Unify queue handling in processing queue

CHANGELIST.md

@@ -47,6 +47,7 @@
 - Ensure dumping commands are tested
 - Add tests around default values
 - Increase sleep time in queue
+- Unify queue handling in processing queue
 
 ### 3.2.4 (2024-11-24)
 

MPF.Frontend/OldDotNet.cs

@@ -0,0 +1,45 @@
+#if NET20 || NET35
+using System.Collections;
+using System.Collections.Generic;
+
+namespace MPF.Frontend
+{
+    internal interface IReadOnlyCollection<T> : IEnumerable<T>
+    {
+        int Count { get; }
+    }
+
+    internal sealed class ConcurrentQueue<T> : IReadOnlyCollection<T>
+    {
+        private Queue<T> _queue = new Queue<T>();
+
+        private object _lock = new object();
+
+        public int Count => _queue.Count;
+
+        public void Enqueue(T item)
+        {
+            lock (_lock)
+            {
+                _queue.Enqueue(item);
+            }
+        }
+
+        public bool TryDequeue(out T item)
+        {
+            lock (_lock)
+            {
+                item = default(T)!;
+                if (_queue.Count == 0)
+                    return false;
+
+                item = _queue.Dequeue();
+                return true;
+            }
+        }
+
+        IEnumerator<T> IEnumerable<T>.GetEnumerator() => _queue.GetEnumerator();
+        IEnumerator IEnumerable.GetEnumerator() => _queue.GetEnumerator();
+    }
+}
+#endif

MPF.Frontend/ProcessingQueue.cs

@@ -1,7 +1,5 @@
 using System;
-#if NET20 || NET35
-using System.Collections.Generic;
-#else
+#if NET40_OR_GREATER || NETCOREAPP
 using System.Collections.Concurrent;
 #endif
 using System.Threading;
@@ -14,11 +12,7 @@ namespace MPF.Frontend
         /// <summary>
         /// Internal queue to hold data to process
         /// </summary>
-#if NET20 || NET35
-        private readonly Queue<T> _internalQueue;
-#else
         private readonly ConcurrentQueue<T> _internalQueue;
-#endif
 
         /// <summary>
         /// Custom processing step for dequeued data
@@ -77,17 +71,12 @@ namespace MPF.Frontend
                     continue;
                 }
 
-#if NET20 || NET35
-                // Get the next item from the queue and invoke the lambda, if possible
-                _customProcessing?.Invoke(_internalQueue.Dequeue());
-#else
                 // Get the next item from the queue
                 if (!_internalQueue.TryDequeue(out var nextItem))
                     continue;
 
                 // Invoke the lambda, if possible
                 _customProcessing?.Invoke(nextItem);
-#endif
             }
         }
     }