class Event(object):
"""An event blocks coroutines until its internal flag is set to True.
Similar to `threading.Event`.
A coroutine can wait for an event to be set. Once it is set, calls to
``yield event.wait()`` will not block unless the event has been cleared:
.. testcode::
from tornado import gen
from tornado.ioloop import IOLoop
from tornado.locks import Event
event = Event()
@gen.coroutine
def waiter():
print("Waiting for event")
yield event.wait()
print("Not waiting this time")
yield event.wait()
print("Done")
@gen.coroutine
def setter():
print("About to set the event")
event.set()
@gen.coroutine
def runner():
yield [waiter(), setter()]
IOLoop.current().run_sync(runner)
.. testoutput::
Waiting for event
About to set the event
Not waiting this time
Done
"""
def __init__(self):
self._future = Future()
def __repr__(self):
return '<%s %s>' % (self.__class__.__name__,
'set' if self.is_set() else 'clear')
def is_set(self):
"""Return ``True`` if the internal flag is true."""
return self._future.done()
def set(self):
"""Set the internal flag to ``True``. All waiters are awakened.
Calling `.wait` once the flag is set will not block.
"""
if not self._future.done():
self._future.set_result(None)
def clear(self):
"""Reset the internal flag to ``False``.
Calls to `.wait` will block until `.set` is called.
"""
if self._future.done():
self._future = Future()
def wait(self, timeout=None):
"""Block until the internal flag is true.
Returns a Future, which raises `tornado.gen.TimeoutError` after a
timeout.
"""
if timeout is None:
return self._future
else:
return gen.with_timeout(timeout, self._future)
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,
io_loop=self.stream.io_loop,
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, self.stream.io_loop,
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)
self.close()
raise gen.Return(False)
finally:
if need_delegate_close:
with _ExceptionLoggingContext(app_log):
delegate.on_connection_close()
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.
.. deprecated:: 4.0
Use `.HTTPMessageDelegate.on_connection_close` instead.
"""
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():
self._finish_future.set_result(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():
self._finish_future.set_result(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():
self._finish_future.set_result(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
# 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
# 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 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:
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)
self._pending_write.add_done_callback(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 is 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:
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:
self._pending_write.add_done_callback(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(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 reponse 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():
self._finish_future.set_result(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")
try:
headers = httputil.HTTPHeaders.parse(data[eol:])
except ValueError:
# probably form split() if there was no ':' in the line
raise httputil.HTTPInputError("Malformed HTTP headers: %r" %
data[eol:100])
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:
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 _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, io_loop, connect):
self.io_loop = io_loop
self.connect = connect
self.future = Future()
self.timeout = None
self.last_error = None
self.remaining = len(addrinfo)
self.primary_addrs, self.secondary_addrs = self.split(addrinfo)
@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):
self.try_connect(iter(self.primary_addrs))
self.set_timout(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
future = self.connect(af, addr)
future.add_done_callback(
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_timeout()
if self.future.done():
# This is a late arrival; just drop it.
stream.close()
else:
self.future.set_result((af, addr, stream))
def set_timout(self, timeout):
self.timeout = self.io_loop.add_timeout(self.io_loop.time() + timeout,
self.on_timeout)
def on_timeout(self):
self.timeout = None
self.try_connect(iter(self.secondary_addrs))
def clear_timeout(self):
if self.timeout is not None:
self.io_loop.remove_timeout(self.timeout)