mirror of https://github.com/python/cpython
669 lines
21 KiB
ReStructuredText
669 lines
21 KiB
ReStructuredText
.. currentmodule:: asyncio
|
|
|
|
.. _asyncio-event-loop:
|
|
|
|
Event loops
|
|
===========
|
|
|
|
The event loop is the central execution device provided by :mod:`asyncio`.
|
|
It provides multiple facilities, amongst which:
|
|
|
|
* Registering, executing and cancelling delayed calls (timeouts).
|
|
|
|
* Creating client and server :ref:`transports <asyncio-transport>` for various
|
|
kinds of communication.
|
|
|
|
* Launching subprocesses and the associated :ref:`transports
|
|
<asyncio-transport>` for communication with an external program.
|
|
|
|
* Delegating costly function calls to a pool of threads.
|
|
|
|
Event loop policies and the default policy
|
|
------------------------------------------
|
|
|
|
Event loop management is abstracted with a *policy* pattern, to provide maximal
|
|
flexibility for custom platforms and frameworks. Throughout the execution of a
|
|
process, a single global policy object manages the event loops available to the
|
|
process based on the calling context. A policy is an object implementing the
|
|
:class:`AbstractEventLoopPolicy` interface.
|
|
|
|
For most users of :mod:`asyncio`, policies never have to be dealt with
|
|
explicitly, since the default global policy is sufficient.
|
|
|
|
The default policy defines context as the current thread, and manages an event
|
|
loop per thread that interacts with :mod:`asyncio`. The module-level functions
|
|
:func:`get_event_loop` and :func:`set_event_loop` provide convenient access to
|
|
event loops managed by the default policy.
|
|
|
|
Event loop functions
|
|
--------------------
|
|
|
|
The following functions are convenient shortcuts to accessing the methods of the
|
|
global policy. Note that this provides access to the default policy, unless an
|
|
alternative policy was set by calling :func:`set_event_loop_policy` earlier in
|
|
the execution of the process.
|
|
|
|
.. function:: get_event_loop()
|
|
|
|
Equivalent to calling ``get_event_loop_policy().get_event_loop()``.
|
|
|
|
.. function:: set_event_loop(loop)
|
|
|
|
Equivalent to calling ``get_event_loop_policy().set_event_loop(loop)``.
|
|
|
|
.. function:: new_event_loop()
|
|
|
|
Equivalent to calling ``get_event_loop_policy().new_event_loop()``.
|
|
|
|
Event loop policy interface
|
|
---------------------------
|
|
|
|
An event loop policy must implement the following interface:
|
|
|
|
.. class:: AbstractEventLoopPolicy
|
|
|
|
.. method:: get_event_loop()
|
|
|
|
Get the event loop for current context. Returns an event loop object
|
|
implementing :class:`BaseEventLoop` interface, or raises an exception in case
|
|
no event loop has been set for the current context and the current policy
|
|
does not specify to create one. It should never return ``None``.
|
|
|
|
.. method:: set_event_loop(loop)
|
|
|
|
Set the event loop of the current context to *loop*.
|
|
|
|
.. method:: new_event_loop()
|
|
|
|
Create and return a new event loop object according to this policy's rules.
|
|
If there's need to set this loop as the event loop of the current context,
|
|
:meth:`set_event_loop` must be called explicitly.
|
|
|
|
Access to the global loop policy
|
|
--------------------------------
|
|
|
|
.. function:: get_event_loop_policy()
|
|
|
|
Get the current event loop policy.
|
|
|
|
.. function:: set_event_loop_policy(policy)
|
|
|
|
Set the current event loop policy. If *policy* is ``None``, the default
|
|
policy is restored.
|
|
|
|
Run an event loop
|
|
-----------------
|
|
|
|
.. method:: BaseEventLoop.run_forever()
|
|
|
|
Run until :meth:`stop` is called.
|
|
|
|
.. method:: BaseEventLoop.run_until_complete(future)
|
|
|
|
Run until the :class:`Future` is done.
|
|
|
|
If the argument is a :ref:`coroutine <coroutine>`, it is wrapped
|
|
in a :class:`Task`.
|
|
|
|
Return the Future's result, or raise its exception.
|
|
|
|
.. method:: BaseEventLoop.is_running()
|
|
|
|
Returns running status of event loop.
|
|
|
|
.. method:: BaseEventLoop.stop()
|
|
|
|
Stop running the event loop.
|
|
|
|
Every callback scheduled before :meth:`stop` is called will run.
