new property maxDurationOpenInHalfOpenState

Author: guyplusplus

README.md

@@ -12,7 +12,8 @@ It supports the 5 states:
 ![State Machine](./state_machine.jpg)
 
 
-The following configuration properties are supported
+The following Resilience4j configuration properties are supported.
+maxDurationOpenInHalfOpenState is a new property described in the sample code paragraph.
 
 | Config property | Default Value | Special Values |
 | ------------- | ------------- | --------|
@@ -23,6 +24,7 @@ The following configuration properties are supported
 | slidingWindowSize  | 100 [s] | 0 to set breaker in DISABLED state, -1 to set breaker in FORCED_OPEN state |
 | minimumNumberOfCalls  | 10 | |
 | waitDurationInOpenState  | 60000 [ms] | |
+| maxDurationOpenInHalfOpenState | 120000 [ms] | If set to 0, there is no limit |
 
 
 ## Sample Code
@@ -41,7 +43,9 @@ loop
       circuitBreaker.callFailed(doSomething duration);
 ```
 
-**Important: `callSucceeded()` or `callFailed()` must always be invoked after `isClosedForThisCall()`. Otherwise breaker in HALF-OPEN state will never move to another state.**
+**Important**: `callSucceeded()` or `callFailed()` must always be invoked after `isClosedForThisCall()`. Otherwise breaker in HALF-OPEN state will never move to another state, waiting for the results of the permittedNumberOfCallsInHalfOpenState calls.
+
+To avoid this situation a new property maxDurationOpenInHalfOpenState is introduced. In HALF-OPEN state, after permittedNumberOfCallsInHalfOpenState calls (`isClosedForThisCall()` returns true), all its subsequent calls (`isClosedForThisCall()` returns false) won't be executed as the circuit is opened. If this situation lasts longer than maxDurationOpenInHalfOpenState ms, the breaker goes back automatically to the CLOSED state.
 
 ## Circuit Breaker Configuration using Properties
 The circuit breaker can easily be configured using `java.util.Properties`, possibly adding prefix, for example:

src/main/java/com/geckotechnology/simpleCircuitBreaker/BreakerHalfOpenState.java

@@ -10,19 +10,36 @@ class BreakerHalfOpenState implements BreakerStateInterface {
     private int failureCallCount = 0;
     private int slowCallDurationCount = 0;
     private int permittedNumberOfCallsInHalfOpenStateSoFar = 0;
+    private long lastOpenCallTimeLimit = 0;
 
 	BreakerHalfOpenState(CircuitBreaker circuitBreaker) {
 		this.circuitBreaker = circuitBreaker;
 	}
 
 	@Override
 	public boolean isClosedForThisCall() {
+		//ensure permittedNumberOfCallsInHalfOpenState calls are executed, by returning true
 		if(permittedNumberOfCallsInHalfOpenStateSoFar < circuitBreaker.getCircuitBreakerConfig().getPermittedNumberOfCallsInHalfOpenState()) {
 			permittedNumberOfCallsInHalfOpenStateSoFar++;
 			return true;
 		}
+		//no more calls allowed
+		//if maxDurationOpenInHalfOpenState is 0, this situation can last forever. Return false 
+		if(circuitBreaker.getCircuitBreakerConfig().getMaxDurationOpenInHalfOpenState() == 0)
+			return false;
+		//There is a time  limit. Check if it is set. If not, it is the first call. Return false
+		if(lastOpenCallTimeLimit == 0) {
+			lastOpenCallTimeLimit = System.currentTimeMillis() + circuitBreaker.getCircuitBreakerConfig().getMaxDurationOpenInHalfOpenState();
+			return false;
+		}
+		if(System.currentTimeMillis() >= lastOpenCallTimeLimit) {
+			//we are beyond maxDurationOpenInHalfOpenState. Need to go back to CLOSED state
+    		logger.warning("maxDurationOpenInHalfOpenState is reached. CallCount: " + callCount + ", failureCallCount: " + failureCallCount + ", slowCallDurationCount: " + slowCallDurationCount);
+    		circuitBreaker.moveToClosedState();
+    		return circuitBreaker.isClosedForThisCall();
+		}
+		//situation normal, no more calls allowed
 		return false;
-		//@TODO add logic so that half open state is not for ever
 	}
 
 	@Override

src/main/java/com/geckotechnology/simpleCircuitBreaker/CircuitBreakerConfig.java

@@ -14,6 +14,7 @@ public class CircuitBreakerConfig {
 	private int slidingWindowSize = 100;
 	private int minimumNumberOfCalls = 10;
 	private long waitDurationOpenedState = 60000;
+	private long maxDurationOpenInHalfOpenState = 120000;
 
 	/**
 	 * Default constructor with default values
@@ -53,6 +54,9 @@ public CircuitBreakerConfig(String prefix, Properties props) {
 		value = props.getProperty(prefix + "waitDurationOpenedState");
 		if(value != null)
 			setWaitDurationOpenedState(Long.parseLong(value));
+		value = props.getProperty(prefix + "maxDurationOpenInHalfOpenState");
+		if(value != null)
+			setMaxDurationOpenInHalfOpenState(Long.parseLong(value));
 	}
 
 	public CircuitBreakerConfig clone() {
@@ -64,6 +68,7 @@ public CircuitBreakerConfig clone() {
 		clone.failureRateThreshold = failureRateThreshold;
 		clone.slowCallRateThreshold = slowCallRateThreshold;
 		clone.waitDurationOpenedState = waitDurationOpenedState;
+		clone.maxDurationOpenInHalfOpenState = maxDurationOpenInHalfOpenState;
 		return clone;
 	}
 
@@ -76,6 +81,7 @@ public void logInfoConfigProperties() {
 		logger.info("\tslidingWindowSize: " + slidingWindowSize);
 		logger.info("\tminimumNumberOfCalls: " + minimumNumberOfCalls);
 		logger.info("\twaitDurationOpenedState: " + waitDurationOpenedState);
+		logger.info("\tmaxDurationOpenInHalfOpenState: " + maxDurationOpenInHalfOpenState);
 	}
 
 	public int getSlidingWindowSize() {
@@ -148,4 +154,14 @@ public void setPermittedNumberOfCallsInHalfOpenState(int permittedNumberOfCallsI
 		this.permittedNumberOfCallsInHalfOpenState = permittedNumberOfCallsInHalfOpenState;
 	}
 
+	public long getMaxDurationOpenInHalfOpenState() {
+		return maxDurationOpenInHalfOpenState;
+	}
+
+	public void setMaxDurationOpenInHalfOpenState(long maxDurationOpenInHalfOpenState) {
+		if(maxDurationOpenInHalfOpenState < 0)
+			throw new IllegalArgumentException("maxDurationOpenInHalfOpenState must be positive or null");
+		this.maxDurationOpenInHalfOpenState = maxDurationOpenInHalfOpenState;
+	}
+
 }

src/test/java/com/geckotechnology/simpleCircuitBreaker/breaker4.config

@@ -4,4 +4,5 @@ slowCallDurationThreshold=528
 minimumNumberOfCalls=20
 failureRateThreshold=75.1
 slowCallRateThreshold=45
-waitDurationOpenedState=2000
+waitDurationOpenedState=2000
+maxDurationOpenInHalfOpenState=500