feat(actix-files): opt-in filesize threshold for faster synchronous reads (#3706)

Co-authored-by: Rob Ede <robjtede@icloud.com>

actix-files/CHANGES.md

@@ -2,6 +2,7 @@
 
 ## Unreleased
 
+- Opt-In filesize threshold for faster synchronus reads that allow for 20x better performance.
 - Minimum supported Rust version (MSRV) is now 1.75.
 
 ## 0.6.6

actix-files/src/chunked.rs

@@ -24,6 +24,7 @@ pin_project! {
         state: ChunkedReadFileState<Fut>,
         counter: u64,
         callback: F,
+        read_sync: bool,
     }
 }
 
@@ -57,6 +58,7 @@ pub(crate) fn new_chunked_read(
     size: u64,
     offset: u64,
     file: File,
+    size_threshold: u64,
 ) -> impl Stream<Item = Result<Bytes, Error>> {
     ChunkedReadFile {
         size,
@@ -69,31 +71,45 @@ pub(crate) fn new_chunked_read(
         },
         counter: 0,
         callback: chunked_read_file_callback,
+        read_sync: size < size_threshold,
     }
 }
 
 #[cfg(not(feature = "experimental-io-uring"))]
-async fn chunked_read_file_callback(
+fn chunked_read_file_callback_sync(
     mut file: File,
     offset: u64,
     max_bytes: usize,
-) -> Result<(File, Bytes), Error> {
+) -> Result<(File, Bytes), io::Error> {
     use io::{Read as _, Seek as _};
 
-    let res = actix_web::web::block(move || {
-        let mut buf = Vec::with_capacity(max_bytes);
+    let mut buf = Vec::with_capacity(max_bytes);
 
-        file.seek(io::SeekFrom::Start(offset))?;
+    file.seek(io::SeekFrom::Start(offset))?;
 
-        let n_bytes = file.by_ref().take(max_bytes as u64).read_to_end(&mut buf)?;
+    let n_bytes = file.by_ref().take(max_bytes as u64).read_to_end(&mut buf)?;
 
-        if n_bytes == 0 {
-            Err(io::Error::from(io::ErrorKind::UnexpectedEof))
-        } else {
-            Ok((file, Bytes::from(buf)))
-        }
-    })
-    .await??;
+    if n_bytes == 0 {
+        Err(io::Error::from(io::ErrorKind::UnexpectedEof))
+    } else {
+        Ok((file, Bytes::from(buf)))
+    }
+}
+
+#[cfg(not(feature = "experimental-io-uring"))]
+#[inline]
+async fn chunked_read_file_callback(
+    file: File,
+    offset: u64,
+    max_bytes: usize,
+    read_sync: bool,
+) -> Result<(File, Bytes), Error> {
+    let res = if read_sync {
+        chunked_read_file_callback_sync(file, offset, max_bytes)?
+    } else {
+        actix_web::web::block(move || chunked_read_file_callback_sync(file, offset, max_bytes))
+            .await??
+    };
 
     Ok(res)
 }
@@ -171,7 +187,7 @@ where
 #[cfg(not(feature = "experimental-io-uring"))]
 impl<F, Fut> Stream for ChunkedReadFile<F, Fut>
 where
-    F: Fn(File, u64, usize) -> Fut,
+    F: Fn(File, u64, usize, bool) -> Fut,
     Fut: Future<Output = Result<(File, Bytes), Error>>,
 {
     type Item = Result<Bytes, Error>;
@@ -193,7 +209,7 @@ where
                         .take()
                         .expect("ChunkedReadFile polled after completion");
 
-                    let fut = (this.callback)(file, offset, max_bytes);
+                    let fut = (this.callback)(file, offset, max_bytes, *this.read_sync);
 
                     this.state
                         .project_replace(ChunkedReadFileState::Future { fut });

actix-files/src/files.rs

@@ -49,6 +49,7 @@ pub struct Files {
     use_guards: Option<Rc<dyn Guard>>,
     guards: Vec<Rc<dyn Guard>>,
     hidden_files: bool,
+    size_threshold: u64,
 }
 
 impl fmt::Debug for Files {
@@ -73,6 +74,7 @@ impl Clone for Files {
             use_guards: self.use_guards.clone(),
             guards: self.guards.clone(),
             hidden_files: self.hidden_files,
+            size_threshold: self.size_threshold,
         }
     }
 }
@@ -119,6 +121,7 @@ impl Files {
             use_guards: None,
             guards: Vec::new(),
             hidden_files: false,
+            size_threshold: 0,
         }
     }
 
