org.apache.flink.statefun.flink.state.processor

Interface StateBootstrapFunction

public interface StateBootstrapFunction

A StateBootstrapFunction defines how to bootstrap state for a StatefulFunction instance with a given input.

Each StateBootstrapFunction instance directly corresponds to a StatefulFunction instance. Likewise, each instance is uniquely identified by an Address, represented by the type and id of the function being bootstrapped. Any state that is persisted by a StateBootstrapFunction instance will be available to the corresponding live StatefulFunction instance having the same address.

For example, consider the following state bootstrap function:

 public class MyStateBootstrapFunction implements StateBootstrapFunction {

     {@code @Persisted}
     private PersistedValue<MyState> state = PersistedValue.of("my-state", MyState.class);

     {@code @Override}
     public void bootstrap(Context context, Object input) {
         state.set(extractStateFromInput(input));
     }
 }
 

Assume that this bootstrap function was provided for function type MyFunctionType, and the id of the bootstrap function instance was id-13. The function writes persisted state of name my-state using the given bootstrap data. After restoring a Stateful Functions application from the savepoint generated using this bootstrap function, the stateful function instance with address (MyFunctionType, id-13) will already have state values available under state name my-state.

Method Summary

Modifier and Type	Method and Description
void	bootstrap(Context context, java.lang.Object bootstrapData) Bootstraps state for this function with the given bootstrap data.

Method Detail

bootstrap

void bootstrap(Context context,
               java.lang.Object bootstrapData)

Bootstraps state for this function with the given bootstrap data.

Parameters:

context - context for the current bootstrap invocation. The provided context instance should not be used outside the scope of the current invocation.

bootstrapData - input to be used for bootstrapping state.