Package com.linecorp.armeria.client.circuitbreaker

Interface CircuitBreakerClientHandler

All Known Implementing Classes:

Resilience4JCircuitBreakerClientHandler

Functional Interface:

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

@UnstableApi
@FunctionalInterface
public interface CircuitBreakerClientHandler

A handler used by a CircuitBreakerClient to integrate with a circuit breaker. One may extend this interface to use a custom circuit breaker with CircuitBreakerClient.

 // using a pre-defined handler
 CircuitBreakerClient.newDecorator(
         CircuitBreakerClientHandler.of(CircuitBreakerMapping.ofDefault()),
         CircuitBreakerRule.onException());


 // defining a custom handler
 CircuitBreakerClient.newDecorator(
         new CircuitBreakerClientHandler() {
             ...
             public CircuitBreakerCallback tryRequest(ClientRequestContext ctx, HttpRequest req) {
                 ...
                 MyCustomCircuitBreaker cb = ...
                 return new CircuitBreakerCallback() {
                     @Override
                     public void onSuccess(RequestContext ctx) {
                         cb.onSuccess();
                     }

                     @Override
                     public void onFailure(RequestContext ctx, @Nullable Throwable throwable) {
                         cb.onFailure();
                     }
                 };
             }
             ...
         },
         CircuitBreakerRule.onException());
 

Method Summary

Modifier and Type	Method	Description
default boolean	isCircuitBreakerException(Exception ex)	Determines if the given Exception is related to a circuit breaker.
static CircuitBreakerClientHandler	of(CircuitBreaker circuitBreaker)	Creates a default CircuitBreakerClientHandler which uses the provided CircuitBreaker to handle requests.
static CircuitBreakerClientHandler	of(CircuitBreakerMapping mapping)	Creates a default CircuitBreakerClientHandler which uses the provided CircuitBreakerMapping to handle requests.
@Nullable CircuitBreakerCallback	tryRequest(ClientRequestContext ctx, Request req)	Invoked by CircuitBreakerClient right before sending a request.

Method Details

of

static CircuitBreakerClientHandler of(CircuitBreaker circuitBreaker)

Creates a default CircuitBreakerClientHandler which uses the provided CircuitBreaker to handle requests.

of

static CircuitBreakerClientHandler of(CircuitBreakerMapping mapping)

Creates a default CircuitBreakerClientHandler which uses the provided CircuitBreakerMapping to handle requests.

tryRequest

@Nullable
@Nullable CircuitBreakerCallback tryRequest(ClientRequestContext ctx,
 Request req)

Invoked by CircuitBreakerClient right before sending a request. In a typical implementation, users may extract the appropriate circuit breaker implementation using the provided ClientRequestContext and Request. Afterwards, one of the following can occur:

• If the circuit breaker rejects the request, an exception such as FailFastException may be thrown.
• If the circuit breaker doesn't reject the request, users may choose to return a CircuitBreakerCallback. A callback method will be invoked depending on the configured CircuitBreakerRule.
• One may return null to proceed normally as if the CircuitBreakerClient doesn't exist.

isCircuitBreakerException

@UnstableApi
default boolean isCircuitBreakerException(Exception ex)

Determines if the given Exception is related to a circuit breaker. This method is invoked by the CircuitBreakerClient to determine if a fallback logic should be executed.