add ServerConfig with env variables

src/server.rs

@@ -4,6 +4,7 @@ use tokio::net::ToSocketAddrs;
 use tokio::{net::TcpListener, sync::Semaphore};
 
 use crate::Result;
+use crate::config::ServerConfig;
 use crate::connection::Connection;
 use crate::database::Database;
 use crate::handler::Handler;
@@ -16,14 +17,23 @@ pub struct Server {
 }
 
 impl Server {
-    const MAX_CONNECTIONS: usize = 256;
+    pub const MAX_CONNECTIONS: usize = 256;
 
-    pub async fn new<Addr: ToSocketAddrs>(addr: Addr) -> Result<Self> {
+    pub async fn new(config: ServerConfig) -> Result<Self> {
+        let addr = format!("{}:{}", config.host, config.port);
+        Self::_new(
+            addr,
+            config.max_connections.unwrap_or(Self::MAX_CONNECTIONS),
+        )
+        .await
+    }
+
+    async fn _new<Addr: ToSocketAddrs>(addr: Addr, max_connections: usize) -> Result<Self> {
         let listener = TcpListener::bind(addr).await?;
 
         Ok(Self {
             db: Database::new(),
-            connection_limit: Arc::new(Semaphore::const_new(Self::MAX_CONNECTIONS)),
+            connection_limit: Arc::new(Semaphore::const_new(max_connections)),
             listener,
         })
     }