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import sys
import _continuation
__version__ = "0.4.0"
# ____________________________________________________________
# Exceptions
class GreenletExit(BaseException):
"""This special exception does not propagate to the parent greenlet; it
can be used to kill a single greenlet."""
error = _continuation.error
# ____________________________________________________________
# Helper function
def getcurrent():
"Returns the current greenlet (i.e. the one which called this function)."
try:
return _tls.current
except AttributeError:
# first call in this thread: current == main
_green_create_main()
return _tls.current
# ____________________________________________________________
# The 'greenlet' class
_continulet = _continuation.continulet
class greenlet(_continulet):
getcurrent = staticmethod(getcurrent)
error = error
GreenletExit = GreenletExit
__main = False
__started = False
def __new__(cls, *args, **kwds):
self = _continulet.__new__(cls)
self.parent = getcurrent()
return self
def __init__(self, run=None, parent=None):
if run is not None:
self.run = run
if parent is not None:
self.parent = parent
def switch(self, *args, **kwds):
"Switch execution to this greenlet, optionally passing the values "
"given as argument(s). Returns the value passed when switching back."
return self.__switch('switch', (args, kwds))
def throw(self, typ=GreenletExit, val=None, tb=None):
"raise exception in greenlet, return value passed when switching back"
return self.__switch('throw', typ, val, tb)
def __switch(target, methodname, *baseargs):
current = getcurrent()
#
while not (target.__main or _continulet.is_pending(target)):
# inlined __nonzero__ ^^^ in case it's overridden
if not target.__started:
if methodname == 'switch':
greenlet_func = _greenlet_start
else:
greenlet_func = _greenlet_throw
_continulet.__init__(target, greenlet_func, *baseargs)
methodname = 'switch'
baseargs = ()
target.__started = True
break
# already done, go to the parent instead
# (NB. infinite loop possible, but unlikely, unless you mess
# up the 'parent' explicitly. Good enough, because a Ctrl-C
# will show that the program is caught in this loop here.)
target = target.parent
# convert a "raise GreenletExit" into "return GreenletExit"
if methodname == 'throw':
try:
raise baseargs[0], baseargs[1]
except GreenletExit, e:
methodname = 'switch'
baseargs = (((e,), {}),)
except:
baseargs = sys.exc_info()[:2] + baseargs[2:]
#
try:
unbound_method = getattr(_continulet, methodname)
args, kwds = unbound_method(current, *baseargs, to=target)
finally:
_tls.current = current
#
if kwds:
if args:
return args, kwds
return kwds
elif len(args) == 1:
return args[0]
else:
return args
def __nonzero__(self):
return self.__main or _continulet.is_pending(self)
@property
def dead(self):
return self.__started and not self
@property
def gr_frame(self):
# xxx this doesn't work when called on either the current or
# the main greenlet of another thread
if self is getcurrent():
return None
if self.__main:
self = getcurrent()
f = _continulet.__reduce__(self)[2][0]
if not f:
return None
return f.f_back.f_back.f_back # go past start(), __switch(), switch()
# ____________________________________________________________
# Internal stuff
try:
from threading import local as _local
except ImportError:
class _local(object): # assume no threads
pass
_tls = _local()
def _green_create_main():
# create the main greenlet for this thread
_tls.current = None
gmain = greenlet.__new__(greenlet)
gmain._greenlet__main = True
gmain._greenlet__started = True
assert gmain.parent is None
_tls.main = gmain
_tls.current = gmain
def _greenlet_start(greenlet, args):
args, kwds = args
_tls.current = greenlet
try:
res = greenlet.run(*args, **kwds)
except GreenletExit, e:
res = e
finally:
_continuation.permute(greenlet, greenlet.parent)
return ((res,), None)
def _greenlet_throw(greenlet, exc, value, tb):
_tls.current = greenlet
try:
raise exc, value, tb
except GreenletExit, e:
res = e
finally:
_continuation.permute(greenlet, greenlet.parent)
return ((res,), None)
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