class HTTP1Connection(httputil.HTTPConnection):
"""Implements the HTTP/1.x protocol.
This class can be on its own for clients, or via `HTTP1ServerConnection`
for servers.
"""
def __init__(self, stream, is_client, params=None, context=None):
"""
:arg stream: an `.IOStream`
:arg bool is_client: client or server
:arg params: a `.HTTP1ConnectionParameters` instance or ``None``
:arg context: an opaque application-defined object that can be accessed
as ``connection.context``.
"""
self.is_client = is_client
self.stream = stream
if params is None:
params = HTTP1ConnectionParameters()
self.params = params
self.context = context
self.no_keep_alive = params.no_keep_alive
# The body limits can be altered by the delegate, so save them
# here instead of just referencing self.params later.
self._max_body_size = (self.params.max_body_size
or self.stream.max_buffer_size)
self._body_timeout = self.params.body_timeout
# _write_finished is set to True when finish() has been called,
# i.e. there will be no more data sent. Data may still be in the
# stream's write buffer.
self._write_finished = False
# True when we have read the entire incoming body.
self._read_finished = False
# _finish_future resolves when all data has been written and flushed
# to the IOStream.
self._finish_future = Future()
# If true, the connection should be closed after this request
# (after the response has been written in the server side,
# and after it has been read in the client)
self._disconnect_on_finish = False
self._clear_callbacks()
# Save the start lines after we read or write them; they
# affect later processing (e.g. 304 responses and HEAD methods
# have content-length but no bodies)
self._request_start_line = None
self._response_start_line = None
self._request_headers = None
# True if we are writing output with chunked encoding.
self._chunking_output = None
# While reading a body with a content-length, this is the
# amount left to read.
self._expected_content_remaining = None
# A Future for our outgoing writes, returned by IOStream.write.
self._pending_write = None
def read_response(self, delegate):
"""Read a single HTTP response.
Typical client-mode usage is to write a request using `write_headers`,
`write`, and `finish`, and then call ``read_response``.
:arg delegate: a `.HTTPMessageDelegate`
Returns a `.Future` that resolves to None after the full response has
been read.
"""
if self.params.decompress:
delegate = _GzipMessageDelegate(delegate, self.params.chunk_size)
return self._read_message(delegate)
@gen.coroutine
def _read_message(self, delegate):
need_delegate_close = False
try:
header_future = self.stream.read_until_regex(
b"\r?\n\r?\n", max_bytes=self.params.max_header_size)
if self.params.header_timeout is None:
header_data = yield header_future
else:
try:
header_data = yield gen.with_timeout(
self.stream.io_loop.time() +
self.params.header_timeout,
header_future,
quiet_exceptions=iostream.StreamClosedError)
except gen.TimeoutError:
self.close()
raise gen.Return(False)
start_line, headers = self._parse_headers(header_data)
if self.is_client:
start_line = httputil.parse_response_start_line(start_line)
self._response_start_line = start_line
else:
start_line = httputil.parse_request_start_line(start_line)
self._request_start_line = start_line
self._request_headers = headers
self._disconnect_on_finish = not self._can_keep_alive(
start_line, headers)
need_delegate_close = True
with _ExceptionLoggingContext(app_log):
header_future = delegate.headers_received(start_line, headers)
if header_future is not None:
yield header_future
if self.stream is None:
# We've been detached.
need_delegate_close = False
raise gen.Return(False)
skip_body = False
if self.is_client:
if (self._request_start_line is not None
and self._request_start_line.method == 'HEAD'):
skip_body = True
code = start_line.code
if code == 304:
# 304 responses may include the content-length header
# but do not actually have a body.
# http://tools.ietf.org/html/rfc7230#section-3.3
skip_body = True
if code >= 100 and code < 200:
# 1xx responses should never indicate the presence of
# a body.
if ('Content-Length' in headers
or 'Transfer-Encoding' in headers):
raise httputil.HTTPInputError(
"Response code %d cannot have body" % code)
