def __init__(self, redis_client: StrictRedis, query_id: str):
self.redis_client = redis_client
self.query_id = query_id
self.state_machine = Finist(redis_client, f"{query_id}-state",
QueryState.KNOWN)
self.state_machine.on(QueryEvent.QUEUE, QueryState.KNOWN,
QueryState.QUEUED)
self.state_machine.on(QueryEvent.EXECUTE, QueryState.QUEUED,
QueryState.EXECUTING)
self.state_machine.on(QueryEvent.ERROR, QueryState.EXECUTING,
QueryState.ERRORED)
self.state_machine.on(QueryEvent.FINISH, QueryState.EXECUTING,
QueryState.COMPLETED)
self.state_machine.on(QueryEvent.CANCEL, QueryState.QUEUED,
QueryState.CANCELLED)
self.state_machine.on(QueryEvent.CANCEL, QueryState.EXECUTING,
QueryState.CANCELLED)
self.state_machine.on(QueryEvent.RESET, QueryState.CANCELLED,
QueryState.RESETTING)
self.state_machine.on(QueryEvent.RESET, QueryState.ERRORED,
QueryState.RESETTING)
self.state_machine.on(QueryEvent.RESET, QueryState.COMPLETED,
QueryState.RESETTING)
self.state_machine.on(QueryEvent.RESET, QueryState.COMPLETED,
QueryState.RESETTING)
self.state_machine.on(QueryEvent.FINISH_RESET, QueryState.RESETTING,
QueryState.KNOWN)
def get_fsm(chat_id):
fsm = Finist(redis_conn, chat_id, "pending")
if fsm.state() == "pending":
# init transitions
fsm.on("approve", "pending", "approved")
fsm.on("auction", "approved", "auction_in")
fsm.on("reset", "approved", "pending")
fsm.on("reset", "pending", "pending")
fsm.on("reset", "auction", "pending")
return fsm
def setup_finist(self):
redis_conn.flushdb()
self.fsm = Finist(redis_conn, "myfsm", "pending")
self.fsm.on("approve", "pending", "approved")
self.fsm.on("cancel", "pending", "cancelled")
self.fsm.on("cancel", "approved", "cancelled")
self.fsm.on("reset", "cancelled", "pending")
def __init__(self, redis_client: StrictRedis, query_id: str):
self.redis_client = redis_client
self.query_id = query_id
must_populate = redis_client.get(f"finist:{query_id}-state") is None
self.state_machine = Finist(redis_client, f"{query_id}-state", QueryState.KNOWN)
if must_populate: # Need to create the state machine for this query
self.state_machine.on(QueryEvent.QUEUE, QueryState.KNOWN, QueryState.QUEUED)
self.state_machine.on(
QueryEvent.EXECUTE, QueryState.QUEUED, QueryState.EXECUTING
)
self.state_machine.on(
QueryEvent.ERROR, QueryState.EXECUTING, QueryState.ERRORED
)
self.state_machine.on(
QueryEvent.FINISH, QueryState.EXECUTING, QueryState.COMPLETED
)
self.state_machine.on(
QueryEvent.CANCEL, QueryState.QUEUED, QueryState.CANCELLED
)
self.state_machine.on(
QueryEvent.CANCEL, QueryState.EXECUTING, QueryState.CANCELLED
)
self.state_machine.on(
QueryEvent.RESET, QueryState.CANCELLED, QueryState.RESETTING
)
self.state_machine.on(
QueryEvent.RESET, QueryState.ERRORED, QueryState.RESETTING
)
self.state_machine.on(
QueryEvent.RESET, QueryState.COMPLETED, QueryState.RESETTING
)
self.state_machine.on(
QueryEvent.RESET, QueryState.COMPLETED, QueryState.RESETTING
)
self.state_machine.on(
QueryEvent.FINISH_RESET, QueryState.RESETTING, QueryState.KNOWN
)
class QueryStateMachine:
"""
Implements a state machine for a query's lifecycle, backed by redis.
Each query, once instantiated, is in one of a number of possible states.
- known, indicating that the query has been created, but not yet run, or queued for storage.
