feat(pbuf): add USRDAT

README.md

@@ -3,16 +3,27 @@ Lightweight & Safe (buffer-writer | general object) pool.
 
 ## Quick Start
 ```go
-import (
-    "crypto/rand"
+package main
 
-    "github.com/fumiama/orbyte/pbuf"
+import (
+	"crypto/rand"
+	"io"
+
+	"github.com/fumiama/orbyte/pbuf"
 )
 
 func main() {
-    b := pbuf.NewBytes(1024) // Allocate Bytes from pool.
-    rand.Read(b.Bytes())     // Do sth.
-    b.KeepAlive()            // Mark as reachable.
-    // After that, b will be auto-reused on GC.
+	buf := pbuf.NewBuffer(nil) // Allocate Buffer from pool.
+	buf.P(func(buf *pbuf.Buffer) {
+		io.CopyN(buf, rand.Reader, 4096) // Do sth.
+	})
+	// After that, buf will be auto-reused on GC.
+
+	b := pbuf.NewBytes(1024) // Allocate Bytes from pool.
+	b.V(func(b []byte) {
+		rand.Read(b) // Do sth.
+	})
+	// After that, b will be auto-reused on GC.
+
 }
 ```