class AsyncResult(object):
"""
Essentially a wrapper for a Tornado TracebackFuture
"""
def __init__(self, future=None):
if future is not None:
self._future = future
else:
self._future = TracebackFuture()
self._future.add_done_callback(functools.partial(async_result_complete, self))
self._condition = threading.Condition()
def ready(self):
"""Return `True` if and only if it holds a value or an
exception"""
return self._future.done()
def successful(self):
"""Return `True` if and only if it is ready and holds a
value"""
return self._future.exception() is None
@property
def exception(self):
return self._future.exception()
def set(self, value=None):
"""Store the value. Wake up the waiters.
:param value: Value to store as the result.
Any waiters blocking on :meth:`get` or :meth:`wait` are woken
up. Sequential calls to :meth:`wait` and :meth:`get` will not
block at all."""
with self._condition:
self._future.set_result(value)
def set_exception(self, exception):
"""Store the exception. Wake up the waiters.
:param exception: Exception to raise when fetching the value.
Any waiters blocking on :meth:`get` or :meth:`wait` are woken
up. Sequential calls to :meth:`wait` and :meth:`get` will not
block at all."""
with self._condition:
self._future.set_exception(exception)
def get(self, block=True, timeout=None):
"""Return the stored value or raise the exception
:param block: Whether this method should block or return
immediately.
:type block: bool
:param timeout: How long to wait for a value when `block` is
`True`.
:type timeout: float
If this instance already holds a value / an exception, return /
raise it immediately. Otherwise, block until :meth:`set` or
:meth:`set_exception` has been called or until the optional
timeout occurs."""
with self._condition:
if self.ready():
return self._future.result()
elif block:
self._condition.wait(timeout)
return self._future.result()
# if we get to this point we timeout
raise KazooTimeoutError()
def get_nowait(self):
"""Return the value or raise the exception without blocking.
If nothing is available, raise the Timeout exception class on
the associated :class:`IHandler` interface."""
return self._future.result()
def wait(self, timeout=None):
"""Block until the instance is ready.
:param timeout: How long to wait for a value
:type timeout: float
If this instance already holds a value / an exception, return /
raise it immediately. Otherwise, block until :meth:`set` or
:meth:`set_exception` has been called or until the optional
timeout occurs."""
with self._condition:
self._condition.wait(timeout)
return self.ready()
def rawlink(self, callback):
"""Register a callback to call when a value or an exception is
set
:param callback:
A callback function to call after :meth:`set` or
:meth:`set_exception` has been called. This function will
be passed a single argument, this instance.
:type callback: func
"""
def on_callback(future):
callback(AsyncResult(future))
IOLoop.current().add_future(self._future, on_callback)
def unlink(self, callback):
"""Remove the callback set by :meth:`rawlink`
:param callback: A callback function to remove.
:type callback: func
"""
def notify(self):
self._condition.notify_all()
