Source code for pyee._executor

# -*- coding: utf-8 -*-

from pyee._base import EventEmitter

from concurrent.futures import ThreadPoolExecutor

__all__ = ["ExecutorEventEmitter"]


[docs]class ExecutorEventEmitter(EventEmitter): """An event emitter class which runs handlers in a ``concurrent.futures`` executor. By default, this class creates a default ``ThreadPoolExecutor``, but a custom executor may also be passed in explicitly to, for instance, use a ``ProcessPoolExecutor`` instead. This class runs all emitted events on the configured executor. Errors captured by the resulting Future are automatically emitted on the ``error`` event. This is unlike the BaseEventEmitter, which have no error handling. The underlying executor may be shut down by calling the ``shutdown`` method. Alternately you can treat the event emitter as a context manager:: with ExecutorEventEmitter() as ee: # Underlying executor open @ee.on('data') def handler(data): print(data) ee.emit('event') # Underlying executor closed Since the function call is scheduled on an executor, emit is always non-blocking. No effort is made to ensure thread safety, beyond using an executor. """ def __init__(self, executor=None): super(ExecutorEventEmitter, self).__init__() if executor: self._executor = executor else: self._executor = ThreadPoolExecutor() def _emit_run(self, f, args, kwargs): future = self._executor.submit(f, *args, **kwargs) @future.add_done_callback def _callback(f): exc = f.exception() if exc: self.emit("error", exc)
[docs] def shutdown(self, wait=True): """Call ``shutdown`` on the internal executor.""" self._executor.shutdown(wait=wait)
def __enter__(self): return self def __exit__(self, type, value, traceback): self.shutdown()