Retaining context in APEX Engine based on policies received in PdpUpdate

Change-Id: I73fad5bf76ed6b4979f5ab76013f204ea82da30b
Issue-ID: POLICY-2215
Signed-off-by: a.sreekumar <ajith.sreekumar@est.tech>

2 files changed, 34 insertions, 10 deletions

diff --git a/services/services-onappf/src/main/java/org/onap/policy/apex/services/onappf/handler/ApexEngineHandler.java b/services/services-onappf/src/main/java/org/onap/policy/apex/services/onappf/handler/ApexEngineHandler.java
index 1953939b7..6a5bb17ff 100644
--- a/services/services-onappf/src/main/java/org/onap/policy/apex/services/onappf/handler/ApexEngineHandler.java
+++ b/services/services-onappf/src/main/java/org/onap/policy/apex/services/onappf/handler/ApexEngineHandler.java
@@ -56,6 +56,35 @@ public class ApexEngineHandler {
      * @throws ApexStarterException if the apex engine instantiation failed using the policies passed
      */
     public ApexEngineHandler(List<ToscaPolicy> policies)  throws ApexStarterException {
+        Map<ToscaPolicyIdentifier, String[]> policyArgsMap = createPolicyArgsMap(policies);
+        LOGGER.debug("Starting apex engine.");
+        try {
+            apexMain = new ApexMain(policyArgsMap);
+        } catch (ApexException e) {
+            throw new ApexStarterException(e);
+        }
+    }
+
+    /**
+     * Updates the Apex Engine with the policy model created from new list of policies.
+     *
+     * @param policies the list of policies
+     * @throws ApexStarterException if the apex engine instantiation failed using the policies passed
+     */
+    public void updateApexEngine(List<ToscaPolicy> policies) throws ApexStarterException {
+        if (null == apexMain || !apexMain.isAlive()) {
+            throw new ApexStarterException("Apex Engine not initialized.");
+        }
+        Map<ToscaPolicyIdentifier, String[]> policyArgsMap = createPolicyArgsMap(policies);
+        try {
+            apexMain.updateModel(policyArgsMap);
+        } catch (ApexException e) {
+            throw new ApexStarterException(e);
+        }
+    }
+
+    private Map<ToscaPolicyIdentifier, String[]> createPolicyArgsMap(List<ToscaPolicy> policies)
+        throws ApexStarterException {
         Map<ToscaPolicyIdentifier, String[]> policyArgsMap = new LinkedHashMap<>();
         for (ToscaPolicy policy : policies) {
             Object properties = policy.getProperties().get("content");
@@ -78,13 +107,7 @@ public class ApexEngineHandler {
             final String[] apexArgs = { "-c", apexConfigFilePath, "-m", modelFilePath };
             policyArgsMap.put(policy.getIdentifier(), apexArgs);
         }
-
-        LOGGER.debug("Starting apex engine.");
-        try {
-            apexMain = new ApexMain(policyArgsMap);
-        } catch (ApexException e) {
-            throw new ApexStarterException(e);
-        }
+        return policyArgsMap;
     }
 
     /**
diff --git a/services/services-onappf/src/main/java/org/onap/policy/apex/services/onappf/handler/PdpUpdateMessageHandler.java b/services/services-onappf/src/main/java/org/onap/policy/apex/services/onappf/handler/PdpUpdateMessageHandler.java
index ecc0bec21..33ac81f5d 100644
--- a/services/services-onappf/src/main/java/org/onap/policy/apex/services/onappf/handler/PdpUpdateMessageHandler.java
+++ b/services/services-onappf/src/main/java/org/onap/policy/apex/services/onappf/handler/PdpUpdateMessageHandler.java
@@ -162,10 +162,11 @@ public class PdpUpdateMessageHandler {
         PdpResponseDetails pdpResponseDetails = null;
         try {
             if (null != apexEngineHandler && apexEngineHandler.isApexEngineRunning()) {
-                apexEngineHandler.shutdown();
+                apexEngineHandler.updateApexEngine(pdpUpdateMsg.getPolicies());
+            } else {
+                apexEngineHandler = new ApexEngineHandler(pdpUpdateMsg.getPolicies());
+                Registry.registerOrReplace(ApexStarterConstants.REG_APEX_ENGINE_HANDLER, apexEngineHandler);
             }
-            apexEngineHandler = new ApexEngineHandler(pdpUpdateMsg.getPolicies());
-            Registry.registerOrReplace(ApexStarterConstants.REG_APEX_ENGINE_HANDLER, apexEngineHandler);
             if (apexEngineHandler.isApexEngineRunning()) {
                 List<ToscaPolicyIdentifier> runningPolicies = apexEngineHandler.getRunningPolicies();
                 if (new HashSet<>(runningPolicies)