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use std::time::{Duration, Instant};
#[derive(Debug, Clone)]
pub struct CircuitBreaker {
failure_count: u32,
failure_threshold: u32,
reset_timeout: Duration,
last_failure_time: Option<Instant>,
state: CircuitBreakerState,
}
#[derive(Debug, Clone, PartialEq)]
enum CircuitBreakerState {
Closed,
Open,
HalfOpen,
}
impl CircuitBreaker {
pub fn new() -> Self {
Self::with_threshold(5)
}
pub fn with_threshold(failure_threshold: u32) -> Self {
Self {
failure_count: 0,
failure_threshold,
reset_timeout: Duration::from_secs(60),
last_failure_time: None,
state: CircuitBreakerState::Closed,
}
}
pub fn with_reset_timeout(mut self, timeout: Duration) -> Self {
self.reset_timeout = timeout;
self
}
pub fn is_open(&self) -> bool {
match self.state {
CircuitBreakerState::Open => {
if let Some(last_failure) = self.last_failure_time {
Instant::now().duration_since(last_failure) < self.reset_timeout
} else {
false
}
}
CircuitBreakerState::HalfOpen => false,
CircuitBreakerState::Closed => false,
}
}
pub fn is_closed(&self) -> bool {
matches!(self.state, CircuitBreakerState::Closed)
}
pub fn is_half_open(&self) -> bool {
matches!(self.state, CircuitBreakerState::HalfOpen)
}
pub fn record_success(&mut self) {
self.failure_count = 0;
self.last_failure_time = None;
self.state = CircuitBreakerState::Closed;
}
pub fn record_failure(&mut self) {
self.failure_count += 1;
self.last_failure_time = Some(Instant::now());
if self.failure_count >= self.failure_threshold {
self.state = CircuitBreakerState::Open;
}
}
pub fn attempt_reset(&mut self) -> bool {
if self.state == CircuitBreakerState::Open {
if let Some(last_failure) = self.last_failure_time {
if Instant::now().duration_since(last_failure) >= self.reset_timeout {
self.state = CircuitBreakerState::HalfOpen;
return true;
}
}
}
false
}
pub fn reset(&mut self) {
self.failure_count = 0;
self.last_failure_time = None;
self.state = CircuitBreakerState::Closed;
}
pub fn failure_count(&self) -> u32 {
self.failure_count
}
pub fn state_name(&self) -> &'static str {
match self.state {
CircuitBreakerState::Closed => "closed",
CircuitBreakerState::Open => "open",
CircuitBreakerState::HalfOpen => "half-open",
}
}
}
impl Default for CircuitBreaker {
fn default() -> Self {
Self::new()
}
}
#[cfg(test)]
mod tests {
use super::*;
use std::thread;
#[test]
fn test_circuit_breaker_closed_state() {
let cb = CircuitBreaker::new();
assert!(cb.is_closed());
assert!(!cb.is_open());
assert!(!cb.is_half_open());
assert_eq!(cb.failure_count(), 0);
}
#[test]
fn test_circuit_breaker_failure_threshold() {
let mut cb = CircuitBreaker::with_threshold(3);
// Record 2 failures - should stay closed
cb.record_failure();
cb.record_failure();
assert!(cb.is_closed());
assert_eq!(cb.failure_count(), 2);
// Record 3rd failure - should open
cb.record_failure();
assert!(cb.is_open());
assert_eq!(cb.failure_count(), 3);
}
#[test]
fn test_circuit_breaker_success_resets() {
let mut cb = CircuitBreaker::with_threshold(2);
// Record failures
cb.record_failure();
cb.record_failure();
assert!(cb.is_open());
// Record success - should close
cb.record_success();
assert!(cb.is_closed());
assert_eq!(cb.failure_count(), 0);
}
#[test]
fn test_circuit_breaker_timeout() {
let mut cb = CircuitBreaker::with_threshold(1)
.with_reset_timeout(Duration::from_millis(100));
// Trigger opening
cb.record_failure();
assert!(cb.is_open());
// Should still be open immediately
assert!(cb.is_open());
// Wait for timeout
thread::sleep(Duration::from_millis(150));
// Should allow attempt reset
assert!(cb.attempt_reset());
assert!(cb.is_half_open());
}
#[test]
fn test_circuit_breaker_manual_reset() {
let mut cb = CircuitBreaker::with_threshold(1);
cb.record_failure();
assert!(cb.is_open());
cb.reset();
assert!(cb.is_closed());
assert_eq!(cb.failure_count(), 0);
}
#[test]
fn test_circuit_breaker_state_names() {
let mut cb = CircuitBreaker::new();
assert_eq!(cb.state_name(), "closed");
cb.record_failure();
cb.record_failure();
cb.record_failure();
cb.record_failure();
cb.record_failure();
assert_eq!(cb.state_name(), "open");
cb.state = CircuitBreakerState::HalfOpen;
assert_eq!(cb.state_name(), "half-open");
}
}
|
