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>

3 files changed, 27 insertions, 12 deletions

diff --git a/core/core-engine/src/main/java/org/onap/policy/apex/core/engine/context/ApexInternalContext.java b/core/core-engine/src/main/java/org/onap/policy/apex/core/engine/context/ApexInternalContext.java
index 3d6a72451..0589e8311 100644
--- a/core/core-engine/src/main/java/org/onap/policy/apex/core/engine/context/ApexInternalContext.java
+++ b/core/core-engine/src/main/java/org/onap/policy/apex/core/engine/context/ApexInternalContext.java
@@ -1,6 +1,7 @@
 /*-
  * ============LICENSE_START=======================================================
  *  Copyright (C) 2016-2018 Ericsson. All rights reserved.
+ *  Modifications Copyright (C) 2019 Nordix Foundation.
  * ================================================================================
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,14 +22,12 @@
 package org.onap.policy.apex.core.engine.context;
 
 import com.google.common.collect.Maps;
-
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.NavigableMap;
 import java.util.Set;
 import java.util.TreeMap;
-
 import org.onap.policy.apex.context.ContextAlbum;
 import org.onap.policy.apex.context.ContextException;
 import org.onap.policy.apex.context.Distributor;
@@ -113,13 +112,24 @@ public class ApexInternalContext implements AxConceptGetter<ContextAlbum> {
      * in the new model.
      *
      * @param newPolicyModel The new incoming Apex model to use for context
+     * @param isSubsequentInstance if the current worker instance being updated is not the first one
      * @throws ContextException On errors on context setting
      */
-    public void update(final AxPolicyModel newPolicyModel) throws ContextException {
+    public void update(final AxPolicyModel newPolicyModel, boolean isSubsequentInstance) throws ContextException {
         if (newPolicyModel == null) {
             throw new ContextException("internal context update failed, supplied model is null");
         }
-
+        // context is shared between all the engine instances
+        // during model update context album only needs to be updated for the first instance.
+        // remaining engine instances can just copy the context
+        if (isSubsequentInstance) {
+            contextAlbums.clear();
+            for (AxArtifactKey contextAlbumKey : ModelService.getModel(AxContextAlbums.class).getAlbumsMap().keySet()) {
+                contextAlbums.put(contextAlbumKey, contextDistributor.createContextAlbum(contextAlbumKey));
+            }
+            key = newPolicyModel.getKey();
+            return;
+        }
         // Get the differences between the existing context and the new context
         final KeyedMapDifference<AxArtifactKey, AxContextAlbum> contextDifference =
                 new ContextComparer().compare(ModelService.getModel(AxContextAlbums.class), newPolicyModel.getAlbums());
@@ -143,11 +153,11 @@ public class ApexInternalContext implements AxConceptGetter<ContextAlbum> {
                         + newContextAlbum.getItemSchema().getId() + "\" on incoming model");
             }
         }
-        
+
         // Remove maps that are no longer used
         for (final Entry<AxArtifactKey, AxContextAlbum> removedContextAlbumEntry : contextDifference.getLeftOnly()
                 .entrySet()) {
-            contextDistributor.removeContextAlbum(removedContextAlbumEntry.getValue());
+            contextDistributor.removeContextAlbum(removedContextAlbumEntry.getKey());
             contextAlbums.remove(removedContextAlbumEntry.getKey());
         }
 
@@ -156,6 +166,11 @@ public class ApexInternalContext implements AxConceptGetter<ContextAlbum> {
 
         // Set up the new context albums
         for (final AxArtifactKey contextAlbumKey : contextDifference.getRightOnly().keySet()) {
+            // In case if a context album is part of previous and current model, but needs to be cleared
+            // for example, due to a major version change
+            if (contextAlbums.containsKey(contextAlbumKey)) {
+                contextDistributor.removeContextAlbum(contextAlbumKey);
+            }
             contextAlbums.put(contextAlbumKey, contextDistributor.createContextAlbum(contextAlbumKey));
         }
 
diff --git a/core/core-engine/src/main/java/org/onap/policy/apex/core/engine/engine/ApexEngine.java b/core/core-engine/src/main/java/org/onap/policy/apex/core/engine/engine/ApexEngine.java
index 2c5167d1b..4c4166380 100644
--- a/core/core-engine/src/main/java/org/onap/policy/apex/core/engine/engine/ApexEngine.java
+++ b/core/core-engine/src/main/java/org/onap/policy/apex/core/engine/engine/ApexEngine.java
@@ -1,6 +1,7 @@
 /*-
  * ============LICENSE_START=======================================================
  *  Copyright (C) 2016-2018 Ericsson. All rights reserved.
+ *  Modifications Copyright (C) 2019 Nordix Foundation.
  * ================================================================================
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,7 +22,6 @@
 package org.onap.policy.apex.core.engine.engine;
 
 import java.util.Map;
-
 import org.onap.policy.apex.core.engine.event.EnEvent;
 import org.onap.policy.apex.model.basicmodel.concepts.ApexException;
 import org.onap.policy.apex.model.basicmodel.concepts.AxArtifactKey;
@@ -49,9 +49,10 @@ public interface ApexEngine {
      * transferred if there is common context in the old and new models.
      *
      * @param apexModel the apex model
+     * @param isSubsequentInstance if the current worker instance being updated is not the first one
      * @throws ApexException on model update errors
      */
-    void updateModel(AxPolicyModel apexModel) throws ApexException;
+    void updateModel(AxPolicyModel apexModel, boolean isSubsequentInstance) throws ApexException;
 
     /**
      * Starts an Apex engine so that it can receive events.
diff --git a/core/core-engine/src/main/java/org/onap/policy/apex/core/engine/engine/impl/ApexEngineImpl.java b/core/core-engine/src/main/java/org/onap/policy/apex/core/engine/engine/impl/ApexEngineImpl.java
index 87ce1230e..9cbd2050f 100644
--- a/core/core-engine/src/main/java/org/onap/policy/apex/core/engine/engine/impl/ApexEngineImpl.java
+++ b/core/core-engine/src/main/java/org/onap/policy/apex/core/engine/engine/impl/ApexEngineImpl.java
@@ -26,7 +26,6 @@ import static org.onap.policy.common.utils.validation.Assertions.argumentNotNull
 import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.Map.Entry;
-
 import org.onap.policy.apex.context.ContextAlbum;
 import org.onap.policy.apex.context.ContextException;
 import org.onap.policy.apex.core.engine.context.ApexInternalContext;
@@ -105,7 +104,7 @@ public class ApexEngineImpl implements ApexEngine {
      * {@inheritDoc}.
      */
     @Override
-    public void updateModel(final AxPolicyModel apexModel) throws ApexException {
+    public void updateModel(final AxPolicyModel apexModel, final boolean isSubsequentInstance) throws ApexException {
         if (apexModel != null) {
             LOGGER.entry("updateModel()->" + key.getId() + ", apexPolicyModel=" + apexModel.getKey().getId());
         } else {
@@ -125,8 +124,8 @@ public class ApexEngineImpl implements ApexEngine {
                 /// New internal context
                 internalContext = new ApexInternalContext(apexModel);
             } else {
-                // Exiting internal context which must be updated
-                internalContext.update(apexModel);
+                // Existing internal context which must be updated
+                internalContext.update(apexModel, isSubsequentInstance);
             }
         } catch (final ContextException e) {
             LOGGER.warn(UPDATE_MODEL + key.getId() + ", error setting the context for engine \"" + key.getId() + "\"",