Class ThresholdCircuitBreaker
java.lang.Object
org.apache.commons.lang3.concurrent.AbstractCircuitBreaker<Long>
org.apache.commons.lang3.concurrent.ThresholdCircuitBreaker
- All Implemented Interfaces:
- CircuitBreaker<Long>
A simple implementation of the Circuit Breaker pattern
 that opens if the requested increment amount is greater than a given threshold.
 
It contains an internal counter that starts in zero, and each call increments the counter by a given amount. If the threshold is zero, the circuit breaker will be in a permanent open state.
An example of use case could be a memory circuit breaker.
 long threshold = 10L;
 ThresholdCircuitBreaker breaker = new ThresholdCircuitBreaker(10L);
 ...
 public void handleRequest(Request request) {
     long memoryUsed = estimateMemoryUsage(request);
     if (breaker.incrementAndCheckState(memoryUsed)) {
         // actually handle this request
     } else {
         // do something else, e.g. send an error code
     }
 }
 
 #Thread safe#
- Since:
- 3.5
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Nested Class SummaryNested classes/interfaces inherited from class org.apache.commons.lang3.concurrent.AbstractCircuitBreakerAbstractCircuitBreaker.State
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Field SummaryFields inherited from class org.apache.commons.lang3.concurrent.AbstractCircuitBreakerPROPERTY_NAME, state
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Constructor SummaryConstructorsConstructorDescriptionThresholdCircuitBreaker(long threshold) Creates a new instance ofThresholdCircuitBreakerand initializes the threshold.
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Method SummaryModifier and TypeMethodDescriptionbooleanChecks the state of this circuit breaker and changes it if necessary.voidclose()Closes this circuit breaker.longGets the threshold.booleanincrementAndCheckState(Long increment) Increments the monitored value and performs a check of the current state of this circuit breaker.Methods inherited from class org.apache.commons.lang3.concurrent.AbstractCircuitBreakeraddChangeListener, changeState, isClosed, isOpen, isOpen, open, removeChangeListener
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Constructor Details- 
ThresholdCircuitBreakerCreates a new instance ofThresholdCircuitBreakerand initializes the threshold.- Parameters:
- threshold- the threshold.
 
 
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Method Details- 
checkStateChecks the state of this circuit breaker and changes it if necessary. The return value indicates whether the circuit breaker is now in state closed; a value of true typically means that the current operation can continue.- Specified by:
- checkStatein interface- CircuitBreaker<Long>
- Specified by:
- checkStatein class- AbstractCircuitBreaker<Long>
- Returns:
- true if the circuit breaker is now closed; false otherwise.
 
- 
closeCloses this circuit breaker. Its state is changed to closed. If this circuit breaker is already closed, this method has no effect.Resets the internal counter back to its initial value (zero). - Specified by:
- closein interface- CircuitBreaker<Long>
- Overrides:
- closein class- AbstractCircuitBreaker<Long>
 
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getThresholdGets the threshold.- Returns:
- the threshold
 
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incrementAndCheckStateIncrements the monitored value and performs a check of the current state of this circuit breaker. This method works likeCircuitBreaker.checkState(), but the monitored value is incremented before the state check is performed.If the threshold is zero, the circuit breaker will be in a permanent open state. - Specified by:
- incrementAndCheckStatein interface- CircuitBreaker<Long>
- Specified by:
- incrementAndCheckStatein class- AbstractCircuitBreaker<Long>
- Parameters:
- increment- value to increment in the monitored value of the circuit breaker
- Returns:
- true if the circuit breaker is now closed; false otherwise
 
 
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