Struct KeyedStateStore 

pub struct KeyedStateStore<K, V> { /* private fields */ }

Typed, partitioned key-value state handle for stateful stream operators.

Serialization is provided by caller-supplied function pointers to keep this crate free of hard-coded codec dependencies.

Implementations

impl<K: Debug, V: Debug + Clone> KeyedStateStore<K, V>

pub fn new( partition: StatePartitionKey, backend: Arc<dyn StateBackend>, key_ser: fn(&K) -> Vec<u8>, val_ser: fn(&V) -> Vec<u8>, val_de: fn(&[u8]) -> Result<V, StreamError>, ) -> Self

Create a new keyed store backed by backend.

pub fn get(&self, key: &K) -> Result<Option<V>, StreamError>

Return the value for key, or None if absent.

pub fn put(&self, key: &K, value: V) -> Result<(), StreamError>

Store value under key.

pub fn delete(&self, key: &K) -> Result<bool, StreamError>

Remove key. Returns true if it existed.

pub fn update_or_default( &self, key: &K, updater: impl FnOnce(Option<V>) -> V, ) -> Result<V, StreamError>

Atomic read-modify-write. updater receives the current value (or None) and returns the new value to store.