def __init__(self, *, context: Context = None) -> None:
super().__init__()
self._context = get_default_context() if context is None else context
self._nodes: Set[Node] = set()
self._nodes_lock = RLock()
# Tasks to be executed (oldest first) 3-tuple Task, Entity, Node
self._tasks: List[Tuple[Task, Optional[WaitableEntityType],
Optional[Node]]] = []
self._tasks_lock = Lock()
# This is triggered when wait_for_ready_callbacks should rebuild the wait list
self._guard = GuardCondition(callback=None,
callback_group=None,
context=self._context)
# True if shutdown has been called
self._is_shutdown = False
self._work_tracker = _WorkTracker()
# Protect against shutdown() being called in parallel in two threads
self._shutdown_lock = Lock()
# State for wait_for_ready_callbacks to reuse generator
self._cb_iter = None
self._last_args = None
self._last_kwargs = None
# Executor cannot use ROS clock because that requires a node
self._clock = Clock(clock_type=ClockType.STEADY_TIME)
self._sigint_gc = SignalHandlerGuardCondition(context)
self._context.on_shutdown(self.wake)
def destroy_guard_condition(self, guard: GuardCondition) -> bool:
"""
Destroy a guard condition created by the node.
:return: ``True`` if successful, ``False`` otherwise.
"""
if guard in self.__guards:
self.__guards.remove(guard)
try:
guard.destroy()
except InvalidHandle:
return False
return True
return False
def create_guard_condition(self, callback, callback_group=None):
if callback_group is None:
callback_group = self._default_callback_group
guard = GuardCondition(callback, callback_group)
self.guards.append(guard)
callback_group.add_entity(guard)
return guard
def create_guard_condition(
self,
callback: Callable,
callback_group: CallbackGroup = None) -> GuardCondition:
"""Create a new guard condition."""
if callback_group is None:
callback_group = self.default_callback_group
guard = GuardCondition(callback, callback_group, context=self.context)
self.guards.append(guard)
callback_group.add_entity(guard)
return guard
class Executor:
"""
The base class for an executor.
An executor controls the threading model used to process callbacks. Callbacks are units of work
like subscription callbacks, timer callbacks, service calls, and received client responses. An
executor controls which threads callbacks get executed in.
A custom executor must define :meth:`spin_once`.
If the executor has any cleanup then it should also define :meth:`shutdown`.
:param context: The context to be associated with, or ``None`` for the default global context.
"""
def __init__(self, *, context: Context = None) -> None:
super().__init__()
self._context = get_default_context() if context is None else context
self._nodes: Set[Node] = set()
self._nodes_lock = RLock()
# Tasks to be executed (oldest first) 3-tuple Task, Entity, Node
self._tasks: List[Tuple[Task, Optional[WaitableEntityType],
Optional[Node]]] = []
self._tasks_lock = Lock()
# This is triggered when wait_for_ready_callbacks should rebuild the wait list
self._guard = GuardCondition(callback=None,
callback_group=None,
context=self._context)
# True if shutdown has been called
self._is_shutdown = False
self._work_tracker = _WorkTracker()
# Protect against shutdown() being called in parallel in two threads
self._shutdown_lock = Lock()
# State for wait_for_ready_callbacks to reuse generator
self._cb_iter = None
self._last_args = None
self._last_kwargs = None
# Executor cannot use ROS clock because that requires a node
self._clock = Clock(clock_type=ClockType.STEADY_TIME)
self._sigint_gc = SignalHandlerGuardCondition(context)
self._context.on_shutdown(self.wake)
@property
def context(self) -> Context:
"""Get the context associated with the executor."""
return self._context
def create_task(self, callback: Union[Callable, Coroutine], *args,
**kwargs) -> Task:
"""
Add a callback or coroutine to be executed during :meth:`spin` and return a Future.
Arguments to this function are passed to the callback.
:param callback: A callback to be run in the executor.
"""
task = Task(callback, args, kwargs, executor=self)
with self._tasks_lock:
self._tasks.append((task, None, None))
self._guard.trigger()
# Task inherits from Future
return task
def shutdown(self, timeout_sec: float = None) -> bool:
"""
Stop executing callbacks and wait for their completion.
:param timeout_sec: Seconds to wait. Block forever if ``None`` or negative.
Don't wait if 0.
:return: ``True`` if all outstanding callbacks finished executing, or ``False`` if the
timeot expires before all outstanding work is done.