- queued, which indicates that a query is going to be executed in future (i.e. `store` has been called on it)
- executing, for queries which are currently running in FlowDB
- completed, indicating that the query has finished running successfully
- errored, when a query has been run but failed to succeed
- cancelled, when execution was terminated by the user
- resetting, when a previously run query is being purged from cache
When the query is in a queued, executing, or resetting state, methods which need
to use the results of the query should wait. The `wait_until_complete` method
will block while the query is in any of these states.
The initial state for the query is 'known'.
Parameters
----------
redis_client : StrictRedis
Client for redis
query_id : str
md5 query identifier
Notes
-----
Creating a new instance of a state machine for a query will not alter the state, as
the state is persisted in redis.
"""
def __init__(self, redis_client: StrictRedis, query_id: str):
self.redis_client = redis_client
self.query_id = query_id
self.state_machine = Finist(redis_client, f"{query_id}-state",
QueryState.KNOWN)
self.state_machine.on(QueryEvent.QUEUE, QueryState.KNOWN,
QueryState.QUEUED)
self.state_machine.on(QueryEvent.EXECUTE, QueryState.QUEUED,
QueryState.EXECUTING)
self.state_machine.on(QueryEvent.ERROR, QueryState.EXECUTING,
QueryState.ERRORED)
self.state_machine.on(QueryEvent.FINISH, QueryState.EXECUTING,
QueryState.COMPLETED)
self.state_machine.on(QueryEvent.CANCEL, QueryState.QUEUED,
QueryState.CANCELLED)
self.state_machine.on(QueryEvent.CANCEL, QueryState.EXECUTING,
QueryState.CANCELLED)
self.state_machine.on(QueryEvent.RESET, QueryState.CANCELLED,
QueryState.RESETTING)
self.state_machine.on(QueryEvent.RESET, QueryState.ERRORED,
QueryState.RESETTING)
self.state_machine.on(QueryEvent.RESET, QueryState.COMPLETED,
QueryState.RESETTING)
self.state_machine.on(QueryEvent.RESET, QueryState.COMPLETED,
QueryState.RESETTING)
self.state_machine.on(QueryEvent.FINISH_RESET, QueryState.RESETTING,
QueryState.KNOWN)
@property
def current_query_state(self) -> QueryState:
"""
Returns
-------
QueryState
Current state of the query this state machine refers to
"""
return QueryState(self.state_machine.state().decode())
@property
def is_executing(self) -> bool:
"""
Returns
-------
bool
True if the query is currently running
"""
return self.current_query_state == QueryState.EXECUTING
@property
def is_queued(self) -> bool:
"""
Returns
-------
bool
True if the the query's store method has been called and it has not begin running
"""
return self.current_query_state == QueryState.QUEUED
@property
def is_completed(self) -> bool:
"""
Returns
-------
bool
True if the query ran successfully and is in cache
"""
return self.current_query_state == QueryState.COMPLETED
@property
def is_finished_executing(self) -> bool:
"""
True if the query state is `completed` or `errored`. I.e., it was previously
executing and is now finished either successfully or with a failure (but it
wasn't cancelled manually).
"""
return (self.current_query_state
== QueryState.COMPLETED) or (self.current_query_state
== QueryState.ERRORED)
@property
def is_errored(self) -> bool:
"""
Returns
-------
bool
True if the query failed to run with an error
"""
return self.current_query_state == QueryState.ERRORED
@property
def is_resetting(self) -> bool:
"""
Returns
-------
bool
True if the query is currently being removed from cache, or recovered from cancellation or error
"""
return self.current_query_state == QueryState.RESETTING
@property
def is_known(self) -> bool:
"""
Returns
-------
bool
True if the query has not been set running and may be queued to do so
"""
return self.current_query_state == QueryState.KNOWN
@property
def is_cancelled(self) -> bool:
"""
Returns
-------
bool
True if the query was previously queued or running but was cancelled
"""
return self.current_query_state == QueryState.CANCELLED
def trigger_event(self, event: QueryEvent) -> Tuple[QueryState, bool]:
"""
Attempts to trigger a state transition - will only transition if a
transition is possible given the current state of the query.
Parameters
----------
event: QueryEvent
Event to trigger
Returns
-------
tuple of QueryState, bool
Returns a tuple of the new query state, and a bool indicating whether this method
call caused a transition to that state
"""
state, trigger_success = self.state_machine.trigger(event)
return QueryState(state.decode()), trigger_success
def cancel(self):
"""
Attempt to mark the query as cancelled.
