Stateful Function

StatefulFunction(key, function_name, partition, operator_name, operator_state, networking, dns, t_id, request_id, fallback_mode, use_fallback_cache, partitioner, protocol)

Bases: Function

Encapsulates a stateful function in a distributed Styx operator.

This class wraps user-defined functions with access to state, networking, partitioning, and chain coordination. It supports fallback execution and asynchronous remote function chaining.

Initializes a stateful function with execution context.

Parameters:

Name	Type	Description	Default
key	Any	The key of the function.	required
function_name	str	Name of the user-defined function.	required
partition	int	Partition ID where this function will execute.	required
operator_name	str	Name of the operator this function belongs to.	required
operator_state	BaseOperatorState	The state backend to use.	required
networking	NetworkingManager	Handles communication and coordination.	required
dns	dict	Mapping of operator partitions to worker locations.	required
t_id	int	Transaction ID.	required
request_id	bytes	Unique identifier for this function invocation.	required
fallback_mode	bool	Whether to enable fallback (recovery) logic.	required
use_fallback_cache	bool	Whether to use cached fallback results.	required
partitioner	BasePartitioner	The partitioning strategy.	required
protocol	BaseTransactionalProtocol	Protocol for function invocation.	required

data property

dict: All state associated with the current operator, and partition.

key property

The key for this function instance.

call_remote_async(operator_name, function_name, key, params=tuple())

Queues a remote asynchronous function call.

Parameters:

Name	Type	Description	Default
operator_name	str	Name of the target operator.	required
function_name	Type | str	Function type or name to invoke.	required
key	Any	Key for the remote call.	required
params	tuple	Parameters for the remote function call.	tuple()

get()

Retrieves the value from state for the current key.

Returns:

Name	Type	Description
object	Any	The current value associated with the key.

put(value)

Stores a value in the state for the current key.

Parameters:

Name	Type	Description	Default
value	Any	The value to store.	required