Add some comments to circuit breaker's closed and half open state thresholding

Author: jhalterman

src/main/java/dev/failsafe/internal/ClosedState.java

@@ -44,8 +44,9 @@ public synchronized void handleConfigChange() {
    */
   @Override
   synchronized void checkThreshold(ExecutionContext<R> context) {
-    // Execution threshold will only be set for time based thresholding
+    // Execution threshold can only be set for time based thresholding
     if (stats.getExecutionCount() >= config.getFailureExecutionThreshold()) {
+      // Failure rate threshold can only be set for time based thresholding
       double failureRateThreshold = config.getFailureRateThreshold();
       if ((failureRateThreshold != 0 && stats.getFailureRate() >= failureRateThreshold) || (failureRateThreshold == 0
         && stats.getFailureCount() >= config.getFailureThreshold()))

src/main/java/dev/failsafe/internal/HalfOpenState.java

@@ -68,8 +68,10 @@ synchronized void checkThreshold(ExecutionContext<R> context) {
       successesExceeded = stats.getSuccessCount() >= successThreshold;
       failuresExceeded = stats.getFailureCount() > successThresholdingCapacity - successThreshold;
     } else {
+      // Failure rate threshold can only be set for time based thresholding
       int failureRateThreshold = config.getFailureRateThreshold();
       if (failureRateThreshold != 0) {
+        // Execution threshold can only be set for time based thresholding
         boolean executionThresholdExceeded = stats.getExecutionCount() >= config.getFailureExecutionThreshold();
         failuresExceeded = executionThresholdExceeded && stats.getFailureRate() >= failureRateThreshold;
         successesExceeded = executionThresholdExceeded && stats.getSuccessRate() > 100 - failureRateThreshold;