Optimize: send method reduces overhead of creating new copy of string

Author: CharryWu

src/http/response.rs

@@ -1,5 +1,8 @@
 use super::StatusCode;
-use std::fmt::{Display, Formatter, Result as FmtResult};
+use std::{
+    fmt::{Display, Formatter, Result as FmtResult},
+    io::{Result as IoResult, Write},
+};
 
 #[derive(Debug)]
 pub struct Response {
@@ -11,17 +14,50 @@ impl Response {
     pub fn new(status_code: StatusCode, body: Option<String>) -> Self {
         Self { status_code, body }
     }
-}
 
-impl Display for Response {
-    fn fmt(&self, f: &mut Formatter<'_>) -> FmtResult {
+    /// Sends the response to the client, without creating a new string.
+    /// This method invokes write! macro directly passing its internal data, instead of returning a copy of the response string.
+    ///
+    /// # Note
+    ///
+    /// This method is more efficient than using `Display` because it avoids the overhead of creating a new string.
+    /// Especially when the response body is large (e.g. HTML pages with megabytes size of HTML content).
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// let response = Response::new(StatusCode::Ok, Some("Hello".to_string()));
+    /// response.send(&mut stream);
+    /// ```
+    ///
+    /// # Arguments
+    ///
+    /// * `stream` - The stream to write the response to.
+    ///
+    /// # Returns
+    /// * `IoResult<()>` - The result of the write operation.
+    pub fn send(&self, stream: &mut impl Write) -> IoResult<()> {
         let body = self.body.as_deref().unwrap_or("");
         write!(
-            f,
+            stream,
             "HTTP/1.1 {} {}\r\n\r\n{}",
             self.status_code,
             self.status_code.reason_phrase(),
             body
         )
     }
 }
+
+// DEPRECATED: use `Response::send` instead
+// impl Display for Response {
+//     fn fmt(&self, f: &mut Formatter<'_>) -> FmtResult {
+//         let body = self.body.as_deref().unwrap_or("");
+//         write!(
+//             f,
+//             "HTTP/1.1 {} {}\r\n\r\n{}",
+//             self.status_code,
+//             self.status_code.reason_phrase(),
+//             body
+//         )
+//     }
+// }

src/server.rs

@@ -63,9 +63,7 @@ impl Server {
                                         Some(DEFAULT_BODY.to_string()),
                                     );
                                     // Write the response to the client
-                                    if let Err(e) =
-                                        sock_stream.write_all(response.to_string().as_bytes())
-                                    {
+                                    if let Err(e) = response.send(&mut sock_stream) {
                                         // If there's an error writing to the client, print the error
                                         println!(
                                             "========== Error: Failed to write response to client ==========\n{}",