@@ -204,6 +207,18 @@ impl Files {
         self
     }
 
+    /// Sets the async file-size threshold.
+    ///
+    /// When a file is larger than the threshold, the reader
+    /// will switch from faster blocking file-reads to slower async reads
+    /// to avoid blocking the main-thread when processing large files.
+    ///
+    /// Default is 0, meaning all files are read asyncly.
+    pub fn set_size_threshold(mut self, size: u64) -> Self {
+        self.size_threshold = size;
+        self
+    }
+
     /// Specifies whether to use ETag or not.
     ///
     /// Default is true.
@@ -367,6 +382,7 @@ impl ServiceFactory<ServiceRequest> for Files {
             file_flags: self.file_flags,
             guards: self.use_guards.clone(),
             hidden_files: self.hidden_files,
+            size_threshold: self.size_threshold,
         };
 
         if let Some(ref default) = *self.default.borrow() {

actix-files/src/named.rs

@@ -80,6 +80,7 @@ pub struct NamedFile {
     pub(crate) content_type: Mime,
     pub(crate) content_disposition: ContentDisposition,
     pub(crate) encoding: Option<ContentEncoding>,
+    pub(crate) size_threshold: u64,
 }
 
 #[cfg(not(feature = "experimental-io-uring"))]
@@ -200,6 +201,7 @@ impl NamedFile {
             encoding,
             status_code: StatusCode::OK,
             flags: Flags::default(),
+            size_threshold: 0,
         })
     }
 
@@ -353,6 +355,18 @@ impl NamedFile {
         self
     }
 
+    /// Sets the async file-size threshold.
+    ///
+    /// When a file is larger than the threshold, the reader
+    /// will switch from faster blocking file-reads to slower async reads
+    /// to avoid blocking the main-thread when processing large files.
+    ///
+    /// Default is 0, meaning all files are read asyncly.
+    pub fn set_size_threshold(mut self, size: u64) -> Self {
+        self.size_threshold = size;
+        self
+    }
+
     /// Specifies whether to return `ETag` header in response.
     ///
     /// Default is true.
@@ -440,7 +454,8 @@ impl NamedFile {
                 res.insert_header((header::CONTENT_ENCODING, current_encoding.as_str()));
             }
 
-            let reader = chunked::new_chunked_read(self.md.len(), 0, self.file);
+            let reader =
+                chunked::new_chunked_read(self.md.len(), 0, self.file, self.size_threshold);
 
             return res.streaming(reader);
         }
@@ -577,7 +592,7 @@ impl NamedFile {
                 .map_into_boxed_body();
         }
 
-        let reader = chunked::new_chunked_read(length, offset, self.file);
+        let reader = chunked::new_chunked_read(length, offset, self.file, self.size_threshold);
 
         if offset != 0 || length != self.md.len() {
             res.status(StatusCode::PARTIAL_CONTENT);

actix-files/src/service.rs

@@ -39,6 +39,7 @@ pub struct FilesServiceInner {
     pub(crate) file_flags: named::Flags,
     pub(crate) guards: Option<Rc<dyn Guard>>,
     pub(crate) hidden_files: bool,
+    pub(crate) size_threshold: u64,
 }
 
 impl fmt::Debug for FilesServiceInner {
@@ -70,7 +71,9 @@ impl FilesService {
         named_file.flags = self.file_flags;
 
         let (req, _) = req.into_parts();
-        let res = named_file.into_response(&req);
+        let res = named_file
+            .set_size_threshold(self.size_threshold)
+            .into_response(&req);
         ServiceResponse::new(req, res)
     }
 
@@ -169,17 +172,7 @@ impl Service<ServiceRequest> for FilesService {
                 }
             } else {
                 match NamedFile::open_async(&path).await {
-                    Ok(mut named_file) => {
-                        if let Some(ref mime_override) = this.mime_override {
-                            let new_disposition = mime_override(&named_file.content_type.type_());
-                            named_file.content_disposition.disposition = new_disposition;
-                        }
-                        named_file.flags = this.file_flags;
-
-                        let (req, _) = req.into_parts();
-                        let res = named_file.into_response(&req);
-                        Ok(ServiceResponse::new(req, res))
-                    }
+                    Ok(named_file) => Ok(this.serve_named_file(req, named_file)),
                     Err(err) => this.handle_err(err, req).await,
                 }
             }