Annotation Interface CircuitBreaker
A circuit breaker aims to prevent further damage by not executing functionality that is doomed to fail. After a failure situation has been detected, circuit breakers prevent methods from being executed and instead throw exceptions immediately. After a certain delay or wait time, the functionality is attempted to be executed again.
A circuit breaker can be in one of the following states:
- Closed: In normal operation, the circuit is closed. If a failure occurs, the Circuit Breaker records the
event. In closed state the
requestVolumeThreshold
andfailureRatio
parameters may be configured in order to specify the conditions under which the breaker will transition the circuit to open. If the failure conditions are met, the circuit will be opened. - Open: When the circuit is open, calls to the service operating under the circuit breaker will fail immediately. A delay may be configured for the circuit breaker. After the specified delay, the circuit transitions to half-open state.
- Half-open: In half-open state, trial executions of the service are allowed. By default one trial call to
the service is permitted. If the call fails, the circuit will return to open state. The
successThreshold
parameter allows the configuration of the number of trial executions that must succeed before the circuit can be closed. After the specified number of successful executions, the circuit will be closed. If a failure occurs before the successThreshold is reached the circuit will transition to open.
When a method returns a result, the following rules are applied to determine whether the result is a success or a failure:
- If the method does not throw a
Throwable
, it is considered a success - Otherwise, if the thrown object is assignable to any value in the
skipOn()
parameter, it is considered a success - Otherwise, if the thrown object is assignable to any value in the
failOn()
parameter, it is considered a failure - Otherwise it is considered a success
Throwable
which is not an Error
or Exception
, non-portable behavior
results.-
Optional Element Summary
Modifier and TypeOptional ElementDescriptionlong
The delay after which an open circuit will transitions to half-open state.The unit of the delay after which an open circuit will transitions to half-open state.The list of exception types which should be considered failures.double
The ratio of failures within the rolling window that will trip the circuit to open.int
The number of consecutive requests in a rolling window.The list of exception types which should not be considered failures.int
The number of successful executions, before a half-open circuit is closed again.
-
Element Details
-
failOn
The list of exception types which should be considered failures.Note that if a method throws a
Throwable
which is not anError
orException
, non-portable behavior results.- Returns:
- the exception types which should be considered failures
- Default:
- {java.lang.Throwable.class}
-
skipOn
The list of exception types which should not be considered failures.This list takes priority over the types listed in
failOn()
.Note that if a method throws a
Throwable
which is not anError
orException
, non-portable behavior results.- Returns:
- the exception types which should not be considered failures
- Default:
- {}
-
delay
long delayThe delay after which an open circuit will transitions to half-open state.The amount of delay is taken from this delay value and the
delayUnit
, and defaults to five seconds. The value must be greater than or equal to0
.0
means no delay.- Returns:
- the delay time after which an open circuit transitions to half-open state
- Default:
- 5000L
-
delayUnit
ChronoUnit delayUnitThe unit of the delay after which an open circuit will transitions to half-open state.- Returns:
- The unit of the delay
- See Also:
- Default:
- MILLIS
-
requestVolumeThreshold
int requestVolumeThresholdThe number of consecutive requests in a rolling window.The circuit breaker will trip if the number of failures exceed the
failureRatio
within the rolling window of consecutive requests. The value must be greater than or equal to1
.- Returns:
- the number of the consecutive requests in a rolling window
- Default:
- 20
-
failureRatio
double failureRatioThe ratio of failures within the rolling window that will trip the circuit to open.The circuit breaker will trip if the number of failures exceed the
failureRatio
within the rolling window of consecutive requests. For example, if therequestVolumeThreshold
is20
andfailureRatio
is.50
, ten or more failures in 20 consecutive requests will trigger the circuit to open. The value must be between0
and1
inclusive.- Returns:
- the failure ratio threshold
- Default:
- 0.5
-
successThreshold
int successThresholdThe number of successful executions, before a half-open circuit is closed again.A half-open circuit will be closed once
successThreshold
executions were made without failures. If a failure occurs while in half-open state the circuit is immediately opened again. The value must be greater than or equal to1
.- Returns:
- the success threshold to fully close the circuit
- Default:
- 1
-