Fixed HibernnateOptimisticLockingExceptions for startproject and team…

src/main/java/org/telscenter/sail/webapp/presentation/web/controllers/student/TeamSignInController.java

@@ -38,6 +38,7 @@

import net.sf.sail.webapp.presentation.web.controllers.ControllerUtil;

import net.sf.sail.webapp.service.UserService;

+import org.springframework.orm.hibernate3.HibernateOptimisticLockingFailureException;

import org.springframework.validation.BindException;

import org.springframework.web.servlet.ModelAndView;

import org.springframework.web.servlet.mvc.SimpleFormController;

@@ -230,7 +231,19 @@ protected synchronized ModelAndView onSubmit(HttpServletRequest request,

ModelAndView modelAndView = new ModelAndView();

/* update run statistics */

-    this.runService.updateRunStatistics(run.getId());

+    int maxLoop = 30;  // to ensure that the following while loop gets run at most this many times.

+    int currentLoopIndex = 0;

+    while(currentLoopIndex < maxLoop) {

+      try {

+        this.runService.updateRunStatistics(run.getId());

+      } catch (HibernateOptimisticLockingFailureException holfe) {

+        // multiple students tried to update run statistics at the same time, resulting in the exception. try again.

+        currentLoopIndex++;

+        continue;

+      }

+      // if it reaches here, it means that HibernateOptimisticLockingFailureException was not thrown, so we can exit the loop.

+      break;

+    }

LaunchProjectParameters launchProjectParameters = new LaunchProjectParameters();

launchProjectParameters.setRun(run);