add refcount file

Author: Noam Preil

arrow/memory/refcount.go

@@ -0,0 +1,41 @@
+package memory
+
+import (
+	"sync/atomic"
+
+	"github.com/apache/arrow-go/v18/arrow/internal/debug"
+)
+
+type Refcount struct {
+	count        atomic.Int64
+	Dependencies []**Refcount
+	Buffers []**Buffer
+	Additional func()
+}
+
+func (r *Refcount) Retain() {
+	r.count.Add(1)
+}
+
+func (r *Refcount) Release() {
+	new := r.count.Add(-1)
+	if new == 0 {
+		for _, buffer := range r.Buffers {
+			(*buffer).Release()
+			*buffer = nil
+		}
+		for _, dependency := range r.Dependencies {
+			(*dependency).Release()
+			*dependency = nil
+		}
+		r.Buffers = nil
+		r.Dependencies = nil
+		if r.Additional != nil {
+			r.Additional()
+		}
+	} else if new < 0 {
+		// This branch can be optimized out when !debug
+		// This avoids an unnecessary extra Load
+		debug.Assert(false, "too many releases")
+	}
+}