Ensure that IndexProxy returns the correct config

When performing recovery of a constraint index, the IndexProxy would
contain an IndexConfiguration object that said that it was a normal
index rather than a constraint index. This was because we did not want
the index to have to go through a tentative phase, but instead go to the
online state immediately.

This issue is solved by separating the configuration of the index from
whether it should flip through a tentative state or not.

There was nothing in the code that depended on this IndexConfiguration
object being correct after recovery, but it is possible that such code
could be written in the future...

community/kernel/src/main/java/org/neo4j/kernel/impl/api/index/IndexProxyCreator.java

@@ -59,15 +59,15 @@ public IndexProxyCreator( IndexSamplingConfig samplingConfig,
     public IndexProxy createPopulatingIndexProxy( final long ruleId,
                                                   final IndexDescriptor descriptor,
                                                   final SchemaIndexProvider.Descriptor providerDescriptor,
-                                                  final boolean constraint,
+                                                  IndexConfiguration config,
+                                                  final boolean flipToTentative,
                                                   final IndexingService.Monitor monitor,
                                                   final IndexPopulationJob populationJob ) throws IOException
     {
         final FlippableIndexProxy flipper = new FlippableIndexProxy();
 
         // TODO: This is here because there is a circular dependency from PopulatingIndexProxy to FlippableIndexProxy
         final String indexUserDescription = indexUserDescription( descriptor, providerDescriptor );
-        final IndexConfiguration config = IndexConfiguration.of( constraint );
         IndexPopulator populator = populatorFromProvider( providerDescriptor, ruleId, descriptor, config,
                 samplingConfig );
 
@@ -96,7 +96,7 @@ public IndexProxy createPopulatingIndexProxy( final long ruleId,
                     descriptor, config, onlineAccessorFromProvider( providerDescriptor, ruleId,
                     config, samplingConfig ), storeView, providerDescriptor, true
             );
-            if ( constraint )
+            if ( flipToTentative )
             {
                 return new TentativeConstraintIndexProxy( flipper, onlineProxy );
             }

community/kernel/src/main/java/org/neo4j/kernel/impl/api/index/IndexingService.java

@@ -41,6 +41,7 @@
 import org.neo4j.kernel.api.exceptions.index.IndexNotFoundKernelException;
 import org.neo4j.kernel.api.exceptions.index.IndexPopulationFailedKernelException;
 import org.neo4j.kernel.api.exceptions.schema.ConstraintVerificationFailedKernelException;
+import org.neo4j.kernel.api.index.IndexConfiguration;
 import org.neo4j.kernel.api.index.IndexDescriptor;
 import org.neo4j.kernel.api.index.IndexUpdater;
 import org.neo4j.kernel.api.index.InternalIndexState;
@@ -210,8 +211,18 @@ public void init()
                     break;
                 case POPULATING:
                     // The database was shut down during population, or a crash has occurred, or some other sad thing.
-                    indexProxy = indexProxyCreator
-                            .createRecoveringIndexProxy( descriptor, providerDescriptor, constraint );
+                    if ( constraint && indexRule.getOwningConstraint() == null )
+                    {
+                        // don't bother rebuilding if we are going to throw the index away anyhow
+                        indexProxy = indexProxyCreator.createFailedIndexProxy(
+                                indexId, descriptor, providerDescriptor, constraint,
+                                failure( "Constraint for index was not committed." ) );
+                    }
+                    else
+                    {
+                        indexProxy = indexProxyCreator
+                                .createRecoveringIndexProxy( descriptor, providerDescriptor, constraint );
+                    }
                     break;
                 case FAILED:
                     IndexPopulationFailure failure = failure( provider.getPopulationFailure( indexId ) );
@@ -269,17 +280,16 @@ public void start() throws Exception
             for ( Map.Entry<Long,RebuildingIndexDescriptor> entry : rebuildingDescriptors.entrySet() )
             {
                 long indexId = entry.getKey();
-                RebuildingIndexDescriptor descriptors = entry.getValue();
-
-                /*
-                 * Passing in "false" for unique here may seem surprising, and.. well, yes, it is, I was surprised too.
-                 * However, it is actually perfectly safe, because whenever we have constraint indexes here, they will
-                 * be in a state where they didn't finish populating, and despite the fact that we re-create them here,
-                 * they will get dropped as soon as recovery is completed by the constraint system.
-                 */
+                RebuildingIndexDescriptor descriptor = entry.getValue();
+
                 IndexProxy proxy = indexProxyCreator.createPopulatingIndexProxy(
-                        indexId, descriptors.getIndexDescriptor(), descriptors.getProviderDescriptor(), false,
-                        monitor, populationJob );
+                        indexId,
+                        descriptor.getIndexDescriptor(),
+                        descriptor.getProviderDescriptor(),
+                        descriptor.getConfiguration(),
+                        false, // never pass through a tentative online state during recovery
+                        monitor,
+                        populationJob );
                 proxy.start();
                 indexMap.putIndexProxy( indexId, proxy );
             }
@@ -524,7 +534,8 @@ public void createIndexes( IndexRule... rules ) throws IOException
             {
                 populationJob = populationJob == null ? newIndexPopulationJob() : populationJob;
                 index = indexProxyCreator.createPopulatingIndexProxy(
-                        ruleId, descriptor, providerDescriptor, constraint, monitor, populationJob );
+                        ruleId, descriptor, providerDescriptor, IndexConfiguration.of( constraint ), constraint,
+                        monitor, populationJob );
                 index.start();
             }
             else