From: Matt Joiner <anacrolix@gmail.com>
Date: Thu, 8 Feb 2024 06:58:12 +0000 (+1100)
Subject: Restore request strategy Torrent.Piece use, without a heap allocation
X-Git-Tag: v1.54.0~5
X-Git-Url: http://www.git.stargrave.org/?a=commitdiff_plain;h=0f46fc993fc0007855bcf72143e9187922bef2a3;p=btrtrc.git

Restore request strategy Torrent.Piece use, without a heap allocation
---

diff --git a/request-strategy-impls.go b/request-strategy-impls.go
index 0b05ed41..5d91e64a 100644
--- a/request-strategy-impls.go
+++ b/request-strategy-impls.go
@@ -44,15 +44,8 @@ type requestStrategyTorrent struct {
 	t *Torrent
 }
 
-func (r requestStrategyTorrent) IgnorePiece(i int) bool {
-	if r.t.ignorePieceForRequests(i) {
-		return true
-	}
-	if r.t.pieceNumPendingChunks(i) == 0 {
-		return true
-	}
-
-	return false
+func (r requestStrategyTorrent) Piece(i int) request_strategy.Piece {
+	return (*requestStrategyPiece)(r.t.piece(i))
 }
 
 func (r requestStrategyTorrent) PieceLength() int64 {
@@ -61,17 +54,14 @@ func (r requestStrategyTorrent) PieceLength() int64 {
 
 var _ request_strategy.Torrent = requestStrategyTorrent{}
 
-type requestStrategyPiece struct {
-	t *Torrent
-	i pieceIndex
-}
+type requestStrategyPiece Piece
 
-func (r requestStrategyPiece) Request() bool {
-	return !r.t.ignorePieceForRequests(r.i)
+func (r *requestStrategyPiece) Request() bool {
+	return !r.t.ignorePieceForRequests(r.index)
 }
 
-func (r requestStrategyPiece) NumPendingChunks() int {
-	return int(r.t.pieceNumPendingChunks(r.i))
+func (r *requestStrategyPiece) NumPendingChunks() int {
+	return int(r.t.pieceNumPendingChunks(r.index))
 }
 
-var _ request_strategy.Piece = requestStrategyPiece{}
+var _ request_strategy.Piece = (*requestStrategyPiece)(nil)
diff --git a/request-strategy-impls_test.go b/request-strategy-impls_test.go
new file mode 100644
index 00000000..f0d3fa18
--- /dev/null
+++ b/request-strategy-impls_test.go
@@ -0,0 +1,29 @@
+package torrent
+
+import (
+	"io"
+	"runtime"
+	"testing"
+
+	"github.com/davecgh/go-spew/spew"
+	qt "github.com/frankban/quicktest"
+
+	request_strategy "github.com/anacrolix/torrent/request-strategy"
+)
+
+func makeRequestStrategyPiece(t request_strategy.Torrent) request_strategy.Piece {
+	return t.Piece(0)
+}
+
+func TestRequestStrategyPieceDoesntAlloc(t *testing.T) {
+	c := qt.New(t)
+	akshalTorrent := &Torrent{pieces: make([]Piece, 1)}
+	rst := requestStrategyTorrent{akshalTorrent}
+	var before, after runtime.MemStats
+	runtime.ReadMemStats(&before)
+	p := makeRequestStrategyPiece(rst)
+	runtime.ReadMemStats(&after)
+	c.Assert(before.HeapAlloc, qt.Equals, after.HeapAlloc)
+	// We have to use p, or it gets optimized away.
+	spew.Fdump(io.Discard, p)
+}
diff --git a/request-strategy/order.go b/request-strategy/order.go
index df656f6d..92793f58 100644
--- a/request-strategy/order.go
+++ b/request-strategy/order.go
@@ -66,7 +66,8 @@ func GetRequestablePieces(
 		lastItem.Set(_i)
 
 		ih := _i.key.InfoHash
-		t := input.Torrent(ih)
+		var t Torrent = input.Torrent(ih)
+		var piece Piece = t.Piece(_i.key.Index)
 		pieceLength := t.PieceLength()
 		if storageLeft != nil {
 			if *storageLeft < pieceLength {
@@ -74,7 +75,7 @@ func GetRequestablePieces(
 			}
 			*storageLeft -= pieceLength
 		}
-		if t.IgnorePiece(_i.key.Index) {
+		if !piece.Request() || piece.NumPendingChunks() == 0 {
 			// TODO: Clarify exactly what is verified. Stuff that's being hashed should be
 			// considered unverified and hold up further requests.
 			return true
diff --git a/request-strategy/torrent.go b/request-strategy/torrent.go
index 5bc438ee..690f8b6d 100644
--- a/request-strategy/torrent.go
+++ b/request-strategy/torrent.go
@@ -1,6 +1,6 @@
 package requestStrategy
 
 type Torrent interface {
-	IgnorePiece(int) bool
+	Piece(int) Piece
 	PieceLength() int64
 }