"""
with self._shutdown_lock:
if not self._is_shutdown:
self._is_shutdown = True
# Tell executor it's been shut down
self._guard.trigger()
if not self._work_tracker.wait(timeout_sec):
return False
# Clean up stuff that won't be used anymore
with self._nodes_lock:
self._nodes = set()
with self._shutdown_lock:
if self._guard:
self._guard.destroy()
self._guard = None
if self._sigint_gc:
self._sigint_gc.destroy()
self._sigint_gc = None
self._cb_iter = None
self._last_args = None
self._last_kwargs = None
return True
def __del__(self):
if self._sigint_gc is not None:
self._sigint_gc.destroy()
def add_node(self, node: 'Node') -> bool:
"""
Add a node whose callbacks should be managed by this executor.
:param node: The node to add to the executor.
:return: ``True`` if the node was added, ``False`` otherwise.
"""
with self._nodes_lock:
if node not in self._nodes:
self._nodes.add(node)
node.executor = self
# Rebuild the wait set so it includes this new node
self._guard.trigger()
return True
return False
def remove_node(self, node: 'Node') -> None:
"""
Stop managing this node's callbacks.
:param node: The node to remove from the executor.
"""
with self._nodes_lock:
try:
self._nodes.remove(node)
except KeyError:
pass
else:
# Rebuild the wait set so it doesn't include this node
self._guard.trigger()
def wake(self) -> None:
"""
Wake the executor because something changed.
This is used to tell the executor when entities are created or destroyed.
"""
if self._guard:
self._guard.trigger()
def get_nodes(self) -> List['Node']:
"""Return nodes that have been added to this executor."""
with self._nodes_lock:
return list(self._nodes)
def spin(self) -> None:
"""Execute callbacks until shutdown."""
while self._context.ok() and not self._is_shutdown:
self.spin_once()
def spin_until_future_complete(self,
future: Future,
timeout_sec: float = None) -> None:
"""Execute callbacks until a given future is done or a timeout occurs."""
if timeout_sec is None or timeout_sec < 0:
while self._context.ok(
) and not future.done() and not self._is_shutdown:
self.spin_once(timeout_sec=timeout_sec)
else:
start = time.monotonic()
end = start + timeout_sec
timeout_left = timeout_sec
while self._context.ok(
) and not future.done() and not self._is_shutdown:
self.spin_once(timeout_sec=timeout_left)
now = time.monotonic()
if now >= end:
return
timeout_left = end - now
def spin_once(self, timeout_sec: float = None) -> None:
"""
Wait for and execute a single callback.
A custom executor should use :meth:`wait_for_ready_callbacks` to get work.
:param timeout_sec: Seconds to wait. Block forever if ``None`` or negative.
Don't wait if 0.
"""
raise NotImplementedError()
def _take_timer(self, tmr):
with tmr.handle as capsule:
_rclpy.rclpy_call_timer(capsule)
async def _execute_timer(self, tmr, _):
await await_or_execute(tmr.callback)
def _take_subscription(self, sub):
with sub.handle as capsule:
msg_info = _rclpy.rclpy_take(capsule, sub.msg_type, sub.raw)
if msg_info is not None:
return msg_info[0]
return None
async def _execute_subscription(self, sub, msg):
if msg:
await await_or_execute(sub.callback, msg)
def _take_client(self, client):
with client.handle as capsule:
return _rclpy.rclpy_take_response(capsule,
client.srv_type.Response)
async def _execute_client(self, client, seq_and_response):
header, response = seq_and_response
if header is not None:
try:
sequence = _rclpy.rclpy_service_info_get_sequence_number(
header)
future = client._pending_requests[sequence]
except KeyError:
# The request was cancelled
pass
else:
future._set_executor(self)
future.set_result(response)
def _take_service(self, srv):
with srv.handle as capsule:
request_and_header = _rclpy.rclpy_take_request(
capsule, srv.srv_type.Request)
return request_and_header
async def _execute_service(self, srv, request_and_header):
if request_and_header is None:
return
(request, header) = request_and_header
if request:
response = await await_or_execute(srv.callback, request,
srv.srv_type.Response())
srv.send_response(response, header)
def _take_guard_condition(self, gc):
gc._executor_triggered = False
async def _execute_guard_condition(self, gc, _):
await await_or_execute(gc.callback)
async def _execute_waitable(self, waitable, data):
for future in waitable._futures:
future._set_executor(self)
await waitable.execute(data)
def _make_handler(self, entity: WaitableEntityType, node: 'Node',
take_from_wait_list: Callable,
call_coroutine: Coroutine) -> Task:
"""
Make a handler that performs work on an entity.
:param entity: An entity to wait on.
:param node: The node associated with the entity.
:param take_from_wait_list: Makes the entity to stop appearing in the wait list.
