A circuit breaker protects a caller from repeatedly invoking an unhealthy dependency. It starts closed, opens after a run of failures, and later becomes half-open so one recovery probe can decide whether normal calls should resume.
Design a CircuitBreakerSimulator class:
CircuitBreakerSimulator() creates a stateless simulator.String[] simulate(String[] events, int failureThreshold) returns the breaker's state after every event.
The initial state is "closed", and the initial consecutive-failure count is zero. Every event is one of "success", "failure", or "timeout".
Apply these transition rules:
- Closed: A success resets the consecutive-failure count to zero and leaves the breaker closed. A failure increments the count and opens the breaker once the count reaches
failureThreshold. A timeout leaves both the state and the count unchanged. - Open: A timeout moves the breaker to
"half_open". Success and failure events are rejected and leave the breaker open. - Half-open: A success resets the consecutive-failure count to zero and closes the breaker. A failure reopens the breaker. A timeout leaves the breaker half-open.
Return the state after applying each event. Every call to simulate starts with a fresh breaker; state must not carry across calls.
Example 1:
Input:
Output:
Explanation: The second consecutive failure reaches the threshold and opens the breaker. The timeout begins a half-open trial, and the successful trial closes the breaker.
Example 2:
Input:
Output:
Explanation: The timeout permits one trial, but that trial fails. A failed half-open probe immediately reopens the breaker.
Constraints
0 <= events.length <= 10^5events[i] is "success", "failure", or "timeout".1 <= failureThreshold <= 10^5- States are returned exactly as
"closed", "open", and "half_open". - At most
100 calls are made to simulate.
Simulate a Circuit Breakermedium