Collapses Layout classes a bit further

Since they no longer need to be split into unique/non-unique

community/kernel/src/main/java/org/neo4j/kernel/impl/index/schema/DateLayout.java

@@ -21,24 +21,15 @@
 
 import org.neo4j.index.internal.gbptree.Layout;
 import org.neo4j.io.pagecache.PageCursor;
-import org.neo4j.kernel.api.schema.index.SchemaIndexDescriptor;
 
 /**
  * {@link Layout} for dates.
  */
-class DateLayout extends BaseLayout<DateSchemaKey>
+class DateLayout extends SchemaLayout<DateSchemaKey>
 {
-    public static Layout<DateSchemaKey,NativeSchemaValue> of( SchemaIndexDescriptor descriptor )
+    DateLayout()
     {
-        return descriptor.type() == SchemaIndexDescriptor.Type.UNIQUE ? DateLayout.UNIQUE : DateLayout.NON_UNIQUE;
-    }
-
-    private static DateLayout UNIQUE = new DateLayout( "UTda", 0, 1 );
-    private static DateLayout NON_UNIQUE = new DateLayout( "NTda", 0, 1 );
-
-    private DateLayout( String layoutName, int majorVersion, int minorVersion )
-    {
-        super( layoutName, majorVersion, minorVersion );
+        super( "Tda", 0, 1 );
     }
 
     @Override

community/kernel/src/main/java/org/neo4j/kernel/impl/index/schema/DateSchemaKey.java

@@ -27,7 +27,7 @@
 /**
  * Includes value and entity id (to be able to handle non-unique values). A value can be any {@link DateValue}.
  */
-class DateSchemaKey extends ComparableNativeSchemaKey<DateSchemaKey>
+class DateSchemaKey extends NativeSchemaKey<DateSchemaKey>
 {
     static final int SIZE =
             Long.BYTES + /* epochDay */

community/kernel/src/main/java/org/neo4j/kernel/impl/index/schema/DurationLayout.java

@@ -21,24 +21,15 @@
 
 import org.neo4j.index.internal.gbptree.Layout;
 import org.neo4j.io.pagecache.PageCursor;
-import org.neo4j.kernel.api.schema.index.SchemaIndexDescriptor;
 
 /**
  * {@link Layout} for durations.
  */
-class DurationLayout extends BaseLayout<DurationSchemaKey>
+class DurationLayout extends SchemaLayout<DurationSchemaKey>
 {
-    public static Layout<DurationSchemaKey,NativeSchemaValue> of( SchemaIndexDescriptor descriptor )
+    DurationLayout()
     {
-        return descriptor.type() == SchemaIndexDescriptor.Type.UNIQUE ? DurationLayout.UNIQUE : DurationLayout.NON_UNIQUE;
-    }
-
-    private static DurationLayout UNIQUE = new DurationLayout( "UTdu", 0, 1 );
-    private static DurationLayout NON_UNIQUE = new DurationLayout( "NTdu", 0, 1 );
-
-    private DurationLayout( String layoutName, int majorVersion, int minorVersion )
-    {
-        super( layoutName, majorVersion, minorVersion );
+        super( "Tdu", 0, 1 );
     }
 
     @Override

community/kernel/src/main/java/org/neo4j/kernel/impl/index/schema/DurationSchemaKey.java

@@ -30,7 +30,7 @@
  * Durations are tricky, because exactly how long a duration is depends on the start date. We therefore sort them by
  * average total time in seconds, but keep the original months and days so we can reconstruct the value.
  */
-class DurationSchemaKey extends ComparableNativeSchemaKey<DurationSchemaKey>
+class DurationSchemaKey extends NativeSchemaKey<DurationSchemaKey>
 {
     /**
      * An average month is 30 days, 10 hours and 30 minutes.

community/kernel/src/main/java/org/neo4j/kernel/impl/index/schema/LocalDateTimeLayout.java

@@ -21,24 +21,15 @@
 
 import org.neo4j.index.internal.gbptree.Layout;
 import org.neo4j.io.pagecache.PageCursor;
-import org.neo4j.kernel.api.schema.index.SchemaIndexDescriptor;
 
