import asyncio
import sys
import warnings
from contextlib import suppress
from typing import Any, Optional
from weakref import WeakKeyDictionary
from ._wrapper import ffi, lib
from .const import CurlECode, CurlMOpt
from .curl import DEFAULT_CACERT, Curl, CurlError
from .utils import CurlCffiWarning
__all__ = ["AsyncCurl"]
if sys.platform == "win32":
# registry of asyncio loop : selector thread
_selectors: WeakKeyDictionary = WeakKeyDictionary()
PROACTOR_WARNING = """
Proactor event loop does not implement add_reader family of methods required.
Registering an additional selector thread for add_reader support.
To avoid this warning use:
asyncio.set_event_loop_policy(WindowsSelectorEventLoopPolicy())
"""
def get_selector(
asyncio_loop: asyncio.AbstractEventLoop,
) -> asyncio.AbstractEventLoop:
"""Get selector-compatible loop
Returns an object with ``add_reader`` family of methods,
either the loop itself or a SelectorThread instance.
Workaround Windows proactor removal of *reader methods.
"""
if asyncio_loop in _selectors:
return _selectors[asyncio_loop]
if not isinstance(
asyncio_loop, getattr(asyncio, "ProactorEventLoop", type(None))
):
return asyncio_loop
warnings.warn(PROACTOR_WARNING, CurlCffiWarning, stacklevel=2)
from ._asyncio_selector import AddThreadSelectorEventLoop
selector_loop = _selectors[asyncio_loop] = AddThreadSelectorEventLoop(
asyncio_loop
) # type: ignore
# patch loop.close to also close the selector thread
loop_close = asyncio_loop.close
def _close_selector_and_loop():
# restore original before calling selector.close,
# which in turn calls eventloop.close!
asyncio_loop.close = loop_close
_selectors.pop(asyncio_loop, None)
selector_loop.close()
asyncio_loop.close = _close_selector_and_loop
return selector_loop
else:
def get_selector(loop: asyncio.AbstractEventLoop) -> asyncio.AbstractEventLoop:
return loop
CURL_POLL_NONE = 0
CURL_POLL_IN = 1
CURL_POLL_OUT = 2
CURL_POLL_INOUT = 3
CURL_POLL_REMOVE = 4
CURL_SOCKET_TIMEOUT = -1
CURL_SOCKET_BAD = -1
CURL_CSELECT_IN = 0x01
CURL_CSELECT_OUT = 0x02
CURL_CSELECT_ERR = 0x04
CURLMSG_DONE = 1
CURLPIPE_NOTHING = 0
CURLPIPE_HTTP1 = 1 # deprecated
CURLPIPE_MULTIPLEX = 2
"""
libcurl provides an event-based system for multiple handles with the following API:
- curl_multi_socket_action, for detecting events
- curl_multi_info_read, for reading the transfer status
There are 2 callbacks:
- socket_function, set by CURLMOPT_SOCKETFUNCTION, will be called for socket events.
- timer_function, set by CURLMOPT_TIMERFUNCTION, will be called when timeouts happen.
And it works like the following:
Set up handles, callbacks first.
When started, curl_multi_socket_action should be called to start everything.
If there are data in/out, libcurl calls the socket_function callback, and it sets up
`process_data` as asyncio loop reader/writer function. `process_data` will call
curl_multi_info_read to determine whether a certain `await perform` has finished.
When idle, libcurl will call the timer_function callback, which sets up a later call
for socket_action to detect events.
"""
@ffi.def_extern()
def timer_function(curlm, timeout_ms: int, clientp: Any) -> int:
"""
see: https://curl.se/libcurl/c/CURLMOPT_TIMERFUNCTION.html
"""
async_curl = ffi.from_handle(clientp)
# Cancel the timer anyway, if it's -1, yes, libcurl says it should be cancelled.
# If not, to add a new timer, we need to cancel the old timer.
if async_curl._timer:
async_curl._timer.cancel() # If already called, cancel does nothing.
async_curl._timer = None
# libcurl says to install a timer which calls socket_action on fire.
async_curl._timer = async_curl.loop.call_later(
timeout_ms / 1000,
async_curl.process_data,
CURL_SOCKET_TIMEOUT, # -1
CURL_POLL_NONE, # 0
)
return 0
@ffi.def_extern()
def socket_function(curl, sockfd: int, what: int, clientp: Any, data: Any) -> int:
"""This callback is called when libcurl decides it's time to interact with certain
sockets"""
async_curl = ffi.from_handle(clientp)
loop = async_curl.loop
# Always remove and re-add fds
if sockfd in async_curl._sockfds:
loop.remove_reader(sockfd)
loop.remove_writer(sockfd)
# Need to read from the socket
if what & CURL_POLL_IN:
loop.add_reader(sockfd, async_curl.process_data, sockfd, CURL_CSELECT_IN)
async_curl._sockfds.add(sockfd)
# Need to write to the socket
if what & CURL_POLL_OUT:
loop.add_writer(sockfd, async_curl.process_data, sockfd, CURL_CSELECT_OUT)
async_curl._sockfds.add(sockfd)
# Need to remove the socket
if what == CURL_POLL_REMOVE:
async_curl._sockfds.remove(sockfd)
return 0
[docs]
class AsyncCurl:
"""Wrapper around curl_multi handle to provide asyncio support. It uses the libcurl
socket_action APIs."""
[docs]
def __init__(self, cacert: str = "", loop=None):
"""
Parameters:
cacert: CA cert path to use, by default, certs from ``certifi`` are used.
loop: EventLoop to use.