# TODO: client delegates will get headers_received twice
# in the case of a 100-continue. Document or change?
yield self._read_message(delegate)
else:
if (headers.get("Expect") == "100-continue"
and not self._write_finished):
self.stream.write(b"HTTP/1.1 100 (Continue)\r\n\r\n")
if not skip_body:
body_future = self._read_body(
start_line.code if self.is_client else 0, headers,
delegate)
if body_future is not None:
if self._body_timeout is None:
yield body_future
else:
try:
yield gen.with_timeout(
self.stream.io_loop.time() +
self._body_timeout,
body_future,
quiet_exceptions=iostream.StreamClosedError)
except gen.TimeoutError:
gen_log.info("Timeout reading body from %s",
self.context)
self.stream.close()
raise gen.Return(False)
self._read_finished = True
if not self._write_finished or self.is_client:
need_delegate_close = False
with _ExceptionLoggingContext(app_log):
delegate.finish()
# If we're waiting for the application to produce an asynchronous
# response, and we're not detached, register a close callback
# on the stream (we didn't need one while we were reading)
if (not self._finish_future.done() and self.stream is not None
and not self.stream.closed()):
self.stream.set_close_callback(self._on_connection_close)
yield self._finish_future
if self.is_client and self._disconnect_on_finish:
self.close()
if self.stream is None:
raise gen.Return(False)
except httputil.HTTPInputError as e:
gen_log.info("Malformed HTTP message from %s: %s", self.context, e)
if not self.is_client:
yield self.stream.write(b'HTTP/1.1 400 Bad Request\r\n\r\n')
self.close()
raise gen.Return(False)
finally:
if need_delegate_close:
with _ExceptionLoggingContext(app_log):
delegate.on_connection_close()
header_future = None
self._clear_callbacks()
raise gen.Return(True)
def _clear_callbacks(self):
"""Clears the callback attributes.
This allows the request handler to be garbage collected more
quickly in CPython by breaking up reference cycles.
"""
self._write_callback = None
self._write_future = None
self._close_callback = None
if self.stream is not None:
self.stream.set_close_callback(None)
def set_close_callback(self, callback):
"""Sets a callback that will be run when the connection is closed.
Note that this callback is slightly different from
`.HTTPMessageDelegate.on_connection_close`: The
`.HTTPMessageDelegate` method is called when the connection is
closed while recieving a message. This callback is used when
there is not an active delegate (for example, on the server
side this callback is used if the client closes the connection
after sending its request but before receiving all the
response.
"""
self._close_callback = stack_context.wrap(callback)
def _on_connection_close(self):
# Note that this callback is only registered on the IOStream
# when we have finished reading the request and are waiting for
# the application to produce its response.
if self._close_callback is not None:
callback = self._close_callback
self._close_callback = None
callback()
if not self._finish_future.done():
future_set_result_unless_cancelled(self._finish_future, None)
self._clear_callbacks()
def close(self):
if self.stream is not None:
self.stream.close()
self._clear_callbacks()
if not self._finish_future.done():
future_set_result_unless_cancelled(self._finish_future, None)
def detach(self):
"""Take control of the underlying stream.
Returns the underlying `.IOStream` object and stops all further
HTTP processing. May only be called during
`.HTTPMessageDelegate.headers_received`. Intended for implementing
protocols like websockets that tunnel over an HTTP handshake.
"""
self._clear_callbacks()
stream = self.stream
self.stream = None
if not self._finish_future.done():
future_set_result_unless_cancelled(self._finish_future, None)
return stream
def set_body_timeout(self, timeout):
"""Sets the body timeout for a single request.
Overrides the value from `.HTTP1ConnectionParameters`.
"""
self._body_timeout = timeout
def set_max_body_size(self, max_body_size):
"""Sets the body size limit for a single request.
Overrides the value from `.HTTP1ConnectionParameters`.
"""
self._max_body_size = max_body_size
def write_headers(self, start_line, headers, chunk=None, callback=None):
"""Implements `.HTTPConnection.write_headers`."""
lines = []
if self.is_client:
self._request_start_line = start_line
lines.append(
utf8('%s %s HTTP/1.1' % (start_line[0], start_line[1])))
# Client requests with a non-empty body must have either a
# Content-Length or a Transfer-Encoding.
self._chunking_output = (start_line.method
in ('POST', 'PUT', 'PATCH')
and 'Content-Length' not in headers
and 'Transfer-Encoding' not in headers)
else:
self._response_start_line = start_line
lines.append(
utf8('HTTP/1.1 %d %s' % (start_line[1], start_line[2])))
self._chunking_output = (
# TODO: should this use
# self._request_start_line.version or
# start_line.version?
self._request_start_line.version == 'HTTP/1.1' and
# 1xx, 204 and 304 responses have no body (not even a zero-length
# body), and so should not have either Content-Length or
# Transfer-Encoding headers.
start_line.code not in (204, 304)
