Package dev.restate.sdk.interceptor

Interface RunContextPropagator

All Known Implementing Classes:

MicrometerRunContextPropagator, OpenTelemetryRunContextPropagator

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@Experimental
@FunctionalInterface
public interface RunContextPropagator

Propagates thread-local state from the thread running the handler code to the thread executing a Restate.run(java.lang.String, java.lang.Class<T>, dev.restate.common.function.ThrowingSupplier<T>) closure.

Restate.run(java.lang.String, java.lang.Class<T>, dev.restate.common.function.ThrowingSupplier<T>) closures are scheduled on the Executor provided in HandlerRunner.Options.setExecutor(Executor). Thread-local state installed on the handler thread (e.g. by a HandlerInterceptor opening a tracing span / observation scope, MDC values, security context, …) is not visible there by default. Implementations of this interface capture that state at submission time and restore it around the closure execution.

capture() is invoked on the handler thread (or whatever thread calls Restate.run(java.lang.String, java.lang.Class<T>, dev.restate.common.function.ThrowingSupplier<T>)) at submission time; RunContextPropagator.CapturedContext.wrap(java.lang.Runnable) is invoked later, and the resulting Runnable executes on the worker thread. The classic shape is:

 () -> {
   var captured = captureCurrentThreadState();
   return runnable -> () -> {
     try (var scope = captured.install()) {
       runnable.run();
     }
   };
 }
 

Propagators are discovered via ServiceLoader (global defaults) or registered explicitly via HandlerRunner.Options.addRunContextPropagator(RunContextPropagator). They apply to every Restate.run(java.lang.String, java.lang.Class<T>, dev.restate.common.function.ThrowingSupplier<T>) execution, including retries.

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static interface	RunContextPropagator.CapturedContext	Thread-local state captured by capture().

Method Summary

Modifier and Type	Method	Description
RunContextPropagator.CapturedContext	capture()	Capture a thread-local state from the calling thread.
static RunContextPropagator	combine(Collection<? extends RunContextPropagator> propagators)
static RunContextPropagator	combine(Stream<? extends RunContextPropagator> propagators)	Combine multiple propagators into a single RunContextPropagator.

Method Details

capture

RunContextPropagator.CapturedContext capture()

Capture a thread-local state from the calling thread.

combine

static RunContextPropagator combine(Stream<? extends RunContextPropagator> propagators)

Combine multiple propagators into a single RunContextPropagator.

capture() captures with all propagators in registration order; at wrap time the first propagator restores outermost.

combine

static RunContextPropagator combine(Collection<? extends RunContextPropagator> propagators)