twisted.internet.asyncioreactor.AsyncioSelectorReactor

class documentation

class AsyncioSelectorReactor(PosixReactorBase): (source)

Constructor: AsyncioSelectorReactor(eventloop)

Implements interfaces: twisted.internet.interfaces.IReactorFDSet

View In Hierarchy

Reactor running on top of asyncio.SelectorEventLoop.

On POSIX platforms, the default event loop is asyncio.SelectorEventLoop. On Windows, the default event loop on Python 3.7 and older is asyncio.WindowsSelectorEventLoop, but on Python 3.8 and newer the default event loop is asyncio.WindowsProactorEventLoop which is incompatible with AsyncioSelectorReactor. Applications that use AsyncioSelectorReactor on Windows with Python 3.8+ must call asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy()) before instantiating and running AsyncioSelectorReactor.

Method __init__ Undocumented
Method addReader I add reader to the set of file descriptors to get read events for.
Method addWriter I add writer to the set of file descriptors to get write events for.
Method callFromThread See twisted.internet.interfaces.IReactorFromThreads.callFromThread.
Method callLater See twisted.internet.interfaces.IReactorTime.callLater.
Method crash See twisted.internet.interfaces.IReactorCore.crash.
Method getReaders Return the list of file descriptors currently monitored for input events by the reactor.
Method getWriters Return the list file descriptors currently monitored for output events by the reactor.
Method iterate See twisted.internet.interfaces.IReactorCore.iterate.
Method removeAll Remove all readers and writers.
Method removeReader Removes an object previously added with addReader.
Method removeWriter Removes an object previously added with addWriter.
Method run Fire 'startup' System Events, move the reactor to the 'running' state, then run the main loop until it is stopped with stop() or crash().
Method stop See twisted.internet.interfaces.IReactorCore.stop.
Method _moveCallLaterSooner Undocumented
Method _onTimer Undocumented
Method _readOrWrite Undocumented
Method _reschedule Undocumented
Method _unregisterFDInAsyncio Compensate for a bug in asyncio where it will not unregister a FD that it cannot handle in the epoll loop. It touches internal asyncio code.
Class Variable _asyncClosed Undocumented
Class Variable _log Undocumented
Instance Variable _asyncioEventloop Undocumented
Instance Variable _continuousPolling Undocumented
Instance Variable _justStopped Undocumented
Instance Variable _readers Undocumented
Instance Variable _scheduledAt Undocumented
Instance Variable _timerHandle Undocumented
Instance Variable _writers Undocumented

Inherited from PosixReactorBase:

Method adoptDatagramPort Add an existing listening SOCK_DGRAM socket to the reactor to monitor for read and write readiness.
Method adoptStreamConnection No summary
Method adoptStreamPort Create a new IListeningPort from an already-initialized socket.
Method connectSSL Connect a client Protocol to a remote SSL socket.
Method connectTCP Connect a TCP client.
Method connectUNIX Connect a client protocol to a UNIX socket.
Method connectUNIXDatagram Connects a ConnectedDatagramProtocol instance to a path.
Method installWaker Install a `waker' to allow threads and signals to wake up the IO thread.
Method listenMulticast Connects a given DatagramProtocol to the given numeric UDP port.
Method listenSSL Connects a given protocol factory to the given numeric TCP/IP port. The connection is a SSL one, using contexts created by the context factory.
Method listenTCP Connects a given protocol factory to the given numeric TCP/IP port.
Method listenUDP Connects a given DatagramProtocol to the given numeric UDP port.
Method listenUNIX Listen on a UNIX socket.
Method listenUNIXDatagram Connects a given DatagramProtocol to the given path.
Method spawnProcess Spawn a process, with a process protocol.
Instance Variable waker Undocumented
Method _removeAll Remove all readers and writers, and list of removed IReadDescriptors and IWriteDescriptors.
Method _signalsFactory Customize reactor signal handling to support child processes on POSIX platforms.
Method _wakerFactory Undocumented
Class Variable _supportedAddressFamilies Undocumented
Instance Variable _childWaker None or a reference to the _SIGCHLDWaker which is used to properly notice child process termination.

Inherited from _DisconnectSelectableMixin (via PosixReactorBase):

Method _disconnectSelectable Utility function for disconnecting a selectable.

