.. currentmodule:: asyncio
===================
Low-level API Index
===================
This page lists all low-level asyncio APIs.
Obtaining the Event Loop
========================
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* - :func:`asyncio.get_running_loop`
- The **preferred** function to get the running event loop.
* - :func:`asyncio.get_event_loop`
- Get an event loop instance (running or current via the current policy).
* - :func:`asyncio.set_event_loop`
- Set the event loop as current via the current policy.
* - :func:`asyncio.new_event_loop`
- Create a new event loop.
.. rubric:: Examples
* :ref:`Using asyncio.get_running_loop() <asyncio_example_future>`.
Event Loop Methods
==================
See also the main documentation section about the
:ref:`asyncio-event-loop-methods`.
.. rubric:: Lifecycle
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* - :meth:`loop.run_until_complete`
- Run a Future/Task/awaitable until complete.
* - :meth:`loop.run_forever`
- Run the event loop forever.
* - :meth:`loop.stop`
- Stop the event loop.
* - :meth:`loop.close`
- Close the event loop.
* - :meth:`loop.is_running`
- Return ``True`` if the event loop is running.
* - :meth:`loop.is_closed`
- Return ``True`` if the event loop is closed.
* - ``await`` :meth:`loop.shutdown_asyncgens`
- Close asynchronous generators.
.. rubric:: Debugging
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* - :meth:`loop.set_debug`
- Enable or disable the debug mode.
* - :meth:`loop.get_debug`
- Get the current debug mode.
.. rubric:: Scheduling Callbacks
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* - :meth:`loop.call_soon`
- Invoke a callback soon.
* - :meth:`loop.call_soon_threadsafe`
- A thread-safe variant of :meth:`loop.call_soon`.
* - :meth:`loop.call_later`
- Invoke a callback *after* the given time.
* - :meth:`loop.call_at`
- Invoke a callback *at* the given time.
.. rubric:: Thread/Interpreter/Process Pool
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* - ``await`` :meth:`loop.run_in_executor`
- Run a CPU-bound or other blocking function in
a :mod:`concurrent.futures` executor.
* - :meth:`loop.set_default_executor`
- Set the default executor for :meth:`loop.run_in_executor`.
.. rubric:: Tasks and Futures
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* - :meth:`loop.create_future`
- Create a :class:`Future` object.
* - :meth:`loop.create_task`
- Schedule coroutine as a :class:`Task`.
* - :meth:`loop.set_task_factory`
- Set a factory used by :meth:`loop.create_task` to
create :class:`Tasks <Task>`.
* - :meth:`loop.get_task_factory`
- Get the factory :meth:`loop.create_task` uses
to create :class:`Tasks <Task>`.
.. rubric:: DNS
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* - ``await`` :meth:`loop.getaddrinfo`
- Asynchronous version of :meth:`socket.getaddrinfo`.
* - ``await`` :meth:`loop.getnameinfo`
- Asynchronous version of :meth:`socket.getnameinfo`.
.. rubric:: Networking and IPC
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* - ``await`` :meth:`loop.create_connection`
- Open a TCP connection.
* - ``await`` :meth:`loop.create_server`
- Create a TCP server.
* - ``await`` :meth:`loop.create_unix_connection`
- Open a Unix socket connection.
* - ``await`` :meth:`loop.create_unix_server`
- Create a Unix socket server.
* - ``await`` :meth:`loop.connect_accepted_socket`
- Wrap a :class:`~socket.socket` into a ``(transport, protocol)``
pair.
* - ``await`` :meth:`loop.create_datagram_endpoint`
- Open a datagram (UDP) connection.
* - ``await`` :meth:`loop.sendfile`
- Send a file over a transport.
* - ``await`` :meth:`loop.start_tls`
- Upgrade an existing connection to TLS.
* - ``await`` :meth:`loop.connect_read_pipe`
- Wrap a read end of a pipe into a ``(transport, protocol)`` pair.
* - ``await`` :meth:`loop.connect_write_pipe`
- Wrap a write end of a pipe into a ``(transport, protocol)`` pair.
.. rubric:: Sockets
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* - ``await`` :meth:`loop.sock_recv`
- Receive data from the :class:`~socket.socket`.
* - ``await`` :meth:`loop.sock_recv_into`
- Receive data from the :class:`~socket.socket` into a buffer.
* - ``await`` :meth:`loop.sock_recvfrom`
- Receive a datagram from the :class:`~socket.socket`.
* - ``await`` :meth:`loop.sock_recvfrom_into`
- Receive a datagram from the :class:`~socket.socket` into a buffer.
