From: Matt Joiner <anacrolix@gmail.com>
Date: Wed, 23 Nov 2016 01:59:23 +0000 (+1100)
Subject: Kick only the worst connection when a piece fails a check
X-Git-Tag: v1.0.0~528
X-Git-Url: http://www.git.stargrave.org/?a=commitdiff_plain;h=fdf75d59c833a26dde9facbd564cb0a203ef07c2;p=btrtrc.git

Kick only the worst connection when a piece fails a check
---

diff --git a/TODO b/TODO
index 9895f044..16e9cbb5 100644
--- a/TODO
+++ b/TODO
@@ -12,4 +12,3 @@
  * Implement BEP 40.
  * Rewrite tracker package to be announce-centric, rather than client. Currently the clients are private and adapted onto by the Announce() func.
  * Move tracker management code in the torrent package to its own file.
- * Kick only the poorest connection when a piece hash fails
diff --git a/connection.go b/connection.go
index 94451c6d..727f97f7 100644
--- a/connection.go
+++ b/connection.go
@@ -1068,3 +1068,7 @@ func (cn *connection) Drop() {
 func (cn *connection) sentHave(piece int) bool {
 	return piece < len(cn.sentHaves) && cn.sentHaves[piece]
 }
+
+func (cn *connection) netGoodPiecesDirtied() int {
+	return cn.goodPiecesDirtied - cn.badPiecesDirtied
+}
diff --git a/misc.go b/misc.go
index a9b024ec..9d26738c 100644
--- a/misc.go
+++ b/misc.go
@@ -81,3 +81,7 @@ func chunkIndexSpec(index int, pieceLength, chunkSize pp.Integer) chunkSpec {
 	}
 	return ret
 }
+
+func connLessTrusted(l, r *connection) bool {
+	return l.netGoodPiecesDirtied() < r.netGoodPiecesDirtied()
+}
diff --git a/torrent.go b/torrent.go
index 89422917..8610a5ec 100644
--- a/torrent.go
+++ b/torrent.go
@@ -1415,18 +1415,18 @@ func (t *Torrent) pieceHashed(piece int, correct bool) {
 		return
 	}
 	p := &t.pieces[piece]
+	touchers := t.reapPieceTouchers(piece)
 	if p.EverHashed {
 		// Don't score the first time a piece is hashed, it could be an
 		// initial check.
 		if correct {
 			pieceHashedCorrect.Add(1)
 		} else {
-			log.Printf("%s: piece %d (%x) failed hash", t, piece, p.Hash)
+			log.Printf("%s: piece %d (%x) failed hash: %d connections contributed", t, piece, p.Hash, len(touchers))
 			pieceHashedNotCorrect.Add(1)
 		}
 	}
 	p.EverHashed = true
-	touchers := t.reapPieceTouchers(piece)
 	if correct {
 		for _, c := range touchers {
 			c.goodPiecesDirtied++
@@ -1437,12 +1437,20 @@ func (t *Torrent) pieceHashed(piece int, correct bool) {
 		}
 		t.updatePieceCompletion(piece)
 	} else if len(touchers) != 0 {
-		log.Printf("dropping and banning %d conns that touched piece", len(touchers))
 		for _, c := range touchers {
+			// Y u do dis peer?!
 			c.badPiecesDirtied++
-			t.cl.banPeerIP(missinggo.AddrIP(c.remoteAddr()))
-			t.dropConnection(c)
 		}
+		slices.Sort(touchers, connLessTrusted)
+		log.Printf("dropping first corresponding conn from trust: %s", func() (ret []int) {
+			for _, c := range touchers {
+				ret = append(ret, c.netGoodPiecesDirtied())
+			}
+			return
+		})
+		c := touchers[0]
+		t.cl.banPeerIP(missinggo.AddrIP(c.remoteAddr()))
+		c.Drop()
 	}
 }