optimize: free old buf

bufiox/defaultbuf.go

@@ -27,10 +27,11 @@ const maxConsecutiveEmptyReads = 100
 var _ Reader = &DefaultReader{}
 
 type DefaultReader struct {
-	buf []byte    // buf[ri:] is the buffer for reading.
-	rd  io.Reader // reader provided by the client
-	ri  int       // buf read positions
-	err error
+	buf    []byte // buf[ri:] is the buffer for reading.
+	oldBuf [][]byte
+	rd     io.Reader // reader provided by the client
+	ri     int       // buf read positions
+	err    error
 
 	maxSizeStats maxSizeStats
 
@@ -97,6 +98,7 @@ func (r *DefaultReader) acquireSlow(n int) int {
 			nbuf = dirtmake.Bytes(ncap, ncap)
 		} else {
 			nbuf = mcache.Malloc(ncap)
+			r.oldBuf = append(r.oldBuf, r.buf)
 		}
 		r.buf = nbuf[:copy(nbuf, r.buf)]
 	}
@@ -184,18 +186,31 @@ func (r *DefaultReader) Read(p []byte) (m int, err error) {
 }
 
 func (r *DefaultReader) Release(e error) error {
-	if len(r.buf)-r.ri == 0 {
-		// release buf
-		r.maxSizeStats.update(cap(r.buf))
-		if !r.disableCache {
+	if !r.disableCache {
+		if r.oldBuf != nil {
+			for _, buf := range r.oldBuf {
+				mcache.Free(buf)
+			}
+		}
+		r.oldBuf = nil
+		if len(r.buf)-r.ri == 0 {
+			// release buf
+			r.maxSizeStats.update(cap(r.buf))
 			mcache.Free(r.buf)
+			r.buf = nil
+			r.ri = 0
+		} else {
+			n := copy(r.buf, r.buf[r.ri:])
+			r.buf = r.buf[:n]
+			r.ri = 0
 		}
-		r.buf = nil
 	} else {
-		n := copy(r.buf, r.buf[r.ri:])
-		r.buf = r.buf[:n]
+		r.oldBuf = nil
+		if len(r.buf)-r.ri == 0 {
+			r.buf = nil
+			r.ri = 0
+		}
 	}
-	r.ri = 0
 	return nil
 }
 
@@ -330,6 +345,11 @@ func (w *DefaultWriter) Flush() (err error) {
 	w.maxSizeStats.update(cap(w.buf))
 	if !w.disableCache {
 		mcache.Free(w.buf)
+		if w.oldBuf != nil {
+			for _, buf := range w.oldBuf {
+				mcache.Free(buf)
+			}
+		}
 	}
 	w.buf = nil
 	w.oldBuf = nil