From bad6f07f5e66238b99d3851b4584ad83feb5d95b Mon Sep 17 00:00:00 2001
From: Matt Joiner <anacrolix@gmail.com>
Date: Fri, 1 Sep 2017 15:26:50 +1000
Subject: [PATCH] Wrap writerCond in tickleWriter and be more selective about
 using it

---
 connection.go | 54 ++++++++++++++++++++++++++++-----------------------
 torrent.go    |  6 ++++--
 2 files changed, 34 insertions(+), 26 deletions(-)

diff --git a/connection.go b/connection.go
index bf418416..b5b167a2 100644
--- a/connection.go
+++ b/connection.go
@@ -236,7 +236,7 @@ func (cn *connection) PeerHasPiece(piece int) bool {
 func (cn *connection) Post(msg pp.Message) {
 	messageTypesPosted.Add(strconv.FormatInt(int64(msg.Type), 10), 1)
 	cn.postedBuffer.Write(msg.MustMarshalBinary())
-	cn.writerCond.Broadcast()
+	cn.tickleWriter()
 }
 
 func (cn *connection) requestMetadataPiece(index int) {
@@ -340,7 +340,7 @@ func (cn *connection) fillWriteBuffer(msg func(pp.Message) bool) {
 	for r := range cn.requests {
 		if _, ok := rs[r]; !ok {
 			sentCancels = true
-			delete(cn.requests, r)
+			cn.deleteRequest(r)
 			// log.Printf("%p: cancelling request: %v", cn, r)
 			if !msg(pp.Message{
 				Type:   pp.Cancel,
@@ -390,7 +390,7 @@ func (cn *connection) writer(keepAliveTimeout time.Duration) {
 		cn.mu().Lock()
 		defer cn.mu().Unlock()
 		if time.Since(lastWrite) >= keepAliveTimeout {
-			cn.writerCond.Broadcast()
+			cn.tickleWriter()
 		}
 		keepAliveTimer.Reset(keepAliveTimeout)
 	})
@@ -498,7 +498,7 @@ func nextRequestState(
 }
 
 func (cn *connection) updateRequests() {
-	cn.writerCond.Broadcast()
+	cn.tickleWriter()
 }
 
 func (cn *connection) desiredRequestState() (map[request]struct{}, bool) {
@@ -522,24 +522,22 @@ func undirtiedChunks(piece int, t *Torrent, f func(chunkSpec) bool) bool {
 	})
 }
 
-func (cn *connection) stopRequestingPiece(piece int) {
-	if cn.pieceRequestOrder.Remove(piece) {
-		cn.writerCond.Broadcast()
-	}
+// check callers updaterequests
+func (cn *connection) stopRequestingPiece(piece int) bool {
+	return cn.pieceRequestOrder.Remove(piece)
 }
 
 // This is distinct from Torrent piece priority, which is the user's
 // preference. Connection piece priority is specific to a connection,
 // pseudorandomly avoids connections always requesting the same pieces and
 // thus wasting effort.
-func (cn *connection) updatePiecePriority(piece int) {
+func (cn *connection) updatePiecePriority(piece int) bool {
 	tpp := cn.t.piecePriority(piece)
 	if !cn.PeerHasPiece(piece) {
 		tpp = PiecePriorityNone
 	}
 	if tpp == PiecePriorityNone {
-		cn.stopRequestingPiece(piece)
-		return
+		return cn.stopRequestingPiece(piece)
 	}
 	prio := cn.getPieceInclination()[piece]
 	switch tpp {
@@ -552,9 +550,7 @@ func (cn *connection) updatePiecePriority(piece int) {
 		panic(tpp)
 	}
 	prio += piece / 3
-	if cn.pieceRequestOrder.Set(piece, prio) {
-		cn.updateRequests()
-	}
+	return cn.pieceRequestOrder.Set(piece, prio)
 }
 
 func (cn *connection) getPieceInclination() []int {
@@ -572,14 +568,16 @@ func (cn *connection) discardPieceInclination() {
 	cn.pieceInclination = nil
 }
 
-func (cn *connection) peerHasPieceChanged(piece int) {
-	cn.updatePiecePriority(piece)
-}
-
 func (cn *connection) peerPiecesChanged() {
 	if cn.t.haveInfo() {
+		prioritiesChanged := false
 		for i := range iter.N(cn.t.numPieces()) {
-			cn.peerHasPieceChanged(i)
+			if cn.updatePiecePriority(i) {
+				prioritiesChanged = true
+			}
+		}
+		if prioritiesChanged {
+			cn.updateRequests()
 		}
 	}
 }
@@ -599,7 +597,9 @@ func (cn *connection) peerSentHave(piece int) error {
 	}
 	cn.raisePeerMinPieces(piece + 1)
 	cn.peerPieces.Set(piece, true)
-	cn.peerHasPieceChanged(piece)
+	if cn.updatePiecePriority(piece) {
+		cn.updateRequests()
+	}
 	return nil
 }
 
@@ -749,10 +749,12 @@ func (c *connection) mainReadLoop() error {
 			// We can then reset our interest.
 			c.updateRequests()
 		case pp.Reject:
-			c.deleteRequest(newRequest(msg.Index, msg.Begin, msg.Length))
+			if c.deleteRequest(newRequest(msg.Index, msg.Begin, msg.Length)) {
+				c.updateRequests()
+			}
 		case pp.Unchoke:
 			c.PeerChoked = false
-			c.writerCond.Broadcast()
+			c.tickleWriter()
 		case pp.Interested:
 			c.PeerInterested = true
 			c.upload()
@@ -950,7 +952,9 @@ func (c *connection) receiveChunk(msg *pp.Message) {
 	req := newRequest(msg.Index, msg.Begin, pp.Integer(len(msg.Piece)))
 
 	// Request has been satisfied.
-	if !c.deleteRequest(req) {
+	if c.deleteRequest(req) {
+		c.updateRequests()
+	} else {
 		unexpectedChunksReceived.Add(1)
 	}
 
@@ -1092,6 +1096,8 @@ func (c *connection) deleteRequest(r request) bool {
 		return false
 	}
 	delete(c.requests, r)
-	c.writerCond.Broadcast()
 	return true
 }
+func (c *connection) tickleWriter() {
+	c.writerCond.Broadcast()
+}
diff --git a/torrent.go b/torrent.go
index b741dde3..7f04e5f3 100644
--- a/torrent.go
+++ b/torrent.go
@@ -798,7 +798,9 @@ func (t *Torrent) maybeNewConns() {
 
 func (t *Torrent) piecePriorityChanged(piece int) {
 	for c := range t.conns {
-		c.updatePiecePriority(piece)
+		if c.updatePiecePriority(piece) {
+			c.updateRequests()
+		}
 	}
 	t.maybeNewConns()
 	t.publishPieceChange(piece)
@@ -1424,7 +1426,7 @@ func (t *Torrent) pieceHashed(piece int, correct bool) {
 
 func (t *Torrent) cancelRequestsForPiece(piece int) {
 	for cn := range t.conns {
-		cn.writerCond.Broadcast()
+		cn.tickleWriter()
 	}
 }
 
-- 
2.50.0