* - ``await`` :meth:`loop.sock_sendall`
- Send data to the :class:`~socket.socket`.
* - ``await`` :meth:`loop.sock_sendto`
- Send a datagram via the :class:`~socket.socket` to the given address.
* - ``await`` :meth:`loop.sock_connect`
- Connect the :class:`~socket.socket`.
* - ``await`` :meth:`loop.sock_accept`
- Accept a :class:`~socket.socket` connection.
* - ``await`` :meth:`loop.sock_sendfile`
- Send a file over the :class:`~socket.socket`.
* - :meth:`loop.add_reader`
- Start watching a file descriptor for read availability.
* - :meth:`loop.remove_reader`
- Stop watching a file descriptor for read availability.
* - :meth:`loop.add_writer`
- Start watching a file descriptor for write availability.
* - :meth:`loop.remove_writer`
- Stop watching a file descriptor for write availability.
.. rubric:: Unix Signals
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* - :meth:`loop.add_signal_handler`
- Add a handler for a :mod:`signal`.
* - :meth:`loop.remove_signal_handler`
- Remove a handler for a :mod:`signal`.
.. rubric:: Subprocesses
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* - :meth:`loop.subprocess_exec`
- Spawn a subprocess.
* - :meth:`loop.subprocess_shell`
- Spawn a subprocess from a shell command.
.. rubric:: Error Handling
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* - :meth:`loop.call_exception_handler`
- Call the exception handler.
* - :meth:`loop.set_exception_handler`
- Set a new exception handler.
* - :meth:`loop.get_exception_handler`
- Get the current exception handler.
* - :meth:`loop.default_exception_handler`
- The default exception handler implementation.
.. rubric:: Examples
* :ref:`Using asyncio.new_event_loop() and loop.run_forever()
<asyncio_example_lowlevel_helloworld>`.
* :ref:`Using loop.call_later() <asyncio_example_call_later>`.
* Using ``loop.create_connection()`` to implement
:ref:`an echo-client <asyncio_example_tcp_echo_client_protocol>`.
* Using ``loop.create_connection()`` to
:ref:`connect a socket <asyncio_example_create_connection>`.
* :ref:`Using add_reader() to watch an FD for read events
<asyncio_example_watch_fd>`.
* :ref:`Using loop.add_signal_handler() <asyncio_example_unix_signals>`.
* :ref:`Using loop.subprocess_exec() <asyncio_example_subprocess_proto>`.
Transports
==========
All transports implement the following methods:
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* - :meth:`transport.close() <BaseTransport.close>`
- Close the transport.
* - :meth:`transport.is_closing() <BaseTransport.is_closing>`
- Return ``True`` if the transport is closing or is closed.
* - :meth:`transport.get_extra_info() <BaseTransport.get_extra_info>`
- Request for information about the transport.
* - :meth:`transport.set_protocol() <BaseTransport.set_protocol>`
- Set a new protocol.
* - :meth:`transport.get_protocol() <BaseTransport.get_protocol>`
- Return the current protocol.
Transports that can receive data (TCP and Unix connections,
pipes, etc). Returned from methods like
:meth:`loop.create_connection`, :meth:`loop.create_unix_connection`,
:meth:`loop.connect_read_pipe`, etc:
.. rubric:: Read Transports
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* - :meth:`transport.is_reading() <ReadTransport.is_reading>`
- Return ``True`` if the transport is receiving.
* - :meth:`transport.pause_reading() <ReadTransport.pause_reading>`
- Pause receiving.
* - :meth:`transport.resume_reading() <ReadTransport.resume_reading>`
- Resume receiving.
Transports that can Send data (TCP and Unix connections,
pipes, etc). Returned from methods like
:meth:`loop.create_connection`, :meth:`loop.create_unix_connection`,
:meth:`loop.connect_write_pipe`, etc:
.. rubric:: Write Transports
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* - :meth:`transport.write() <WriteTransport.write>`
- Write data to the transport.
* - :meth:`transport.writelines() <WriteTransport.writelines>`
- Write buffers to the transport.
* - :meth:`transport.can_write_eof() <WriteTransport.can_write_eof>`
- Return :const:`True` if the transport supports sending EOF.
* - :meth:`transport.write_eof() <WriteTransport.write_eof>`
- Close and send EOF after flushing buffered data.
* - :meth:`transport.abort() <WriteTransport.abort>`
- Close the transport immediately.
