Add SymbolCache

Cache/SymbolCache.cs

@@ -0,0 +1,88 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading;
+using MarketData.MarketDataModel;
+using MarketData.Helper;
+using MarketData;
+using MarketData.Utils;
+using System.Windows.Media.Animation;
+using MarketData.DataAccess;
+
+namespace TradeBlotter.Cache
+{
+  public class SymbolCache : IDisposable
+  {
+    private List<String> symbolCache=new List<String>();
+    private Object thisLock=new Object();
+    private Thread cacheMonitorThread=null;
+    private volatile bool threadRun=true;
+    private int cacheRefreshAfter=60000;        // Invalidate cache after
+    private static SymbolCache symbolCacheInstance=null;
+
+    private SymbolCache()
+    {
+      cacheMonitorThread=new Thread(new ThreadStart(ThreadProc));
+      cacheMonitorThread.Start();
+    }
+    public static SymbolCache GetInstance()
+    {
+      lock(typeof(SymbolCache))
+      {
+        if(null==symbolCacheInstance) symbolCacheInstance=new SymbolCache();
+        return symbolCacheInstance;
+      }
+    }
+    public void Clear()
+    {
+      lock(thisLock)
+      {
+        symbolCache=new List<string>();
+      }
+    }
+    public void Dispose()
+    {
+      lock(thisLock)
+      {
+			  if(null==symbolCacheInstance || false==threadRun)return;
+        threadRun=false;
+        if(null!=cacheMonitorThread)
+        {
+          MDTrace.WriteLine(LogLevel.DEBUG,String.Format("[SymbolCache:Dispose]Thread state is {0}.  Joining main thread...",Utility.ThreadStateToString(cacheMonitorThread)));
+          cacheMonitorThread.Join(5000);
+          cacheMonitorThread=null;
+          MDTrace.WriteLine(LogLevel.DEBUG,"[SymbolCache:Dispose] End.");
+        }
+        symbolCacheInstance=null;
+      }
+    }
+
+    public List<String> GetSymbols()
+    {
+      lock(this)
+      {
+        if(0==symbolCache.Count)symbolCache=PricingDA.GetSymbols();
+        return symbolCache;
+      }
+    }
+    private void ThreadProc()
+    {
+      int quantums=0;
+      int quantumInterval=1000;
+      while(threadRun)
+      {
+        Thread.Sleep(quantumInterval);
+        quantums+=quantumInterval;
+        if(quantums>cacheRefreshAfter)
+        {
+          quantums=0;
+          lock(thisLock)
+          {
+            symbolCache.Clear();
+          }
+        }
+      }
+    }
+  }
+}