org.apache.flink.statefun.sdk.java

Interface AddressScopedStorage

All Known Implementing Classes:

ConcurrentAddressScopedStorage

public interface AddressScopedStorage

An AddressScopedStorage is used for reading and writing persistent values that is managed by Stateful Functions for fault-tolerance and consistency.

All access to the storage is scoped to the current invoked function instance, identified by the instance's Address. This means that within an invocation, function instances may only access it's own persisted values through this storage.

Method Summary

Modifier and Type	Method and Description
<T> java.util.Optional<T>	get(ValueSpec<T> spec) Gets the value of the provided ValueSpec, scoped to the current invoked Address.
<T> void	remove(ValueSpec<T> spec) Removes the prior value set for the provided ValueSpec, scoped to the current invoked Address.
<T> void	set(ValueSpec<T> spec, T value) Sets the value for the provided ValueSpec, scoped to the current invoked Address.

Method Detail

get

<T> java.util.Optional<T> get(ValueSpec<T> spec)

Gets the value of the provided ValueSpec, scoped to the current invoked Address.

Type Parameters:

T - the type of the value.

Parameters:

spec - the ValueSpec to read the value for.

Returns:

the value, or Optional.empty() if there was not prior value set.

Throws:

IllegalStorageAccessException - if the provided ValueSpec is not recognized by the storage (e.g., if it wasn't registered for the accessing function).

set

<T> void set(ValueSpec<T> spec,
             T value)

Sets the value for the provided ValueSpec, scoped to the current invoked Address.

Type Parameters:

T - the type of the value.

Parameters:

spec - the ValueSpec to write the new value for.

value - the new value to set.

Throws:

IllegalStorageAccessException - if the provided ValueSpec is not recognized by the storage (e.g., if it wasn't registered for the accessing function).

remove

<T> void remove(ValueSpec<T> spec)

Removes the prior value set for the provided ValueSpec, scoped to the current invoked Address.

After removing the value, calling get(ValueSpec) for the same spec will return an Optional.empty().

Type Parameters:

T - the type of the value.

Parameters:

spec - the ValueSpec to remove the prior value for.

Throws:

IllegalStorageAccessException - if the provided ValueSpec is not recognized by the storage (e.g., if it wasn't registered for the accessing function).