Source code for rpyc.core.async

import time


[docs]class AsyncResultTimeout(Exception): """an exception that represents an :class:`AsyncResult` that has timed out""" pass
[docs]class AsyncResult(object): """*AsyncResult* represents a computation that occurs in the background and will eventually have a result. Use the :attr:`value` property to access the result (which will block if the result has not yet arrived). """ __slots__ = ["_conn", "_is_ready", "_is_exc", "_callbacks", "_obj", "_ttl"] def __init__(self, conn): self._conn = conn self._is_ready = False self._is_exc = None self._obj = None self._callbacks = [] self._ttl = None def __repr__(self): if self._is_ready: state = "ready" elif self._is_exc: state = "error" elif self.expired: state = "expired" else: state = "pending" return "<AsyncResult object (%s) at 0x%08x>" % (state, id(self)) def __call__(self, is_exc, obj): if self.expired: return self._is_exc = is_exc self._obj = obj self._is_ready = True for cb in self._callbacks: cb(self) del self._callbacks[:]
[docs] def wait(self): """Waits for the result to arrive. If the AsyncResult object has an expiry set, and the result did not arrive within that timeout, an :class:`AsyncResultTimeout` exception is raised""" if self._is_ready: return if self._ttl is None: while not self._is_ready: self._conn.serve() else: while True: timeout = self._ttl - time.time() self._conn.poll(timeout = max(timeout, 0)) if self._is_ready: break if timeout <= 0: raise AsyncResultTimeout("result expired")
[docs] def add_callback(self, func): """Adds a callback to be invoked when the result arrives. The callback function takes a single argument, which is the current AsyncResult (``self``). If the result has already arrived, the function is invoked immediately. :param func: the callback function to add """ if self._is_ready: func(self) else: self._callbacks.append(func)
[docs] def set_expiry(self, timeout): """Sets the expiry time (in seconds, relative to now) or ``None`` for unlimited time :param timeout: the expiry time in seconds or ``None`` """ if timeout is None: self._ttl = None else: self._ttl = time.time() + timeout
@property def ready(self): """Indicates whether the result has arrived""" if self.expired: return False if not self._is_ready: self._conn.poll_all() return self._is_ready @property def error(self): """Indicates whether the returned result is an exception""" if self.ready: return self._is_exc return False @property def expired(self): """Indicates whether the AsyncResult has expired""" if self._is_ready or self._ttl is None: return False else: return time.time() > self._ttl @property def value(self): """Returns the result of the operation. If the result has not yet arrived, accessing this property will wait for it. If the result does not arrive before the expiry time elapses, :class:`AsyncResultTimeout` is raised. If the returned result is an exception, it will be raised here. Otherwise, the result is returned directly. """ self.wait() if self._is_exc: raise self._obj else: return self._obj