Fix session management in manual trigger page

In ManualTriggerAction, session is always created if nothing.
It might be issue if session is closed before build.

This patch creates session once then reuse it.

Fix for JENKINS-19013

Task-Url: https://issues.jenkins-ci.org/browse/JENKINS-19013

src/main/java/com/sonyericsson/hudson/plugins/gerrit/trigger/hudsontrigger/actions/manual/ManualTriggerAction.java

@@ -37,13 +37,15 @@
 import com.sonyericsson.hudson.plugins.gerrit.trigger.events.ManualPatchsetCreated;
 import com.sonyericsson.hudson.plugins.gerrit.trigger.hudsontrigger.GerritTriggerParameters;
 import com.sonyericsson.hudson.plugins.gerrit.trigger.utils.StringUtil;
+
 import hudson.Extension;
 import hudson.model.Hudson;
 import hudson.model.ParameterValue;
 import hudson.model.RootAction;
 import hudson.security.Permission;
 import net.sf.json.JSONArray;
 import net.sf.json.JSONObject;
+
 import org.kohsuke.stapler.QueryParameter;
 import org.kohsuke.stapler.StaplerRequest;
 import org.kohsuke.stapler.StaplerResponse;
@@ -56,6 +58,8 @@
 import java.util.LinkedList;
 import java.util.List;
 
+import javax.servlet.http.HttpSession;
+
 import static com.sonyericsson.hudson.plugins.gerrit.trigger.utils.StringUtil.getPluginImageUrl;
 
 /**
@@ -283,7 +287,12 @@ public void doGerritSearch(@QueryParameter("queryString") final String queryStri
         @QueryParameter("selectedServer") final String selectedServer, StaplerRequest request,
                                StaplerResponse response) throws IOException {
 
-        request.getSession(true).setAttribute("selectedServer", selectedServer);
+        HttpSession session = request.getSession();
+        // Create session if nothing.
+        if (session == null) {
+            session = request.getSession(true);
+        }
+        session.setAttribute("selectedServer", selectedServer);
         if (!isServerEnabled(selectedServer)) {
             response.sendRedirect2(".");
             return;
@@ -293,20 +302,20 @@ public void doGerritSearch(@QueryParameter("queryString") final String queryStri
 
         if (config != null) {
             GerritQueryHandler handler = new GerritQueryHandler(config);
-            clearSessionData(request);
-            request.getSession(true).setAttribute("queryString", queryString);
+            clearSessionData(session);
+            session.setAttribute("queryString", queryString);
 
             try {
                 List<JSONObject> json = handler.queryJava(queryString, true, true, false);
-                request.getSession(true).setAttribute(SESSION_RESULT, json);
+                session.setAttribute(SESSION_RESULT, json);
                 //TODO Implement some smart default selection.
                 //That can notice that a specific revision is searched or that there is only one result etc.
             } catch (GerritQueryException gqe) {
                 logger.debug("Bad query. ", gqe);
-                request.getSession(true).setAttribute(SESSION_SEARCH_ERROR, gqe);
+                session.setAttribute(SESSION_SEARCH_ERROR, gqe);
             } catch (Exception ex) {
                 logger.warn("Could not query Gerrit for [" + queryString + "]", ex);
-                request.getSession(true).setAttribute(SESSION_SEARCH_ERROR, ex);
+                session.setAttribute(SESSION_SEARCH_ERROR, ex);
             }
             response.sendRedirect2(".");
         } else {
@@ -327,28 +336,37 @@ public void doGerritSearch(@QueryParameter("queryString") final String queryStri
     public void doBuild(@QueryParameter("selectedIds") String selectedIds, StaplerRequest request,
                         StaplerResponse response) throws IOException {
 
-        String selectedServer = (String)request.getSession().getAttribute("selectedServer");
+        HttpSession session = request.getSession();
+        if (session == null) {
+            logger.debug("Session alreay closed.");
+            session = request.getSession(true);
+            session.setAttribute(SESSION_BUILD_ERROR, Messages.ErrorSessionAlreadyClosed());
+            response.sendRedirect2(".");
+            return;
+        }
+
+        String selectedServer = (String)session.getAttribute("selectedServer");
         if (!isServerEnabled(selectedServer)) {
             response.sendRedirect2(".");
             return;
         }
         Hudson.getInstance().checkPermission(PluginImpl.MANUAL_TRIGGER);
 
