def blocking_call_from_thread(self, callback, timeout):
"""Call the given function from a thread, and wait for the result synchronously
for as long as the timeout will allow.
Args:
callback: Callable function to be invoked from the thread.
timeout (:obj: int): Number of seconds to wait for the response before
raising an exception.
Returns:
The results from the callback, or a timeout exception.
"""
manual_event = ManualResetEventSlim(False)
result_placeholder = {'manual_event': manual_event}
ThreadPool.QueueUserWorkItem(WaitCallback(callback),
result_placeholder)
# Wait with timeout results bool indicating success/failure
if timeout and manual_event.Wait(timeout * 1000,
self.cancellation_token):
return result_placeholder
# Wait without timeouts raises in case of failure triggered by cancellation
if not timeout:
manual_event.Wait(self.cancellation_token)
return result_placeholder
self.raise_timeout_exception()
class CliEventLoopManager(object):
"""Manage the main event loop using .NET threads.
For the time being, this implementation is pretty light
and mostly relies on .NET async doing "the right thing(tm)"
with a sprinkle of threading here and there.
"""
def __init__(self):
self._init_cancellation()
self._disconnect_event = ManualResetEventSlim(False)
def _init_cancellation(self):
"""Initialize the cancellation source and token."""
self.cancellation_token_source = CancellationTokenSource()
self.cancellation_token = self.cancellation_token_source.Token
self.cancellation_token.Register(
lambda: LOGGER.debug('Started token cancelation'))
def run_forever(self):
"""Kick-starts a blocking loop while the ROS client is connected."""
self._disconnect_event.Wait(self.cancellation_token)
LOGGER.debug('Received disconnect event on main loop')
def call_later(self, delay, callback):
"""Call the given function after a certain period of time has passed.
Args:
delay (:obj:`int`): Number of seconds to wait before invoking the callback.
callback (:obj:`callable`): Callable function to be invoked when the delay has elapsed.
"""
# NOTE: Maybe there's a more elegant way of doing this
def closure():
Thread.Sleep(delay * 1000)
callback()
Task.Factory.StartNew(closure, self.cancellation_token)
def call_in_thread(self, callback):
"""Call the given function on a thread.
Args:
callback (:obj:`callable`): Callable function to be invoked in a thread.
"""
Task.Factory.StartNew(callback, self.cancellation_token)
def terminate(self):
"""Signals the termination of the main event loop."""
self._disconnect_event.Set()
if self.cancellation_token_source:
self.cancellation_token_source.Cancel()
# Renew to allow re-connects
self._init_cancellation()
def start_listening(self):
"""Starts listening asynchronously while the socket is open.
The inter-thread synchronization between this and the async
reception threads is sync'd with a manual reset event."""
try:
LOGGER.debug('About to start listening, socket state: %s',
self.socket.State)
while self.socket and self.socket.State == WebSocketState.Open:
mre = ManualResetEventSlim(False)
content = []
buffer = Array.CreateInstance(Byte, RECEIVE_CHUNK_SIZE)
self.receive_chunk_async(
None, dict(buffer=buffer, content=content, mre=mre))
LOGGER.debug('Waiting for messages...')
try:
mre.Wait(self.factory.manager.cancellation_token)
except SystemError:
LOGGER.debug(
'Cancellation detected on listening thread, exiting...'
)
break
try:
message_payload = ''.join(content)
LOGGER.debug('Message reception completed|<pre>%s</pre>',
message_payload)
self.on_message(message_payload)
except Exception:
LOGGER.exception(
'Exception on start_listening while trying to handle message received.'
+
'It could indicate a bug in user code on message handlers. Message skipped.'
)
except Exception:
LOGGER.exception(
'Exception on start_listening, processing will be aborted')
raise
finally:
LOGGER.debug('Leaving the listening thread')
def __init__(self):
self._init_cancellation()
self._disconnect_event = ManualResetEventSlim(False)
class CliEventLoopManager(object):
"""Manage the main event loop using .NET threads.
For the time being, this implementation is pretty light
and mostly relies on .NET async doing "the right thing(tm)"
with a sprinkle of threading here and there.
"""
def __init__(self):
self._init_cancellation()
self._disconnect_event = ManualResetEventSlim(False)
def _init_cancellation(self):
"""Initialize the cancellation source and token."""
self.cancellation_token_source = CancellationTokenSource()
self.cancellation_token = self.cancellation_token_source.Token
self.cancellation_token.Register(
lambda: LOGGER.debug('Started token cancellation'))
def run(self):
"""Kick-starts a non-blocking event loop.
In this implementation, this is a no-op."""
pass
def run_forever(self):
"""Kick-starts a blocking loop while the ROS client is connected."""
self._disconnect_event.Wait(self.cancellation_token)
LOGGER.debug('Received disconnect event on main loop')
def call_later(self, delay, callback):
"""Call the given function after a certain period of time has passed.
Args:
delay (:obj:`int`): Number of seconds to wait before invoking the callback.
callback (:obj:`callable`): Callable function to be invoked when the delay has elapsed.
"""
# NOTE: Maybe there's a more elegant way of doing this
def closure():
Thread.Sleep(delay * 1000)
callback()
Task.Factory.StartNew(closure, self.cancellation_token)
def call_in_thread(self, callback):
"""Call the given function on a thread.
Args:
callback (:obj:`callable`): Callable function to be invoked in a thread.
"""
Task.Factory.StartNew(callback, self.cancellation_token)
def blocking_call_from_thread(self, callback, timeout):
"""Call the given function from a thread, and wait for the result synchronously
for as long as the timeout will allow.
Args:
callback: Callable function to be invoked from the thread.
timeout (:obj: int): Number of seconds to wait for the response before
raising an exception.
Returns:
The results from the callback, or a timeout exception.
"""
manual_event = ManualResetEventSlim(False)
result_placeholder = {'manual_event': manual_event}
ThreadPool.QueueUserWorkItem(WaitCallback(callback),
result_placeholder)
# Wait with timeout results bool indicating success/failure
if timeout and manual_event.Wait(timeout * 1000,
self.cancellation_token):
return result_placeholder
# Wait without timeouts raises in case of failure triggered by cancellation
if not timeout:
manual_event.Wait(self.cancellation_token)
return result_placeholder
self.raise_timeout_exception()
def raise_timeout_exception(self, _result=None, _timeout=None):
"""Callback called on timeout.
Args:
_result: Unused--required by Twister.
_timeout: Unused--required by Twister.
Raises:
An exception.
"""
raise Exception('No service response received')
def get_inner_callback(self, result_placeholder):
"""Get the callback which, when called, provides result_placeholder with the result.
Args:
result_placeholder: (:obj: dict): Object in which to store the result.
Returns:
A callable which provides result_placeholder with the result in the case of success.
"""
def inner_callback(result):
result_placeholder['result'] = result
result_placeholder['manual_event'].Set()
return inner_callback
def get_inner_errback(self, result_placeholder):
"""Get the errback which, when called, provides result_placeholder with the error.
Args:
result_placeholder: (:obj: dict): Object in which to store the result.
Returns:
A callable which provides result_placeholder with the error in the case of failure.
"""
def inner_errback(error):
result_placeholder['exception'] = error
result_placeholder['manual_event'].Set()
return inner_errback
def terminate(self):
"""Signals the termination of the main event loop."""
self._disconnect_event.Set()
if self.cancellation_token_source:
self.cancellation_token_source.Cancel()
# Renew to allow re-connects
self._init_cancellation()