import asyncio import collections import warnings from typing import List # noqa from typing import Awaitable, Callable, Generic, Optional, Tuple, TypeVar from .base_protocol import BaseProtocol from .helpers import BaseTimerContext, set_exception, set_result from .log import internal_logger try: # pragma: no cover from typing import Deque # noqa except ImportError: from typing_extensions import Deque # noqa __all__ = ( 'EMPTY_PAYLOAD', 'EofStream', 'StreamReader', 'DataQueue', 'FlowControlDataQueue') DEFAULT_LIMIT = 2 ** 16 _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 # NOQA if rv == b'': raise StopAsyncIteration # NOQA 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 # NOQA return rv class AsyncStreamReaderMixin: def __aiter__(self) -> AsyncStreamIterator[bytes]: return AsyncStreamIterator(self.readline) # type: ignore 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 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 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 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=DEFAULT_LIMIT, 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 != 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 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: if self._exception is not None: raise self._exception line = [] line_size = 0 not_enough = True while not_enough: while self._buffer and not_enough: offset = self._buffer_offset ichar = self._buffer[0].find(b'\n', offset) + 1 # Read from current offset to found b'\n' or to the end. data = self._read_nowait_chunk(ichar - offset if ichar else -1) line.append(data) line_size += len(data) if ichar: not_enough = False if line_size > self._high_water: raise ValueError('Line is too long') if self._eof: break if not_enough: await self._wait('readline') return b''.join(line) 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 is 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(AsyncStreamReaderMixin): 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'' 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) -> bytes: return b'' EMPTY_PAYLOAD = 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=DEFAULT_LIMIT, 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()