|
|
Callback scheduled after :meth:`stop` is called won't. However, those
|
|
callbacks will run if :meth:`run_forever` is called again later.
|
|
|
|
.. method:: BaseEventLoop.close()
|
|
|
|
Close the event loop. The loop should not be running.
|
|
|
|
This clears the queues and shuts down the executor, but does not wait for
|
|
the executor to finish.
|
|
|
|
This is idempotent and irreversible. No other methods should be called after
|
|
this one.
|
|
|
|
|
|
Calls
|
|
-----
|
|
|
|
.. method:: BaseEventLoop.call_soon(callback, \*args)
|
|
|
|
Arrange for a callback to be called as soon as possible.
|
|
|
|
This operates as a FIFO queue, callbacks are called in the order in
|
|
which they are registered. Each callback will be called exactly once.
|
|
|
|
Any positional arguments after the callback will be passed to the
|
|
callback when it is called.
|
|
|
|
An instance of :class:`asyncio.Handle` is returned.
|
|
|
|
.. method:: BaseEventLoop.call_soon_threadsafe(callback, \*args)
|
|
|
|
Like :meth:`call_soon`, but thread safe.
|
|
|
|
|
|
.. _asyncio-delayed-calls:
|
|
|
|
Delayed calls
|
|
-------------
|
|
|
|
The event loop has its own internal clock for computing timeouts.
|
|
Which clock is used depends on the (platform-specific) event loop
|
|
implementation; ideally it is a monotonic clock. This will generally be
|
|
a different clock than :func:`time.time`.
|
|
|
|
.. note::
|
|
|
|
Timeouts (relative *delay* or absolute *when*) should not exceed one day.
|
|
|
|
|
|
.. method:: BaseEventLoop.call_later(delay, callback, *args)
|
|
|
|
Arrange for the *callback* to be called after the given *delay*
|
|
seconds (either an int or float).
|
|
|
|
An instance of :class:`asyncio.Handle` is returned.
|
|
|
|
*callback* will be called exactly once per call to :meth:`call_later`.
|
|
If two callbacks are scheduled for exactly the same time, it is
|
|
undefined which will be called first.
|
|
|
|
The optional positional *args* will be passed to the callback when it
|
|
is called. If you want the callback to be called with some named
|
|
arguments, use a closure or :func:`functools.partial`.
|
|
|
|
.. method:: BaseEventLoop.call_at(when, callback, *args)
|
|
|
|
Arrange for the *callback* to be called at the given absolute timestamp
|
|
*when* (an int or float), using the same time reference as :meth:`time`.
|
|
|
|
This method's behavior is the same as :meth:`call_later`.
|
|
|
|
.. method:: BaseEventLoop.time()
|
|
|
|
Return the current time, as a :class:`float` value, according to the
|
|
event loop's internal clock.
|
|
|
|
.. seealso::
|
|
|
|
The :func:`asyncio.sleep` function.
|
|
|
|
|
|
Creating connections
|
|
--------------------
|
|
|
|
.. method:: BaseEventLoop.create_connection(protocol_factory, host=None, port=None, \*, ssl=None, family=0, proto=0, flags=0, sock=None, local_addr=None, server_hostname=None)
|
|
|
|
Create a streaming transport connection to a given Internet *host* and
|
|
*port*: socket family :py:data:`~socket.AF_INET` or
|
|
:py:data:`~socket.AF_INET6` depending on *host* (or *family* if specified),
|
|
socket type :py:data:`~socket.SOCK_STREAM`. *protocol_factory* must be a
|
|
callable returning a :ref:`protocol <asyncio-protocol>` instance.
|
|
|
|
This method is a :ref:`coroutine <coroutine>` which will try to
|
|
establish the connection in the background. When successful, the
|
|
coroutine returns a ``(transport, protocol)`` pair.
|
|
|
|
The chronological synopsis of the underlying operation is as follows:
|
|
|
|
#. The connection is established, and a :ref:`transport <asyncio-transport>`
|
|
is created to represent it.
|
|
|
|
#. *protocol_factory* is called without arguments and must return a
|
|
:ref:`protocol <asyncio-protocol>` instance.
|
|
|
|
#. The protocol instance is tied to the transport, and its
|
|
:meth:`connection_made` method is called.
|
|
|
|
#. The coroutine returns successfully with the ``(transport, protocol)``
|
|
pair.
|
|
|
|
The created transport is an implementation-dependent bidirectional stream.
