98 lines
2.9 KiB
Python
98 lines
2.9 KiB
Python
"""General purpose event handling routines"""
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from .compat import *
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__all__ = ["EventHandler", "MPEventHandler"]
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_HASMP = True
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try:
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from multiprocessing import Pool
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except ImportError:
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_HASMP = False
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class EventHandler(object):
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"""A simple event handling class, which manages callbacks to be
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executed.
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"""
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def __init__(self, sender):
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self.callbacks = []
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self.sender = sender
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def __call__(self, *args):
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"""Executes all callbacks.
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Executes all connected callbacks in the order of addition,
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passing the sender of the EventHandler as first argument and the
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optional args as second, third, ... argument to them.
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"""
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return [callback(self.sender, *args) for callback in self.callbacks]
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def __iadd__(self, callback):
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"""Adds a callback to the EventHandler."""
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self.add(callback)
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return self
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def __isub__(self, callback):
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"""Removes a callback from the EventHandler."""
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self.remove(callback)
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return self
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def __len__(self):
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"""Gets the amount of callbacks connected to the EventHandler."""
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return len(self.callbacks)
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def __getitem__(self, index):
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return self.callbacks[index]
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def __setitem__(self, index, value):
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self.callbacks[index] = value
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def __delitem__(self, index):
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del self.callbacks[index]
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def add(self, callback):
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"""Adds a callback to the EventHandler."""
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if not callable(callback):
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raise TypeError("callback mus be callable")
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self.callbacks.append(callback)
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def remove(self, callback):
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"""Removes a callback from the EventHandler."""
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self.callbacks.remove(callback)
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def _mp_callback(args):
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# args = (function, sender, (args))
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fargs = args[2]
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return args[0](args[1], *fargs)
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class MPEventHandler(EventHandler):
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"""An asynchronous event handling class in which callbacks are
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executed in parallel.
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It is the responsibility of the caller code to ensure that every
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object used maintains a consistent state. The MPEventHandler class
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will not apply any locks, synchronous state changes or anything else
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to the arguments being used. Consider it a "fire-and-forget" event
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handling strategy
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"""
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def __init__(self, sender, maxprocs=None):
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if not _HASMP:
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raise UnsupportedError(MPEventHandler,
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"no multiprocessing support found")
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super(MPEventHandler, self).__init__(sender)
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self.maxprocs = maxprocs
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def __call__(self, *args):
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if self.maxprocs is not None:
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pool = Pool(processes=self.maxprocs)
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else:
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pool = Pool()
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psize = len(self.callbacks)
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pv = zip(self.callbacks, [self.sender] * psize, [args[:]] * psize)
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results = pool.map_async(_mp_callback, pv)
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pool.close()
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pool.join()
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return results
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