1 files changed, 109 insertions, 0 deletions
diff --git a/mcs/class/Managed.Windows.Forms/System.Windows.Forms/XEventQueue.cs b/mcs/class/Managed.Windows.Forms/System.Windows.Forms/XEventQueue.cs
new file mode 100644
index 00000000000..313bafd8b05
--- /dev/null
+++ b/mcs/class/Managed.Windows.Forms/System.Windows.Forms/XEventQueue.cs
@@ -0,0 +1,109 @@
+//
+// System.Windows.Forms.XEventQueue
+//
+// Author(s):
+//  Jackson Harper (jackson@ximian.com)
+//
+// Copyright (C) Novell, Inc (http://www.novell.com)
+//
+
+using System;
+using System.Threading;
+using System.Collections;
+
+
+namespace System.Windows.Forms {
+
+	internal class XEventQueue {
+
+		private XQueue xqueue;
+		private XQueue lqueue;	// Events inserted from threads other then the main X thread
+
+		private static readonly int InitialXEventSize = 100;
+		private static readonly int InitialLXEventSize = 10;
+
+		public XEventQueue ()
+		{
+			xqueue = new XQueue (InitialXEventSize);
+			lqueue = new XQueue (InitialLXEventSize);
+		}
+
+		public int Count {
+			get {
+				lock (lqueue) {
+					return xqueue.Count + lqueue.Count;
+				}
+			}
+		}
+
+		public void Enqueue (XEvent xevent)
+		{
+			xqueue.Enqueue (xevent);
+		}
+
+		public void EnqueueLocked (XEvent xevent)
+		{
+			lock (lqueue) {
+				lqueue.Enqueue (xevent);
+			}
+		}
+
+		public XEvent Dequeue ()
+		{
+			if (xqueue.Count == 0) {
+				lock (lqueue) {
+					return lqueue.Dequeue ();
+				}
+			}
+			return xqueue.Dequeue ();
+		}
+
+		private class XQueue {
+
+			private XEvent [] xevents;
+			private int head;
+			private int tail;
+			private int size;
+			
+			public XQueue (int size)
+			{
+				xevents = new XEvent [size];
+			}
+
+			public int Count {
+				get { return size; }
+			}
+
+			public void Enqueue (XEvent xevent)
+			{
+				if (size == xevents.Length)
+					Grow ();
+				
+				xevents [tail] = xevent;
+				tail = (tail + 1) % xevents.Length;
+				size++;
+			}
+
+			public XEvent Dequeue ()
+			{
+				if (size < 1)
+					throw new Exception ("Attempt to dequeue empty queue.");
+				XEvent res = xevents [head];
+				head = (head + 1) % xevents.Length;
+				size--;
+				return res;
+			}
+
+			private void Grow ()
+			{
+				int newcap = (xevents.Length * 2);
+				XEvent [] na = new XEvent [newcap];
+				xevents.CopyTo (na, 0);
+				xevents = na;
+				head = 0;
+				tail = head + size;
+			}
+		}
+	}
+}
+