Initial QSfera import

Server/vendor/github.com/nats-io/nats-server/v2/server/elastic/elastic.go

@@ -0,0 +1,60 @@
+// Copyright 2025 The NATS Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package elastic
+
+import (
+	"weak"
+)
+
+func Make[T any](ptr *T) *Pointer[T] {
+	return &Pointer[T]{
+		weak: weak.Make(ptr),
+	}
+}
+
+type Pointer[T any] struct {
+	weak   weak.Pointer[T]
+	strong *T
+}
+
+func (e *Pointer[T]) Set(ptr *T) {
+	e.weak = weak.Make(ptr)
+	if e.strong != nil {
+		e.strong = ptr
+	}
+}
+
+func (e *Pointer[T]) Strengthen() {
+	if e == nil || e.strong != nil {
+		return
+	}
+	e.strong = e.weak.Value()
+}
+
+func (e *Pointer[T]) Weaken() {
+	if e == nil || e.strong == nil {
+		return
+	}
+	e.strong = nil
+}
+
+func (e *Pointer[T]) Value() *T {
+	if e == nil {
+		return nil
+	}
+	if e.strong != nil {
+		return e.strong
+	}
+	return e.weak.Value()
+}