and (start_line.code < 100 or start_line.code >= 200) and
# No need to chunk the output if a Content-Length is specified.
'Content-Length' not in headers and
# Applications are discouraged from touching Transfer-Encoding,
# but if they do, leave it alone.
'Transfer-Encoding' not in headers)
# If connection to a 1.1 client will be closed, inform client
if (self._request_start_line.version == 'HTTP/1.1'
and self._disconnect_on_finish):
headers['Connection'] = 'close'
# If a 1.0 client asked for keep-alive, add the header.
if (self._request_start_line.version == 'HTTP/1.0'
and self._request_headers.get('Connection',
'').lower() == 'keep-alive'):
headers['Connection'] = 'Keep-Alive'
if self._chunking_output:
headers['Transfer-Encoding'] = 'chunked'
if (not self.is_client and (self._request_start_line.method == 'HEAD'
or start_line.code == 304)):
self._expected_content_remaining = 0
elif 'Content-Length' in headers:
self._expected_content_remaining = int(headers['Content-Length'])
else:
self._expected_content_remaining = None
# TODO: headers are supposed to be of type str, but we still have some
# cases that let bytes slip through. Remove these native_str calls when those
# are fixed.
header_lines = (native_str(n) + ": " + native_str(v)
for n, v in headers.get_all())
if PY3:
lines.extend(l.encode('latin1') for l in header_lines)
else:
lines.extend(header_lines)
for line in lines:
if b'\n' in line:
raise ValueError('Newline in header: ' + repr(line))
future = None
if self.stream.closed():
future = self._write_future = Future()
future.set_exception(iostream.StreamClosedError())
future.exception()
else:
if callback is not None:
warnings.warn(
"callback argument is deprecated, use returned Future instead",
DeprecationWarning)
self._write_callback = stack_context.wrap(callback)
else:
future = self._write_future = Future()
data = b"\r\n".join(lines) + b"\r\n\r\n"
if chunk:
data += self._format_chunk(chunk)
self._pending_write = self.stream.write(data)
future_add_done_callback(self._pending_write,
self._on_write_complete)
return future
def _format_chunk(self, chunk):
if self._expected_content_remaining is not None:
self._expected_content_remaining -= len(chunk)
if self._expected_content_remaining < 0:
# Close the stream now to stop further framing errors.
self.stream.close()
raise httputil.HTTPOutputError(
"Tried to write more data than Content-Length")
if self._chunking_output and chunk:
# Don't write out empty chunks because that means END-OF-STREAM
# with chunked encoding
return utf8("%x" % len(chunk)) + b"\r\n" + chunk + b"\r\n"
else:
return chunk
def write(self, chunk, callback=None):
"""Implements `.HTTPConnection.write`.
For backwards compatibility it is allowed but deprecated to
skip `write_headers` and instead call `write()` with a
pre-encoded header block.
"""
future = None
if self.stream.closed():
future = self._write_future = Future()
self._write_future.set_exception(iostream.StreamClosedError())
self._write_future.exception()
else:
if callback is not None:
warnings.warn(
"callback argument is deprecated, use returned Future instead",
DeprecationWarning)
self._write_callback = stack_context.wrap(callback)
else:
future = self._write_future = Future()
self._pending_write = self.stream.write(self._format_chunk(chunk))
self._pending_write.add_done_callback(self._on_write_complete)
return future
def finish(self):
"""Implements `.HTTPConnection.finish`."""
if (self._expected_content_remaining is not None
and self._expected_content_remaining != 0
and not self.stream.closed()):
self.stream.close()
raise httputil.HTTPOutputError(
"Tried to write %d bytes less than Content-Length" %
self._expected_content_remaining)
if self._chunking_output:
if not self.stream.closed():
self._pending_write = self.stream.write(b"0\r\n\r\n")
self._pending_write.add_done_callback(self._on_write_complete)