Returns
-------
tuple of QueryState, bool
Returns a tuple of the new query state, and a bool indicating whether the caller
triggered the query to be cancelled with this call
"""
return self.trigger_event(QueryEvent.CANCEL)
def enqueue(self):
"""
Attempt to mark the query as queued.
Returns
-------
tuple of QueryState, bool
Returns a tuple of the new query state, and a bool indicating whether the caller
triggered the query to be queued with this call
"""
return self.trigger_event(QueryEvent.QUEUE)
def raise_error(self):
"""
Attempt to mark the query as having errored while running.
Returns
-------
tuple of QueryState, bool
Returns a tuple of the new query state, and a bool indicating whether the caller
marked the query as erroring with this call
"""
return self.trigger_event(QueryEvent.ERROR)
def execute(self):
"""
Attempt to mark the query as in the process of executing.
Returns
-------
tuple of QueryState, bool
Returns a tuple of the new query state, and a bool indicating whether the caller
marked the query as executing with this call
"""
return self.trigger_event(QueryEvent.EXECUTE)
def finish(self):
"""
Attempt to mark the query as completed.
Returns
-------
tuple of QueryState, bool
Returns a tuple of the new query state, and a bool indicating whether the caller
marked the query as finished with this call
"""
return self.trigger_event(QueryEvent.FINISH)
def reset(self):
"""
Attempt to mark the query as in the process of resetting.
Returns
-------
tuple of QueryState, bool
Returns a tuple of the new query state, and a bool indicating whether the caller
triggered the query to be reset with this call
"""
return self.trigger_event(QueryEvent.RESET)
def finish_resetting(self):
"""
Attempt to mark the query as having finished resetting.
Returns
-------
tuple of QueryState, bool
Returns a tuple of the new query state, and a bool indicating whether the caller
marked the reset as complete with this call.
"""
return self.trigger_event(QueryEvent.FINISH_RESET)
def wait_until_complete(self, sleep_duration=1):
"""
Blocks until the query is in a state where its result is determinate
(i.e., one of "know", "errored", "completed", "cancelled").
"""
if self.is_executing or self.is_queued or self.is_resetting:
while not (self.is_finished_executing or self.is_cancelled
or self.is_known):
_sleep(sleep_duration)
class FinistTest(unittest.TestCase):
"""docstring for FinistTest"""
def __init__(self, *args, **kwargs):
super(FinistTest, self).__init__(*args, **kwargs)
self.setup_finist()
def setup_finist(self):
redis_conn.flushdb()
self.fsm = Finist(redis_conn, "myfsm", "pending")
self.fsm.on("approve", "pending", "approved")
self.fsm.on("cancel", "pending", "cancelled")
self.fsm.on("cancel", "approved", "cancelled")
self.fsm.on("reset", "cancelled", "pending")
def send_event(self, event):
# Change event for the FSM
self.fsm.trigger(event)
def setup_finist_with_client(self):
self.fsm2 = Finist(redis_conn, "myfsm", "pending")
def test_run(self):
# Verify initial state
self.assertEqual("pending", self.fsm.state())
# Send an event
self.send_event("approve")
# Verify transition to "approved"
self.assertEqual("approved", self.fsm.state())
# Send an event
self.send_event("cancel")
# Verify transition to "cancelled"
self.assertEqual("cancelled", self.fsm.state())
# Send an event
self.send_event("approve")
# Verify state remains as "cancelled"
self.assertEqual("cancelled", self.fsm.state())
# Create a different fsm with client
self.setup_finist_with_client()
# Verify state remains as "cancelled"
self.assertEqual("cancelled", self.fsm2.state())
state, changed = self.fsm.trigger("reset")
# A successful event returns true
self.assertEqual(True, changed)
self.assertEqual("pending", state)
state, changed = self.fsm.trigger("reset")
# An unsuccessful event returns false
self.assertEqual(False, changed)
self.assertEqual("pending", state)
# Delete an event
self.fsm.rm("approve")
state, changed = self.fsm.trigger("approve")
# Non existent events return false
self.assertEqual(False, changed)
self.assertEqual("pending", state)
def setup_finist_with_client(self):
self.fsm2 = Finist(redis_conn, "myfsm", "pending")
