18.5.1. Base Event Loop¶
Source code: Lib/asyncio/events.py
The event loop is the central execution device provided by asyncio
.
It provides multiple facilities, including:
Registering, executing and cancelling delayed calls (timeouts).
Creating client and server transports for various kinds of communication.
Launching subprocesses and the associated transports for communication with an external program.
Delegating costly function calls to a pool of threads.
-
class
asyncio.
BaseEventLoop
¶ This class is an implementation detail. It is a subclass of
AbstractEventLoop
and may be a base class of concrete event loop implementations found inasyncio
. It should not be used directly; useAbstractEventLoop
instead.BaseEventLoop
should not be subclassed by third-party code; the internal interface is not stable.
-
class
asyncio.
AbstractEventLoop
¶ Abstract base class of event loops.
Esta classe não é seguro para thread.
18.5.1.1. Run an event loop¶
-
AbstractEventLoop.
run_forever
()¶ Run until
stop()
is called. Ifstop()
is called beforerun_forever()
is called, this polls the I/O selector once with a timeout of zero, runs all callbacks scheduled in response to I/O events (and those that were already scheduled), and then exits. Ifstop()
is called whilerun_forever()
is running, this will run the current batch of callbacks and then exit. Note that callbacks scheduled by callbacks will not run in that case; they will run the next timerun_forever()
is called.Alterado na versão 3.5.1.
-
AbstractEventLoop.
run_until_complete
(future)¶ Run until the
Future
is done.If the argument is a coroutine object, it is wrapped by
ensure_future()
.Return the Future’s result, or raise its exception.
-
AbstractEventLoop.
is_running
()¶ Returns running status of event loop.
-
AbstractEventLoop.
stop
()¶ Stop running the event loop.
This causes
run_forever()
to exit at the next suitable opportunity (see there for more details).Alterado na versão 3.5.1.
-
AbstractEventLoop.
is_closed
()¶ Returns
True
if the event loop was closed.Novo na versão 3.4.2.
-
AbstractEventLoop.
close
()¶ Close the event loop. The loop must not be running. Pending callbacks will be lost.
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.
-
coroutine
AbstractEventLoop.
shutdown_asyncgens
()¶ Schedule all currently open asynchronous generator objects to close with an
aclose()
call. After calling this method, the event loop will issue a warning whenever a new asynchronous generator is iterated. Should be used to finalize all scheduled asynchronous generators reliably. Example:try: loop.run_forever() finally: loop.run_until_complete(loop.shutdown_asyncgens()) loop.close()
Novo na versão 3.6.
18.5.1.2. Calls¶
Most asyncio
functions don’t accept keywords. If you want to pass
keywords to your callback, use functools.partial()
. For example,
loop.call_soon(functools.partial(print, "Hello", flush=True))
will call
print("Hello", flush=True)
.
Nota
functools.partial()
is better than lambda
functions, because
asyncio
can inspect functools.partial()
object to display
parameters in debug mode, whereas lambda
functions have a poor
representation.
-
AbstractEventLoop.
call_soon
(callback, *args)¶ Arrange for a callback to be called as soon as possible. The callback is called after
call_soon()
returns, when control returns to the event loop.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
asyncio.Handle
is returned, which can be used to cancel the callback.
-
AbstractEventLoop.
call_soon_threadsafe
(callback, *args)¶ Like
call_soon()
, but thread safe.Veja a seção concorrência e multithreading da documentação.
18.5.1.3. 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 time.time()
.
Nota
Timeouts (relative delay or absolute when) should not exceed one day.
-
AbstractEventLoop.
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
asyncio.Handle
is returned, which can be used to cancel the callback.callback will be called exactly once per call to
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
functools.partial()
.
-
AbstractEventLoop.
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
AbstractEventLoop.time()
.O comportamento deste método é o mesmo que
call_later()
.An instance of
asyncio.Handle
is returned, which can be used to cancel the callback.