 /**
  * {@link Layout} for local date times.
  */
-class LocalDateTimeLayout extends BaseLayout<LocalDateTimeSchemaKey>
+class LocalDateTimeLayout extends SchemaLayout<LocalDateTimeSchemaKey>
 {
-    public static Layout<LocalDateTimeSchemaKey,NativeSchemaValue> of( SchemaIndexDescriptor descriptor )
+    LocalDateTimeLayout()
     {
-        return descriptor.type() == SchemaIndexDescriptor.Type.UNIQUE ? LocalDateTimeLayout.UNIQUE : LocalDateTimeLayout.NON_UNIQUE;
-    }
-
-    private static LocalDateTimeLayout UNIQUE = new LocalDateTimeLayout( "UTld", 0, 1 );
-    private static LocalDateTimeLayout NON_UNIQUE = new LocalDateTimeLayout( "NTld", 0, 1 );
-
-    private LocalDateTimeLayout( String layoutName, int majorVersion, int minorVersion )
-    {
-        super( layoutName, majorVersion, minorVersion );
+        super( "Tld", 0, 1 );
     }
 
     @Override

community/kernel/src/main/java/org/neo4j/kernel/impl/index/schema/LocalDateTimeSchemaKey.java

@@ -27,7 +27,7 @@
 /**
  * Includes value and entity id (to be able to handle non-unique values). A value can be any {@link LocalDateTimeValue}.
  */
-class LocalDateTimeSchemaKey extends ComparableNativeSchemaKey<LocalDateTimeSchemaKey>
+class LocalDateTimeSchemaKey extends NativeSchemaKey<LocalDateTimeSchemaKey>
 {
     static final int SIZE =
             Long.BYTES +    /* epochSecond */

community/kernel/src/main/java/org/neo4j/kernel/impl/index/schema/LocalTimeLayout.java

@@ -21,24 +21,15 @@
 
 import org.neo4j.index.internal.gbptree.Layout;
 import org.neo4j.io.pagecache.PageCursor;
-import org.neo4j.kernel.api.schema.index.SchemaIndexDescriptor;
 
 /**
  * {@link Layout} for local times.
  */
-class LocalTimeLayout extends BaseLayout<LocalTimeSchemaKey>
+class LocalTimeLayout extends SchemaLayout<LocalTimeSchemaKey>
 {
-    public static Layout<LocalTimeSchemaKey,NativeSchemaValue> of( SchemaIndexDescriptor descriptor )
+    LocalTimeLayout()
     {
-        return descriptor.type() == SchemaIndexDescriptor.Type.UNIQUE ? LocalTimeLayout.UNIQUE : LocalTimeLayout.NON_UNIQUE;
-    }
-
-    private static LocalTimeLayout UNIQUE = new LocalTimeLayout( "UTlt", 0, 1 );
-    private static LocalTimeLayout NON_UNIQUE = new LocalTimeLayout( "NTlt", 0, 1 );
-
-    private LocalTimeLayout( String layoutName, int majorVersion, int minorVersion )
-    {
-        super( layoutName, majorVersion, minorVersion );
+        super( "Tlt", 0, 1 );
     }
 
     @Override

community/kernel/src/main/java/org/neo4j/kernel/impl/index/schema/LocalTimeSchemaKey.java

@@ -27,7 +27,7 @@
 /**
  * Includes value and entity id (to be able to handle non-unique values). A value can be any {@link LocalTimeValue}.
  */
-class LocalTimeSchemaKey extends ComparableNativeSchemaKey<LocalTimeSchemaKey>
+class LocalTimeSchemaKey extends NativeSchemaKey<LocalTimeSchemaKey>
 {
     static final int SIZE =
             Long.BYTES + /* nanoOfDay */

community/kernel/src/main/java/org/neo4j/kernel/impl/index/schema/NativeIndexProvider.java

