)
# self._http_chunk_splits contains logical byte offsets from start of
# the body transfer. Each offset is the offset of the end of a chunk.
# "Logical" means bytes, accessible for a user.
# If no chunks containig logical data were received, current position
# is difinitely zero.
pos = self._http_chunk_splits[-1] if self._http_chunk_splits else 0
if self.total_bytes == pos:
# We should not add empty chunks here. So we check for that.
# Note, when chunked + gzip is used, we can receive a chunk
# of compressed data, but that data may not be enough for gzip FSM
# to yield any uncompressed data. That's why current position may
# not change after receiving a chunk.
return
self._http_chunk_splits.append(self.total_bytes)
# wake up readchunk when end of http chunk received
waiter = self._waiter
if waiter is not None:
self._waiter = None
set_result(waiter, None)
async def _wait(self, func_name: str) -> None:
# 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
)
waiter = self._waiter = self._loop.create_future()
try:
if self._timer:
with self._timer:
await waiter
else:
await waiter
finally:
self._waiter = None
async def readline(self) -> bytes:
return await self.readuntil()
async def readuntil(self, separator: bytes = b"\n") -> bytes:
seplen = len(separator)
if seplen == 0:
raise ValueError("Separator should be at least one-byte string")
if self._exception is not None:
raise self._exception
chunk = b""
chunk_size = 0
not_enough = True
while not_enough:
while self._buffer and not_enough:
offset = self._buffer_offset
ichar = self._buffer[0].find(separator, offset) + 1
# Read from current offset to found separator or to the end.
data = self._read_nowait_chunk(ichar - offset if ichar else -1)
chunk += data
chunk_size += len(data)
if ichar:
not_enough = False
if chunk_size > self._high_water:
raise ValueError("Chunk too big")
if self._eof:
break
if not_enough:
await self._wait("readuntil")
return chunk
async def read(self, n: int = -1) -> bytes:
if self._exception is not None:
raise self._exception
# migration problem; with DataQueue you have to catch
# EofStream exception, so common way is to run payload.read() inside
# infinite loop. what can cause real infinite loop with StreamReader
# lets keep this code one major release.
if __debug__:
if self._eof and not self._buffer:
self._eof_counter = getattr(self, "_eof_counter", 0) + 1
if self._eof_counter > 5:
internal_logger.warning(
"Multiple access to StreamReader in eof state, "
"might be infinite loop.",
stack_info=True,
)
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.readany() until EOF.
blocks = []
while True:
block = await self.readany()
if not block:
break
blocks.append(block)
return b"".join(blocks)
# TODO: should be `if` instead of `while`
# because waiter maybe triggered on chunk end,
# without feeding any data
while not self._buffer and not self._eof:
await self._wait("read")
return self._read_nowait(n)
async def readany(self) -> bytes:
if self._exception is not None:
raise self._exception
# TODO: should be `if` instead of `while`
# because waiter maybe triggered on chunk end,
# without feeding any data
while not self._buffer and not self._eof:
await self._wait("readany")
return self._read_nowait(-1)
async def readchunk(self) -> Tuple[bytes, bool]:
"""Returns a tuple of (data, end_of_http_chunk).
When chunked transfer
encoding is used, end_of_http_chunk is a boolean indicating if the end
of the data corresponds to the end of a HTTP chunk , otherwise it is
always False.
"""
while True:
if self._exception is not None:
raise self._exception
while self._http_chunk_splits:
pos = self._http_chunk_splits.pop(0)
if pos == self._cursor:
return (b"", True)
if pos > self._cursor:
return (self._read_nowait(pos - self._cursor), True)
internal_logger.warning(
"Skipping HTTP chunk end due to data "
"consumption beyond chunk boundary"
)
if self._buffer:
return (self._read_nowait_chunk(-1), False)
# return (self._read_nowait(-1), False)
if self._eof:
# Special case for signifying EOF.
# (b'', True) is not a final return value actually.
return (b"", False)
await self._wait("readchunk")
async def readexactly(self, n: int) -> bytes:
if self._exception is not None:
raise self._exception
blocks = [] # type: List[bytes]
while n > 0:
block = await self.read(n)
if not block:
partial = b"".join(blocks)
raise asyncio.IncompleteReadError(partial, len(partial) + n)
blocks.append(block)
n -= len(block)
return b"".join(blocks)
def read_nowait(self, n: int = -1) -> bytes:
# default was changed to be consistent with .read(-1)
#
# I believe the most users don't know about the method and
# they are not affected.
if self._exception is not None:
raise self._exception
if self._waiter and not self._waiter.done():
raise RuntimeError(
"Called while some coroutine is waiting for incoming data."