-
AbstractEventLoop.
time
()¶ Return the current time, as a
float
value, according to the event loop’s internal clock.
Ver também
A função asyncio.sleep()
.
18.5.1.4. Futuros¶
-
AbstractEventLoop.
create_future
()¶ Create an
asyncio.Future
object attached to the loop.This is a preferred way to create futures in asyncio, as event loop implementations can provide alternative implementations of the Future class (with better performance or instrumentation).
Novo na versão 3.5.2.
18.5.1.5. Tarefas¶
-
AbstractEventLoop.
create_task
(coro)¶ Schedule the execution of a coroutine object: wrap it in a future. Return a
Task
object.Laços de eventos de terceiros podem usar suas próprias subclasses de
Task
para interoperabilidade. Neste caso, o tipo do resultado é uma subclasse deTask
.This method was added in Python 3.4.2. Use the
async()
function to support also older Python versions.Novo na versão 3.4.2.
-
AbstractEventLoop.
set_task_factory
(factory)¶ Set a task factory that will be used by
AbstractEventLoop.create_task()
.If factory is
None
the default task factory will be set.If factory is a callable, it should have a signature matching
(loop, coro)
, where loop will be a reference to the active event loop, coro will be a coroutine object. The callable must return anasyncio.Future
compatible object.Novo na versão 3.4.4.
-
AbstractEventLoop.
get_task_factory
()¶ Return a task factory, or
None
if the default one is in use.Novo na versão 3.4.4.
18.5.1.6. Creating connections¶
-
coroutine
AbstractEventLoop.
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
AF_INET
orAF_INET6
depending on host (or family if specified), socket typeSOCK_STREAM
. protocol_factory must be a callable returning a protocol instance.This method is a coroutine which will try to establish the connection in the background. When successful, the coroutine returns a
(transport, protocol)
pair.A sinopse cronológica da operação subjacente é conforme abaixo:
The connection is established, and a transport is created to represent it.
protocol_factory is called without arguments and must return a protocol instance.
The protocol instance is tied to the transport, and its
connection_made()
method is called.The coroutine returns successfully with the
(transport, protocol)
pair.
O transporte criado é um stream bi-direcional dependente de implementação.
Nota
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 that 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
ssl.SSLContext
object, this context is used to create the transport; if ssl isTrue
, a context with some unspecified default settings is used.Ver também
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 são os endereços familiares, protocolos e sinalizadores opcionais a serem passados por getaddrinfo() para resolução do host. Se fornecidos, eles devem ser todos inteiros e constantes correspondentes do módulo
socket
.sock, if given, should be an existing, already connected
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.
Alterado na versão 3.5: On Windows with
ProactorEventLoop
, SSL/TLS is now supported.Ver também
The
open_connection()
function can be used to get a pair of (StreamReader
,StreamWriter
) instead of a protocol.
-
coroutine
AbstractEventLoop.
create_datagram_endpoint
(protocol_factory, local_addr=None, remote_addr=None, *, family=0, proto=0, flags=0, reuse_address=None, reuse_port=None, allow_broadcast=None, sock=None)¶ Nota
O parâmetro reuse_address não é mais suportado, assim como usar
SO_REUSEADDR
representa uma preocupação de segurança significativa para UDP. Passarreuse_address=True
explicitamente irá levantar uma exceção.When multiple processes with differing UIDs assign sockets to an indentical UDP socket address with
SO_REUSEADDR
, incoming packets can become randomly distributed among the sockets.Para plataformas suportadas, reuse_port pode ser usado como um substituto para funcionalidades similares. Com reuse_port,
SO_REUSEPORT
é usado ao invés, o qual especificamente previne processos com diferentes UIDs de atribuir soquetes para o mesmo endereço do soquete.Cria uma conexão de datagrama.
