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]:
"""Returns an asynchronous iterator that yields all the 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:
"""Returns an asynchronous iterator that yields 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]
[docs]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)
[docs] 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
[docs] 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
[docs] 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
[docs] async def readline(self) -> bytes:
return await self.readuntil()
[docs] 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
[docs] 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)
[docs] 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)
[docs] 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")
[docs] 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)
[docs] 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()