)
return self._read_nowait(n)
def _read_nowait_chunk(self, n: int) -> bytes:
first_buffer = self._buffer[0]
offset = self._buffer_offset
if n != -1 and len(first_buffer) - offset > n:
data = first_buffer[offset : offset + n]
self._buffer_offset += n
elif offset:
self._buffer.popleft()
data = first_buffer[offset:]
self._buffer_offset = 0
else:
data = self._buffer.popleft()
self._size -= len(data)
self._cursor += len(data)
chunk_splits = self._http_chunk_splits
# Prevent memory leak: drop useless chunk splits
while chunk_splits and chunk_splits[0] < self._cursor:
chunk_splits.pop(0)
if self._size < self._low_water and self._protocol._reading_paused:
self._protocol.resume_reading()
return data
def _read_nowait(self, n: int) -> bytes:
"""Read not more than n bytes, or whole buffer if n == -1"""
chunks = []
while self._buffer:
chunk = self._read_nowait_chunk(n)
chunks.append(chunk)
if n != -1:
n -= len(chunk)
if n == 0:
break
return b"".join(chunks) if chunks else b""
class EmptyStreamReader(StreamReader): # lgtm [py/missing-call-to-init]
def __init__(self) -> None:
pass
def exception(self) -> Optional[BaseException]:
return None
def set_exception(self, exc: BaseException) -> None:
pass
def on_eof(self, callback: Callable[[], None]) -> None:
try:
callback()
except Exception:
internal_logger.exception("Exception in eof callback")
def feed_eof(self) -> None:
pass
def is_eof(self) -> bool:
return True
def at_eof(self) -> bool:
return True
async def wait_eof(self) -> None:
return
def feed_data(self, data: bytes, n: int = 0) -> None:
pass
async def readline(self) -> bytes:
return b""
async def read(self, n: int = -1) -> bytes:
return b""
# TODO add async def readuntil
async def readany(self) -> bytes:
return b""
async def readchunk(self) -> Tuple[bytes, bool]:
return (b"", True)
async def readexactly(self, n: int) -> bytes:
raise asyncio.IncompleteReadError(b"", n)
def read_nowait(self, n: int = -1) -> bytes:
return b""
EMPTY_PAYLOAD: Final[StreamReader] = EmptyStreamReader()
class DataQueue(Generic[_T]):
"""DataQueue is a general-purpose blocking queue with one reader."""
def __init__(self, loop: asyncio.AbstractEventLoop) -> None:
self._loop = loop
self._eof = False
self._waiter = None # type: Optional[asyncio.Future[None]]
self._exception = None # type: Optional[BaseException]
self._size = 0
self._buffer = collections.deque() # type: Deque[Tuple[_T, int]]
def __len__(self) -> int:
return len(self._buffer)
def is_eof(self) -> bool:
return self._eof
def at_eof(self) -> bool:
return self._eof and not self._buffer
def exception(self) -> Optional[BaseException]:
return self._exception
def set_exception(self, exc: BaseException) -> None:
self._eof = True
self._exception = exc
waiter = self._waiter
if waiter is not None:
self._waiter = None
set_exception(waiter, exc)
def feed_data(self, data: _T, size: int = 0) -> None:
self._size += size
self._buffer.append((data, size))
waiter = self._waiter
if waiter is not None:
self._waiter = None
set_result(waiter, None)
def feed_eof(self) -> None:
self._eof = True
waiter = self._waiter
if waiter is not None:
self._waiter = None
set_result(waiter, None)
async def read(self) -> _T:
if not self._buffer and not self._eof:
assert not self._waiter
self._waiter = self._loop.create_future()
try:
await self._waiter
except (asyncio.CancelledError, asyncio.TimeoutError):
self._waiter = None
raise
if self._buffer:
data, size = self._buffer.popleft()
self._size -= size
return data
else:
if self._exception is not None:
raise self._exception
else:
raise EofStream
def __aiter__(self) -> AsyncStreamIterator[_T]:
return AsyncStreamIterator(self.read)
class FlowControlDataQueue(DataQueue[_T]):
"""FlowControlDataQueue resumes and pauses an underlying stream.
It is a destination for parsed data.
"""
def __init__(
self, protocol: BaseProtocol, limit: int, *, loop: asyncio.AbstractEventLoop
) -> None:
super().__init__(loop=loop)
self._protocol = protocol
self._limit = limit * 2
def feed_data(self, data: _T, size: int = 0) -> None:
super().feed_data(data, size)
if self._size > self._limit and not self._protocol._reading_paused:
self._protocol.pause_reading()
async def read(self) -> _T:
try:
return await super().read()
finally:
if self._size < self._limit and self._protocol._reading_paused:
self._protocol.resume_reading()
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