From: Matt Joiner <anacrolix@gmail.com>
Date: Wed, 20 Aug 2025 01:41:25 +0000 (+1000)
Subject: Avoid buffering to write zeroes
X-Git-Url: http://www.git.stargrave.org/?a=commitdiff_plain;h=73284a700c84ec718e4a103c8147eb966d54e497;p=btrtrc.git

Avoid buffering to write zeroes
---

diff --git a/storage/file-piece.go b/storage/file-piece.go
index f9b73c25..b753de9b 100644
--- a/storage/file-piece.go
+++ b/storage/file-piece.go
@@ -367,7 +367,7 @@ func (me *filePieceImpl) writeFileTo(w io.Writer, fileIndex int, extent segments
 		// Write zeroes until the end of the hole we're in.
 		var n1 int64
 		n := min(dataOffset-extent.Start, extent.Length)
-		n1, err = io.CopyN(w, zeroReader{}, n)
+		n1, err = writeZeroes(w, n)
 		packageExpvarMap.Add("bytesReadSkippedHole", n1)
 		written += n1
 		if err != nil {
diff --git a/storage/io.go b/storage/io.go
new file mode 100644
index 00000000..947be816
--- /dev/null
+++ b/storage/io.go
@@ -0,0 +1,20 @@
+package storage
+
+import (
+	"io"
+)
+
+var zeroes [4 << 10]byte
+
+func writeZeroes(w io.Writer, n int64) (written int64, err error) {
+	for n > 0 {
+		var w1 int
+		w1, err = w.Write(zeroes[:min(int64(len(zeroes)), n)][:])
+		written += int64(w1)
+		if err != nil {
+			break
+		}
+		n -= int64(w1)
+	}
+	return
+}