tokio-postgres: buffer sockets to avoid excessive syscalls

The current implementation forwards all read requests to the operating
system through the socket causing excessive system calls. The effect is
magnified when the underlying Socket is wrapped around a TLS
implementation.

This commit changes the underlying socket to be read-buffered by default
with a buffer size of 16K, following the implementation of the official
client.

Signed-off-by: Petros Angelatos <petrosagg@gmail.com>

Author: petrosagg

tokio-postgres/src/socket.rs

@@ -1,16 +1,16 @@
 use std::io;
 use std::pin::Pin;
 use std::task::{Context, Poll};
-use tokio::io::{AsyncRead, AsyncWrite, ReadBuf};
+use tokio::io::{AsyncRead, AsyncWrite, BufReader, ReadBuf};
 use tokio::net::TcpStream;
 #[cfg(unix)]
 use tokio::net::UnixStream;
 
 #[derive(Debug)]
 enum Inner {
-    Tcp(TcpStream),
+    Tcp(BufReader<TcpStream>),
     #[cfg(unix)]
-    Unix(UnixStream),
+    Unix(BufReader<UnixStream>),
 }
 
 /// The standard stream type used by the crate.
@@ -21,12 +21,12 @@ pub struct Socket(Inner);
 
 impl Socket {
     pub(crate) fn new_tcp(stream: TcpStream) -> Socket {
-        Socket(Inner::Tcp(stream))
+        Socket(Inner::Tcp(BufReader::with_capacity(16 * 1024, stream)))
     }
 
     #[cfg(unix)]
     pub(crate) fn new_unix(stream: UnixStream) -> Socket {
-        Socket(Inner::Unix(stream))
+        Socket(Inner::Unix(BufReader::with_capacity(16 * 1024, stream)))
     }
 }