1 files changed, 72 insertions, 0 deletions
diff --git a/src/adaptive.rs b/src/adaptive.rs
new file mode 100644
index 0000000..ca9e0fc
--- /dev/null
+++ b/src/adaptive.rs
@@ -0,0 +1,72 @@
+use std::sync::Arc;
+use tokio::sync::{OwnedSemaphorePermit, Semaphore};
+
+pub struct AdaptiveConcurrency {
+    current_concurrent: usize,
+    min_concurrent: usize,
+    max_concurrent: usize,
+    failure_streak: usize,
+    success_count: usize,
+    fail_count: usize,
+    semaphore: Arc<Semaphore>,
+}
+
+impl AdaptiveConcurrency {
+    pub fn new(max_concurrent: usize) -> Self {
+        let initial = num_cpus::get().min(max_concurrent);
+        AdaptiveConcurrency {
+            current_concurrent: initial,
+            min_concurrent: 1,
+            max_concurrent,
+            failure_streak: 0,
+            success_count: 0,
+            fail_count: 0,
+            semaphore: Arc::new(Semaphore::new(initial)),
+        }
+    }
+
+    pub fn on_success(&mut self) {
+        self.success_count += 1;
+        self.failure_streak = 0;
+
+        if self.success_count % 10 == 0 && self.current_concurrent < self.max_concurrent {
+            self.current_concurrent += 1;
+            self.semaphore
+                .add_permits(1);
+        }
+    }
+
+    pub fn on_failure(&mut self) {
+        self.fail_count += 1;
+        self.failure_streak += 1;
+
+        if self.failure_streak >= 3 && self.current_concurrent > self.min_concurrent {
+            let new_concurrent = (self.current_concurrent / 2).max(self.min_concurrent);
+            let reduction = self.current_concurrent - new_concurrent;
+            self.current_concurrent = new_concurrent;
+
+            for _ in 0..reduction {
+                let _ = self
+                    .semaphore
+                    .try_acquire();
+            }
+        }
+    }
+
+    pub fn get_concurrent(&self) -> usize {
+        self.current_concurrent
+    }
+
+    pub fn semaphore(&self) -> Arc<Semaphore> {
+        self.semaphore
+            .clone()
+    }
+}
+
+pub async fn acquire_slot(semaphore: &Arc<Semaphore>) -> OwnedSemaphorePermit {
+    semaphore
+        .clone()
+        .acquire_owned()
+        .await
+        .unwrap()
+}