internal/pkg: read buffer free list

Reader has a non-insignificant buffer that is worth saving as well.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/pkg/pkg.go

@@ -466,7 +466,7 @@ type Cache struct {
 	// Synchronises entry into exclusive artifacts for the cure method.
 	exclMu sync.Mutex
 	// Buffered I/O free list, must not be accessed directly.
-	bufioPool sync.Pool
+	brPool, bwPool sync.Pool
 
 	// Unlocks the on-filesystem cache. Must only be called from Close.
 	unlock func()
@@ -548,6 +548,26 @@ func (c *Cache) unsafeIdent(a Artifact, encodeKind bool) (
 	return
 }
 
+// getReader is like [bufio.NewReader] but for brPool.
+func (c *Cache) getReader(r io.Reader) *bufio.Reader {
+	br := c.brPool.Get().(*bufio.Reader)
+	br.Reset(r)
+	return br
+}
+
+// putReader adds br to brPool.
+func (c *Cache) putReader(br *bufio.Reader) { c.brPool.Put(br) }
+
+// getWriter is like [bufio.NewWriter] but for bwPool.
+func (c *Cache) getWriter(w io.Writer) *bufio.Writer {
+	bw := c.bwPool.Get().(*bufio.Writer)
+	bw.Reset(w)
+	return bw
+}
+
+// putWriter adds bw to bwPool.
+func (c *Cache) putWriter(bw *bufio.Writer) { c.bwPool.Put(bw) }
+
 // A ChecksumMismatchError describes an [Artifact] with unexpected content.
 type ChecksumMismatchError struct {
 	// Actual and expected checksums.
@@ -1214,13 +1234,6 @@ func (c *Cache) exitCure(a Artifact, curesExempt bool) {
 	<-c.cures
 }
 
-// getWriter is like [bufio.NewWriter] but for bufioPool.
-func (c *Cache) getWriter(w io.Writer) *bufio.Writer {
-	bw := c.bufioPool.Get().(*bufio.Writer)
-	bw.Reset(w)
-	return bw
-}
-
 // measuredReader implements [io.ReadCloser] and measures the checksum during
 // Close. If the underlying reader is not read to EOF, Close blocks until all
 // remaining data is consumed and validated.
@@ -1303,9 +1316,6 @@ func (r *RContext) NewMeasuredReader(
 	return r.cache.newMeasuredReader(rc, checksum)
 }
 
-// putWriter adds bw to bufioPool.
-func (c *Cache) putWriter(bw *bufio.Writer) { c.bufioPool.Put(bw) }
-
 // cure implements Cure without checking the full dependency graph.
 func (c *Cache) cure(a Artifact, curesExempt bool) (
 	pathname *check.Absolute,
@@ -1713,13 +1723,16 @@ func open(
 		msg:  msg,
 		base: base,
 
+		identPool: sync.Pool{New: func() any { return new(extIdent) }},
+
 		ident:        make(map[unique.Handle[ID]]unique.Handle[Checksum]),
 		identErr:     make(map[unique.Handle[ID]]error),
 		identPending: make(map[unique.Handle[ID]]<-chan struct{}),
+
+		brPool: sync.Pool{New: func() any { return new(bufio.Reader) }},
+		bwPool: sync.Pool{New: func() any { return new(bufio.Writer) }},
 	}
 	c.ctx, c.cancel = context.WithCancel(ctx)
-	c.identPool.New = func() any { return new(extIdent) }
-	c.bufioPool.New = func() any { return new(bufio.Writer) }
 
 	if lock || !testing.Testing() {
 		if unlock, err := lockedfile.MutexAt(