ttl command

src/client.rs

@@ -144,6 +144,32 @@ impl Client {
         Ok(r.try_get_u8()? == 1)
     }
 
+    pub async fn ttl(&mut self, key: &str) -> Result<Option<u64>> {
+        let mut bytes = BytesMut::new();
+        bytes.put_u16(3);
+        bytes.put_slice(b"ttl");
+
+        let key_length: u16 = key
+            .len()
+            .try_into()
+            .map_err(|_| AppError::KeyLength(key.len()))?;
+
+        bytes.put_u16(key_length);
+        bytes.put_slice(key.as_bytes());
+
+        self.connection.write(bytes.into()).await?;
+
+        let mut r = self.get_response().await?;
+
+        let ttl = match r.try_get_u8()? {
+            1 => Some(r.try_get_u64()?),
+            0 => None,
+            _ => return Err(AppError::InvalidCommandResponse),
+        };
+
+        Ok(ttl)
+    }
+
     async fn get_response(&mut self) -> Result<Bytes> {
         self.connection
             .read_bytes()