From: Matt Joiner <anacrolix@gmail.com>
Date: Thu, 9 Sep 2021 12:16:24 +0000 (+1000)
Subject: Make readahead algorithm linear
X-Git-Tag: v1.32.0~88
X-Git-Url: http://www.git.stargrave.org/?a=commitdiff_plain;h=58483ae3990f2eefa9e570db2d74ff02637686ec;p=btrtrc.git

Make readahead algorithm linear
---

diff --git a/reader.go b/reader.go
index 745409f4..78a2ff00 100644
--- a/reader.go
+++ b/reader.go
@@ -5,7 +5,6 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"math"
 	"sync"
 
 	"github.com/anacrolix/log"
@@ -292,7 +291,7 @@ func (r *reader) log(m log.Msg) {
 	r.t.logger.Log(m.Skip(1))
 }
 
-// Implementation inspired from an arbitrary comment I found on HN.
-func (r *reader) sqrtReadahead() int64 {
-	return int64(math.Sqrt(float64(r.pos - r.contiguousReadStartPos)))
+// Implementation inspired by https://news.ycombinator.com/item?id=27019613.
+func (r *reader) defaultReadaheadFunc() int64 {
+	return r.pos - r.contiguousReadStartPos
 }
diff --git a/t.go b/t.go
index 8da39883..ebb32883 100644
--- a/t.go
+++ b/t.go
@@ -42,7 +42,7 @@ func (t *Torrent) newReader(offset, length int64) Reader {
 		offset: offset,
 		length: length,
 	}
-	r.readaheadFunc = r.sqrtReadahead
+	r.readaheadFunc = r.defaultReadaheadFunc
 	t.addReader(&r)
 	return &r
 }