def _transition() -> bool:
with app.session.begin_nested():
lock_label(app, label)
current_state = get_current_state(app, label, state_machine)
if isinstance(current_state, Action):
return process_action(
app=app,
state=current_state,
state_machine=state_machine,
label=label,
)
elif isinstance(current_state, Gate): # pragma: no branch
if not current_state.trigger_on_entry:
return False
return process_gate(
app=app,
state=current_state,
state_machine=state_machine,
label=label,
)
else:
raise RuntimeError( # pragma: no cover
"Unsupported state type {0}".format(current_state), )
def process_cron(
process: LabelStateProcessor,
get_labels: Callable[[StateMachine, State], Iterable[str]],
app: App,
state_machine: StateMachine,
state: State,
):
"""
Cron event entrypoint.
"""
with app.new_session():
relevant_labels = get_labels(state_machine, state)
for label_name in relevant_labels:
with suppress_exceptions(app.logger):
label = LabelRef(name=label_name, state_machine=state_machine.name)
could_progress = False
with app.new_session():
lock_label(app, label)
current_state = get_current_state(app, label, state_machine)
if current_state != state:
continue
could_progress = process(
app=app,
state=state,
state_machine=state_machine,
label=label,
)
with app.new_session():
if could_progress:
process_transitions(app, label)
def delete_label(app: App, label: LabelRef) -> None:
"""
Deletes the metadata for a label and marks the label as deleted.
The history for the label is not changed (in order to allow post-hoc
analysis of the path the label took through the state machine).
"""
state_machine = get_state_machine(app, label) # Raises UnknownStateMachine
try:
row = lock_label(app, label)
except UnknownLabel:
return
if row is None or row.deleted:
return
# Record the label as having been deleted and remove its metadata
row.metadata = {}
row.deleted = True
# Add a history entry for the deletion
current_state = get_current_state(app, label, state_machine)
if current_state is None:
raise AssertionError(f"Active label {label} has no current state!")
row.history.append(History(
old_state=current_state.name,
new_state=None,
))
def _process_transitions_for_metadata_update(
app: App,
label: LabelRef,
state_machine: StateMachine,
state_pending_update: State,
):
with app.session.begin_nested():
lock_label(app, label)
current_state = get_current_state(app, label, state_machine)
if state_pending_update != current_state:
# We have raced with another update, and are no longer in
# the state for which we needed an update, so we should
# stop.
return
if not isinstance(current_state, Gate): # pragma: no branch
# Cannot be hit because of the semantics of
# `needs_gate_evaluation_for_metadata_change`. Here to
# appease mypy.
raise RuntimeError( # pragma: no cover
"Label not in a gate", )
could_progress = process_gate(
app=app,
state=current_state,
state_machine=state_machine,
label=label,
)
if could_progress:
process_transitions(app, label)
def test_get_current_state_for_label_in_invalid_state(custom_app,
create_label):
state_to_be_removed = Gate(
name='start',
triggers=[],
next_states=ConstantNextState('end'),
exit_condition=ExitConditionProgram('false'),
)
end_state = Gate(
name='end',
triggers=[],
next_states=NoNextStates(),
exit_condition=ExitConditionProgram('false'),
)
app = custom_app(
state_machines={
'test_machine':
StateMachine(
name='test_machine',
states=[state_to_be_removed, end_state],
feeds=[],
webhooks=[],
),
})
label = create_label('foo', 'test_machine', {})
state_machine = app.config.state_machines['test_machine']
# Remove the state which we expect the label to be in from the state
# machine; this is logically equivalent to loading a new config which does
# not have the state
del state_machine.states[0]
with app.new_session():
with pytest.raises(Exception):
utils.get_current_state(app, label, state_machine)
def test_does_not_need_gate_evaluation_for_metadata_change_with_action(
app, create_label, mock_webhook):
state_machine = app.config.state_machines['test_machine']
# Force the action to fail here so that the label is left in the action
# state.
with mock_webhook(WebhookResult.FAIL):
label = create_label('foo', 'test_machine', {'should_progress': True})
with app.new_session():
current_state = utils.get_current_state(
app,
label,
state_machine,
)
assert current_state.name == 'perform_action'
assert utils.needs_gate_evaluation_for_metadata_change(
app,
state_machine,
label,
{},
) == (False, current_state)
def test_needs_gate_evaluation_for_metadata_change(app, create_label):
label = create_label('foo', 'test_machine', {})
state_machine = app.config.state_machines['test_machine']
with app.new_session():
current_state = utils.get_current_state(
app,
label,
state_machine,
)
assert utils.needs_gate_evaluation_for_metadata_change(
app,
state_machine,
label,
{'foo': 'bar'},
) == (False, current_state)
assert utils.needs_gate_evaluation_for_metadata_change(
app,
state_machine,
label,
{'should_progress': 'bar'},
) == (True, current_state)
def test_get_current_state_for_deleted_label(app, create_deleted_label):
label = create_deleted_label('foo', 'test_machine')
state_machine = app.config.state_machines['test_machine']
with app.new_session():
assert utils.get_current_state(app, label, state_machine) is None
def test_get_current_state(app, create_label):
label = create_label('foo', 'test_machine', {})
state_machine = app.config.state_machines['test_machine']
state = state_machine.states[0]
with app.new_session():
assert utils.get_current_state(app, label, state_machine) == state
def get_label_state(app: App, label: LabelRef) -> Optional[State]:
"""Finds the current state of a label."""
state_machine = get_state_machine(app, label)
return get_current_state(app, label, state_machine)