From ca6d4b816221214798bc68f2b182f9fa822e115f Mon Sep 17 00:00:00 2001
From: Petros Angelatos <petrosagg@gmail.com>
Date: Mon, 24 May 2021 17:54:24 +0200
Subject: [PATCH] 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>
---
 postgres-native-tls/src/lib.rs | 5 +++--
 postgres-openssl/src/lib.rs    | 5 +++--
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/postgres-native-tls/src/lib.rs b/postgres-native-tls/src/lib.rs
index 70e34812..2f2e6e6a 100644
--- a/postgres-native-tls/src/lib.rs
+++ b/postgres-native-tls/src/lib.rs
@@ -51,7 +51,7 @@ use std::future::Future;
 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_postgres::tls;
 #[cfg(feature = "runtime")]
 use tokio_postgres::tls::MakeTlsConnect;
@@ -115,6 +115,7 @@ where
     type Future = Pin<Box<dyn Future<Output = Result<TlsStream<S>, native_tls::Error>> + Send>>;
 
     fn connect(self, stream: S) -> Self::Future {
+        let stream = BufReader::with_capacity(8192, stream);
         let future = async move {
             let stream = self.connector.connect(&self.domain, stream).await?;
 
@@ -126,7 +127,7 @@ where
 }
 
 /// The stream returned by `TlsConnector`.
-pub struct TlsStream<S>(tokio_native_tls::TlsStream<S>);
+pub struct TlsStream<S>(tokio_native_tls::TlsStream<BufReader<S>>);
 
 impl<S> AsyncRead for TlsStream<S>
 where
diff --git a/postgres-openssl/src/lib.rs b/postgres-openssl/src/lib.rs
index dce3dff5..f3c0b930 100644
--- a/postgres-openssl/src/lib.rs
+++ b/postgres-openssl/src/lib.rs
@@ -57,7 +57,7 @@ use std::pin::Pin;
 #[cfg(feature = "runtime")]
 use std::sync::Arc;
 use std::task::{Context, Poll};
-use tokio::io::{AsyncRead, AsyncWrite, ReadBuf};
+use tokio::io::{AsyncRead, AsyncWrite, BufReader, ReadBuf};
 use tokio_openssl::SslStream;
 use tokio_postgres::tls;
 #[cfg(feature = "runtime")]
@@ -140,6 +140,7 @@ where
     type Future = Pin<Box<dyn Future<Output = Result<TlsStream<S>, Self::Error>> + Send>>;
 
     fn connect(self, stream: S) -> Self::Future {
+        let stream = BufReader::with_capacity(8192, stream);
         let future = async move {
             let ssl = self.ssl.into_ssl(&self.domain)?;
             let mut stream = SslStream::new(ssl, stream)?;
@@ -182,7 +183,7 @@ impl Error for ConnectError {
 }
 
 /// The stream returned by `TlsConnector`.
-pub struct TlsStream<S>(SslStream<S>);
+pub struct TlsStream<S>(SslStream<BufReader<S>>);
 
 impl<S> AsyncRead for TlsStream<S>
 where