feat(http2): add max_pending_accept_reset_streams(num) back to HTTP…

…/2 server builder (#3507)

In places where required, the `max_pending_accept_reset_streams` option was reimplemented, as in PR #3201

cc #3461

src/proto/h2/server.rs

@@ -49,6 +49,7 @@ pub(crate) struct Config {
     pub(crate) max_frame_size: u32,
     pub(crate) enable_connect_protocol: bool,
     pub(crate) max_concurrent_streams: Option<u32>,
+    pub(crate) max_pending_accept_reset_streams: Option<usize>,
     pub(crate) keep_alive_interval: Option<Duration>,
     pub(crate) keep_alive_timeout: Duration,
     pub(crate) max_send_buffer_size: usize,
@@ -64,6 +65,7 @@ impl Default for Config {
             max_frame_size: DEFAULT_MAX_FRAME_SIZE,
             enable_connect_protocol: false,
             max_concurrent_streams: Some(200),
+            max_pending_accept_reset_streams: None,
             keep_alive_interval: None,
             keep_alive_timeout: Duration::from_secs(20),
             max_send_buffer_size: DEFAULT_MAX_SEND_BUF_SIZE,
@@ -131,6 +133,9 @@ where
         if let Some(max) = config.max_concurrent_streams {
             builder.max_concurrent_streams(max);
         }
+        if let Some(max) = config.max_pending_accept_reset_streams {
+            builder.max_pending_accept_reset_streams(max);
+        }
         if config.enable_connect_protocol {
             builder.enable_connect_protocol();
         }

src/server/conn/http2.rs

@@ -120,6 +120,17 @@ impl<E> Builder<E> {
         }
     }
 
+    /// Configures the maximum number of pending reset streams allowed before a GOAWAY will be sent.
+    ///
+    /// This will default to the default value set by the [`h2` crate](https://crates.io/crates/h2).
+    /// As of v0.4.0, it is 20.
+    ///
+    /// See <https://github.com/hyperium/hyper/issues/2877> for more information.
+    pub fn max_pending_accept_reset_streams(&mut self, max: impl Into<Option<usize>>) -> &mut Self {
+        self.h2_builder.max_pending_accept_reset_streams = max.into();
+        self
+    }
+
     /// Sets the [`SETTINGS_INITIAL_WINDOW_SIZE`][spec] option for HTTP2
     /// stream-level flow control.
     ///