149 lines
4.5 KiB
Python
149 lines
4.5 KiB
Python
import thread, sys
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__all__ = ['greenlet', 'main', 'getcurrent']
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class greenlet(object):
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__slots__ = ('run', '_controller')
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def __init__(self, run=None, parent=None):
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if run is not None:
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self.run = run
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if parent is not None:
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self.parent = parent
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def switch(self, *args):
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global _passaround_
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_passaround_ = None, args, None
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self._controller.switch(self)
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exc, val, tb = _passaround_
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del _passaround_
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if exc is None:
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if isinstance(val, tuple) and len(val) == 1:
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return val[0]
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else:
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return val
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else:
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raise exc, val, tb
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def __nonzero__(self):
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return self._controller.isactive()
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def __new__(cls, *args, **kwds):
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self = object.__new__(cls)
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self._controller = _Controller()
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return self
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def __del__(self):
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#print 'DEL:', self
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if self._controller.parent is None:
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return # don't kill the main greenlet
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while self._controller.isactive():
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self._controller.kill(self)
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def getparent(self):
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return self._controller.parent
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def setparent(self, nparent):
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if not isinstance(nparent, greenlet):
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raise TypeError, "parent must be a greenlet"
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p = nparent
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while p is not None:
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if p is self:
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raise ValueError, "cyclic parent chain"
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p = p._controller.parent
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self._controller.parent = nparent
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parent = property(getparent, setparent)
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del getparent
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del setparent
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class _Controller:
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# Controllers are separated from greenlets to allow greenlets to be
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# deallocated while running, when their last reference goes away.
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# Care is taken to keep only references to controllers in thread's
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# frames' local variables.
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# _Controller.parent: the parent greenlet.
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# _Controller.lock: the lock used for synchronization
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# it is not set before the greenlet starts
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# it is None after the greenlet stops
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def __init__(self):
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self.parent = _current_
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def isactive(self):
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return getattr(self, 'lock', None) is not None
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def switch(self, target):
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previous = _current_._controller
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self.switch_no_wait(target)
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# wait until someone releases this thread's lock
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previous.lock.acquire()
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def switch_no_wait(self, target):
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# lock tricks: each greenlet has its own lock which is almost always
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# in 'acquired' state:
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# * the current greenlet runs with its lock acquired
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# * all other greenlets wait on their own lock's acquire() call
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global _current_
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try:
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while 1:
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_current_ = target
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lock = self.lock
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if lock is not None:
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break
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target = self.parent
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self = target._controller
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except AttributeError:
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# start the new greenlet
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lock = self.lock = thread.allocate_lock()
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lock.acquire()
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thread.start_new_thread(self.run_thread, (target.run,))
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else:
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# release (re-enable) the target greenlet's thread
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lock.release()
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def run_thread(self, run):
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#print 'ENTERING', self
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global _passaround_
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exc, val, tb = _passaround_
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if exc is None:
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try:
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result = run(*val)
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except SystemExit, e:
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_passaround_ = None, (e,), None
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except:
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_passaround_ = sys.exc_info()
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else:
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_passaround_ = None, (result,), None
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self.lock = None
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#print 'LEAVING', self
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self.switch_no_wait(self.parent)
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def kill(self, target):
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# see comments in greenlet.c:green_dealloc()
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global _passaround_
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self._parent_ = _current_
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_passaround_ = SystemExit, None, None
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self.switch(target)
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exc, val, tb = _passaround_
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del _passaround_
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if exc is not None:
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if val is None:
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print >> sys.stderr, "Exception", "%s" % (exc,),
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else:
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print >> sys.stderr, "Exception", "%s: %s" % (exc, val),
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print >> sys.stderr, "in", self, "ignored"
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_current_ = None
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main = greenlet()
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main._controller.lock = thread.allocate_lock()
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main._controller.lock.acquire()
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_current_ = main
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def getcurrent():
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return _current_
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