def serve(self, timeout=1, wait_for_lock=True):
"""Serves a single request or reply that arrives within the given
time frame (default is 1 sec). Note that the dispatching of a request
might trigger multiple (nested) requests, thus this function may be
reentrant.
:returns: ``True`` if a request or reply were received, ``False``
otherwise.
"""
timeout = Timeout(timeout)
with self._recv_event:
if not self._recvlock.acquire(False):
return (wait_for_lock
and self._recv_event.wait(timeout.timeleft()))
try:
data = self._channel.poll(timeout) and self._channel.recv()
if not data:
return False
except EOFError:
self.close()
raise
finally:
self._recvlock.release()
with self._recv_event:
self._recv_event.notify_all()
self._dispatch(data)
return True
def poll(self, timeout):
"""indicates whether the stream has data to read (within *timeout*
seconds)"""
timeout = Timeout(timeout)
try:
p = poll(
) # from lib.compat, it may be a select object on non-Unix platforms
p.register(self.fileno(), "r")
while True:
try:
rl = p.poll(timeout.timeleft())
except select_error:
ex = sys.exc_info()[1]
if ex.args[0] == errno.EINTR:
continue
else:
raise
else:
break
except ValueError:
# if the underlying call is a select(), then the following errors may happen:
# - "ValueError: filedescriptor cannot be a negative integer (-1)"
# - "ValueError: filedescriptor out of range in select()"
# let's translate them to select.error
ex = sys.exc_info()[1]
raise select_error(str(ex))
return bool(rl)
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``
"""
self._ttl = Timeout(timeout)
def __init__(self, conn):
self._conn = conn
self._is_ready = False
self._is_exc = None
self._obj = None
self._callbacks = []
self._ttl = Timeout(None)
def poll(self, timeout, interval=0.1):
"""a poor man's version of select()"""
timeout = Timeout(timeout)
try:
while True:
if win32pipe.PeekNamedPipe(self.incoming, 0)[1] != 0:
return True
if timeout.expired():
return False
timeout.sleep(interval)
except TypeError:
ex = sys.exc_info()[1]
if not self.closed:
raise
raise EOFError(ex)
def poll_all(self, timeout=0):
"""Serves all requests and replies that arrive within the given interval.
:returns: ``True`` if at least a single transaction was served, ``False`` otherwise
"""
at_least_once = False
timeout = Timeout(timeout)
try:
while True:
if self.poll(timeout):
at_least_once = True
if timeout.expired():
break
except EOFError:
pass
return at_least_once
def poll(self, timeout, interval=0.001):
"""Windows version of select()"""
timeout = Timeout(timeout)
try:
if timeout.finite:
wait_time = int(max(1, timeout.timeleft() * 1000))
else:
wait_time = win32event.INFINITE
if not self.poll_read:
hr, self.poll_buffer = win32file.ReadFile(self.incoming,
self.poll_buffer,
self.read_overlapped)
self.poll_read = True
if hr == 0:
return True
res = win32event.WaitForSingleObject(self.read_overlapped.hEvent, wait_time)
return res == win32event.WAIT_OBJECT_0
except TypeError:
ex = sys.exc_info()[1]
if not self.closed:
raise
raise EOFError(ex)
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 = Timeout(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[:]
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"""
while not self._is_ready and not self._ttl.expired():
self._conn.serve(self._ttl)
if not self._is_ready:
raise AsyncResultTimeout("result expired")
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)
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``
"""
self._ttl = Timeout(timeout)
@property
def ready(self):
"""Indicates whether the result has arrived"""
if self._is_ready:
return True
if self._ttl.expired():
return False
self._conn.poll_all()
return self._is_ready
@property
def error(self):
"""Indicates whether the returned result is an exception"""
return self.ready and self._is_exc
@property
def expired(self):
"""Indicates whether the AsyncResult has expired"""
return not self._is_ready and self._ttl.expired()
@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