diff --git a/Implab/Implab.csproj b/Implab/Implab.csproj
--- a/Implab/Implab.csproj
+++ b/Implab/Implab.csproj
@@ -155,6 +155,7 @@
     <Compile Include="AbstractPromise.cs" />
     <Compile Include="Promise.cs" />
     <Compile Include="PromiseTransientException.cs" />
+    <Compile Include="Parallels\Signal.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
   <ItemGroup />
diff --git a/Implab/Parallels/AsyncQueue.cs b/Implab/Parallels/AsyncQueue.cs
--- a/Implab/Parallels/AsyncQueue.cs
+++ b/Implab/Parallels/AsyncQueue.cs
@@ -454,7 +454,7 @@ namespace Implab.Parallels {
             } while(true);
         }
             
-        T[] ReadChunks(Chunk chunk, object last) {
+        static T[] ReadChunks(Chunk chunk, object last) {
             var result = new List<T>();
             var buffer = new T[DEFAULT_CHUNK_SIZE];
             int actual;
diff --git a/Implab/Parallels/Signal.cs b/Implab/Parallels/Signal.cs
new file mode 100644
--- /dev/null
+++ b/Implab/Parallels/Signal.cs
@@ -0,0 +1,31 @@
+using System;
+using System.Threading;
+
+namespace Implab.Parallels {
+    /// <summary>
+    /// Implements simple signalling logic using <see cref="Monitor.PulseAll(object)"/>.
+    /// </summary>
+    public class Signal {
+        readonly object m_lock = new object();
+        bool m_state;
+
+        public void Set() {
+            lock(m_lock) {
+                m_state = true;
+                Monitor.PulseAll(m_lock);
+            }
+        }
+
+        public void Wait() {
+            lock (m_lock)
+                if (!m_state)
+                    Monitor.Wait(m_lock);
+        }
+
+        public bool Wait(int timeout) {
+            lock (m_lock)
+                return m_state || Monitor.Wait(m_lock, timeout);
+        }
+    }
+}
+
diff --git a/Implab/Safe.cs b/Implab/Safe.cs
--- a/Implab/Safe.cs
+++ b/Implab/Safe.cs
@@ -36,13 +36,26 @@ namespace Implab
                 throw new ArgumentOutOfRangeException(paramName);
         }
 
-        public static void Dispose(params IDisposable[] objects)
-        {
-            foreach(var d in objects)
+        public static void Dispose(params IDisposable[] objects) {
+            foreach (var d in objects)
                 if (d != null)
                     d.Dispose();
         }
 
+        public static void Dispose(params object[] objects) {
+            foreach (var obj in objects) {
+                var d = obj as IDisposable;
+                if (d != null)
+                    d.Dispose();
+            }
+        }
+
+        public static void Dispose(object obj) {
+            var d = obj as IDisposable;
+            if (d != null)
+                d.Dispose();
+        }
+
         [DebuggerStepThrough]
         public static IPromise<T> InvokePromise<T>(Func<T> action) {
             ArgumentNotNull(action, "action");