性能优化

src-tauri/src/download_engine/rate_limit.rs

@@ -38,7 +38,7 @@ impl RateLimiter {
         // 尝试在当前窗口消费（用作用域确保 MutexGuard 在 await 前释放）
         let over_limit = {
             let now = std::time::Instant::now();
-            let mut start = self.window_start.lock().unwrap();
+            let mut start = self.window_start.lock().unwrap_or_else(|e| e.into_inner());
             let elapsed = now.duration_since(*start);
 
             // 窗口过期，重置
@@ -72,3 +72,64 @@ impl Clone for RateLimiter {
         Self::new(self.limit.load(Ordering::Relaxed))
     }
 }
+
+#[cfg(test)]
+mod rate_limiter_tests {
+    use super::*;
+    use std::time::Instant;
+
+    #[tokio::test]
+    async fn zero_limit_never_blocks() {
+        let limiter = RateLimiter::new(0);
+        let start = Instant::now();
+        limiter.consume(1024 * 1024).await;
+        limiter.consume(u64::MAX).await;
+        assert!(start.elapsed() < Duration::from_millis(50));
+    }
+
+    #[tokio::test]
+    async fn under_limit_returns_immediately() {
+        let limiter = RateLimiter::new(100_000); // 100KB/s
+        let start = Instant::now();
+        limiter.consume(1024).await;
+        assert!(start.elapsed() < Duration::from_millis(50));
+    }
+
+    #[tokio::test]
+    async fn exceeding_limit_waits_proportionally() {
+        // 限速 200 B/s：先消耗 100 未超限，再消耗 150 → 超限 50 → 等待约 250ms
+        let limiter = RateLimiter::new(200);
+        limiter.consume(100).await;
+        let start = Instant::now();
+        limiter.consume(150).await;
+        let elapsed = start.elapsed();
+        assert!(
+            elapsed >= Duration::from_millis(200),
+            "等待时间不足: {:?}",
+            elapsed
+        );
+        assert!(elapsed < Duration::from_millis(1100));
+    }
+
+    #[tokio::test]
+    async fn window_resets_after_one_second() {
+        // 限速 100 B/s：第一窗口耗尽后，1.1s 窗口重置，再消耗 100 不应阻塞
+        let limiter = RateLimiter::new(100);
+        limiter.consume(100).await;
+        tokio::time::sleep(Duration::from_millis(1100)).await;
+        let start = Instant::now();
+        limiter.consume(100).await;
+        assert!(start.elapsed() < Duration::from_millis(100));
+    }
+
+    #[tokio::test]
+    async fn set_limit_takes_effect_dynamically() {
+        let limiter = RateLimiter::new(0);
+        limiter.consume(1024).await; // 不限速
+        limiter.set_limit(100);
+        limiter.consume(100).await;
+        let start = Instant::now();
+        limiter.consume(100).await; // 累计 200 > 100 → 等待 1000ms
+        assert!(start.elapsed() >= Duration::from_millis(900));
+    }
+}