Add DynamicPool

ln.types.csproj

@@ -97,6 +97,7 @@
     <Compile Include="odb\ng\index\IndexPath.cs" />
     <Compile Include="PathHelper.cs" />
     <Compile Include="threads\ThreadHelpers.cs" />
+    <Compile Include="threads\DynamicPool.cs" />
     <Compile Include="threads\PoolThread.cs" />
   </ItemGroup>
   <ItemGroup>

threads/DynamicPool.cs

@@ -0,0 +1,61 @@
+using System;
+using System.Threading;
+namespace ln.types.threads
+{
+    public class DynamicPool : Pool
+    {
+        public int Timeout { get; set; }
+
+        public DynamicPool() :this(Environment.ProcessorCount){}
+        public DynamicPool(int maxPoolSize)
+            :base(maxPoolSize)
+        {
+            Timeout = 15000;
+        }
+
+        public override void Start()
+        {
+            if ((State == PoolState.RUN) || (State == PoolState.SHUTDOWN))
+                throw new NotSupportedException("Pool can only be started if not running");
+
+            State = PoolState.RUN;
+        }
+
+        protected override PoolJob WaitForJob(PoolThread poolThread)
+        {
+            if (State == PoolState.RUN)
+            {
+                lock (waitingThreads)
+                {
+                    PoolJob poolJob = Dequeue(poolThread);
+                    if (poolJob != null)
+                        return poolJob;
+
+                    waitingThreads.Add(poolThread);
+                    Monitor.Wait(waitingThreads, Timeout);
+                    waitingThreads.Remove(poolThread);
+
+                    poolJob = Dequeue(poolThread);
+                    return poolJob;
+                }
+            }
+            return null;
+        }
+
+        protected override void PulseWaitingThread()
+        {
+            lock (waitingThreads)
+            {
+                if (waitingThreads.Count > 0)
+                {
+                    Monitor.Pulse(waitingThreads);
+                }
+                else if (CurrentPoolSize < PoolSize)
+                {
+                    CreatePoolThread();
+                }
+            }
+        }
+
+    }
+}