Inherited from ReactorBase (via PosixReactorBase, _DisconnectSelectableMixin):

Method addSystemEventTrigger See twisted.internet.interfaces.IReactorCore.addSystemEventTrigger.
Method callInThread See twisted.internet.interfaces.IReactorInThreads.callInThread.
Method callWhenRunning See twisted.internet.interfaces.IReactorCore.callWhenRunning.
Method disconnectAll Disconnect every reader, and writer in the system.
Method doIteration Do one iteration over the readers and writers which have been added.
Method fireSystemEvent See twisted.internet.interfaces.IReactorCore.fireSystemEvent.
Method getDelayedCalls See twisted.internet.interfaces.IReactorTime.getDelayedCalls
Method getThreadPool See twisted.internet.interfaces.IReactorThreads.getThreadPool.
Method mainLoop Undocumented
Method removeSystemEventTrigger See twisted.internet.interfaces.IReactorCore.removeSystemEventTrigger.
Method resolve Return a Deferred that will resolve a hostname.
Method runUntilCurrent Run all pending timed calls.
Method sigBreak Handle a SIGBREAK interrupt.
Method sigInt Handle a SIGINT interrupt.
Method sigTerm Handle a SIGTERM interrupt.
Method startRunning Method called when reactor starts: do some initialization and fire startup events.
Method suggestThreadPoolSize See twisted.internet.interfaces.IReactorThreads.suggestThreadPoolSize.
Method timeout Determine the longest time the reactor may sleep (waiting on I/O notification, perhaps) before it must wake up to service a time-related event.
Method wakeUp Wake up the event loop.
Class Variable __name__ Undocumented
Class Variable installed Undocumented
Class Variable seconds Get the current time in seconds.
Instance Variable running See IReactorCore.running
Instance Variable threadCallQueue Undocumented
Instance Variable threadpool Undocumented
Instance Variable threadpoolShutdownID Undocumented
Instance Variable usingThreads Undocumented
Method _addInternalReader Add a read descriptor which is part of the implementation of the reactor itself.
Method _cancelCallLater Undocumented
Method _initThreadPool Create the threadpool accessible with callFromThread.
Method _initThreads Undocumented
Method _insertNewDelayedCalls Undocumented
Method _makeSignalHandling Get an appropriate signal handling object.
Method _reallyStartRunning Method called to transition to the running state. This should happen in the during startup event trigger phase.
Method _removeInternalReader Remove a read descriptor which is part of the implementation of the reactor itself.
Method _stopThreadPool Stop the reactor threadpool. This method is only valid if there is currently a threadpool (created by _initThreadPool). It is not intended to be called directly; instead, it will be called by a shutdown trigger created in ...
Method _uninstallHandler Undocumented
Class Variable _lock Undocumented
Instance Variable _cancellations Undocumented
Instance Variable _eventTriggers Undocumented
Instance Variable _exitSignal See _ISupportsExitSignalCapturing._exitSignal
Instance Variable _installSignalHandlers A flag which indicates whether any signal handlers will be installed during startup. This includes handlers for SIGCHLD to monitor child processes, and SIGINT, SIGTERM, and SIGBREAK
Instance Variable _internalReaders Undocumented
Instance Variable _newTimedCalls Undocumented
Instance Variable _pendingTimedCalls Undocumented
Instance Variable _registerAsIOThread A flag controlling whether the reactor will register the thread it is running in as the I/O thread when it starts. If True, registration will be done, otherwise it will not be.
Instance Variable _signals An object which knows how to install and uninstall the reactor's signal-handling behavior.
Instance Variable _started A flag which is true from the time reactor.run is called until the time reactor.run returns. This is used to prevent calls to reactor.run on a running reactor. This should be replaced with an explicit state machine.
Instance Variable _startedBefore Undocumented
Instance Variable _stopped A flag which is true between paired calls to reactor.run and reactor.stop. This should be replaced with an explicit state machine.
Instance Variable _threadpoolStartupID Undocumented

Inherited from PluggableResolverMixin (via PosixReactorBase, _DisconnectSelectableMixin, ReactorBase):

Method installNameResolver See IReactorPluggableNameResolver.
Method installResolver See IReactorPluggableResolver.
Instance Variable resolver The installed IResolverSimple.
Property nameResolver Implementation of read-only IReactorPluggableNameResolver.nameResolver.
Instance Variable _nameResolver The installed IHostnameResolver.
def __init__(self, eventloop: Optional[AbstractEventLoop] = None): (source)
overrides twisted.internet.base.ReactorBase.__init__

Undocumented

def addReader(self, reader): (source)
from twisted.internet.interfaces.IReactorFDSet
overrides twisted.internet.base.ReactorBase.addReader

I add reader to the set of file descriptors to get read events for.

Parameters
readerAn IReadDescriptor provider that will be checked for read events until it is removed from the reactor with removeReader.
def addWriter(self, writer): (source)
from twisted.internet.interfaces.IReactorFDSet
overrides twisted.internet.base.ReactorBase.addWriter

I add writer to the set of file descriptors to get write events for.

Parameters
writerAn IWriteDescriptor provider that will be checked for write events until it is removed from the reactor with removeWriter.
def callFromThread(self, f, *args, **kwargs): (source)
from twisted.internet.interfaces.IReactorFromThreads
overrides twisted.internet.base.ReactorBase.callFromThread
def callLater(self, seconds, f, *args, **kwargs): (source)
from twisted.internet.interfaces.IReactorTime
overrides twisted.internet.base.ReactorBase.callLater

See twisted.internet.interfaces.IReactorTime.callLater.

def crash(self): (source)
from twisted.internet.interfaces.IReactorCore
overrides twisted.internet.base.ReactorBase.crash

See twisted.internet.interfaces.IReactorCore.crash.