Create datagram connection: socket family
AF_INET
orAF_INET6
depending on host (or family if specified), socket typeSOCK_DGRAM
. protocol_factory must be a callable returning a protocol instance.This method is a coroutine which will try to establish the connection in the background. When successful, the coroutine returns a
(transport, protocol)
pair.Options changing how the connection is created:
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 usinggetaddrinfo()
.remote_addr, se fornecido, é uma tupla de
(remote_host, remote_port)
usada para conectar o soquete a um endereço remoto. O remote_host e a remote_port são procurados usandogetaddrinfo()
.family, proto, flags são os endereços familiares, protocolo e flags opcionais a serem passados para
getaddrinfo()
para resolução do host. Se fornecido, esses devem ser todos inteiros do módulo de constantessocket
correspondente.reuse_port tells the kernel to allow this endpoint to be bound to the same port as other existing endpoints are bound to, so long as they all set this flag when being created. This option is not supported on Windows and some UNIX’s. If the
SO_REUSEPORT
constant is not defined then this capability is unsupported.allow_broadcast avisa o kernel para permitir que este endpoint envie mensagens para o endereço de broadcast.
sock pode opcionalmente ser especificado em ordem para usar um objeto
socket.socket
pre-existente, já conectado, para ser usado pelo transporte. Se especificado, local_addr e remote_addr devem ser omitidos (devem serNone
).
On Windows with
ProactorEventLoop
, this method is not supported.Veja protocolo UDP eco cliente e protocolo UDP eco servidor para exemplos.
Alterado na versão 3.4.4: Os parâmetros family, proto, flags, reuse_address, reuse_port, *allow_broadcast, e sock foram adicionados.
Alterado na versão 3.6.10: The reuse_address parameter is no longer supporter due to security concerns
-
coroutine
AbstractEventLoop.
create_unix_connection
(protocol_factory, path, *, ssl=None, sock=None, server_hostname=None)¶ Create UNIX connection: socket family
AF_UNIX
, socket typeSOCK_STREAM
. TheAF_UNIX
socket family is used to communicate between processes on the same machine efficiently.This method is a coroutine which will try to establish the connection in the background. When successful, the coroutine returns a
(transport, protocol)
pair.path is the name of a UNIX domain socket, and is required unless a sock parameter is specified. Abstract UNIX sockets,
str
, andbytes
paths are supported.See the
AbstractEventLoop.create_connection()
method for parameters.Availability: UNIX.
18.5.1.7. Creating listening connections¶
-
coroutine
AbstractEventLoop.
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, reuse_port=None)¶ Create a TCP server (socket type
SOCK_STREAM
) bound to host and port.Return a
Server
object, itssockets
attribute contains created sockets. Use theServer.close()
method to stop the server: close listening sockets.Parâmetros:
The host parameter can be a string, in that case the TCP server is bound to host and port. The host parameter can also be a sequence of strings and in that case the TCP server is bound to all hosts of the sequence. 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
socket.AF_INET
orAF_INET6
to force the socket to use IPv4 or IPv6. If not set it will be determined from host (defaults tosocket.AF_UNSPEC
).flags é uma máscara de bits para
getaddrinfo()
.sock can optionally be specified in order to use a preexisting socket object. If specified, host and port should be omitted (must be
None
).backlog é o número máximo de conexões enfileiradas pasadas para
listen()
(padrão é 100).ssl pode ser definido para um
SSLContext
para habilitar SSL sobre as conexões aceitas.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.reuse_port diz ao kernel para permitir que este endpoint seja vinculado a mesma porta que outros endpoints existentes estão vinculados, contanto que todos eles definam este sinalizador quando forem criados. Esta opção não é suportada no Windows.
This method is a coroutine.
Alterado na versão 3.5: On Windows with
ProactorEventLoop
, SSL/TLS is now supported.Ver também
The function
start_server()
creates a (StreamReader
,StreamWriter
) pair and calls back a function with this pair.Alterado na versão 3.5.1: The host parameter can now be a sequence of strings.
