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"""Common code for event loop implementations.""" |
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import logging |
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import signal |
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import threading |
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logger = logging.getLogger(__name__) |
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debug, info, warn = (logger.debug, logger.info, logger.warning,) |
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# When signals are restored, the event loop library may reset SIGINT to SIG_DFL |
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# which exits the program. To be able to restore the python interpreter to it's |
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# default state, we keep a reference to the default handler |
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default_int_handler = signal.getsignal(signal.SIGINT) |
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main_thread = threading.current_thread() |
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class BaseEventLoop(object): |
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"""Abstract base class for all event loops. |
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Event loops act as the bottom layer for Nvim sessions created by this |
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library. They hide system/transport details behind a simple interface for |
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reading/writing bytes to the connected Nvim instance. |
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This class exposes public methods for interacting with the underlying |
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event loop and delegates implementation-specific work to the following |
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methods, which subclasses are expected to implement: |
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- `_init()`: Implementation-specific initialization |
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- `_connect_tcp(address, port)`: connect to Nvim using tcp/ip |
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- `_connect_socket(path)`: Same as tcp, but use a UNIX domain socket or |
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or named pipe. |
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- `_connect_stdio()`: Use stdin/stdout as the connection to Nvim |
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- `_connect_child(argv)`: Use the argument vector `argv` to spawn an |
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embedded Nvim that has it's stdin/stdout connected to the event loop. |
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- `_start_reading()`: Called after any of _connect_* methods. Can be used |
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to perform any post-connection setup or validation. |
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- `_send(data)`: Send `data`(byte array) to Nvim. The data is only |
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- `_run()`: Runs the event loop until stopped or the connection is closed. |
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calling the following methods when some event happens: |
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actually sent when the event loop is running. |
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- `_on_data(data)`: When Nvim sends some data. |
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- `_on_signal(signum)`: When a signal is received. |
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- `_on_error(message)`: When a non-recoverable error occurs(eg: |
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connection lost) |
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- `_stop()`: Stop the event loop |
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- `_interrupt(data)`: Like `stop()`, but may be called from other threads |
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this. |
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- `_setup_signals(signals)`: Add implementation-specific listeners for |
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for `signals`, which is a list of OS-specific signal numbers. |
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- `_teardown_signals()`: Removes signal listeners set by `_setup_signals` |
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""" |
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def __init__(self, transport_type, *args): |
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"""Initialize and connect the event loop instance. |
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The only arguments are the transport type and transport-specific |
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configuration, like this: |
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>>> BaseEventLoop('tcp', '127.0.0.1', 7450) |
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Traceback (most recent call last): |
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... |
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AttributeError: 'BaseEventLoop' object has no attribute '_init' |
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>>> BaseEventLoop('socket', '/tmp/nvim-socket') |
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Traceback (most recent call last): |
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... |
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AttributeError: 'BaseEventLoop' object has no attribute '_init' |
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>>> BaseEventLoop('stdio') |
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Traceback (most recent call last): |
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... |
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AttributeError: 'BaseEventLoop' object has no attribute '_init' |
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>>> BaseEventLoop('child', ['nvim', '--embed', '-u', 'NONE']) |
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Traceback (most recent call last): |
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... |
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AttributeError: 'BaseEventLoop' object has no attribute '_init' |
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This calls the implementation-specific initialization |
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`_init`, one of the `_connect_*` methods(based on `transport_type`) |
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and `_start_reading()` |
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""" |
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self._transport_type = transport_type |
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self._signames = dict((k, v) for v, k in signal.__dict__.items() |
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if v.startswith('SIG')) |
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self._on_data = None |
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self._error = None |
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self._init() |
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getattr(self, '_connect_{0}'.format(transport_type))(*args) |
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self._start_reading() |
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def connect_tcp(self, address, port): |
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"""Connect to tcp/ip `address`:`port`. Delegated to `_connect_tcp`.""" |
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info('Connecting to TCP address: %s:%d', address, port) |
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self._connect_tcp(address, port) |
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def connect_socket(self, path): |
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"""Connect to socket at `path`. Delegated to `_connect_socket`.""" |
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info('Connecting to %s', path) |
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self._connect_socket(path) |
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def connect_stdio(self): |
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"""Connect using stdin/stdout. Delegated to `_connect_stdio`.""" |
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info('Preparing stdin/stdout for streaming data') |
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self._connect_stdio() |
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def connect_child(self, argv): |
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"""Connect a new Nvim instance. Delegated to `_connect_child`.""" |
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info('Spawning a new nvim instance') |
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self._connect_child(argv) |
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def send(self, data): |
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"""Queue `data` for sending to Nvim.""" |
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debug("Sending '%s'", data) |
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self._send(data) |
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def threadsafe_call(self, fn): |
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"""Call a function in the event loop thread. |
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This is the only safe way to interact with a session from other |
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threads. |
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""" |
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self._threadsafe_call(fn) |
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def run(self, data_cb): |
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"""Run the event loop.""" |
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if self._error: |
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err = self._error |
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if isinstance(self._error, KeyboardInterrupt): |
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# KeyboardInterrupt is not destructive(it may be used in |
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# the REPL). |
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# After throwing KeyboardInterrupt, cleanup the _error field |
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# so the loop may be started again |
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self._error = None |
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raise err |
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self._on_data = data_cb |
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if threading.current_thread() == main_thread: |
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self._setup_signals([signal.SIGINT, signal.SIGTERM]) |
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debug('Entering event loop') |
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self._run() |
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debug('Exited event loop') |
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if threading.current_thread() == main_thread: |
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self._teardown_signals() |
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signal.signal(signal.SIGINT, default_int_handler) |
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self._on_data = None |
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def stop(self): |
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"""Stop the event loop.""" |
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self._stop() |
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debug('Stopped event loop') |
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def _on_signal(self, signum): |
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msg = 'Received {0}'.format(self._signames[signum]) |
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debug(msg) |
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if signum == signal.SIGINT and self._transport_type == 'stdio': |
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# When the transport is stdio, we are probably running as a Nvim |
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# child process. In that case, we don't want to be killed by |
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# ctrl+C |
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return |
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cls = Exception |
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if signum == signal.SIGINT: |
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cls = KeyboardInterrupt |
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self._error = cls(msg) |
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self.stop() |
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def _on_error(self, error): |
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debug(error) |
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self._error = IOError(error) |
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self.stop() |
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def _on_interrupt(self): |
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self.stop() |
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