Less IndexReaderFactory instances on StoreStatement

so only created if they are actually used, when caller needs an
IndexReader or LabelScanReader.

community/kernel/src/main/java/org/neo4j/kernel/impl/api/KernelStatement.java

@@ -33,7 +33,6 @@
 import org.neo4j.kernel.api.txstate.TxStateHolder;
 import org.neo4j.kernel.impl.locking.Locks;
 import org.neo4j.storageengine.api.StorageStatement;
-import org.neo4j.storageengine.api.schema.LabelScanReader;
 
 public class KernelStatement implements TxStateHolder, Statement
 {
@@ -42,12 +41,12 @@ public class KernelStatement implements TxStateHolder, Statement
     private final StorageStatement storeStatement;
     private final KernelTransactionImplementation transaction;
     private final OperationsFacade facade;
-    private LabelScanReader labelScanReader;
     private int referenceCount;
     private boolean closed;
 
-    public KernelStatement( KernelTransactionImplementation transaction, TxStateHolder txStateHolder,
-                            Locks.Client locks, StatementOperationParts operations, StorageStatement storeStatement, Procedures procedures )
+    public KernelStatement( KernelTransactionImplementation transaction,
+            TxStateHolder txStateHolder, Locks.Client locks,
+            StatementOperationParts operations, StorageStatement storeStatement, Procedures procedures )
     {
         this.transaction = transaction;
         this.locks = locks;
@@ -155,12 +154,6 @@ final void forceClose()
     private void cleanupResources()
     {
         storeStatement.close();
-
-        if ( null != labelScanReader )
-        {
-            labelScanReader.close();
-        }
-
         transaction.releaseStatement( this );
     }
 

community/kernel/src/main/java/org/neo4j/kernel/impl/api/store/StoreStatement.java

@@ -58,18 +58,19 @@ public class StoreStatement implements StorageStatement
     private final NeoStores neoStores;
     private final NodeStore nodeStore;
     private final RelationshipStore relationshipStore;
-    private final IndexReaderFactory indexReaderFactory;
-    private final Supplier<LabelScanReader> labelScanReaderSupplier;
+    private final Supplier<IndexReaderFactory> indexReaderFactorySupplier;
+    private IndexReaderFactory indexReaderFactory;
+    private final Supplier<LabelScanReader> labelScanStore;
     private LabelScanReader labelScanReader;
     private boolean closed;
 
     public StoreStatement( final NeoStores neoStores, final LockService lockService,
-            IndexReaderFactory indexReaderFactory,
+            Supplier<IndexReaderFactory> indexReaderFactory,
             Supplier<LabelScanReader> labelScanReaderSupplier )
     {
         this.neoStores = neoStores;
-        this.indexReaderFactory = indexReaderFactory;
-        this.labelScanReaderSupplier = labelScanReaderSupplier;
+        this.indexReaderFactorySupplier = indexReaderFactory;
+        this.labelScanStore = labelScanReaderSupplier;
         this.nodeStore = neoStores.getNodeStore();
         this.relationshipStore = neoStores.getRelationshipStore();
 
@@ -155,7 +156,10 @@ public Cursor<RelationshipItem> relationshipsGetAllCursor()
     public void close()
     {
         assert !closed;
-        indexReaderFactory.close();
+        if ( indexReaderFactory != null )
+        {
+            indexReaderFactory.close();
+        }
         if ( labelScanReader != null )
         {
             labelScanReader.close();
@@ -209,22 +213,25 @@ protected boolean fetchNext()
     @Override
     public LabelScanReader getLabelScanReader()
     {
-        if ( labelScanReader == null )
-        {
-            labelScanReader = labelScanReaderSupplier.get();
-        }
-        return labelScanReader;
+        return labelScanReader != null ?
+                labelScanReader : (labelScanReader = labelScanStore.get());
+    }
+
+    private IndexReaderFactory indexReaderFactory()
+    {
+        return indexReaderFactory != null ?
+                indexReaderFactory : (indexReaderFactory = indexReaderFactorySupplier.get());
     }
 
     @Override
     public IndexReader getIndexReader( IndexDescriptor descriptor ) throws IndexNotFoundKernelException
     {
-        return indexReaderFactory.newReader( descriptor );
+        return indexReaderFactory().newReader( descriptor );
     }
 
     @Override
     public IndexReader getFreshIndexReader( IndexDescriptor descriptor ) throws IndexNotFoundKernelException
     {
-        return indexReaderFactory.newUnCachedReader( descriptor );
+        return indexReaderFactory().newUnCachedReader( descriptor );
     }
 }

community/kernel/src/main/java/org/neo4j/kernel/impl/storageengine/impl/recordstorage/RecordStorageEngine.java