:param call_coroutine: Does the work the entity is ready for
"""
# Mark this so it doesn't get added back to the wait list
entity._executor_event = True
async def handler(entity, gc, is_shutdown, work_tracker):
if is_shutdown or not entity.callback_group.beginning_execution(
entity):
# Didn't get the callback, or the executor has been ordered to stop
entity._executor_event = False
gc.trigger()
return
with work_tracker:
arg = take_from_wait_list(entity)
# Signal that this has been 'taken' and can be added back to the wait list
entity._executor_event = False
gc.trigger()
try:
await call_coroutine(entity, arg)
finally:
entity.callback_group.ending_execution(entity)
# Signal that work has been done so the next callback in a mutually exclusive
# callback group can get executed
gc.trigger()
task = Task(
handler,
(entity, self._guard, self._is_shutdown, self._work_tracker),
executor=self)
with self._tasks_lock:
self._tasks.append((task, entity, node))
return task
def can_execute(self, entity: WaitableEntityType) -> bool:
"""
Determine if a callback for an entity can be executed.
:param entity: Subscription, Timer, Guard condition, etc
:returns: ``True`` if the entity callback can be executed, ``False`` otherwise.
"""
return not entity._executor_event and entity.callback_group.can_execute(
entity)
def _wait_for_ready_callbacks(
self,
timeout_sec: float = None,
nodes: List['Node'] = None
) -> Generator[Tuple[Task, WaitableEntityType, 'Node'], None, None]:
"""
Yield callbacks that are ready to be executed.
:raise TimeoutException: on timeout.
:raise ShutdownException: on if executor was shut down.
:param timeout_sec: Seconds to wait. Block forever if ``None`` or negative.
Don't wait if 0.
:param nodes: A list of nodes to wait on. Wait on all nodes if ``None``.
"""
timeout_timer = None
timeout_nsec = timeout_sec_to_nsec(timeout_sec)
if timeout_nsec > 0:
timeout_timer = Timer(None,
None,
timeout_nsec,
self._clock,
context=self._context)
yielded_work = False
while not yielded_work and not self._is_shutdown:
# Refresh "all" nodes in case executor was woken by a node being added or removed
nodes_to_use = nodes
if nodes is None:
nodes_to_use = self.get_nodes()
# Yield tasks in-progress before waiting for new work
tasks = None
with self._tasks_lock:
tasks = list(self._tasks)
if tasks:
for task, entity, node in reversed(tasks):
if (not task.executing() and not task.done()
and (node is None or node in nodes_to_use)):
yielded_work = True
yield task, entity, node
with self._tasks_lock:
# Get rid of any tasks that are done
self._tasks = list(
filter(lambda t_e_n: not t_e_n[0].done(), self._tasks))
# Gather entities that can be waited on
subscriptions: List[Subscription] = []
guards: List[GuardCondition] = []
timers: List[Timer] = []
clients: List[Client] = []
services: List[Service] = []
waitables: List[Waitable] = []
for node in nodes_to_use:
subscriptions.extend(
filter(self.can_execute, node.subscriptions))
timers.extend(filter(self.can_execute, node.timers))
clients.extend(filter(self.can_execute, node.clients))
services.extend(filter(self.can_execute, node.services))
node_guards = filter(self.can_execute, node.guards)
waitables.extend(filter(self.can_execute, node.waitables))
# retrigger a guard condition that was triggered but not handled
for gc in node_guards:
if gc._executor_triggered:
gc.trigger()
guards.append(gc)
if timeout_timer is not None:
timers.append(timeout_timer)
guards.append(self._guard)
guards.append(self._sigint_gc)
entity_count = NumberOfEntities(len(subscriptions), len(guards),
len(timers), len(clients),
len(services))
for waitable in waitables:
entity_count += waitable.get_num_entities()
# Construct a wait set
with _WaitSet() as wait_set, ExitStack() as context_stack:
sub_capsules = []
for sub in subscriptions:
try:
sub_capsules.append(
context_stack.enter_context(sub.handle))
except InvalidHandle:
entity_count.num_subscriptions -= 1
client_capsules = []
for cli in clients:
try:
client_capsules.append(
context_stack.enter_context(cli.handle))
except InvalidHandle:
entity_count.num_clients -= 1
service_capsules = []
for srv in services:
try:
service_capsules.append(
context_stack.enter_context(srv.handle))
except InvalidHandle:
entity_count.num_services -= 1
timer_capsules = []
for tmr in timers:
try:
timer_capsules.append(
context_stack.enter_context(tmr.handle))
except InvalidHandle:
entity_count.num_timers -= 1
guard_capsules = []
for gc in guards:
