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from NetProxy import NetProxyWrapper, _get_conn, _get_oid
from Lib import raise_exception
class AsyncNetProxy(NetProxyWrapper):
"""wraps an exiting synchronous netproxy to make is asynchronous
(remote operations return AsyncResult objects)"""
__slots__ = []
def __request__(self, handler, *args):
res = AsyncResult(_get_conn(self))
_get_conn(self).async_request(res.callback, handler, _get_oid(self), *args)
return res
# must return a string... and it's not meaningful to return the repr of an async result
def __repr__(self, *args):
return self.__request__("handle_repr", *args).result
def __str__(self, *args):
return self.__request__("handle_str", *args).result
class AsyncResult(object):
"""represents the result of an asynchronous operation"""
STATE_PENDING = "pending"
STATE_READY = "ready"
STATE_EXCEPTION = "exception"
__slots__ = ["conn", "_state", "_result", "_on_ready"]
def __init__(self, conn):
self.conn = conn
self._state = self.STATE_PENDING
self._result = None
self._on_ready = None
def __repr__(self):
return "<AsyncResult (%s) at 0x%08x>" % (self._state, id(self))
def callback(self, obj, is_exception):
self._result = obj
if is_exception:
self._state = self.STATE_EXCEPTION
else:
self._state = self.STATE_READY
if self._on_ready is not None:
self._on_ready(self)
def _get_on_ready(self):
return self._ready_callback
def _set_on_ready(self, obj):
self._on_ready = obj
if self._state != self.STATE_PENDING:
self._on_ready(self)
def _get_is_ready(self):
if self._state == self.STATE_PENDING:
self.conn.poll()
return self._state != self.STATE_PENDING
def _get_result(self):
while self._state == self.STATE_PENDING:
self.conn.serve()
if self._state == self.STATE_READY:
return self._result
elif self._state == self.STATE_EXCEPTION:
raise_exception(*self._result)
is_ready = property(_get_is_ready,
doc = "indicates whether or not the result is ready")
result = property(_get_result,
doc = "the value of the async result (may block)")
on_ready = property(_get_on_ready, _set_on_ready,
doc = "if not None, specifies a callback which is called when the result is ready")
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