The AI Interview - Master AI/ML Interviews

Implement circuit breaker for agent tool resilience:

States:

CLOSED: Normal operation, calls pass through
OPEN: Failure threshold reached, calls blocked immediately
HALF_OPEN: Testing if service recovered (limited calls allowed)

Transitions:

CLOSED -> OPEN: failure_count >= failure_threshold
OPEN -> HALF_OPEN: now - last_failure > recovery_timeout
HALF_OPEN -> CLOSED: half_open_calls_successful >= half_open_max_calls
HALF_OPEN -> OPEN: Any failure in half-open

Methods:

can_execute(): Check if call allowed in current state
record_success/failure(): Update state
call(func, ...): Execute with protection, returns {'result': ..., 'state': ..., 'allowed': bool}

Examples

Example 1:

Input: cb = CircuitBreaker(failure_threshold=2); cb.record_failure(); cb.record_failure(); cb.can_execute()

Output: False

Explanation: 2 failures >= threshold, circuit OPEN, calls blocked

Starter Code

class CircuitBreaker:
    """
    Circuit breaker pattern for agent tool calls.
    Prevents cascading failures.
    """
    
    STATES = ['CLOSED', 'OPEN', 'HALF_OPEN']
    
    def __init__(self, failure_threshold=5, recovery_timeout=30, half_open_max_calls=3):
        self.failure_threshold = failure_threshold
        self.recovery_timeout = recovery_timeout
        self.half_open_max_calls = half_open_max_calls
        
        self.state = 'CLOSED'
        self.failure_count = 0
        self.last_failure_time = None
        self.half_open_calls = 0
    
    def can_execute(self):
        """Check if call should be allowed"""
        # Your implementation here
        pass
    
    def record_success(self):
        """Record successful call"""
        # Your implementation here
        pass
    
    def record_failure(self):
        """Record failed call"""
        # Your implementation here
        pass
    
    def call(self, func, *args, **kwargs):
        """Execute func with circuit breaker protection"""
        # Your implementation here
        pass

Circuit Breaker for Tool Calls

Examples

Starter Code