CA just released API Gateway 9.3 - New Features and Enhancements are listed here.
There is a new feature which I think is pretty cool - Apply Circuit Breaker assertion.
The Apply Circuit Breaker assertion defines thresholds for failure conditions which, when exceeded, prevent blocks of your policy from executing for a configurable period.
This is ideal for avoiding bottlenecks that arise due to request processing slowdowns that are caused by sluggish or malfunctioning back-end systems.
Once the Apply Circuit Breaker assertion detects a circuit has exceeded a threshold, the assertion fails and none of its child assertions execute. Depending on the surrounding policy logic, a failed Apply Circuit Breaker assertion could cause further branching or it could fail the entire policy.
After a predetermined timeout period, the circuit resets and the bypassed portion is once again live.
Going to try it soon! :)