try:
guard_capsules.append(
context_stack.enter_context(gc.handle))
except InvalidHandle:
entity_count.num_guard_conditions -= 1
context_capsule = context_stack.enter_context(
self._context.handle)
_rclpy.rclpy_wait_set_init(
wait_set, entity_count.num_subscriptions,
entity_count.num_guard_conditions, entity_count.num_timers,
entity_count.num_clients, entity_count.num_services,
entity_count.num_events, context_capsule)
_rclpy.rclpy_wait_set_clear_entities(wait_set)
for sub_capsule in sub_capsules:
_rclpy.rclpy_wait_set_add_entity('subscription', wait_set,
sub_capsule)
for cli_capsule in client_capsules:
_rclpy.rclpy_wait_set_add_entity('client', wait_set,
cli_capsule)
for srv_capsule in service_capsules:
_rclpy.rclpy_wait_set_add_entity('service', wait_set,
srv_capsule)
for tmr_capsule in timer_capsules:
_rclpy.rclpy_wait_set_add_entity('timer', wait_set,
tmr_capsule)
for gc_capsule in guard_capsules:
_rclpy.rclpy_wait_set_add_entity('guard_condition',
wait_set, gc_capsule)
for waitable in waitables:
waitable.add_to_wait_set(wait_set)
# Wait for something to become ready
_rclpy.rclpy_wait(wait_set, timeout_nsec)
if self._is_shutdown:
raise ShutdownException()
if not self._context.ok():
raise ExternalShutdownException()
# get ready entities
subs_ready = _rclpy.rclpy_get_ready_entities(
'subscription', wait_set)
guards_ready = _rclpy.rclpy_get_ready_entities(
'guard_condition', wait_set)
timers_ready = _rclpy.rclpy_get_ready_entities(
'timer', wait_set)
clients_ready = _rclpy.rclpy_get_ready_entities(
'client', wait_set)
services_ready = _rclpy.rclpy_get_ready_entities(
'service', wait_set)
# Mark all guards as triggered before yielding since they're auto-taken
for gc in guards:
if gc.handle.pointer in guards_ready:
gc._executor_triggered = True
# Check waitables before wait set is destroyed
for node in nodes_to_use:
for wt in node.waitables:
# Only check waitables that were added to the wait set
if wt in waitables and wt.is_ready(wait_set):
handler = self._make_handler(
wt, node, lambda e: e.take_data(),
self._execute_waitable)
yielded_work = True
yield handler, wt, node
# Process ready entities one node at a time
for node in nodes_to_use:
for tmr in node.timers:
if tmr.handle.pointer in timers_ready:
with tmr.handle as capsule:
# Check timer is ready to workaround rcl issue with cancelled timers
if _rclpy.rclpy_is_timer_ready(capsule):
if tmr.callback_group.can_execute(tmr):
handler = self._make_handler(
tmr, node, self._take_timer,
self._execute_timer)
yielded_work = True
yield handler, tmr, node
for sub in node.subscriptions:
if sub.handle.pointer in subs_ready:
if sub.callback_group.can_execute(sub):
handler = self._make_handler(
sub, node, self._take_subscription,
self._execute_subscription)
yielded_work = True
yield handler, sub, node
for gc in node.guards:
if gc._executor_triggered:
if gc.callback_group.can_execute(gc):
handler = self._make_handler(
gc, node, self._take_guard_condition,
self._execute_guard_condition)
yielded_work = True
yield handler, gc, node
for client in node.clients:
if client.handle.pointer in clients_ready:
if client.callback_group.can_execute(client):
handler = self._make_handler(
client, node, self._take_client,
self._execute_client)
yielded_work = True
yield handler, client, node
for srv in node.services:
if srv.handle.pointer in services_ready:
if srv.callback_group.can_execute(srv):
handler = self._make_handler(
srv, node, self._take_service,
self._execute_service)
yielded_work = True
yield handler, srv, node
# Check timeout timer
if (timeout_nsec == 0
or (timeout_timer is not None
and timeout_timer.handle.pointer in timers_ready)):
raise TimeoutException()
if self._is_shutdown:
raise ShutdownException()
def wait_for_ready_callbacks(
self, *args, **kwargs) -> Tuple[Task, WaitableEntityType, 'Node']:
"""
Return callbacks that are ready to be executed.
The arguments to this function are passed to the internal method
:meth:`_wait_for_ready_callbacks` to get a generator for ready callbacks:
.. Including the docstring for the hidden function for reference
.. automethod:: _wait_for_ready_callbacks
"""
while True:
if self._cb_iter is None or self._last_args != args or self._last_kwargs != kwargs:
# Create a new generator
self._last_args = args
self._last_kwargs = kwargs
self._cb_iter = self._wait_for_ready_callbacks(*args, **kwargs)
try:
return next(self._cb_iter)
except StopIteration:
# Generator ran out of work
self._cb_iter = None