-
coroutine
AbstractEventLoop.
create_unix_server
(protocol_factory, path=None, *, sock=None, backlog=100, ssl=None)¶ Similar to
AbstractEventLoop.create_server()
, but specific to the socket familyAF_UNIX
.This method is a coroutine.
Availability: UNIX.
-
coroutine
BaseEventLoop.
connect_accepted_socket
(protocol_factory, sock, *, ssl=None)¶ Handle an accepted connection.
This is used by servers that accept connections outside of asyncio but that use asyncio to handle them.
Parâmetros:
sock is a preexisting socket object returned from an
accept
call.ssl pode ser definido para um
SSLContext
para habilitar SSL sobre as conexões aceitas.
This method is a coroutine. When completed, the coroutine returns a
(transport, protocol)
pair.Novo na versão 3.5.3.
18.5.1.8. Watch file descriptors¶
On Windows with SelectorEventLoop
, only socket handles are supported
(ex: pipe file descriptors are not supported).
On Windows with ProactorEventLoop
, these methods are not supported.
-
AbstractEventLoop.
add_reader
(fd, callback, *args)¶ Start watching the file descriptor for read availability and then call the callback with specified arguments.
-
AbstractEventLoop.
remove_reader
(fd)¶ Stop watching the file descriptor for read availability.
-
AbstractEventLoop.
add_writer
(fd, callback, *args)¶ Start watching the file descriptor for write availability and then call the callback with specified arguments.
-
AbstractEventLoop.
remove_writer
(fd)¶ Stop watching the file descriptor for write availability.
The watch a file descriptor for read events
example uses the low-level AbstractEventLoop.add_reader()
method to register
the file descriptor of a socket.
18.5.1.9. Low-level socket operations¶
-
coroutine
AbstractEventLoop.
sock_recv
(sock, nbytes)¶ Receive data from the socket. Modeled after blocking
socket.socket.recv()
method.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.
With
SelectorEventLoop
event loop, the socket sock must be non-blocking.This method is a coroutine.
-
coroutine
AbstractEventLoop.
sock_sendall
(sock, data)¶ Send data to the socket. Modeled after blocking
socket.socket.sendall()
method.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.With
SelectorEventLoop
event loop, the socket sock must be non-blocking.This method is a coroutine.
-
coroutine
AbstractEventLoop.
sock_connect
(sock, address)¶ Connect to a remote socket at address. Modeled after blocking
socket.socket.connect()
method.With
SelectorEventLoop
event loop, the socket sock must be non-blocking.This method is a coroutine.
Alterado na versão 3.5.2:
address
no longer needs to be resolved.sock_connect
will try to check if the address is already resolved by callingsocket.inet_pton()
. If not,AbstractEventLoop.getaddrinfo()
will be used to resolve the address.Ver também
AbstractEventLoop.create_connection()
andasyncio.open_connection()
.
-
coroutine
AbstractEventLoop.
sock_accept
(sock)¶ Accept a connection. Modeled after blocking
socket.socket.accept()
.O soquete deve estar vinculado a um endereço e escutando por conexões. O valor de retorno é um par
(conn, address)
onde conn é um novo objeto de soquete usável para enviar e receber dados na conexão, e address é o endereço vinculado ao soquete no outro extremo da conexão.The socket sock must be non-blocking.
This method is a coroutine.
Ver também
18.5.1.10. Resolve host name¶
-
coroutine
AbstractEventLoop.
getaddrinfo
(host, port, *, family=0, type=0, proto=0, flags=0)¶ This method is a coroutine, similar to
socket.getaddrinfo()
function but non-blocking.
-
coroutine
AbstractEventLoop.
getnameinfo
(sockaddr, flags=0)¶ This method is a coroutine, similar to
socket.getnameinfo()
function but non-blocking.
18.5.1.11. Connect pipes¶
On Windows with SelectorEventLoop
, these methods are not supported.
Use ProactorEventLoop
to support pipes on Windows.