@@ -106,7 +106,6 @@
 import org.neo4j.storageengine.api.StoreReadLayer;
 import org.neo4j.storageengine.api.TransactionApplicationMode;
 import org.neo4j.storageengine.api.lock.ResourceLocker;
-import org.neo4j.storageengine.api.schema.LabelScanReader;
 import org.neo4j.storageengine.api.schema.SchemaRule;
 import org.neo4j.storageengine.api.txstate.ReadableTransactionState;
 import org.neo4j.storageengine.api.txstate.TxStateVisitor;
@@ -218,6 +217,7 @@ public RecordStorageEngine(
                     schemaStorage, neoStores, indexingService,
                     storeStatementSupplier( neoStores, config, lockService ) );
             storeLayer = new CacheLayer( diskLayer, schemaCache );
+
             legacyIndexApplierLookup = new LegacyIndexApplierLookup.Direct( legacyIndexProviderLookup );
 
             labelScanStoreSync = new WorkSync<>( labelScanStore::newWriter );
@@ -248,11 +248,12 @@ private Supplier<StorageStatement> storeStatementSupplier(
     {
         final LockService currentLockService =
                 config.get( use_read_locks_on_property_reads ) ? lockService : NO_LOCK_SERVICE;
-        final Supplier<LabelScanReader> labelScanReaderSupplier = labelScanStore::newReader;
+        final Supplier<IndexReaderFactory> indexReaderFactory = () -> {
+            return new IndexReaderFactory.Caching( indexingService );
+        };
 
         return () -> {
-            return new StoreStatement( neoStores, currentLockService,
-                    new IndexReaderFactory.Caching( indexingService ), labelScanReaderSupplier );
+            return new StoreStatement( neoStores, currentLockService, indexReaderFactory, labelScanStore::newReader );
         };
     }
 

community/kernel/src/test/java/org/neo4j/kernel/impl/api/KernelStatementTest.java

@@ -37,7 +37,7 @@ public void shouldThrowTerminateExceptionWhenTransactionTerminated() throws Exce
         when( transaction.shouldBeTerminated() ).thenReturn( true );
 
         KernelStatement statement = new KernelStatement(
-            transaction, null, null, null, null, new Procedures() );
+            transaction, null, null, null, null, null );
 
         statement.readOperations().nodeExists( 0 );
     }

community/kernel/src/test/java/org/neo4j/kernel/impl/api/KernelTransactionsTest.java

@@ -24,6 +24,7 @@
 import org.mockito.stubbing.Answer;
 
 import java.util.Collection;
+import java.util.function.Supplier;
 
 import org.neo4j.kernel.api.KernelTransaction;
 import org.neo4j.kernel.api.exceptions.TransactionFailureException;
@@ -209,7 +210,7 @@ private static KernelTransactions newKernelTransactions( TransactionCommitProces
         NeoStores neoStores = mock( NeoStores.class );
 
         StoreStatement storeStatement = new StoreStatement( neoStores, new ReentrantLockService(),
-                mock( IndexReaderFactory.class ), null );
+                mock( Supplier.class ), null );
         StoreReadLayer readLayer = mock( StoreReadLayer.class );
         when( readLayer.acquireStatement() ).thenReturn( storeStatement );
 

community/kernel/src/test/java/org/neo4j/kernel/impl/api/store/DiskLayerTest.java

@@ -48,7 +48,7 @@
 /**
  * Base class for disk layer tests, which test read-access to committed data.
  */
-public class DiskLayerTest
+public abstract class DiskLayerTest
 {
     @SuppressWarnings( "deprecation" )
     protected GraphDatabaseAPI db;

community/kernel/src/test/java/org/neo4j/kernel/impl/api/store/StoreStatementTest.java

@@ -21,8 +21,8 @@
 
 import org.junit.Test;
 
-import org.neo4j.kernel.api.labelscan.LabelScanStore;
-import org.neo4j.kernel.impl.api.IndexReaderFactory;
+import java.util.function.Supplier;
+
 import org.neo4j.kernel.impl.locking.LockService;
 import org.neo4j.kernel.impl.store.NeoStores;
 import org.neo4j.storageengine.api.schema.LabelScanReader;
@@ -39,13 +39,13 @@ public class StoreStatementTest
     public void shouldCloseOpenedLabelScanReader() throws Exception
     {
         // given
-        LabelScanStore scanStore = mock( LabelScanStore.class );
+        Supplier<LabelScanReader> scanStore = mock( Supplier.class );
         LabelScanReader scanReader = mock( LabelScanReader.class );
 
-        when( scanStore.newReader() ).thenReturn( scanReader );
+        when( scanStore.get() ).thenReturn( scanReader );
         StoreStatement statement = new StoreStatement(
                 mock( NeoStores.class ), LockService.NO_LOCK_SERVICE,
-                mock( IndexReaderFactory.class ), scanStore::newReader );
+                mock( Supplier.class ), scanStore );
 
         // when
         LabelScanReader actualReader = statement.getLabelScanReader();
@@ -57,7 +57,7 @@ public void shouldCloseOpenedLabelScanReader() throws Exception
         statement.close();
 
         // then
-        verify( scanStore ).newReader();
+        verify( scanStore ).get();
         verifyNoMoreInteractions( scanStore );
 
         verify( scanReader ).close();