From 99a64bcf63fec02b0d5cc15bd792750ebf6db633 Mon Sep 17 00:00:00 2001
From: Matt Joiner <anacrolix@gmail.com>
Date: Thu, 2 Dec 2021 13:10:02 +1100
Subject: [PATCH] Wait between duplicate requests

---
 peerconn.go   |  4 ++++
 requesting.go | 17 ++++++++++++++++-
 torrent.go    |  8 +++++---
 3 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/peerconn.go b/peerconn.go
index fc3d9df3..7f8a78f1 100644
--- a/peerconn.go
+++ b/peerconn.go
@@ -620,6 +620,7 @@ func (cn *Peer) request(r RequestIndex) (more bool, err error) {
 	}
 	cn.validReceiveChunks[r]++
 	cn.t.pendingRequests.Inc(r)
+	cn.t.lastRequested[r] = time.Now()
 	cn.updateExpectingChunks()
 	ppReq := cn.t.requestIndexToRequest(r)
 	for _, f := range cn.callbacks.SentRequest {
@@ -1550,6 +1551,9 @@ func (c *Peer) deleteRequest(r RequestIndex) bool {
 	}
 	c.updateExpectingChunks()
 	c.t.pendingRequests.Dec(r)
+	if c.t.pendingRequests.Get(r) == 0 {
+		delete(c.t.lastRequested, r)
+	}
 	return true
 }
 
diff --git a/requesting.go b/requesting.go
index 5e02b79b..6a611b94 100644
--- a/requesting.go
+++ b/requesting.go
@@ -119,6 +119,12 @@ func (p *peerRequests) Less(i, j int) bool {
 	ml = ml.Int(
 		int(leftPiece.availability),
 		int(rightPiece.availability))
+	leftLastRequested := p.peer.t.lastRequested[leftRequest]
+	rightLastRequested := p.peer.t.lastRequested[rightRequest]
+	ml = ml.EagerSameLess(
+		leftLastRequested.Equal(rightLastRequested),
+		leftLastRequested.Before(rightLastRequested),
+	)
 	ml = ml.Uint32(leftPieceIndex, rightPieceIndex)
 	ml = ml.Uint32(leftRequest, rightRequest)
 	return ml.MustLess()
@@ -177,6 +183,13 @@ func (p *Peer) getDesiredRequestState() (desired desiredRequestState) {
 						return
 					}
 				}
+				// Note that we can still be interested if we filter all requests due to being
+				// recently requested from another peer.
+				if !p.actualRequestState.Requests.Contains(r) {
+					if time.Since(p.t.lastRequested[r]) < time.Second {
+						return
+					}
+				}
 				requestHeap.requestIndexes = append(requestHeap.requestIndexes, r)
 			})
 		},
@@ -276,10 +289,12 @@ func (p *Peer) applyRequestState(next desiredRequestState) bool {
 			break
 		}
 	}
+	// TODO: This may need to change, we might want to update even if there were no requests due to
+	// filtering them for being recently requested already.
 	p.updateRequestsTimer.Stop()
 	if more {
 		p.needRequestUpdate = ""
-		if !current.Requests.IsEmpty() {
+		if current.Interested {
 			p.updateRequestsTimer.Reset(3 * time.Second)
 		}
 	}
diff --git a/torrent.go b/torrent.go
index c4ecf07f..30ccbb08 100644
--- a/torrent.go
+++ b/torrent.go
@@ -139,6 +139,7 @@ type Torrent struct {
 
 	// Count of each request across active connections.
 	pendingRequests pendingRequests
+	lastRequested   map[RequestIndex]time.Time
 	// Chunks we've written to since the corresponding piece was last checked.
 	dirtyChunks roaring.Bitmap
 
@@ -463,6 +464,7 @@ func (t *Torrent) onSetInfo() {
 	close(t.gotMetainfoC)
 	t.updateWantPeersEvent()
 	t.pendingRequests.Init(t.numRequests())
+	t.lastRequested = make(map[RequestIndex]time.Time)
 	t.tryCreateMorePieceHashers()
 	t.iterPeers(func(p *Peer) {
 		p.onGotInfo(t.info)
@@ -1110,9 +1112,9 @@ func (t *Torrent) maybeNewConns() {
 func (t *Torrent) piecePriorityChanged(piece pieceIndex, reason string) {
 	if t._pendingPieces.Contains(uint32(piece)) {
 		t.iterPeers(func(c *Peer) {
-			if c.actualRequestState.Interested {
-				return
-			}
+			// if c.actualRequestState.Interested {
+			// 	return
+			// }
 			if !c.isLowOnRequests() {
 				return
 			}