|
|
|
|
.. note::
|
|
*protocol_factory* can be any kind of callable, not necessarily
|
|
a class. For example, if you want to use a pre-created
|
|
protocol instance, you can pass ``lambda: my_protocol``.
|
|
|
|
Options allowing to change how the connection is created:
|
|
|
|
* *ssl*: if given and not false, a SSL/TLS transport is created
|
|
(by default a plain TCP transport is created). If *ssl* is
|
|
a :class:`ssl.SSLContext` object, this context is used to create
|
|
the transport; if *ssl* is :const:`True`, a context with some
|
|
unspecified default settings is used.
|
|
|
|
.. seealso:: :ref:`SSL/TLS security considerations <ssl-security>`
|
|
|
|
* *server_hostname*, is only for use together with *ssl*,
|
|
and sets or overrides the hostname that the target server's certificate
|
|
will be matched against. By default the value of the *host* argument
|
|
is used. If *host* is empty, there is no default and you must pass a
|
|
value for *server_hostname*. If *server_hostname* is an empty
|
|
string, hostname matching is disabled (which is a serious security
|
|
risk, allowing for man-in-the-middle-attacks).
|
|
|
|
* *family*, *proto*, *flags* are the optional address family, protocol
|
|
and flags to be passed through to getaddrinfo() for *host* resolution.
|
|
If given, these should all be integers from the corresponding
|
|
:mod:`socket` module constants.
|
|
|
|
* *sock*, if given, should be an existing, already connected
|
|
:class:`socket.socket` object to be used by the transport.
|
|
If *sock* is given, none of *host*, *port*, *family*, *proto*, *flags*
|
|
and *local_addr* should be specified.
|
|
|
|
* *local_addr*, if given, is a ``(local_host, local_port)`` tuple used
|
|
to bind the socket to locally. The *local_host* and *local_port*
|
|
are looked up using getaddrinfo(), similarly to *host* and *port*.
|
|
|
|
.. seealso::
|
|
|
|
The :func:`open_connection` function can be used to get a pair of
|
|
(:class:`StreamReader`, :class:`StreamWriter`) instead of a protocol.
|
|
|
|
|
|
.. method:: BaseEventLoop.create_datagram_endpoint(protocol_factory, local_addr=None, remote_addr=None, \*, family=0, proto=0, flags=0)
|
|
|
|
Create datagram connection: socket family :py:data:`~socket.AF_INET` or
|
|
:py:data:`~socket.AF_INET6` depending on *host* (or *family* if specified),
|
|
socket type :py:data:`~socket.SOCK_DGRAM`.
|
|
|
|
This method is a :ref:`coroutine <coroutine>` which will try to
|
|
establish the connection in the background. When successful, the
|
|
coroutine returns a ``(transport, protocol)`` pair.
|
|
|
|
See the :meth:`BaseEventLoop.create_connection` method for parameters.
|
|
|
|
|
|
.. method:: BaseEventLoop.create_unix_connection(protocol_factory, path, \*, ssl=None, sock=None, server_hostname=None)
|
|
|
|
Create UNIX connection: socket family :py:data:`~socket.AF_UNIX`, socket
|
|
type :py:data:`~socket.SOCK_STREAM`. The :py:data:`~socket.AF_UNIX` socket
|
|
family is used to communicate between processes on the same machine
|
|
efficiently.
|
|
|
|
This method is a :ref:`coroutine <coroutine>` which will try to
|
|
establish the connection in the background. When successful, the
|
|
coroutine returns a ``(transport, protocol)`` pair.
|
|
|
|
See the :meth:`BaseEventLoop.create_connection` method for parameters.
|
|
|
|
Availability: UNIX.
|
|
|
|
|
|
Creating listening connections
|
|
------------------------------
|
|
|
|
.. method:: BaseEventLoop.create_server(protocol_factory, host=None, port=None, \*, family=socket.AF_UNSPEC, flags=socket.AI_PASSIVE, sock=None, backlog=100, ssl=None, reuse_address=None)
|
|
|
|
A :ref:`coroutine <coroutine>` method which creates a TCP server bound to
|
|
host and port.
|
|
|
|
The return value is a :class:`AbstractServer` object which can be used to stop
|
|
the service.
|
|
|
|
If *host* is an empty string or None all interfaces are assumed
|
|
and a list of multiple sockets will be returned (most likely
|
|
one for IPv4 and another one for IPv6).
