feat: add flate pool to reuse the reader (#949)

Author: jeevatkm

client_test.go

@@ -538,6 +538,14 @@ func TestClientSettingsCoverage(t *testing.T) {
 	c.EnableRetryDefaultConditions()
 	assertEqual(t, true, c.IsRetryDefaultConditions())
 
+	nr := nopReader{}
+	n, err1 := nr.Read(nil)
+	assertEqual(t, 0, n)
+	assertEqual(t, io.EOF, err1)
+	b, err1 := nr.ReadByte()
+	assertEqual(t, byte(0), b)
+	assertEqual(t, io.EOF, err1)
+
 	// [Start] Custom Transport scenario
 	ct := dcnl()
 	ct.SetTransport(&CustomRoundTripper1{})

stream.go

@@ -13,6 +13,7 @@ import (
 	"encoding/xml"
 	"errors"
 	"io"
+	"sync"
 )
 
 var (
@@ -106,13 +107,12 @@ func (gz *gzipReader) Close() error {
 	return nil
 }
 
-func decompressDeflate(r io.ReadCloser) (io.ReadCloser, error) {
-	d := &deflateReader{
-		s: r,
-		r: flate.NewReader(r),
-	}
+var flatePool = sync.Pool{New: func() any { return flate.NewReader(nopReader{}) }}
 
-	return d, nil
+func decompressDeflate(r io.ReadCloser) (io.ReadCloser, error) {
+	fr := flatePool.Get().(io.ReadCloser)
+	err := fr.(flate.Resetter).Reset(r, nil)
+	return &deflateReader{s: r, r: fr}, err
 }
 
 type deflateReader struct {
@@ -125,7 +125,9 @@ func (d *deflateReader) Read(p []byte) (n int, err error) {
 }
 
 func (d *deflateReader) Close() error {
-	closeq(d.r)
+	if err := d.r.(flate.Resetter).Reset(nopReader{}, nil); err == nil {
+		flatePool.Put(d.r)
+	}
 	closeq(d.s)
 	return nil
 }
@@ -209,3 +211,10 @@ func (r *nopReadCloser) Read(p []byte) (int, error) {
 }
 
 func (r *nopReadCloser) Close() error { return nil }
+
+var _ flate.Reader = (*nopReader)(nil)
+
+type nopReader struct{}
+
+func (nopReader) Read([]byte) (int, error) { return 0, io.EOF }
+func (nopReader) ReadByte() (byte, error)  { return 0, io.EOF }