From 0f799a7768997c37e3e1b6861c097c4cd934acde Mon Sep 17 00:00:00 2001
From: Alex Auvolat <alex@adnab.me>
Date: Tue, 6 Sep 2022 19:42:49 +0200
Subject: [PATCH] Implement Least Attained First scheduling of streams

---
 src/send.rs | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/src/send.rs b/src/send.rs
index 780bbcf..2606434 100644
--- a/src/send.rs
+++ b/src/send.rs
@@ -59,6 +59,7 @@ struct SendQueueItem {
 	prio: RequestPriority,
 	order_tag: Option<OrderTag>,
 	data: ByteStreamReader,
+	sent: usize,
 }
 
 impl SendQueue {
@@ -106,7 +107,7 @@ impl SendQueuePriority {
 			let i = order_vec.iter().take_while(|o2| **o2 < order).count();
 			order_vec.insert(i, order);
 		}
-		self.items.push_back(item);
+		self.items.push_front(item);
 	}
 	fn remove(&mut self, id: RequestID) {
 		if let Some(i) = self.items.iter().position(|x| x.id == id) {
@@ -139,7 +140,11 @@ impl SendQueuePriority {
 					_ => unreachable!(),
 				});
 
-				if eos || packet.is_err() {
+				let is_err = packet.is_err();
+				let data_frame = DataFrame::from_packet(packet, !eos);
+				item.sent += data_frame.data().len();
+
+				if eos || is_err {
 					if let Some(OrderTag(stream, order)) = item.order_tag {
 						assert_eq!(
 							self.order.get_mut(&stream).unwrap().pop_front(),
@@ -147,10 +152,16 @@ impl SendQueuePriority {
 						)
 					}
 					self.items.remove(j);
+				} else {
+					for k in j..self.items.len() - 1 {
+						if self.items[k].sent >= self.items[k + 1].sent {
+							self.items.swap(k, k + 1);
+						} else {
+							break;
+						}
+					}
 				}
 
-				let data_frame = DataFrame::from_packet(packet, !eos);
-
 				return Poll::Ready((id, data_frame));
 			}
 		}
@@ -160,7 +171,7 @@ impl SendQueuePriority {
 	fn dump(&self, prio: u8) -> String {
 		self.items
 			.iter()
-			.map(|i| format!("[{} {} {:?}]", prio, i.id, i.order_tag))
+			.map(|i| format!("[{} {} {:?} @{}]", prio, i.id, i.order_tag, i.sent))
 			.collect::<Vec<_>>()
 			.join(" ")
 	}
@@ -294,6 +305,7 @@ pub(crate) trait SendLoop: Sync {
 								prio,
 								order_tag,
 								data: ByteStreamReader::new(data),
+								sent: 0,
 							})
 						}
 						Some(SendItem::Cancel(id)) => {