self._write_finished = True
# If the app finished the request while we're still reading,
# divert any remaining data away from the delegate and
# close the connection when we're done sending our response.
# Closing the connection is the only way to avoid reading the
# whole input body.
if not self._read_finished:
self._disconnect_on_finish = True
# No more data is coming, so instruct TCP to send any remaining
# data immediately instead of waiting for a full packet or ack.
self.stream.set_nodelay(True)
if self._pending_write is None:
self._finish_request(None)
else:
future_add_done_callback(self._pending_write, self._finish_request)
def _on_write_complete(self, future):
exc = future.exception()
if exc is not None and not isinstance(exc, iostream.StreamClosedError):
future.result()
if self._write_callback is not None:
callback = self._write_callback
self._write_callback = None
self.stream.io_loop.add_callback(callback)
if self._write_future is not None:
future = self._write_future
self._write_future = None
future_set_result_unless_cancelled(future, None)
def _can_keep_alive(self, start_line, headers):
if self.params.no_keep_alive:
return False
connection_header = headers.get("Connection")
if connection_header is not None:
connection_header = connection_header.lower()
if start_line.version == "HTTP/1.1":
return connection_header != "close"
elif ("Content-Length" in headers
or headers.get("Transfer-Encoding", "").lower() == "chunked"
or getattr(start_line, 'method', None) in ("HEAD", "GET")):
# start_line may be a request or response start line; only
# the former has a method attribute.
return connection_header == "keep-alive"
return False
def _finish_request(self, future):
self._clear_callbacks()
if not self.is_client and self._disconnect_on_finish:
self.close()
return
# Turn Nagle's algorithm back on, leaving the stream in its
# default state for the next request.
self.stream.set_nodelay(False)
if not self._finish_future.done():
future_set_result_unless_cancelled(self._finish_future, None)
def _parse_headers(self, data):
# The lstrip removes newlines that some implementations sometimes
# insert between messages of a reused connection. Per RFC 7230,
# we SHOULD ignore at least one empty line before the request.
# http://tools.ietf.org/html/rfc7230#section-3.5
data = native_str(data.decode('latin1')).lstrip("\r\n")
# RFC 7230 section allows for both CRLF and bare LF.
eol = data.find("\n")
start_line = data[:eol].rstrip("\r")
headers = httputil.HTTPHeaders.parse(data[eol:])
return start_line, headers
def _read_body(self, code, headers, delegate):
if "Content-Length" in headers:
if "Transfer-Encoding" in headers:
# Response cannot contain both Content-Length and
# Transfer-Encoding headers.
# http://tools.ietf.org/html/rfc7230#section-3.3.3
raise httputil.HTTPInputError(
"Response with both Transfer-Encoding and Content-Length")
if "," in headers["Content-Length"]:
# Proxies sometimes cause Content-Length headers to get
# duplicated. If all the values are identical then we can
# use them but if they differ it's an error.
pieces = re.split(r',\s*', headers["Content-Length"])
if any(i != pieces[0] for i in pieces):
raise httputil.HTTPInputError(
"Multiple unequal Content-Lengths: %r" %
headers["Content-Length"])
headers["Content-Length"] = pieces[0]
try:
content_length = int(headers["Content-Length"])
except ValueError:
# Handles non-integer Content-Length value.
raise httputil.HTTPInputError(
"Only integer Content-Length is allowed: %s" %
headers["Content-Length"])
if content_length > self._max_body_size:
raise httputil.HTTPInputError("Content-Length too long")
else:
content_length = None
if code == 204:
# This response code is not allowed to have a non-empty body,
# and has an implicit length of zero instead of read-until-close.
# http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.3
if ("Transfer-Encoding" in headers
or content_length not in (None, 0)):
raise httputil.HTTPInputError(
"Response with code %d should not have body" % code)
content_length = 0
if content_length is not None:
return self._read_fixed_body(content_length, delegate)
if headers.get("Transfer-Encoding", "").lower() == "chunked":
return self._read_chunked_body(delegate)
if self.is_client:
return self._read_body_until_close(delegate)
return None
@gen.coroutine
def _read_fixed_body(self, content_length, delegate):
while content_length > 0:
body = yield self.stream.read_bytes(min(self.params.chunk_size,
content_length),
partial=True)
content_length -= len(body)
if not self._write_finished or self.is_client:
with _ExceptionLoggingContext(app_log):
ret = delegate.data_received(body)
if ret is not None:
yield ret
@gen.coroutine
def _read_chunked_body(self, delegate):
# TODO: "chunk extensions" http://tools.ietf.org/html/rfc2616#section-3.6.1
total_size = 0
while True:
chunk_len = yield self.stream.read_until(b"\r\n", max_bytes=64)
chunk_len = int(chunk_len.strip(), 16)
if chunk_len == 0:
crlf = yield self.stream.read_bytes(2)
if crlf != b'\r\n':
raise httputil.HTTPInputError(
"improperly terminated chunked request")
return
total_size += chunk_len
if total_size > self._max_body_size:
raise httputil.HTTPInputError("chunked body too large")
bytes_to_read = chunk_len
while bytes_to_read:
chunk = yield self.stream.read_bytes(min(
bytes_to_read, self.params.chunk_size),
partial=True)
bytes_to_read -= len(chunk)
if not self._write_finished or self.is_client:
with _ExceptionLoggingContext(app_log):
ret = delegate.data_received(chunk)
if ret is not None:
yield ret
# chunk ends with \r\n
crlf = yield self.stream.read_bytes(2)
assert crlf == b"\r\n"
@gen.coroutine
def _read_body_until_close(self, delegate):
body = yield self.stream.read_until_close()
if not self._write_finished or self.is_client:
with _ExceptionLoggingContext(app_log):
delegate.data_received(body)
class WaitIterator(object):
"""Provides an iterator to yield the results of futures as they finish.
