Auto-buffer HTTP connections when TLS is set up

src/client.rs

@@ -119,6 +119,15 @@ where
             #[cfg(not(feature = "embedded-tls"))]
             Err(Error::InvalidUrl(nourl::Error::UnsupportedScheme))
         } else {
+            #[cfg(feature = "embedded-tls")]
+            match self.tls.as_mut() {
+                Some(tls) => Ok(HttpConnection::PlainBuffered(BufferedWrite::new(
+                    buffered_io_adapter::ConnErrorAdapter(conn),
+                    tls.write_buffer,
+                ))),
+                None => Ok(HttpConnection::Plain(conn)),
+            }
+            #[cfg(not(feature = "embedded-tls"))]
             Ok(HttpConnection::Plain(conn))
         }
     }
@@ -155,15 +164,17 @@ where
 
 /// Represents a HTTP connection that may be encrypted or unencrypted.
 #[allow(clippy::large_enum_variant)]
-pub enum HttpConnection<'m, T>
+pub enum HttpConnection<'m, C>
 where
-    T: Read + Write,
+    C: Read + Write,
 {
-    Plain(T),
+    Plain(C),
+    #[cfg(feature = "embedded-tls")]
+    PlainBuffered(BufferedWrite<'m, buffered_io_adapter::ConnErrorAdapter<C>>),
     #[cfg(feature = "embedded-tls")]
-    Tls(embedded_tls::TlsConnection<'m, T, embedded_tls::Aes128GcmSha256>),
+    Tls(embedded_tls::TlsConnection<'m, C, embedded_tls::Aes128GcmSha256>),
     #[cfg(not(feature = "embedded-tls"))]
-    Tls(&'m mut T), // Variant is never actually created, but we need it to avoid "unused lifetime" warning
+    Tls((&'m mut (), core::convert::Infallible)), // Variant is impossible to create, but we need it to avoid "unused lifetime" warning
 }
 
 impl<'conn, T> HttpConnection<'conn, T>
@@ -200,7 +211,12 @@ where
     async fn read(&mut self, buf: &mut [u8]) -> Result<usize, Self::Error> {
         match self {
             Self::Plain(conn) => conn.read(buf).await.map_err(|e| e.kind()),
+            #[cfg(feature = "embedded-tls")]
+            Self::PlainBuffered(conn) => conn.read(buf).await.map_err(|e| e.kind()),
+            #[cfg(feature = "embedded-tls")]
             Self::Tls(conn) => conn.read(buf).await.map_err(|e| e.kind()),
+            #[cfg(not(feature = "embedded-tls"))]
+            _ => unreachable!(),
         }
     }
 }
@@ -212,14 +228,24 @@ where
     async fn write(&mut self, buf: &[u8]) -> Result<usize, Self::Error> {
         match self {
             Self::Plain(conn) => conn.write(buf).await.map_err(|e| e.kind()),
+            #[cfg(feature = "embedded-tls")]
+            Self::PlainBuffered(conn) => conn.write(buf).await.map_err(|e| e.kind()),
+            #[cfg(feature = "embedded-tls")]
             Self::Tls(conn) => conn.write(buf).await.map_err(|e| e.kind()),
+            #[cfg(not(feature = "embedded-tls"))]
+            _ => unreachable!(),
         }
     }
 
     async fn flush(&mut self) -> Result<(), Self::Error> {
         match self {
             Self::Plain(conn) => conn.flush().await.map_err(|e| e.kind()),
+            #[cfg(feature = "embedded-tls")]
+            Self::PlainBuffered(conn) => conn.flush().await.map_err(|e| e.kind()),
+            #[cfg(feature = "embedded-tls")]
             Self::Tls(conn) => conn.flush().await.map_err(|e| e.kind()),
+            #[cfg(not(feature = "embedded-tls"))]
+            _ => unreachable!(),
         }
     }
 }
@@ -241,9 +267,10 @@ where
     C: Read + Write,
     B: RequestBody,
 {
-    /// Turn the request into a buffered request
+    /// Turn the request into a buffered request.
     ///
-    /// This is most likely only relevant for non-tls endpoints, as `embedded-tls` buffers internally.
+    /// This is only relevant if no TLS is used, as `embedded-tls` buffers internally and we reuse
+    /// its buffer for non-TLS connections.
     pub fn into_buffered<'buf>(
         self,
         tx_buf: &'buf mut [u8],
@@ -328,7 +355,8 @@ where
 {
     /// Turn the resource into a buffered resource
     ///
-    /// This is most likely only relevant for non-tls endpoints, as `embedded-tls` buffers internally.
+    /// This is only relevant if no TLS is used, as `embedded-tls` buffers internally and we reuse
+    /// its buffer for non-TLS connections.
     pub fn into_buffered<'buf>(
         self,
         tx_buf: &'buf mut [u8],