Implement M3.5.7: Rate limiting + idempotency (20 tests)

crates/mem-cli/src/idempotency.rs

@@ -0,0 +1,129 @@
+use std::collections::HashMap;
+use std::sync::{Arc, Mutex};
+use std::time::{Duration, Instant};
+
+#[cfg(test)]
+use serde_json::json;
+
+/// Cached ingest response with expiry
+#[derive(Clone, Debug)]
+struct CachedResponse {
+    response: serde_json::Value,
+    inserted_at: Instant,
+    ttl: Duration,
+}
+
+impl CachedResponse {
+    fn is_expired(&self) -> bool {
+        self.inserted_at.elapsed() > self.ttl
+    }
+}
+
+/// Idempotency store for ingest operations
+pub struct IdempotencyStore {
+    cache: Arc<Mutex<HashMap<String, CachedResponse>>>,
+    ttl: Duration,
+}
+
+impl IdempotencyStore {
+    pub fn new(ttl_seconds: u64) -> Self {
+        Self {
+            cache: Arc::new(Mutex::new(HashMap::new())),
+            ttl: Duration::from_secs(ttl_seconds),
+        }
+    }
+
+    /// Get cached response for ingest_id. Returns None if not found or expired.
+    pub fn get(&self, ingest_id: &str) -> Option<serde_json::Value> {
+        let mut cache = self.cache.lock().unwrap();
+        
+        if let Some(cached) = cache.get(ingest_id) {
+            if !cached.is_expired() {
+                return Some(cached.response.clone());
+            }
+        }
+
+        // Clean up expired entry
+        cache.remove(ingest_id);
+        None
+    }
+
+    /// Store response for ingest_id
+    pub fn set(&self, ingest_id: String, response: serde_json::Value) {
+        let mut cache = self.cache.lock().unwrap();
+        cache.insert(
+            ingest_id,
+            CachedResponse {
+                response,
+                inserted_at: Instant::now(),
+                ttl: self.ttl,
+            },
+        );
+    }
+
+    /// Evict expired entries (background maintenance)
+    pub fn evict_expired(&self) {
+        let mut cache = self.cache.lock().unwrap();
+        cache.retain(|_, v| !v.is_expired());
+    }
+
+    /// Clear all entries (for testing)
+    #[cfg(test)]
+    pub fn clear(&self) {
+        let mut cache = self.cache.lock().unwrap();
+        cache.clear();
+    }
+
+    /// Get cache size (for testing)
+    #[cfg(test)]
+    pub fn len(&self) -> usize {
+        let cache = self.cache.lock().unwrap();
+        cache.len()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_idempotency_store_basic() {
+        let store = IdempotencyStore::new(60);
+        let response = json!({"ingest_id": "test-123", "status": "pending"});
+
+        store.set("test-123".to_string(), response.clone());
+        assert_eq!(store.get("test-123"), Some(response));
+    }
+
+    #[test]
+    fn test_idempotency_store_expiry() {
+        let store = IdempotencyStore::new(0);
+        let response = json!({"ingest_id": "test-123", "status": "pending"});
+
+        store.set("test-123".to_string(), response);
+        std::thread::sleep(Duration::from_millis(10));
+
+        assert_eq!(store.get("test-123"), None);
+    }
+
+    #[test]
+    fn test_idempotency_missing_key() {
+        let store = IdempotencyStore::new(60);
+        assert_eq!(store.get("nonexistent"), None);
+    }
+
+    #[test]
+    fn test_idempotency_evict_expired() {
+        let store = IdempotencyStore::new(1);
+        store.set("key1".to_string(), json!({"data": "value1"}));
+        store.set("key2".to_string(), json!({"data": "value2"}));
+
+        assert_eq!(store.len(), 2);
+
+        std::thread::sleep(Duration::from_secs(1));
+        std::thread::sleep(Duration::from_millis(100));
+
+        store.evict_expired();
+        assert_eq!(store.len(), 0);
+    }
+}