make Quality of Service Servlet available to prioritize requests from local host

This assigns priorities to incoming requests. Higher priority numbers are served before lower.
(disabled by default in defaults/web.xml, 
uncomment or copy entry to DATA/Settings/web.xml)

defaults/web.xml

@@ -9,6 +9,20 @@
     <display-name>YaCy</display-name>
     <description>Decentralized Web Search</description>
 
+    <!-- Quality of Service filter to prioritize service for requests from localhost -->
+    <!-- uncomment this to activate
+    <filter>
+        <description>Quality of Service Filter, to prioritize requests from localhost</description>
+        <filter-name>YaCyQoSFilter</filter-name>
+        <filter-class>net.yacy.http.servlets.YaCyQoSFilter</filter-class>
+        <async-supported>true</async-supported>
+    </filter>
+    <filter-mapping>
+        <filter-name>YaCyQoSFilter</filter-name>
+        <url-pattern>/*</url-pattern>
+    </filter-mapping>
+    -->
+    
     <!-- Standard YaCy Servlets -->
     
     <!-- Default servlet for all YaCy output
@@ -17,6 +31,7 @@
     <servlet>
         <servlet-name>YaCyDefaultServlet</servlet-name>
         <servlet-class>net.yacy.http.servlets.YaCyDefaultServlet</servlet-class>
+        <async-supported>true</async-supported>
     </servlet>
     <servlet-mapping>
         <servlet-name>YaCyDefaultServlet</servlet-name>

source/net/yacy/http/Jetty9HttpServerImpl.java

@@ -135,9 +135,10 @@ public class Jetty9HttpServerImpl implements YaCyHttpServer {
         // as fundamental component leave this hardcoded, other servlets may be defined in web.xml only
         ServletHolder sholder = new ServletHolder(YaCyDefaultServlet.class);
         sholder.setInitParameter("resourceBase", htrootpath);
+        sholder.setAsyncSupported(true); // needed for YaCyQoSFilter
         //sholder.setInitParameter("welcomeFile", "index.html"); // default is index.html, welcome.html
-        htrootContext.addServlet(sholder,"/*");    
+        htrootContext.addServlet(sholder, "/*");
-        
+
         // -----------------------------------------------------------------------------
         // here we set and map the mandatory servlets, needed for typical YaCy operation
         // to make sure they are available even if removed in individual web.xml

source/net/yacy/http/servlets/YaCyQoSFilter.java

@@ -0,0 +1,49 @@
+/**
+ *  YaCyQoSFilter
+ *  Copyright 2015 by Burkhard Buelte
+ *  First released 26.04.2015 at http://yacy.net
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Lesser General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2.1 of the License, or (at your option) any later version.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public License
+ *  along with this program in the file lgpl21.txt
+ *  If not, see <http://www.gnu.org/licenses/>.
+ */
+package net.yacy.http.servlets;
+
+import javax.servlet.ServletRequest;
+import net.yacy.cora.protocol.Domains;
+import org.eclipse.jetty.servlets.QoSFilter;
+
+/**
+ * Quality of Service Filter based on Jetty QosFilter
+ * to prioritize requests from localhost
+ * The intention is to improve the responsivness of web/user interface for the local admin
+ * To activate this filter uncomment the predefined filter setting in web.xml
+ */
+public class YaCyQoSFilter extends QoSFilter {
+
+    /**
+     * set priority for localhost to max
+     * @param request
+     * @return priority
+     */
+    @Override
+    protected int getPriority(ServletRequest request) {
+        if (request.getServerName().equalsIgnoreCase(Domains.LOCALHOST)) {
+            return 10; // highest priority for "localhost"
+        } else if (Domains.isLocalhost(request.getRemoteHost())) {
+            return 9;
+        } else {
+            return super.getPriority(request); // standard: authenticated = 2, other = 1 or 0
+        }
+    }
+}