|
|
|
|
*family* can be set to either :data:`~socket.AF_INET` or
|
|
:data:`~socket.AF_INET6` to force the socket to use IPv4 or IPv6. If not set
|
|
it will be determined from host (defaults to :data:`~socket.AF_UNSPEC`).
|
|
|
|
*flags* is a bitmask for :meth:`getaddrinfo`.
|
|
|
|
*sock* can optionally be specified in order to use a preexisting
|
|
socket object.
|
|
|
|
*backlog* is the maximum number of queued connections passed to
|
|
:meth:`~socket.socket.listen` (defaults to 100).
|
|
|
|
ssl can be set to an :class:`~ssl.SSLContext` to enable SSL over the
|
|
accepted connections.
|
|
|
|
*reuse_address* tells the kernel to reuse a local socket in
|
|
TIME_WAIT state, without waiting for its natural timeout to
|
|
expire. If not specified will automatically be set to True on
|
|
UNIX.
|
|
|
|
.. seealso::
|
|
|
|
The function :func:`start_server` creates a (:class:`StreamReader`,
|
|
:class:`StreamWriter`) pair and calls back a function with this pair.
|
|
|
|
|
|
.. method:: BaseEventLoop.create_unix_server(protocol_factory, path=None, \*, sock=None, backlog=100, ssl=None)
|
|
|
|
Similar to :meth:`BaseEventLoop.create_server`, but specific to the
|
|
socket family :py:data:`~socket.AF_UNIX`.
|
|
|
|
Availability: UNIX.
|
|
|
|
|
|
|
|
Watch file descriptors
|
|
----------------------
|
|
|
|
.. method:: BaseEventLoop.add_reader(fd, callback, \*args)
|
|
|
|
Start watching the file descriptor for read availability and then call the
|
|
*callback* with specified arguments.
|
|
|
|
.. method:: BaseEventLoop.remove_reader(fd)
|
|
|
|
Stop watching the file descriptor for read availability.
|
|
|
|
.. method:: BaseEventLoop.add_writer(fd, callback, \*args)
|
|
|
|
Start watching the file descriptor for write availability and then call the
|
|
*callback* with specified arguments.
|
|
|
|
.. method:: BaseEventLoop.remove_writer(fd)
|
|
|
|
Stop watching the file descriptor for write availability.
|
|
|
|
|
|
Low-level socket operations
|
|
---------------------------
|
|
|
|
.. method:: BaseEventLoop.sock_recv(sock, nbytes)
|
|
|
|
Receive data from the socket. The return value is a bytes object
|
|
representing the data received. The maximum amount of data to be received
|
|
at once is specified by *nbytes*.
|
|
|
|
This method is a :ref:`coroutine <coroutine>`.
|
|
|
|
.. seealso::
|
|
|
|
The :meth:`socket.socket.recv` method.
|
|
|
|
.. method:: BaseEventLoop.sock_sendall(sock, data)
|
|
|
|
Send data to the socket. The socket must be connected to a remote socket.
|
|
This method continues to send data from *data* until either all data has
|
|
been sent or an error occurs. ``None`` is returned on success. On error,
|
|
an exception is raised, and there is no way to determine how much data, if
|
|
any, was successfully processed by the receiving end of the connection.
|
|
|
|
This method is a :ref:`coroutine <coroutine>`.
|
|
|
|
.. seealso::
|
|
|
|
The :meth:`socket.socket.sendall` method.
|
|
|
|
.. method:: BaseEventLoop.sock_connect(sock, address)
|
|
|
|
Connect to a remote socket at *address*.
|
|
|
|
The *address* must be already resolved to avoid the trap of hanging the
|
|
entire event loop when the address requires doing a DNS lookup. For
|
|
example, it must be an IP address, not an hostname, for
|
|
:py:data:`~socket.AF_INET` and :py:data:`~socket.AF_INET6` address families.
|
|
Use :meth:`getaddrinfo` to resolve the hostname asynchronously.
|
|
|
|
This method is a :ref:`coroutine <coroutine>`.
|
|
|
|
.. seealso::
|
|
|
|
The :meth:`BaseEventLoop.create_connection` method, the
|
|
:func:`open_connection` function and the :meth:`socket.socket.connect`
|
|
method.
|
|
|
|
|
|
.. method:: BaseEventLoop.sock_accept(sock)
|
|
|
|
Accept a connection. The socket must be bound to an address and listening
|
|
for connections. The return value is a pair ``(conn, address)`` where *conn*
|
|
is a *new* socket object usable to send and receive data on the connection,
|
|
and *address* is the address bound to the socket on the other end of the
|
|
connection.
