Buffer short responses (2) (#531)

* Response: build reader at construction time

* Remove unwrapping/rewrapping DeadlineStream

* Let into_reader() provide Sync + 'static

* Prebuffer Vec use known capacity

Co-authored-by: Martin Algesten <martin@algesten.se>

src/stream.rs

@@ -50,7 +50,7 @@ impl<T: ReadWrite + ?Sized> ReadWrite for Box<T> {
 // after the provided deadline, and sets timeouts on the underlying
 // TcpStream to ensure read() doesn't block beyond the deadline.
 // When the From trait is used to turn a DeadlineStream back into a
-// Stream (by PoolReturningRead), the timeouts are removed.
+// Stream (by PoolReturnRead), the timeouts are removed.
 pub(crate) struct DeadlineStream {
     stream: Stream,
     deadline: Option<Instant>,
@@ -60,6 +60,10 @@ impl DeadlineStream {
     pub(crate) fn new(stream: Stream, deadline: Option<Instant>) -> Self {
         DeadlineStream { stream, deadline }
     }
+
+    pub(crate) fn inner_ref(&self) -> &Stream {
+        &self.stream
+    }
 }
 
 impl From<DeadlineStream> for Stream {
@@ -184,6 +188,10 @@ impl Stream {
         stream
     }
 
+    pub(crate) fn buffer(&self) -> &[u8] {
+        self.inner.buffer()
+    }
+
     fn from_tcp_stream(t: TcpStream) -> Stream {
         Stream::logged_create(Stream {
             inner: BufReader::new(Box::new(t)),