# HG changeset patch
# Parent d1650bbc02cafaae8c1c6700875aebffbbe0a329
Bug #187469 - NullPointerException at org.netbeans.modules.dlight.management.api.DLightSession.prepareContext

diff --git a/dlight.management/src/org/netbeans/modules/dlight/management/api/DLightSession.java b/dlight.management/src/org/netbeans/modules/dlight/management/api/DLightSession.java
--- a/dlight.management/src/org/netbeans/modules/dlight/management/api/DLightSession.java
+++ b/dlight.management/src/org/netbeans/modules/dlight/management/api/DLightSession.java
@@ -734,6 +734,25 @@
                     context.addDLightTargetExecutionEnviromentProvider((DLightTarget.ExecutionEnvVariablesProvider) toolCollector);
                 }
 
+                /*
+                 * DataCollector usually acts as IndicatorDataProvider..
+                 * It could be that infrastructure cannot provide all needed
+                 * storages for the collector. This means that collector will
+                 * not be able to *store* any data, still it *may* be able to
+                 * act as an IndicatorDataProvider (with transient data).
+                 *
+                 * So do unconditional init with serviceInfoDataStorage.
+                 * This will give a chance for collector to at least provide
+                 * some information for Indicators...
+                 *
+                 * Note: It is collector's responsibility to handle the
+                 * situation when it was not initialized with DataStorages!
+                 *
+                 * Note: Collector *will* be notified about session start even
+                 * if it was not initialized with any DataStorage.
+                 *
+                 */
+
                 if (currentStorages != null && !currentStorages.isEmpty()) {
                     if (storages == null) {
                         storages = new ArrayList<DataStorage>();
@@ -745,9 +764,9 @@
                             storages.add(storage);
                         }
                     }
-                    toolCollector.init(serviceInfoDataStorage);
+
                     toolCollector.init(currentStorages, target);
-                    addDataFilterListener(toolCollector);
+
                     if (notAttachableDataCollector == null && !toolCollector.isAttachable()) {
                         notAttachableDataCollector = toolCollector;
                     }
@@ -756,6 +775,9 @@
                     log.log(Level.SEVERE, "Cannot find storage for collector {0}", toolCollector); // NOI18N
                 }
 
+                toolCollector.init(serviceInfoDataStorage);
+                addDataFilterListener(toolCollector);
+                
                 target.addTargetListener(toolCollector);
             }
             for (DataCollector<?> c : collectors) {
@@ -769,10 +791,8 @@
                 idp.init(serviceInfoDataStorage);
                 addDataFilterListener(idp);
             }
-
         }
 
-
         // at the end, initialize data filters (_temporarily_ here, as info
         // about filters is stored in target's info...
 
@@ -792,7 +812,6 @@
             ((SubstitutableTarget) target).substitute(notAttachableDataCollector.getCmd(), notAttachableDataCollector.getArgs());
         }
         return true;
-
     }
 
     /**
diff --git a/dlight.management/src/org/netbeans/modules/dlight/management/api/impl/DataStorageManager.java b/dlight.management/src/org/netbeans/modules/dlight/management/api/impl/DataStorageManager.java
--- a/dlight.management/src/org/netbeans/modules/dlight/management/api/impl/DataStorageManager.java
+++ b/dlight.management/src/org/netbeans/modules/dlight/management/api/impl/DataStorageManager.java
@@ -43,6 +43,7 @@
 
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -137,16 +138,38 @@
     }
 
     /**
-     *  Returns existing or  new instance of DataStorage
-     *  for requested schema (if it can be found within all available DataStorages)
+     * Returns existing or new instance of DataStorage
+     * for requested schema (if it can be found within all available DataStorages)
+     *
+     * If collector requires several storages and infrastructure cannot provide
+     * *all* of them, then an empty list is returned.
+     * So this method guarantees to return either fully loaded map or nothing.
+     *
      */
-    public synchronized  Map<DataStorageType, DataStorage> getDataStoragesFor(DLightSession session, DataCollector<?> collector) {
+    public synchronized Map<DataStorageType, DataStorage> getDataStoragesFor(DLightSession session, DataCollector<?> collector) {
+        if (session == null || collector == null) {
+            return Collections.<DataStorageType, DataStorage>emptyMap();
+        }
+
         Map<DataStorageType, DataStorage> result = new HashMap<DataStorageType, DataStorage>();
+
         for (DataStorageType type : collector.getRequiredDataStorageTypes()) {
-            result.put(type, getDataStorageFor(session, type, collector.getDataTablesMetadata()));
-        }
-        return result;
-    }
+            final DataStorage dataStorage = getDataStorageFor(session, type, collector.getDataTablesMetadata());
+
+            if (dataStorage == null) {
+                DLightLogger.getLogger(DataStorageManager.class).log(Level.INFO,
+                        "DataStorageManager.getDataStoragesFor(DLightSession, DataCollector<?>):" // NOI18N
+                        + " cannot find storage of type {0} [session={1}, collector={2}]." // NOI18N
+                        + " NO storages will be returned", // NOI18N
+                        new Object[]{type, session.getDisplayName(), collector.getName()});
+                return Collections.<DataStorageType, DataStorage>emptyMap();
+            }
+
+            result.put(type, dataStorage);
+         }
+
+         return result;
+     }
 
     public synchronized ServiceInfoDataStorage getServiceInfoDataStorageFor(String uniqueKey) {
         if (uniqueKey == null) {
@@ -484,9 +507,16 @@
                 DataStorage newStorage = storage.createStorage();
                 if (newStorage instanceof ProxyDataStorage) {
                     ProxyDataStorage proxyStorage = (ProxyDataStorage) newStorage;
-                    DataStorage backendStorage = getDataStorageFor(session, proxyStorage.getBackendDataStorageType(), proxyStorage.getBackendTablesMetadata());
+                    DataStorageType requiredStorageType = proxyStorage.getBackendDataStorageType();
+                    List<DataTableMetadata> requiredTables = proxyStorage.getBackendTablesMetadata();
+                    DataStorage backendStorage = getDataStorageFor(session, requiredStorageType, requiredTables);
+                    if (backendStorage == null) {
+                        // Means that required (for this proxy) storage cannot be found ...
+                        continue;
+                    }
                     proxyStorage.attachTo(backendStorage);
                 }
+
                 if (newStorage != null) {
                     newStorage.createTables(tableMetadatas);
                     if (activeSessionStorages == null) {
@@ -507,9 +537,15 @@
                     if (newStorage != null) {
                         if (newStorage instanceof ProxyDataStorage) {
                             ProxyDataStorage proxyStorage = (ProxyDataStorage) newStorage;
-                            DataStorage backendStorage = getDataStorageFor(session, proxyStorage.getBackendDataStorageType(), proxyStorage.getBackendTablesMetadata());
+                            DataStorageType requiredStorageType = proxyStorage.getBackendDataStorageType();
+                            List<DataTableMetadata> requiredTables = proxyStorage.getBackendTablesMetadata();
+                            DataStorage backendStorage = getDataStorageFor(session, requiredStorageType, requiredTables);
+                            if (backendStorage == null) {
+                                continue;
+                            }
                             proxyStorage.attachTo(backendStorage);
                         }
+
                         newStorage.createTables(tableMetadatas);
 
                         return newStorage;