Yielding a set of futures like this:
``results = yield [future1, future2]``
pauses the coroutine until both ``future1`` and ``future2``
return, and then restarts the coroutine with the results of both
futures. If either future is an exception, the expression will
raise that exception and all the results will be lost.
If you need to get the result of each future as soon as possible,
or if you need the result of some futures even if others produce
errors, you can use ``WaitIterator``::
wait_iterator = gen.WaitIterator(future1, future2)
while not wait_iterator.done():
try:
result = yield wait_iterator.next()
except Exception as e:
print("Error {} from {}".format(e, wait_iterator.current_future))
else:
print("Result {} received from {} at {}".format(
result, wait_iterator.current_future,
wait_iterator.current_index))
Because results are returned as soon as they are available the
output from the iterator *will not be in the same order as the
input arguments*. If you need to know which future produced the
current result, you can use the attributes
``WaitIterator.current_future``, or ``WaitIterator.current_index``
to get the index of the future from the input list. (if keyword
arguments were used in the construction of the `WaitIterator`,
``current_index`` will use the corresponding keyword).
On Python 3.5, `WaitIterator` implements the async iterator
protocol, so it can be used with the ``async for`` statement (note
that in this version the entire iteration is aborted if any value
raises an exception, while the previous example can continue past
individual errors)::
async for result in gen.WaitIterator(future1, future2):
print("Result {} received from {} at {}".format(
result, wait_iterator.current_future,
wait_iterator.current_index))
.. versionadded:: 4.1
.. versionchanged:: 4.3
Added ``async for`` support in Python 3.5.
"""
def __init__(self, *args, **kwargs):
if args and kwargs:
raise ValueError("You must provide args or kwargs, not both")
if kwargs:
self._unfinished = dict((f, k) for (k, f) in kwargs.items())
futures = list(kwargs.values())
else:
self._unfinished = dict((f, i) for (i, f) in enumerate(args))
futures = args
self._finished = collections.deque()
self.current_index = self.current_future = None
self._running_future = None
for future in futures:
future_add_done_callback(future, self._done_callback)
def done(self):
"""Returns True if this iterator has no more results."""
if self._finished or self._unfinished:
return False
# Clear the 'current' values when iteration is done.
self.current_index = self.current_future = None
return True
def next(self):
"""Returns a `.Future` that will yield the next available result.
Note that this `.Future` will not be the same object as any of
the inputs.
"""
self._running_future = Future()
if self._finished:
self._return_result(self._finished.popleft())
return self._running_future
def _done_callback(self, done):
if self._running_future and not self._running_future.done():
self._return_result(done)
else:
self._finished.append(done)
def _return_result(self, done):
"""Called set the returned future's state that of the future
we yielded, and set the current future for the iterator.
"""
chain_future(done, self._running_future)
self.current_future = done
self.current_index = self._unfinished.pop(done)
def __aiter__(self):
return self
def __anext__(self):
if self.done():
# Lookup by name to silence pyflakes on older versions.
raise getattr(builtins, 'StopAsyncIteration')()
return self.next()
class _Connector(object):
"""A stateless implementation of the "Happy Eyeballs" algorithm.
"Happy Eyeballs" is documented in RFC6555 as the recommended practice
for when both IPv4 and IPv6 addresses are available.
