def initialize(self, io_loop, max_clients=10,
hostname_mapping=None, max_buffer_size=104857600,
resolver=None, defaults=None):
"""Creates a AsyncHTTPClient.
Only a single AsyncHTTPClient instance exists per IOLoop
in order to provide limitations on the number of pending connections.
force_instance=True may be used to suppress this behavior.
max_clients is the number of concurrent requests that can be
in progress. Note that this arguments are only used when the
client is first created, and will be ignored when an existing
client is reused.
hostname_mapping is a dictionary mapping hostnames to IP addresses.
It can be used to make local DNS changes when modifying system-wide
settings like /etc/hosts is not possible or desirable (e.g. in
unittests).
max_buffer_size is the number of bytes that can be read by IOStream. It
defaults to 100mb.
"""
super(SimpleAsyncHTTPClient, self).initialize(io_loop,
defaults=defaults)
self.max_clients = max_clients
self.queue = collections.deque()
self.active = {}
self.waiting = {}
self.max_buffer_size = max_buffer_size
if resolver:
self.resolver = resolver
self.own_resolver = False
else:
self.resolver = Resolver(io_loop=io_loop)
self.own_resolver = True
if hostname_mapping is not None:
self.resolver = OverrideResolver(resolver=self.resolver,
mapping=hostname_mapping)
class SimpleAsyncHTTPClient(AsyncHTTPClient):
"""Non-blocking HTTP client with no external dependencies.
This class implements an HTTP 1.1 client on top of Tornado's IOStreams.
It does not currently implement all applicable parts of the HTTP
specification, but it does enough to work with major web service APIs.
Some features found in the curl-based AsyncHTTPClient are not yet
supported. In particular, proxies are not supported, connections
are not reused, and callers cannot select the network interface to be
used.
"""
def initialize(self, io_loop, max_clients=10,
hostname_mapping=None, max_buffer_size=104857600,
resolver=None, defaults=None):
"""Creates a AsyncHTTPClient.
Only a single AsyncHTTPClient instance exists per IOLoop
in order to provide limitations on the number of pending connections.
force_instance=True may be used to suppress this behavior.
max_clients is the number of concurrent requests that can be
in progress. Note that this arguments are only used when the
client is first created, and will be ignored when an existing
client is reused.
hostname_mapping is a dictionary mapping hostnames to IP addresses.
It can be used to make local DNS changes when modifying system-wide
settings like /etc/hosts is not possible or desirable (e.g. in
unittests).
max_buffer_size is the number of bytes that can be read by IOStream. It
defaults to 100mb.
"""
super(SimpleAsyncHTTPClient, self).initialize(io_loop,
defaults=defaults)
self.max_clients = max_clients
self.queue = collections.deque()
self.active = {}
self.waiting = {}
self.max_buffer_size = max_buffer_size
if resolver:
self.resolver = resolver
self.own_resolver = False
else:
self.resolver = Resolver(io_loop=io_loop)
self.own_resolver = True
if hostname_mapping is not None:
self.resolver = OverrideResolver(resolver=self.resolver,
mapping=hostname_mapping)
def close(self):
super(SimpleAsyncHTTPClient, self).close()
if self.own_resolver:
self.resolver.close()
def fetch_impl(self, request, callback):
key = object()
self.queue.append((key, request, callback))
if not len(self.active) < self.max_clients:
timeout_handle = self.io_loop.add_timeout(
self.io_loop.time() + min(request.connect_timeout,
request.request_timeout),
functools.partial(self._on_timeout, key))
else:
timeout_handle = None
self.waiting[key] = (request, callback, timeout_handle)
self._process_queue()
if self.queue:
gen_log.debug("max_clients limit reached, request queued. "
"%d active, %d queued requests." % (
len(self.active), len(self.queue)))
def _process_queue(self):
with stack_context.NullContext():
while self.queue and len(self.active) < self.max_clients:
key, request, callback = self.queue.popleft()
if key not in self.waiting:
continue
self._remove_timeout(key)
self.active[key] = (request, callback)
release_callback = functools.partial(self._release_fetch, key)
self._handle_request(request, release_callback, callback)
def _handle_request(self, request, release_callback, final_callback):
_HTTPConnection(self.io_loop, self, request, release_callback,
final_callback, self.max_buffer_size, self.resolver)
def _release_fetch(self, key):
del self.active[key]
self._process_queue()
def _remove_timeout(self, key):
if key in self.waiting:
request, callback, timeout_handle = self.waiting[key]
if timeout_handle is not None:
self.io_loop.remove_timeout(timeout_handle)
del self.waiting[key]
def _on_timeout(self, key):
request, callback, timeout_handle = self.waiting[key]
self.queue.remove((key, request, callback))
timeout_response = HTTPResponse(
request, 599, error=HTTPError(599, "Timeout"),
request_time=self.io_loop.time() - request.start_time)
self.io_loop.add_callback(callback, timeout_response)
del self.waiting[key]