-        request.getSession(true).removeAttribute(SESSION_BUILD_ERROR);
+        session.removeAttribute(SESSION_BUILD_ERROR);
         String[] selectedRows = null;
         if (selectedIds != null && selectedIds.length() > 0) {
             selectedRows = selectedIds.split("\\[\\]");
         }
         if (selectedRows == null || selectedRows.length <= 0) {
             logger.debug("No builds selected.");
-            request.getSession(true).setAttribute(SESSION_BUILD_ERROR, Messages.ErrorSelectSomethingToBuild());
+            session.setAttribute(SESSION_BUILD_ERROR, Messages.ErrorSelectSomethingToBuild());
             response.sendRedirect2(".");
         } else {
             logger.debug("Something to build.");
-            List<JSONObject> result = (List<JSONObject>)request.getSession(true).getAttribute(SESSION_RESULT);
+            List<JSONObject> result = (List<JSONObject>)session.getAttribute(SESSION_RESULT);
             TriggerMonitor monitor = new TriggerMonitor();
             logger.trace("Putting monitor into session.");
-            request.getSession(true).setAttribute(SESSION_TRIGGER_MONITOR, monitor);
+            session.setAttribute(SESSION_TRIGGER_MONITOR, monitor);
             logger.trace("Calling to index the search result.");
             HashMap<String, JSONObject> indexed = indexResult(result);
             logger.debug("Creating and triggering events.");
@@ -372,13 +390,13 @@ public void doBuild(@QueryParameter("selectedIds") String selectedIds, StaplerRe
     /**
      * Clears the HTTP session from search and manual-trigger related data.
      *
-     * @param request the request with the HTTP session.
+     * @param session the HTTP session.
      */
-    private void clearSessionData(StaplerRequest request) {
-        request.getSession(true).removeAttribute(SESSION_SEARCH_ERROR);
-        request.getSession(true).removeAttribute(SESSION_BUILD_ERROR);
-        request.getSession(true).removeAttribute(SESSION_RESULT);
-        request.getSession(true).removeAttribute(SESSION_TRIGGER_MONITOR);
+    private void clearSessionData(HttpSession session) {
+        session.removeAttribute(SESSION_SEARCH_ERROR);
+        session.removeAttribute(SESSION_BUILD_ERROR);
+        session.removeAttribute(SESSION_RESULT);
+        session.removeAttribute(SESSION_TRIGGER_MONITOR);
     }
 
     /**

src/main/resources/com/sonyericsson/hudson/plugins/gerrit/trigger/Messages.properties

@@ -74,6 +74,8 @@ ManualGerritTrigger=\
   Query and Trigger Gerrit Patches
 ErrorSelectSomethingToBuild=\
   Please select something to build.
+ErrorSessionAlreadyClosed=\
+  Session is already closed. Please search again.
 GerritPermissionGroup=\
   Gerrit
 ManualTriggerPermissionDescription=\

src/main/resources/com/sonyericsson/hudson/plugins/gerrit/trigger/Messages_ja.properties

@@ -74,6 +74,8 @@ ManualGerritTrigger=\
   Gerrit\u30d1\u30c3\u30c1\u306e\u30af\u30a8\u30ea\u3068\u30c8\u30ea\u30ac\u30fc
 ErrorSelectSomethingToBuild=\
   \u30d3\u30eb\u30c9\u3092\u9078\u629e\u3057\u3066\u304f\u3060\u3055\u3044
+ErrorSessionAlreadyClosed=\
+  \u30bb\u30c3\u30b7\u30e7\u30f3\u304c\u5207\u308c\u307e\u3057\u305f\u3002\u518d\u5ea6\u691c\u7d22\u3057\u3066\u304f\u3060\u3055\u3044
 GerritPermissionGroup=\
   Gerrit
 ManualTriggerPermissionDescription=\