-
coroutine
AbstractEventLoop.
connect_read_pipe
(protocol_factory, pipe)¶ Register read pipe in eventloop.
protocol_factory should instantiate object with
Protocol
interface. pipe is a file-like object. Return pair(transport, protocol)
, where transport supports theReadTransport
interface.Com o
SelectorEventLoop
do laço de eventos, o pipe é definido para modo não bloqueante.This method is a coroutine.
-
coroutine
AbstractEventLoop.
connect_write_pipe
(protocol_factory, pipe)¶ Register write pipe in eventloop.
protocol_factory should instantiate object with
BaseProtocol
interface. pipe is file-like object. Return pair(transport, protocol)
, where transport supportsWriteTransport
interface.Com o
SelectorEventLoop
do laço de eventos, o pipe é definido para modo não bloqueante.This method is a coroutine.
Ver também
The AbstractEventLoop.subprocess_exec()
and
AbstractEventLoop.subprocess_shell()
methods.
18.5.1.12. UNIX signals¶
Availability: UNIX only.
-
AbstractEventLoop.
add_signal_handler
(signum, callback, *args)¶ Add a handler for a signal.
Levanta
ValueError
se o número do sinal é inválido ou impossível de capturar. LevantaRuntimeError
se existe um problema definindo o tratador.
-
AbstractEventLoop.
remove_signal_handler
(sig)¶ Remove a handler for a signal.
Return
True
if a signal handler was removed,False
if not.
Ver também
O módulo signal
.
18.5.1.13. Executor¶
Call a function in an Executor
(pool of threads or
pool of processes). By default, an event loop uses a thread pool executor
(ThreadPoolExecutor
).
-
coroutine
AbstractEventLoop.
run_in_executor
(executor, func, *args)¶ Arrange for a func to be called in the specified executor.
The executor argument should be an
Executor
instance. The default executor is used if executor isNone
.Use functools.partial to pass keywords to the *func*.
This method is a coroutine.
Alterado na versão 3.5.3:
BaseEventLoop.run_in_executor()
no longer configures themax_workers
of the thread pool executor it creates, instead leaving it up to the thread pool executor (ThreadPoolExecutor
) to set the default.
-
AbstractEventLoop.
set_default_executor
(executor)¶ Set the default executor used by
run_in_executor()
.
18.5.1.14. Tratando erros da API¶
Permite customizar como exceções são tratadas no laço de eventos.
-
AbstractEventLoop.
set_exception_handler
(handler)¶ Define handler como o novo tratador de exceções do laço de eventos.
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)
, whereloop
will be a reference to the active event loop,context
will be adict
object (seecall_exception_handler()
documentation for details about context).
-
AbstractEventLoop.
get_exception_handler
()¶ Return the exception handler, or
None
if the default one is in use.Novo na versão 3.5.2.
-
AbstractEventLoop.
default_exception_handler
(context)¶ Tratador de exceção padrão.
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.
parâmetro context tem o mesmo significado que em
call_exception_handler()
.
-
AbstractEventLoop.
call_exception_handler
(context)¶ Chama o tratador de exceção do laço de eventos atual.
context is a
dict
object containing the following keys (new keys may be introduced later):‘message’: Mensagem de erro;
‘exception’ (opcional): Objeto Exception;
‘future’ (opcional): instância de
asyncio.Future
;‘handle’ (opcional): instância de
asyncio.Handle
;‘protocol’ (opcional): instância de Protocol;
‘transport’ (opcional): instância de Transport;
‘socket’ (optional):
socket.socket
instance.
Nota
Note: this method should not be overloaded in subclassed event loops. For any custom exception handling, use
set_exception_handler()
method.
18.5.1.15. Debug mode¶
-
AbstractEventLoop.
get_debug
()¶ Obtém o modo de debug (
bool
) do laço de eventos.O valor padrão é
True
se a variável de ambientePYTHONASYNCIODEBUG
estiver definida para uma string não vazia,False
caso contrário.Novo na versão 3.4.2.
