# HG changeset patch
# User Ivo Smits <Ivo@UCIS.nl>
# Date 1381846974 -7200
# Node ID b7bc27c6734eece4cff8a9466e8fbfa217bc624a
# Parent  abe0d55a22012061b2f2eb3d74292e28a806e978
Added WorkQueue class

diff -r abe0d55a2201 -r b7bc27c6734e UCIS.Core.csproj
--- a/UCIS.Core.csproj	Tue Oct 15 16:19:45 2013 +0200
+++ b/UCIS.Core.csproj	Tue Oct 15 16:22:54 2013 +0200
@@ -175,6 +175,7 @@
     <Compile Include="Util\PrebufferingStream.cs" />
     <Compile Include="Util\QueuedPacketStream.cs" />
     <Compile Include="Util\TapeArchive.cs" />
+    <Compile Include="Util\WorkQueue.cs" />
     <Compile Include="VNCServer\IFramebuffer.cs" />
     <Compile Include="VNCServer\VNCServer.cs" />
     <Compile Include="Windows\ServiceManager.cs" />
diff -r abe0d55a2201 -r b7bc27c6734e Util/WorkQueue.cs
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Util/WorkQueue.cs	Tue Oct 15 16:22:54 2013 +0200
@@ -0,0 +1,97 @@
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Windows.Forms;
+using SysThreadPool = System.Threading.ThreadPool;
+
+namespace UCIS.Util {
+	public class WorkQueue : WorkQueue<MethodInvoker> {
+		public WorkQueue() : base(Handler) { }
+		private static void Handler(MethodInvoker item) { item(); }
+	}
+	public class WorkQueue<TWork> : IDisposable {
+		Queue<TWork> queue = new Queue<TWork>();
+		Action<TWork> callback = null;
+		int maxIdleWorkers = 0;
+		int maxWorkers = 1;
+		int idleWorkers = 0;
+		int workers = 0;
+
+		public Boolean UseFrameworkThreadpool { get; set; }
+
+		public WorkQueue(Action<TWork> callback) {
+			this.callback = callback;
+			UseFrameworkThreadpool = true;
+		}
+		public void Dispose() {
+			maxWorkers = 0;
+			lock (queue) Monitor.PulseAll(queue);
+		}
+
+		public int MaxIdleWorkers {
+			get { return maxIdleWorkers; }
+			set {
+				maxIdleWorkers = value;
+				lock (queue) Monitor.PulseAll(queue);
+			}
+		}
+		public int MaxWorkers {
+			get { return maxWorkers; }
+			set {
+				maxWorkers = value;
+				lock (queue) Monitor.PulseAll(queue);
+			}
+		}
+		public int TotalWorkers { get { return workers; } }
+		public int IdleWorkers { get { return idleWorkers; } }
+
+		public void Enqueue(TWork item) {
+			lock (queue) {
+				queue.Enqueue(item);
+				Monitor.Pulse(queue);
+				if (workers < maxWorkers && idleWorkers == 0) StartWorker();
+			}
+		}
+		public void Clear() { lock (queue) queue.Clear(); }
+		public int Count { get { lock (queue) return queue.Count; } }
+
+		private void StartWorker() {
+			lock (queue) {
+				if (workers >= maxWorkers) return;
+				if (UseFrameworkThreadpool) {
+					SysThreadPool.QueueUserWorkItem(Worker);
+				} else {
+					(new Thread(Worker)).Start();
+				}
+				workers++;
+			}
+		}
+		private void RaiseEvent(Action<WorkQueue<TWork>> callback) {
+			if (callback != null) callback(this);
+		}
+		private void Worker(Object state) {
+			while (true) {
+				TWork item;
+				lock (queue) {
+					if (workers >= maxWorkers) {
+						workers--;
+						break;
+					}
+					if (queue.Count == 0) {
+						if (idleWorkers >= maxIdleWorkers) {
+							workers--;
+							queue.TrimExcess();
+							break;
+						}
+						idleWorkers++;
+						Monitor.Wait(queue);
+						idleWorkers--;
+						if (queue.Count == 0) continue;
+					}
+					item = queue.Dequeue();
+				}
+				callback(item);
+			}
+		}
+	}
+}