* - :meth:`transport.get_write_buffer_size()
<WriteTransport.get_write_buffer_size>`
- Return the current size of the output buffer.
* - :meth:`transport.get_write_buffer_limits()
<WriteTransport.get_write_buffer_limits>`
- Return high and low water marks for write flow control.
* - :meth:`transport.set_write_buffer_limits()
<WriteTransport.set_write_buffer_limits>`
- Set new high and low water marks for write flow control.
Transports returned by :meth:`loop.create_datagram_endpoint`:
.. rubric:: Datagram Transports
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* - :meth:`transport.sendto() <DatagramTransport.sendto>`
- Send data to the remote peer.
* - :meth:`transport.abort() <DatagramTransport.abort>`
- Close the transport immediately.
Low-level transport abstraction over subprocesses.
Returned by :meth:`loop.subprocess_exec` and
:meth:`loop.subprocess_shell`:
.. rubric:: Subprocess Transports
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* - :meth:`transport.get_pid() <SubprocessTransport.get_pid>`
- Return the subprocess process id.
* - :meth:`transport.get_pipe_transport()
<SubprocessTransport.get_pipe_transport>`
- Return the transport for the requested communication pipe
(*stdin*, *stdout*, or *stderr*).
* - :meth:`transport.get_returncode() <SubprocessTransport.get_returncode>`
- Return the subprocess return code.
* - :meth:`transport.kill() <SubprocessTransport.kill>`
- Kill the subprocess.
* - :meth:`transport.send_signal() <SubprocessTransport.send_signal>`
- Send a signal to the subprocess.
* - :meth:`transport.terminate() <SubprocessTransport.terminate>`
- Stop the subprocess.
* - :meth:`transport.close() <SubprocessTransport.close>`
- Kill the subprocess and close all pipes.
Protocols
=========
Protocol classes can implement the following **callback methods**:
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* - ``callback`` :meth:`connection_made() <BaseProtocol.connection_made>`
- Called when a connection is made.
* - ``callback`` :meth:`connection_lost() <BaseProtocol.connection_lost>`
- Called when the connection is lost or closed.
* - ``callback`` :meth:`pause_writing() <BaseProtocol.pause_writing>`
- Called when the transport's buffer goes over the high water mark.
* - ``callback`` :meth:`resume_writing() <BaseProtocol.resume_writing>`
- Called when the transport's buffer drains below the low water mark.
.. rubric:: Streaming Protocols (TCP, Unix Sockets, Pipes)
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* - ``callback`` :meth:`data_received() <Protocol.data_received>`
- Called when some data is received.
* - ``callback`` :meth:`eof_received() <Protocol.eof_received>`
- Called when an EOF is received.
.. rubric:: Buffered Streaming Protocols
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* - ``callback`` :meth:`get_buffer() <BufferedProtocol.get_buffer>`
- Called to allocate a new receive buffer.
* - ``callback`` :meth:`buffer_updated() <BufferedProtocol.buffer_updated>`
- Called when the buffer was updated with the received data.
* - ``callback`` :meth:`eof_received() <BufferedProtocol.eof_received>`
- Called when an EOF is received.
.. rubric:: Datagram Protocols
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* - ``callback`` :meth:`datagram_received()
<DatagramProtocol.datagram_received>`
- Called when a datagram is received.
* - ``callback`` :meth:`error_received() <DatagramProtocol.error_received>`
- Called when a previous send or receive operation raises an
:class:`OSError`.
.. rubric:: Subprocess Protocols
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* - ``callback`` :meth:`~SubprocessProtocol.pipe_data_received`
- Called when the child process writes data into its
*stdout* or *stderr* pipe.
* - ``callback`` :meth:`~SubprocessProtocol.pipe_connection_lost`
- Called when one of the pipes communicating with
the child process is closed.
* - ``callback`` :meth:`process_exited()
<SubprocessProtocol.process_exited>`
- Called when the child process has exited. It can be called before
:meth:`~SubprocessProtocol.pipe_data_received` and
:meth:`~SubprocessProtocol.pipe_connection_lost` methods.
Event Loop Policies
===================
Policies is a low-level mechanism to alter the behavior of
functions like :func:`asyncio.get_event_loop`. See also
the main :ref:`policies section <asyncio-policies>` for more
details.
.. rubric:: Accessing Policies
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* - :meth:`asyncio.get_event_loop_policy`
- Return the current process-wide policy.
* - :meth:`asyncio.set_event_loop_policy`
- Set a new process-wide policy.
* - :class:`AbstractEventLoopPolicy`
- Base class for policy objects.
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