-
AbstractEventLoop.
set_debug
(enabled: bool)¶ Define o modo de debug do laço de eventos.
Novo na versão 3.4.2.
Ver também
18.5.1.16. Server¶
-
class
asyncio.
Server
¶ Server listening on sockets.
Object created by the
AbstractEventLoop.create_server()
method and thestart_server()
function. Don’t instantiate the class directly.-
close
()¶ Para de servir: fecha soquetes que estavam ouvindo e define o atributo
sockets
paraNone
.Os soquetes que representam conexões de clientes existentes que estão chegando são deixados em aberto.
O servidor é fechado de forma assíncrona, use a corrotina
wait_closed()
para aguartar até que o servidor esteja fechado.
-
sockets
¶ List of
socket.socket
objects the server is listening to, orNone
if the server is closed.
-
18.5.1.17. Handle¶
-
class
asyncio.
Handle
¶ A callback wrapper object returned by
AbstractEventLoop.call_soon()
,AbstractEventLoop.call_soon_threadsafe()
,AbstractEventLoop.call_later()
, andAbstractEventLoop.call_at()
.-
cancel
()¶ Cancel the call. If the callback is already canceled or executed, this method has no effect.
-
18.5.1.18. Event loop examples¶
18.5.1.18.1. Hello World com call_soon()¶
Example using the AbstractEventLoop.call_soon()
method to schedule a
callback. The callback displays "Hello World"
and then stops the event
loop:
import asyncio
def hello_world(loop):
print('Hello World')
loop.stop()
loop = asyncio.get_event_loop()
# Schedule a call to hello_world()
loop.call_soon(hello_world, loop)
# Blocking call interrupted by loop.stop()
loop.run_forever()
loop.close()
Ver também
The Hello World coroutine example uses a coroutine.
18.5.1.18.2. Exibe a data atual com call_later()¶
Example of callback displaying the current date every second. The callback uses
the AbstractEventLoop.call_later()
method to reschedule itself during 5
seconds, and then stops the event loop:
import asyncio
import datetime
def display_date(end_time, loop):
print(datetime.datetime.now())
if (loop.time() + 1.0) < end_time:
loop.call_later(1, display_date, end_time, loop)
else:
loop.stop()
loop = asyncio.get_event_loop()
# Schedule the first call to display_date()
end_time = loop.time() + 5.0
loop.call_soon(display_date, end_time, loop)
# Blocking call interrupted by loop.stop()
loop.run_forever()
loop.close()
Ver também
The coroutine displaying the current date example uses a coroutine.
18.5.1.18.3. Observa um descritor de arquivo por eventos de leitura¶
Wait until a file descriptor received some data using the
AbstractEventLoop.add_reader()
method and then close the event loop:
import asyncio
try:
from socket import socketpair
except ImportError:
from asyncio.windows_utils import socketpair
# Create a pair of connected file descriptors
rsock, wsock = socketpair()
loop = asyncio.get_event_loop()
def reader():
data = rsock.recv(100)
print("Received:", data.decode())
# We are done: unregister the file descriptor
loop.remove_reader(rsock)
# Stop the event loop
loop.stop()
# Register the file descriptor for read event
loop.add_reader(rsock, reader)
# Simulate the reception of data from the network
loop.call_soon(wsock.send, 'abc'.encode())
# Run the event loop
loop.run_forever()
# We are done, close sockets and the event loop
rsock.close()
wsock.close()
loop.close()
Ver também
The register an open socket to wait for data using a protocol example uses a low-level protocol created by the
AbstractEventLoop.create_connection()
method.
The register an open socket to wait for data using streams example uses high-level streams
created by the open_connection()
function in a coroutine.
18.5.1.18.4. Define tratadores de sinais para SIGINT e SIGTERM¶
Register handlers for signals SIGINT
and SIGTERM
using
the AbstractEventLoop.add_signal_handler()
method:
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())
try:
loop.run_forever()
finally:
loop.close()
This example only works on UNIX.