|
|
|
|
This method is a :ref:`coroutine <coroutine>`.
|
|
|
|
.. seealso::
|
|
|
|
The :meth:`BaseEventLoop.create_server` method, the :func:`start_server`
|
|
function and the :meth:`socket.socket.accept` method.
|
|
|
|
|
|
Resolve host name
|
|
-----------------
|
|
|
|
.. method:: BaseEventLoop.getaddrinfo(host, port, \*, family=0, type=0, proto=0, flags=0)
|
|
|
|
This method is a :ref:`coroutine <coroutine>`, similar to
|
|
:meth:`socket.getaddrinfo` function but non-blocking.
|
|
|
|
.. method:: BaseEventLoop.getnameinfo(sockaddr, flags=0)
|
|
|
|
This method is a :ref:`coroutine <coroutine>`, similar to
|
|
:meth:`socket.getnameinfo` function but non-blocking.
|
|
|
|
|
|
Connect pipes
|
|
-------------
|
|
|
|
.. method:: BaseEventLoop.connect_read_pipe(protocol_factory, pipe)
|
|
|
|
Register read pipe in eventloop.
|
|
|
|
*protocol_factory* should instantiate object with :class:`Protocol`
|
|
interface. pipe is file-like object already switched to nonblocking.
|
|
Return pair (transport, protocol), where transport support
|
|
:class:`ReadTransport` interface.
|
|
|
|
This method is a :ref:`coroutine <coroutine>`.
|
|
|
|
.. method:: BaseEventLoop.connect_write_pipe(protocol_factory, pipe)
|
|
|
|
Register write pipe in eventloop.
|
|
|
|
*protocol_factory* should instantiate object with :class:`BaseProtocol`
|
|
interface. Pipe is file-like object already switched to nonblocking.
|
|
Return pair (transport, protocol), where transport support
|
|
:class:`WriteTransport` interface.
|
|
|
|
This method is a :ref:`coroutine <coroutine>`.
|
|
|
|
.. seealso::
|
|
|
|
The :meth:`BaseEventLoop.subprocess_exec` and
|
|
:meth:`BaseEventLoop.subprocess_shell` methods.
|
|
|
|
|
|
UNIX signals
|
|
------------
|
|
|
|
Availability: UNIX only.
|
|
|
|
.. method:: BaseEventLoop.add_signal_handler(signum, callback, \*args)
|
|
|
|
Add a handler for a signal.
|
|
|
|
Raise :exc:`ValueError` if the signal number is invalid or uncatchable.
|
|
Raise :exc:`RuntimeError` if there is a problem setting up the handler.
|
|
|
|
.. method:: BaseEventLoop.remove_signal_handler(sig)
|
|
|
|
Remove a handler for a signal.
|
|
|
|
Return ``True`` if a signal handler was removed, ``False`` if not.
|
|
|
|
.. seealso::
|
|
|
|
The :mod:`signal` module.
|
|
|
|
|
|
Executor
|
|
--------
|
|
|
|
Call a function in an :class:`~concurrent.futures.Executor` (pool of threads or
|
|
pool of processes). By default, an event loop uses a thread pool executor
|
|
(:class:`~concurrent.futures.ThreadPoolExecutor`).
|
|
|
|
.. method:: BaseEventLoop.run_in_executor(executor, callback, \*args)
|
|
|
|
Arrange for a callback to be called in the specified executor.
|
|
|
|
The *executor* argument should be an :class:`~concurrent.futures.Executor`
|
|
instance. The default executor is used if *executor* is ``None``.
|
|
|
|
This method is a :ref:`coroutine <coroutine>`.
|
|
|
|
.. method:: BaseEventLoop.set_default_executor(executor)
|
|
|
|
Set the default executor used by :meth:`run_in_executor`.
|
|
|
|
|
|
Error Handling API
|
|
------------------
|
|
|
|
Allows to customize how exceptions are handled in the event loop.
|
|
|
|
.. method:: BaseEventLoop.set_exception_handler(handler)
|
|
|
|
Set *handler* as the new event loop exception handler.
|
|
|
|
If *handler* is ``None``, the default exception handler will
|
|
be set.
|
|
|
|
If *handler* is a callable object, it should have a
|
|
matching signature to ``(loop, context)``, where ``loop``
|
|
will be a reference to the active event loop, ``context``
|
|
will be a ``dict`` object (see :meth:`call_exception_handler`
|
|
documentation for details about context).
