From 3f40ab9b7f3e0718622fc8a3bd8f66afe421a3cc Mon Sep 17 00:00:00 2001
From: Radovan Synek <rsynek@redhat.com>
Date: Sun, 23 Jun 2019 21:53:41 +0200
Subject: [PATCH] PLANNER-1540 Check if solver got lost from http session

---
 .../webexamples/cloudbalancing/CloudBalancingWebAction.java  | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/optaplanner-webexamples/src/main/java/org/optaplanner/webexamples/cloudbalancing/CloudBalancingWebAction.java b/optaplanner-webexamples/src/main/java/org/optaplanner/webexamples/cloudbalancing/CloudBalancingWebAction.java
index 69409af540..ab28d4006c 100644
--- a/optaplanner-webexamples/src/main/java/org/optaplanner/webexamples/cloudbalancing/CloudBalancingWebAction.java
+++ b/optaplanner-webexamples/src/main/java/org/optaplanner/webexamples/cloudbalancing/CloudBalancingWebAction.java
@@ -46,6 +46,11 @@ public void setup(HttpSession session) {
 
     public void solve(final HttpSession session) {
         final Solver<CloudBalance> solver = (Solver<CloudBalance>) session.getAttribute(CloudBalancingSessionAttributeName.SOLVER);
+        if (solver == null) {
+            throw new IllegalStateException("Solver (" + solver + ") cannot be null. As the Solver is not serializable, "
+                                                    + "it might have got lost during a passivation.");
+        }
+
         final CloudBalance unsolvedSolution = (CloudBalance) session.getAttribute(CloudBalancingSessionAttributeName.SHOWN_SOLUTION);
 
         solver.addEventListener(new SolverEventListener<CloudBalance>() {