Don't eagerly acquire distributed (SQL) locks (#10171)

src/Umbraco.Core/Collections/StackQueue.cs

@@ -0,0 +1,60 @@
+using System.Collections.Generic;
+
+namespace Umbraco.Core.Collections
+{
+    /// <summary>
+    /// Collection that can be both a queue and a stack.
+    /// </summary>
+    /// <typeparam name="T"></typeparam>
+    public class StackQueue<T>
+    {
+        private readonly LinkedList<T> _linkedList = new LinkedList<T>();
+
+        public void Clear()
+        {
+            _linkedList.Clear();
+        }
+
+        public void Push(T obj)
+        {
+            _linkedList.AddFirst(obj);
+        }
+
+        public void Enqueue(T obj)
+        {
+            _linkedList.AddFirst(obj);
+        }
+
+        public T Pop()
+        {
+            var obj = _linkedList.First.Value;
+            _linkedList.RemoveFirst();
+            return obj;
+        }
+
+        public T Dequeue()
+        {
+            var obj = _linkedList.Last.Value;
+            _linkedList.RemoveLast();
+            return obj;
+        }
+
+        public T PeekStack()
+        {
+            return _linkedList.First.Value;
+        }
+
+        public T PeekQueue()
+        {
+            return _linkedList.Last.Value;
+        }
+
+        public int Count
+        {
+            get
+            {
+                return _linkedList.Count;
+            }
+        }
+    }
+}