flow_guard/
limiter.rs

1/* * Created and Developed by: Cleiton Augusto Correa Bezerra
2 */
3
4use crate::error::FlowError;
5use crate::LimitStrategy;
6use std::sync::Arc;
7use std::time::Instant;
8
9use crate::semaphore::DynamicSemaphore;
10
11#[derive(Clone)]
12pub struct FlowGuard<S: LimitStrategy> {
13    strategy: Arc<S>,
14    semaphore: Arc<DynamicSemaphore>,
15}
16
17impl<S: LimitStrategy + 'static> FlowGuard<S> {
18    pub fn new(strategy: S) -> Self {
19        let initial_limit = strategy.current_limit();
20        Self {
21            strategy: Arc::new(strategy),
22            semaphore: Arc::new(DynamicSemaphore::new(initial_limit)),
23        }
24    }
25
26    pub async fn run<F, T, E>(&self, f: F) -> Result<T, FlowError<E>>
27    where
28        F: std::future::Future<Output = Result<T, E>>,
29    {
30        // 1. Tenta adquirir permissão (Backpressure dinâmico)
31        let _permit = self
32            .semaphore
33            .acquire()
34            .await
35            .map_err(|_| FlowError::Dropped)?;
36
37        let start = Instant::now();
38
39        // 2. Executa a tarefa do usuário
40        let result = f.await;
41
42        let duration = start.elapsed();
43
44        // 3. Informa a estratégia sobre o sucesso ou falha
45        match &result {
46            Ok(_) => self.strategy.on_success(duration),
47            Err(_) => self.strategy.on_error(),
48        }
49
50        // 4. ATUALIZAÇÃO CRÍTICA: Atualiza o semáforo com o novo limite
51        let new_limit = self.strategy.current_limit();
52        self.semaphore.set_limit(new_limit);
53
54        // 5. Retorna o resultado
55        result.map_err(FlowError::AppError)
56    }
57
58    // Métodos para observabilidade
59    pub fn current_limit(&self) -> usize {
60        self.strategy.current_limit()
61    }
62
63    pub fn available_permits(&self) -> usize {
64        self.semaphore.available_permits()
65    }
66}
flow_guard/limiter.rs

flow_guard/
limiter.rs