|
|
|
|
.. method:: BaseEventLoop.default_exception_handler(context)
|
|
|
|
Default exception handler.
|
|
|
|
This is called when an exception occurs and no exception
|
|
handler is set, and can be called by a custom exception
|
|
handler that wants to defer to the default behavior.
|
|
|
|
*context* parameter has the same meaning as in
|
|
:meth:`call_exception_handler`.
|
|
|
|
.. method:: BaseEventLoop.call_exception_handler(context)
|
|
|
|
Call the current event loop exception handler.
|
|
|
|
*context* is a ``dict`` object containing the following keys
|
|
(new keys may be introduced later):
|
|
|
|
* 'message': Error message;
|
|
* 'exception' (optional): Exception object;
|
|
* 'future' (optional): :class:`asyncio.Future` instance;
|
|
* 'handle' (optional): :class:`asyncio.Handle` instance;
|
|
* 'protocol' (optional): :ref:`Protocol <asyncio-protocol>` instance;
|
|
* 'transport' (optional): :ref:`Transport <asyncio-transport>` instance;
|
|
* 'socket' (optional): :class:`socket.socket` instance.
|
|
|
|
.. note::
|
|
|
|
Note: this method should not be overloaded in subclassed
|
|
event loops. For any custom exception handling, use
|
|
:meth:`set_exception_handler()` method.
|
|
|
|
Debug mode
|
|
----------
|
|
|
|
.. method:: BaseEventLoop.get_debug()
|
|
|
|
Get the debug mode (:class:`bool`) of the event loop, ``False`` by default.
|
|
|
|
.. method:: BaseEventLoop.set_debug(enabled: bool)
|
|
|
|
Set the debug mode of the event loop.
|
|
|
|
.. seealso::
|
|
|
|
The :ref:`Develop with asyncio <asyncio-dev>` section.
|
|
|
|
|
|
Server
|
|
------
|
|
|
|
.. class:: AbstractServer
|
|
|
|
Abstract server returned by :func:`BaseEventLoop.create_server`.
|
|
|
|
.. method:: close()
|
|
|
|
Stop serving. This leaves existing connections open.
|
|
|
|
.. method:: wait_closed()
|
|
|
|
A :ref:`coroutine <coroutine>` to wait until service is closed.
|
|
|
|
|
|
Handle
|
|
------
|
|
|
|
.. class:: Handle
|
|
|
|
A callback wrapper object returned by :func:`BaseEventLoop.call_soon`,
|
|
:func:`BaseEventLoop.call_soon_threadsafe`, :func:`BaseEventLoop.call_later`,
|
|
and :func:`BaseEventLoop.call_at`.
|
|
|
|
.. method:: cancel()
|
|
|
|
Cancel the call.
|
|
|
|
|
|
.. _asyncio-hello-world-callback:
|
|
|
|
Example: Hello World (callback)
|
|
-------------------------------
|
|
|
|
Print ``Hello World`` every two seconds, using a callback::
|
|
|
|
import asyncio
|
|
|
|
def print_and_repeat(loop):
|
|
print('Hello World')
|
|
loop.call_later(2, print_and_repeat, loop)
|
|
|
|
loop = asyncio.get_event_loop()
|
|
loop.call_soon(print_and_repeat, loop)
|
|
loop.run_forever()
|
|
|
|
.. seealso::
|
|
|
|
:ref:`Hello World example using a coroutine <asyncio-hello-world-coroutine>`.
|
|
|
|
|
|
Example: Set signal handlers for SIGINT and SIGTERM
|
|
---------------------------------------------------
|
|
|
|
Register handlers for signals :py:data:`SIGINT` and :py:data:`SIGTERM`::
|
|
|
|
import asyncio
|
|
import functools
|
|
import os
|
|
import signal
|
|
|
|
def ask_exit(signame):
|
|
print("got signal %s: exit" % signame)
|
|
loop.stop()
|
|
|
|
loop = asyncio.get_event_loop()
|
|
for signame in ('SIGINT', 'SIGTERM'):
|
|
loop.add_signal_handler(getattr(signal, signame),
|
|
functools.partial(ask_exit, signame))
|
|
|
|
print("Event loop running forever, press CTRL+c to interrupt.")
|
|
print("pid %s: send SIGINT or SIGTERM to exit." % os.getpid())
|
|
loop.run_forever()
|
|
|