Module io.helidon.faulttolerance

Package io.helidon.faulttolerance

Interface CircuitBreaker

All Superinterfaces:

FtHandler, RuntimeType.Api<CircuitBreakerConfig>

public interface CircuitBreaker
extends FtHandler, RuntimeType.Api<CircuitBreakerConfig>

CircuitBreaker protects a potentially failing endpoint from overloading and the application from spending resources on those endpoints.

In case too many errors are detected, the circuit opens and all new requests fail with a CircuitBreakerOpenException for a period of time. After this period, attempts are made to check if the service is up again - if so, the circuit closes and requests can process as usual again.

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static enum	CircuitBreaker.State	A circuit breaker can be in any of 3 possible states as defined by this enum.

Field Summary

Fields

Modifier and Type	Field	Description
static final String	FT_CIRCUITBREAKER_CALLS_TOTAL	Counter for all the calls in a timeout.
static final String	FT_CIRCUITBREAKER_OPENED_TOTAL	Counter for the number of times a circuit breaks has moved from CircuitBreaker.State.CLOSED to CircuitBreaker.State.OPEN.

Method Summary

Modifier and Type	Method	Description
static CircuitBreakerConfig.Builder	builder()	A new circuit breaker fluent API builder.
static CircuitBreaker	create(CircuitBreakerConfig config)	Create a new circuit builder based on its configuration.
static CircuitBreaker	create(Consumer<CircuitBreakerConfig.Builder> builderConsumer)	Create a new circuit breaker with a possibility to customize its configuration.
CircuitBreaker.State	state()	Current breaker state.
void	state(CircuitBreaker.State newState)	Set state of this circuit breaker.

Methods inherited from interface io.helidon.faulttolerance.FtHandler

invoke, name

Methods inherited from interface io.helidon.builder.api.RuntimeType.Api

prototype

Field Details

FT_CIRCUITBREAKER_CALLS_TOTAL

static final String FT_CIRCUITBREAKER_CALLS_TOTAL

Counter for all the calls in a timeout.

See Also:

• Constant Field Values

FT_CIRCUITBREAKER_OPENED_TOTAL

static final String FT_CIRCUITBREAKER_OPENED_TOTAL

Counter for the number of times a circuit breaks has moved from CircuitBreaker.State.CLOSED to CircuitBreaker.State.OPEN.

See Also:

• Constant Field Values

Method Details

create

static CircuitBreaker create(CircuitBreakerConfig config)

Create a new circuit builder based on its configuration.

Parameters:

config - circuit breaker configuration

Returns:

a new circuit breaker

create

static CircuitBreaker create(Consumer<CircuitBreakerConfig.Builder> builderConsumer)

Create a new circuit breaker with a possibility to customize its configuration.

Parameters:

builderConsumer - consumer of configuration

Returns:

a new circuit breaker

builder

static CircuitBreakerConfig.Builder builder()

A new circuit breaker fluent API builder.

Returns:

a new builder

state

CircuitBreaker.State state()

Current breaker state. As the state may change within nanoseconds, this is for information only.

Returns:

current breaker state

state

void state(CircuitBreaker.State newState)

Set state of this circuit breaker. Note that all usual processes to re-close or open the circuit are in progress.

• If set to CircuitBreaker.State.OPEN, a timer will set it to half open in a while
• If set to CircuitBreaker.State.HALF_OPEN, it may close after first successful request
• If set to CircuitBreaker.State.CLOSED, it may open again if requests fail

So a subsequent call to state() may yield a different state than configured here

Parameters:

newState - state to configure