"""
self._curlm = lib.curl_multi_init()
self._cacert = cacert or DEFAULT_CACERT
self._curl2future: dict[Curl, asyncio.Future] = {} # curl to future map
self._curl2curl: dict[ffi.CData, Curl] = {} # c curl to Curl
self._sockfds: set[int] = set() # sockfds
self.loop = get_selector(
loop if loop is not None else asyncio.get_running_loop()
)
self._timeout_checker = self.loop.create_task(self._force_timeout())
self._timer: Optional[asyncio.TimerHandle] = None
self._setup()
def _setup(self):
self.setopt(CurlMOpt.TIMERFUNCTION, lib.timer_function)
self.setopt(CurlMOpt.SOCKETFUNCTION, lib.socket_function)
self._self_handle = ffi.new_handle(self)
self.setopt(CurlMOpt.SOCKETDATA, self._self_handle)
self.setopt(CurlMOpt.TIMERDATA, self._self_handle)
# self.setopt(CurlMOpt.PIPELINING, CURLPIPE_NOTHING)
[docs]
async def close(self):
"""Close and cleanup running timers, readers, writers and handles."""
# Close and wait for the force timeout checker to complete
self._timeout_checker.cancel()
with suppress(asyncio.CancelledError):
await self._timeout_checker
# Close all pending futures
for curl, future in self._curl2future.items():
lib.curl_multi_remove_handle(self._curlm, curl._curl)
if not future.done() and not future.cancelled():
future.set_result(None)
# Cleanup curl_multi handle
lib.curl_multi_cleanup(self._curlm)
self._curlm = None
# Remove add readers and writers
for sockfd in self._sockfds:
self.loop.remove_reader(sockfd)
self.loop.remove_writer(sockfd)
# Cancel all time functions
if self._timer:
self._timer.cancel()
async def _force_timeout(self):
"""This coroutine is used to safeguard from any missing signals from curl, and
put everything back on track"""
while True:
if not self._curlm:
break
self.socket_action(CURL_SOCKET_TIMEOUT, CURL_POLL_NONE)
await asyncio.sleep(0.1)
[docs]
def add_handle(self, curl: Curl):
"""Add a curl handle to be managed by curl_multi. This is the equivalent of
`perform` in the async world."""
curl._ensure_cacert()
errcode = lib.curl_multi_add_handle(self._curlm, curl._curl)
self._check_error(errcode)
future = self.loop.create_future()
self._curl2future[curl] = future
self._curl2curl[curl._curl] = curl
return future
[docs]
def socket_action(self, sockfd: int, ev_bitmask: int) -> int:
"""wrapper for curl_multi_socket_action,
returns the number of running curl handles."""
running_handle = ffi.new("int *")
errcode = lib.curl_multi_socket_action(
self._curlm, sockfd, ev_bitmask, running_handle
)
self._check_error(errcode)
return running_handle[0]
[docs]
def process_data(self, sockfd: int, ev_bitmask: int):
"""Call curl_multi_info_read to read data for given socket."""
if not self._curlm:
warnings.warn(
"Curlm already closed! quitting from process_data",
CurlCffiWarning,
stacklevel=2,
)
return
self.socket_action(sockfd, ev_bitmask)
msg_in_queue = ffi.new("int *")
while True:
try:
curl_msg = lib.curl_multi_info_read(self._curlm, msg_in_queue)
# NULL is returned as a signal that no more to be get at this point
if curl_msg == ffi.NULL:
break
if curl_msg.msg == CURLMSG_DONE:
curl = self._curl2curl[curl_msg.easy_handle]
retcode = curl_msg.data.result
if retcode == 0:
self.set_result(curl)
else:
self.set_exception(curl, curl._get_error(retcode, "perform"))
else:
print("NOT DONE") # Will not reach, for nothing else being defined.
except Exception:
warnings.warn(
"Unexpected curl multi state in process_data, "
"please open an issue on GitHub\n",
CurlCffiWarning,
stacklevel=2,
)
def _pop_future(self, curl: Curl):
errcode = lib.curl_multi_remove_handle(self._curlm, curl._curl)
self._check_error(errcode)
self._curl2curl.pop(curl._curl, None)
return self._curl2future.pop(curl, None)
[docs]
def remove_handle(self, curl: Curl):
"""Cancel a future for given curl handle."""
future = self._pop_future(curl)
if future and not future.done() and not future.cancelled():
future.cancel()
[docs]
def set_result(self, curl: Curl):
"""Mark a future as done for given curl handle."""
future = self._pop_future(curl)
if future and not future.done() and not future.cancelled():
future.set_result(None)
[docs]
def set_exception(self, curl: Curl, exception):
"""Raise exception of a future for given curl handle."""
future = self._pop_future(curl)
if future and not future.done() and not future.cancelled():
future.set_exception(exception)
def _check_error(self, errcode: int, *args: Any):
if errcode == CurlECode.OK:
return
errmsg = lib.curl_multi_strerror(errcode)
action = " ".join([str(a) for a in args])
raise CurlError(
f"Failed in {action}, multi: ({errcode}) {errmsg}. "
"See https://curl.se/libcurl/c/libcurl-errors.html first for more "
"details. Please open an issue on GitHub to help debug this error.",
)
[docs]
def setopt(self, option, value):
"""Wrapper around curl_multi_setopt."""
if option in (
CurlMOpt.PIPELINING,
CurlMOpt.MAXCONNECTS,
CurlMOpt.MAX_HOST_CONNECTIONS,
CurlMOpt.MAX_PIPELINE_LENGTH,
CurlMOpt.MAX_TOTAL_CONNECTIONS,
CurlMOpt.MAX_CONCURRENT_STREAMS,
):
c_value = ffi.new("long*", value)
else:
c_value = value
return lib.curl_multi_setopt(self._curlm, option, c_value)