ip/session monitoring

brouter-server/src/main/java/btools/server/IpAccessMonitor.java

@@ -0,0 +1,42 @@
+package btools.server;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class IpAccessMonitor 
+{
+  private static Object sync = new Object();
+  private static HashMap<String,Long> ipAccess = new HashMap<String,Long>();
+  private static long MAX_IDLE = 900000; // 15 minutes
+  
+  public static boolean touchIpAccess( String ip )
+  {
+    long t = System.currentTimeMillis();
+    synchronized( sync )
+    {
+      Long lastTime = ipAccess.get( ip );
+      if ( lastTime == null || t - lastTime.longValue() > MAX_IDLE )
+      {
+        ipAccess.put( ip, Long.valueOf( t ) );
+        cleanup(t);
+        return true; // new session detected
+      }
+      ipAccess.put( ip, Long.valueOf( t ) ); // touch existing session
+      return false;
+    }
+  }
+  
+  private static void cleanup( long t )
+  {
+    HashMap<String,Long> newMap = new HashMap<String,Long>(ipAccess.size());
+    for( Map.Entry<String,Long> e : ipAccess.entrySet() )
+    {
+      if ( t - e.getValue().longValue() <= MAX_IDLE )
+      {
+        newMap.put( e.getKey(), e.getValue() );
+      }
+    }
+    ipAccess = newMap;
+  }
+    
+}