Reset reactor state tracking attributes and re-initialize certain state-transition helpers which were set up in __init__ but later destroyed (through use).

def getReaders(self): (source)
from twisted.internet.interfaces.IReactorFDSet
overrides twisted.internet.base.ReactorBase.getReaders

Return the list of file descriptors currently monitored for input events by the reactor.

Returns
the list of file descriptors monitored for input events.
def getWriters(self): (source)
from twisted.internet.interfaces.IReactorFDSet
overrides twisted.internet.base.ReactorBase.getWriters

Return the list file descriptors currently monitored for output events by the reactor.

Returns
the list of file descriptors monitored for output events.
def iterate(self, timeout): (source)
from twisted.internet.interfaces.IReactorCore
overrides twisted.internet.base.ReactorBase.iterate

See twisted.internet.interfaces.IReactorCore.iterate.

def removeAll(self): (source)
from twisted.internet.interfaces.IReactorFDSet
overrides twisted.internet.base.ReactorBase.removeAll

Remove all readers and writers.

Should not remove reactor internal reactor connections (like a waker).

Returns
A list of IReadDescriptor and IWriteDescriptor providers which were removed.
def removeReader(self, reader): (source)
from twisted.internet.interfaces.IReactorFDSet
overrides twisted.internet.base.ReactorBase.removeReader

Removes an object previously added with addReader.

def removeWriter(self, writer): (source)
from twisted.internet.interfaces.IReactorFDSet
overrides twisted.internet.base.ReactorBase.removeWriter

Removes an object previously added with addWriter.

def run(self, installSignalHandlers=True): (source)
from twisted.internet.interfaces.IReactorCore
overrides twisted.internet.base.ReactorBase.run

Fire 'startup' System Events, move the reactor to the 'running' state, then run the main loop until it is stopped with stop() or crash().

def stop(self): (source)
from twisted.internet.interfaces.IReactorCore
overrides twisted.internet.base.ReactorBase.stop

See twisted.internet.interfaces.IReactorCore.stop.

def _moveCallLaterSooner(self, tple): (source)
overrides twisted.internet.base.ReactorBase._moveCallLaterSooner

Undocumented

def _onTimer(self): (source)

Undocumented

def _readOrWrite(self, selectable, read): (source)

Undocumented

def _reschedule(self): (source)

Undocumented

def _unregisterFDInAsyncio(self, fd): (source)

Compensate for a bug in asyncio where it will not unregister a FD that it cannot handle in the epoll loop. It touches internal asyncio code.

A description of the bug by markrwilliams:

The add_writer method of asyncio event loops isn't atomic because all the Selector classes in the selector module internally record a file object before passing it to the platform's selector implementation. If the platform's selector decides the file object isn't acceptable, the resulting exception doesn't cause the Selector to un-track the file object.

The failing/hanging stdio test goes through the following sequence of events (roughly):

* The first connection.write(intToByte(value)) call hits the asyncio reactor's addWriter method.

* addWriter calls the asyncio loop's add_writer method, which happens to live on _BaseSelectorEventLoop.

* The asyncio loop's add_writer method checks if the file object has been registered before via the selector's get_key method.

* It hasn't, so the KeyError block runs and calls the selector's register method

* Code examples that follow use EpollSelector, but the code flow holds true for any other selector implementation. The selector's register method first calls through to the next register method in the MRO

* That next method is always _BaseSelectorImpl.register which creates a SelectorKey instance for the file object, stores it under the file object's file descriptor, and then returns it.

* Control returns to the concrete selector implementation, which asks the operating system to track the file descriptor using the right API.

* The operating system refuses! An exception is raised that, in this case, the asyncio reactor handles by creating a _ContinuousPolling object to watch the file descriptor.

* The second connection.write(intToByte(value)) call hits the asyncio reactor's addWriter method, which hits the add_writer method. But the loop's selector's get_key method now returns a SelectorKey! Now the asyncio reactor's addWriter method thinks the asyncio loop will watch the file descriptor, even though it won't.

_asyncClosed: bool = (source)

Undocumented

_log = (source)

Undocumented

_asyncioEventloop: AbstractEventLoop = (source)

Undocumented

_continuousPolling = (source)

Undocumented

_justStopped: bool = (source)
overrides twisted.internet.base.ReactorBase._justStopped

Undocumented

_readers: Dict[Type[FileDescriptor], int] = (source)

Undocumented

_scheduledAt = (source)

Undocumented

_timerHandle = (source)

Undocumented

_writers: Dict[Type[FileDescriptor], int] = (source)

Undocumented