handle_static_file_download: optimize small files

Avoid chuncked transfer for small files.

src/main.rs

@@ -167,7 +167,26 @@ fn handle_sync_api_request<'a>(
 
 fn handle_static_file_download(filename: PathBuf) ->  BoxFut {
 
-    let response = File::open(filename)
+    let response = tokio::fs::metadata(filename.clone())
+        .map_err(|err| format_err!("File access problems: {}", err))
+        .and_then(|metadata| {
+            println!("TEST METADATA {:?} {}", metadata, metadata.len());
+
+            if metadata.len() < 1024*8 {
+                println!("SMALL SIZED FILE");
+                Either::A(File::open(filename)
+                    .map_err(|err| format_err!("File open failed: {}", err))
+                    .and_then(|file| {
+                        let buf: Vec<u8> = Vec::new();
+                        tokio::io::read_to_end(file, buf)
+                            .map_err(|err| format_err!("File read failed: {}", err))
+                            .and_then(|data| Ok(Response::new(data.1.into())))
+                    }))
+
+            } else {
+                Either::B(
+                    File::open(filename)
+                        .map_err(|err| format_err!("File open failed: {}", err))
                     .and_then(|file| {
                         let payload = tokio_codec::FramedRead::new(file, tokio_codec::BytesCodec::new()).
                             map(|bytes| {
@@ -180,13 +199,8 @@ fn handle_static_file_download(filename: PathBuf) ->  BoxFut {
                            .status(StatusCode::OK)
                            .body(body)
                            .unwrap())
-        })
+                    }))
-        .or_else(|err| {
+            }
-            // fixme: set content type and other headers
-            Ok(Response::builder()
-               .status(StatusCode::NOT_FOUND)
-               .body(format!("File access problems: {}\n", err).into())
-               .unwrap())
         });
 
     return Box::new(response);