In this implementation, we partition the addresses by family, and
make the first connection attempt to whichever address was
returned first by ``getaddrinfo``. If that connection fails or
times out, we begin a connection in parallel to the first address
of the other family. If there are additional failures we retry
with other addresses, keeping one connection attempt per family
in flight at a time.
http://tools.ietf.org/html/rfc6555
"""
def __init__(self, addrinfo, connect):
self.io_loop = IOLoop.current()
self.connect = connect
self.future = Future()
self.timeout = None
self.connect_timeout = None
self.last_error = None
self.remaining = len(addrinfo)
self.primary_addrs, self.secondary_addrs = self.split(addrinfo)
self.streams = set()
@staticmethod
def split(addrinfo):
"""Partition the ``addrinfo`` list by address family.
Returns two lists. The first list contains the first entry from
``addrinfo`` and all others with the same family, and the
second list contains all other addresses (normally one list will
be AF_INET and the other AF_INET6, although non-standard resolvers
may return additional families).
"""
primary = []
secondary = []
primary_af = addrinfo[0][0]
for af, addr in addrinfo:
if af == primary_af:
primary.append((af, addr))
else:
secondary.append((af, addr))
return primary, secondary
def start(self, timeout=_INITIAL_CONNECT_TIMEOUT, connect_timeout=None):
self.try_connect(iter(self.primary_addrs))
self.set_timeout(timeout)
if connect_timeout is not None:
self.set_connect_timeout(connect_timeout)
return self.future
def try_connect(self, addrs):
try:
af, addr = next(addrs)
except StopIteration:
# We've reached the end of our queue, but the other queue
# might still be working. Send a final error on the future
# only when both queues are finished.
if self.remaining == 0 and not self.future.done():
self.future.set_exception(self.last_error
or IOError("connection failed"))
return
stream, future = self.connect(af, addr)
self.streams.add(stream)
future_add_done_callback(
future, functools.partial(self.on_connect_done, addrs, af, addr))
def on_connect_done(self, addrs, af, addr, future):
self.remaining -= 1
try:
stream = future.result()
except Exception as e:
if self.future.done():
return
# Error: try again (but remember what happened so we have an
# error to raise in the end)
self.last_error = e
self.try_connect(addrs)
if self.timeout is not None:
# If the first attempt failed, don't wait for the
# timeout to try an address from the secondary queue.
self.io_loop.remove_timeout(self.timeout)
self.on_timeout()
return
self.clear_timeouts()
if self.future.done():
# This is a late arrival; just drop it.
stream.close()
else:
self.streams.discard(stream)
self.future.set_result((af, addr, stream))
self.close_streams()
def set_timeout(self, timeout):
self.timeout = self.io_loop.add_timeout(self.io_loop.time() + timeout,
self.on_timeout)
def on_timeout(self):
self.timeout = None
if not self.future.done():
self.try_connect(iter(self.secondary_addrs))
def clear_timeout(self):
if self.timeout is not None:
self.io_loop.remove_timeout(self.timeout)
def set_connect_timeout(self, connect_timeout):
self.connect_timeout = self.io_loop.add_timeout(
connect_timeout, self.on_connect_timeout)
def on_connect_timeout(self):
if not self.future.done():
self.future.set_exception(TimeoutError())
self.close_streams()
def clear_timeouts(self):
if self.timeout is not None:
self.io_loop.remove_timeout(self.timeout)
if self.connect_timeout is not None:
self.io_loop.remove_timeout(self.connect_timeout)
def close_streams(self):
for stream in self.streams:
stream.close()
class Runner(object):
"""Internal implementation of `tornado.gen.engine`.
Maintains information about pending callbacks and their results.
The results of the generator are stored in ``result_future`` (a
`.Future`)
"""
def __init__(self, gen, result_future, first_yielded):
self.gen = gen
self.result_future = result_future
self.future = _null_future
self.yield_point = None
self.pending_callbacks = None
self.results = None
self.running = False
self.finished = False
self.had_exception = False
self.io_loop = IOLoop.current()
# For efficiency, we do not create a stack context until we
# reach a YieldPoint (stack contexts are required for the historical
# semantics of YieldPoints, but not for Futures). When we have
# done so, this field will be set and must be called at the end
# of the coroutine.
self.stack_context_deactivate = None
if self.handle_yield(first_yielded):
gen = result_future = first_yielded = None
self.run()
def register_callback(self, key):
"""Adds ``key`` to the list of callbacks."""
