From f71304b44905cdc71f9e8a708156c72878b2f1aa Mon Sep 17 00:00:00 2001
From: Sean McArthur <sean@seanmonstar.com>
Date: Wed, 23 Oct 2019 14:29:15 -0700
Subject: [PATCH] refactor(client): use pin_project for Resolve futures

---
 src/client/connect/dns.rs  |  6 ++---
 src/client/connect/http.rs | 45 ++++++++++++++++++++------------------
 2 files changed, 27 insertions(+), 24 deletions(-)

diff --git a/src/client/connect/dns.rs b/src/client/connect/dns.rs
index 03e30f09..0160a268 100644
--- a/src/client/connect/dns.rs
+++ b/src/client/connect/dns.rs
@@ -17,14 +17,14 @@ use std::str::FromStr;
 
 use tokio_sync::{mpsc, oneshot};
 
-use crate::common::{Future, Never, Pin, Poll, Unpin, task};
+use crate::common::{Future, Never, Pin, Poll, task};
 
 /// Resolve a hostname to a set of IP addresses.
-pub trait Resolve: Unpin {
+pub trait Resolve {
     /// The set of IP addresses to try to connect to.
     type Addrs: Iterator<Item=IpAddr>;
     /// A Future of the resolved set of addresses.
-    type Future: Future<Output=Result<Self::Addrs, io::Error>> + Unpin;
+    type Future: Future<Output=Result<Self::Addrs, io::Error>>;
     /// Resolve a hostname.
     fn resolve(&self, name: Name) -> Self::Future;
 }
diff --git a/src/client/connect/http.rs b/src/client/connect/http.rs
index b67f29a1..1ed5ef8c 100644
--- a/src/client/connect/http.rs
+++ b/src/client/connect/http.rs
@@ -9,6 +9,7 @@ use std::time::Duration;
 use http::uri::{Scheme, Uri};
 use futures_util::{TryFutureExt, FutureExt};
 use net2::TcpBuilder;
+use pin_project::{pin_project, project};
 use tokio_net::driver::Handle;
 use tokio_net::tcp::TcpStream;
 use tokio_timer::{Delay, Timeout};
@@ -359,7 +360,9 @@ impl StdError for InvalidUrl {
 }
 /// A Future representing work to connect to a URL.
 #[must_use = "futures do nothing unless polled"]
+#[pin_project]
 pub struct HttpConnecting<R: Resolve = GaiResolver> {
+    #[pin]
     state: State<R>,
     handle: Option<Handle>,
     connect_timeout: Option<Duration>,
@@ -372,61 +375,61 @@ pub struct HttpConnecting<R: Resolve = GaiResolver> {
     recv_buffer_size: Option<usize>,
 }
 
+#[pin_project]
 enum State<R: Resolve> {
     Lazy(R, String, Option<IpAddr>),
-    Resolving(R::Future, Option<IpAddr>),
+    Resolving(#[pin] R::Future, Option<IpAddr>),
     Connecting(ConnectingTcp),
     Error(Option<io::Error>),
 }
 
-impl<R: Resolve> Future for HttpConnecting<R>
-where
-    R::Future: Unpin,
-{
+impl<R: Resolve> Future for HttpConnecting<R> {
     type Output = Result<(TcpStream, Connected), io::Error>;
 
-    fn poll(mut self: Pin<&mut Self>, cx: &mut task::Context<'_>) -> Poll<Self::Output> {
-        let me = &mut *self;
+    #[project]
+    fn poll(self: Pin<&mut Self>, cx: &mut task::Context<'_>) -> Poll<Self::Output> {
+        let mut me = self.project();
         loop {
             let state;
-            match me.state {
-                State::Lazy(ref resolver, ref mut host, local_addr) => {
+            #[project]
+            match me.state.as_mut().project() {
+                State::Lazy(ref resolver, ref mut host, ref local_addr) => {
                     // If the host is already an IP addr (v4 or v6),
                     // skip resolving the dns and start connecting right away.
-                    if let Some(addrs) = dns::IpAddrs::try_parse(host, me.port) {
+                    if let Some(addrs) = dns::IpAddrs::try_parse(host, *me.port) {
                         state = State::Connecting(ConnectingTcp::new(
-                            local_addr, addrs, me.connect_timeout, me.happy_eyeballs_timeout, me.reuse_address));
+                            **local_addr, addrs, *me.connect_timeout, *me.happy_eyeballs_timeout, *me.reuse_address));
                     } else {
                         let name = dns::Name::new(mem::replace(host, String::new()));
-                        state = State::Resolving(resolver.resolve(name), local_addr);
+                        state = State::Resolving(resolver.resolve(name), **local_addr);
                     }
                 },
-                State::Resolving(ref mut future, local_addr) => {
-                    let addrs =  ready!(Pin::new(future).poll(cx))?;
-                    let port = me.port;
+                State::Resolving(future, local_addr) => {
+                    let addrs =  ready!(future.poll(cx))?;
+                    let port = *me.port;
                     let addrs = addrs
                         .map(|addr| SocketAddr::new(addr, port))
                         .collect();
                     let addrs = dns::IpAddrs::new(addrs);
                     state = State::Connecting(ConnectingTcp::new(
-                        local_addr, addrs, me.connect_timeout, me.happy_eyeballs_timeout, me.reuse_address));
+                        *local_addr, addrs, *me.connect_timeout, *me.happy_eyeballs_timeout, *me.reuse_address));
                 },
                 State::Connecting(ref mut c) => {
                     let sock = ready!(c.poll(cx, &me.handle))?;
 
                     if let Some(dur) = me.keep_alive_timeout {
-                        sock.set_keepalive(Some(dur))?;
+                        sock.set_keepalive(Some(*dur))?;
                     }
 
                     if let Some(size) = me.send_buffer_size {
-                        sock.set_send_buffer_size(size)?;
+                        sock.set_send_buffer_size(*size)?;
                     }
 
                     if let Some(size) = me.recv_buffer_size {
-                        sock.set_recv_buffer_size(size)?;
+                        sock.set_recv_buffer_size(*size)?;
                     }
 
-                    sock.set_nodelay(me.nodelay)?;
+                    sock.set_nodelay(*me.nodelay)?;
 
                     let extra = HttpInfo {
                         remote_addr: sock.peer_addr()?,
@@ -438,7 +441,7 @@ where
                 },
                 State::Error(ref mut e) => return Poll::Ready(Err(e.take().expect("polled more than once"))),
             }
-            me.state = state;
+            me.state.set(state);
         }
     }
 }