feat: Use std::io::BufWriter with a 64KB buffer for dumping data

neqo-bin/src/bin/client/http09.rs

@@ -10,7 +10,7 @@ use std::{
     cell::RefCell,
     collections::{HashMap, VecDeque},
     fs::File,
-    io::Write,
+    io::{BufWriter, Write},
     net::SocketAddr,
     path::PathBuf,
     rc::Rc,
@@ -26,7 +26,7 @@ use neqo_transport::{
 use url::Url;
 
 use super::{get_output_file, Args, KeyUpdateState, Res};
-use crate::qlog_new;
+use crate::{qlog_new, BUFWRITER_BUFFER_SIZE};
 
 pub struct Handler<'a> {
     streams: HashMap<StreamId, Option<File>>,
@@ -219,7 +219,7 @@ impl<'b> Handler<'b> {
         client: &mut Connection,
         stream_id: StreamId,
         output_read_data: bool,
-        maybe_out_file: &mut Option<File>,
+        maybe_out_file: &mut Option<BufWriter<File>>,
     ) -> Res<bool> {
         let mut data = vec![0; 4096];
         loop {
@@ -228,7 +228,7 @@ impl<'b> Handler<'b> {
                 return Ok(fin);
             }
 
-            if let Some(out_file) = maybe_out_file {
+            if let Some(ref mut out_file) = maybe_out_file {
                 out_file.write_all(&data[..sz])?;
             } else if !output_read_data {
                 println!("READ[{stream_id}]: {sz} bytes");
@@ -253,15 +253,21 @@ impl<'b> Handler<'b> {
                 return Ok(());
             }
             Some(maybe_out_file) => {
+                let mut buf_writer = maybe_out_file
+                    .take()
+                    .map(|file| BufWriter::with_capacity(BUFWRITER_BUFFER_SIZE, file));
+
                 let fin_recvd = Self::read_from_stream(
                     client,
                     stream_id,
                     self.args.output_read_data,
-                    maybe_out_file,
+                    &mut buf_writer,
                 )?;
 
                 if fin_recvd {
-                    if maybe_out_file.is_none() {
+                    if buf_writer.is_some() {
+                        buf_writer.take().unwrap().flush()?;
+                    } else {
                         println!("<FIN[{stream_id}]>");
                     }
                     self.streams.remove(&stream_id);

neqo-bin/src/bin/client/http3.rs

@@ -11,7 +11,7 @@ use std::{
     collections::{HashMap, VecDeque},
     fmt::Display,
     fs::File,
-    io::Write,
+    io::{BufWriter, Write},
     net::SocketAddr,
     path::PathBuf,
     rc::Rc,
@@ -26,7 +26,7 @@ use neqo_transport::{
 };
 use url::Url;
 
-use crate::{get_output_file, qlog_new, Args, KeyUpdateState, Res};
+use crate::{get_output_file, qlog_new, Args, KeyUpdateState, Res, BUFWRITER_BUFFER_SIZE};
 
 pub(crate) struct Handler<'a> {
     #[allow(
@@ -255,8 +255,10 @@ impl StreamHandlerType {
         match handler_type {
             Self::Download => {
                 let out_file = get_output_file(url, &args.output_dir, all_paths);
+                let buf_writer =
+                    out_file.map(|file| BufWriter::with_capacity(BUFWRITER_BUFFER_SIZE, file));
                 client.stream_close_send(client_stream_id).unwrap();
-                Box::new(DownloadStreamHandler { out_file })
+                Box::new(DownloadStreamHandler { buf_writer })
             }
             Self::Upload => Box::new(UploadStreamHandler {
                 data: vec![42; args.upload_size],
@@ -269,12 +271,12 @@ impl StreamHandlerType {
 }
 
 struct DownloadStreamHandler {
-    out_file: Option<File>,
+    buf_writer: Option<BufWriter<File>>,
 }
 
 impl StreamHandler for DownloadStreamHandler {
     fn process_header_ready(&mut self, stream_id: StreamId, fin: bool, headers: Vec<Header>) {
-        if self.out_file.is_none() {
+        if self.buf_writer.is_none() {
             println!("READ HEADERS[{stream_id}]: fin={fin} {headers:?}");
         }
     }
@@ -287,9 +289,9 @@ impl StreamHandler for DownloadStreamHandler {
         sz: usize,
         output_read_data: bool,
     ) -> Res<bool> {
-        if let Some(out_file) = &mut self.out_file {
+        if let Some(buf_writer) = &mut self.buf_writer {
             if sz > 0 {
-                out_file.write_all(&data[..sz])?;
+                buf_writer.write_all(&data[..sz])?;
             }
             return Ok(true);
         } else if !output_read_data {
@@ -300,8 +302,12 @@ impl StreamHandler for DownloadStreamHandler {
             println!("READ[{}]: 0x{}", stream_id, hex(&data));
         }
 
-        if fin && self.out_file.is_none() {
-            println!("<FIN[{stream_id}]>");
+        if fin {
+            if let Some(mut buf_writer) = self.buf_writer.take() {
+                buf_writer.flush()?;
+            } else {
+                println!("<FIN[{stream_id}]>");
+            }
         }
 
         Ok(true)

neqo-bin/src/bin/client/main.rs

@@ -36,6 +36,8 @@ use url::{Origin, Url};
 mod http09;
 mod http3;
 
+const BUFWRITER_BUFFER_SIZE: usize = 64 * 1024;
+
 #[derive(Debug)]
 pub enum ClientError {
     ArgumentError(&'static str),