if self.pending_callbacks is None:
# Lazily initialize the old-style YieldPoint data structures.
self.pending_callbacks = set()
self.results = {}
if key in self.pending_callbacks:
raise KeyReuseError("key %r is already pending" % (key, ))
self.pending_callbacks.add(key)
def is_ready(self, key):
"""Returns true if a result is available for ``key``."""
if self.pending_callbacks is None or key not in self.pending_callbacks:
raise UnknownKeyError("key %r is not pending" % (key, ))
return key in self.results
def set_result(self, key, result):
"""Sets the result for ``key`` and attempts to resume the generator."""
self.results[key] = result
if self.yield_point is not None and self.yield_point.is_ready():
try:
future_set_result_unless_cancelled(
self.future, self.yield_point.get_result())
except:
future_set_exc_info(self.future, sys.exc_info())
self.yield_point = None
self.run()
def pop_result(self, key):
"""Returns the result for ``key`` and unregisters it."""
self.pending_callbacks.remove(key)
return self.results.pop(key)
def run(self):
"""Starts or resumes the generator, running until it reaches a
yield point that is not ready.
"""
if self.running or self.finished:
return
try:
self.running = True
while True:
future = self.future
if not future.done():
return
self.future = None
try:
orig_stack_contexts = stack_context._state.contexts
exc_info = None
try:
value = future.result()
except Exception:
self.had_exception = True
exc_info = sys.exc_info()
future = None
if exc_info is not None:
try:
yielded = self.gen.throw(*exc_info)
finally:
# Break up a reference to itself
# for faster GC on CPython.
exc_info = None
else:
yielded = self.gen.send(value)
if stack_context._state.contexts is not orig_stack_contexts:
self.gen.throw(
stack_context.StackContextInconsistentError(
'stack_context inconsistency (probably caused '
'by yield within a "with StackContext" block)')
)
except (StopIteration, Return) as e:
self.finished = True
self.future = _null_future
if self.pending_callbacks and not self.had_exception:
# If we ran cleanly without waiting on all callbacks
# raise an error (really more of a warning). If we
# had an exception then some callbacks may have been
# orphaned, so skip the check in that case.
raise LeakedCallbackError(
"finished without waiting for callbacks %r" %
self.pending_callbacks)
future_set_result_unless_cancelled(
self.result_future, _value_from_stopiteration(e))
self.result_future = None
self._deactivate_stack_context()
return
except Exception:
self.finished = True
self.future = _null_future
future_set_exc_info(self.result_future, sys.exc_info())
self.result_future = None
self._deactivate_stack_context()
return
if not self.handle_yield(yielded):
return
yielded = None
finally:
self.running = False
def handle_yield(self, yielded):
# Lists containing YieldPoints require stack contexts;
# other lists are handled in convert_yielded.
if _contains_yieldpoint(yielded):
yielded = multi(yielded)
if isinstance(yielded, YieldPoint):
# YieldPoints are too closely coupled to the Runner to go
# through the generic convert_yielded mechanism.
self.future = Future()
def start_yield_point():
try:
yielded.start(self)
if yielded.is_ready():
future_set_result_unless_cancelled(
self.future, yielded.get_result())
else:
self.yield_point = yielded
except Exception:
self.future = Future()
future_set_exc_info(self.future, sys.exc_info())
if self.stack_context_deactivate is None:
# Start a stack context if this is the first
# YieldPoint we've seen.
with stack_context.ExceptionStackContext(
self.handle_exception) as deactivate:
self.stack_context_deactivate = deactivate
def cb():
start_yield_point()
self.run()
self.io_loop.add_callback(cb)
return False
else:
start_yield_point()
else:
try:
self.future = convert_yielded(yielded)
except BadYieldError:
self.future = Future()
future_set_exc_info(self.future, sys.exc_info())
if self.future is moment:
self.io_loop.add_callback(self.run)
return False
elif not self.future.done():
def inner(f):
# Break a reference cycle to speed GC.
f = None # noqa
self.run()
self.io_loop.add_future(self.future, inner)
return False
return True
def result_callback(self, key):
return stack_context.wrap(
_argument_adapter(functools.partial(self.set_result, key)))
def handle_exception(self, typ, value, tb):
if not self.running and not self.finished:
self.future = Future()
future_set_exc_info(self.future, (typ, value, tb))
self.run()
return True
else:
return False
def _deactivate_stack_context(self):
if self.stack_context_deactivate is not None:
self.stack_context_deactivate()
self.stack_context_deactivate = None