@@ -50,8 +50,8 @@ abstract class NativeIndexProvider<KEY extends NativeSchemaKey,VALUE extends Nat
     protected final RecoveryCleanupWorkCollector recoveryCleanupWorkCollector;
     protected final boolean readOnly;
 
-    protected NativeIndexProvider( Descriptor descriptor, int priority, Factory directoryStructureFactory, PageCache pageCache,
-                                   FileSystemAbstraction fs, Monitor monitor, RecoveryCleanupWorkCollector recoveryCleanupWorkCollector, boolean readOnly )
+    protected NativeIndexProvider( Descriptor descriptor, int priority, Factory directoryStructureFactory, PageCache pageCache, FileSystemAbstraction fs,
+            Monitor monitor, RecoveryCleanupWorkCollector recoveryCleanupWorkCollector, boolean readOnly )
     {
         super( descriptor, priority, directoryStructureFactory );
         this.pageCache = pageCache;
@@ -61,6 +61,8 @@ protected NativeIndexProvider( Descriptor descriptor, int priority, Factory dire
         this.readOnly = readOnly;
     }
 
+    abstract Layout<KEY,VALUE> layout( SchemaIndexDescriptor descriptor );
+
     @Override
     public IndexPopulator getPopulator( long indexId, SchemaIndexDescriptor descriptor, IndexSamplingConfig samplingConfig )
     {
@@ -70,8 +72,7 @@ public IndexPopulator getPopulator( long indexId, SchemaIndexDescriptor descript
         }
 
         File storeFile = nativeIndexFileFromIndexId( indexId );
-        Layout<KEY,VALUE> layout = layout( descriptor );
-        return newIndexPopulator( storeFile, layout, descriptor, indexId, samplingConfig );
+        return newIndexPopulator( storeFile, layout( descriptor ), descriptor, indexId, samplingConfig );
     }
 
     protected abstract IndexPopulator newIndexPopulator( File storeFile, Layout<KEY, VALUE> layout, SchemaIndexDescriptor descriptor, long indexId,
@@ -82,8 +83,7 @@ public IndexAccessor getOnlineAccessor(
             long indexId, SchemaIndexDescriptor descriptor, IndexSamplingConfig samplingConfig ) throws IOException
     {
         File storeFile = nativeIndexFileFromIndexId( indexId );
-        Layout<KEY,VALUE> layout = layout( descriptor );
-        return newIndexAccessor( storeFile, layout, descriptor, indexId, samplingConfig );
+        return newIndexAccessor( storeFile, layout( descriptor ), descriptor, indexId, samplingConfig );
     }
 
     protected abstract IndexAccessor newIndexAccessor( File storeFile, Layout<KEY,VALUE> layout, SchemaIndexDescriptor descriptor,
@@ -129,23 +129,6 @@ public StoreMigrationParticipant storeMigrationParticipant( FileSystemAbstractio
         return StoreMigrationParticipant.NOT_PARTICIPATING;
     }
 
-    private Layout<KEY,VALUE> layout( SchemaIndexDescriptor descriptor )
-    {
-        switch ( descriptor.type() )
-        {
-        case GENERAL:
-            return layoutNonUnique();
-        case UNIQUE:
-            return layoutUnique();
-        default:
-            throw new UnsupportedOperationException( "Can not create index accessor of type " + descriptor.type() );
-        }
-    }
-
-    protected abstract Layout<KEY,VALUE> layoutUnique();
-
-    protected abstract Layout<KEY,VALUE> layoutNonUnique();
-
     private File nativeIndexFileFromIndexId( long indexId )
     {
         return new File( directoryStructure().directoryForIndex( indexId ), indexFileName( indexId ) );

community/kernel/src/main/java/org/neo4j/kernel/impl/index/schema/NativeSchemaKey.java

@@ -28,7 +28,7 @@
  * This is the abstraction of what NativeSchemaIndex with friends need from a schema key.
  * Note that it says nothing about how keys are compared, serialized, read, written, etc. That is the job of Layout.
  */
-abstract class NativeSchemaKey extends ValueWriter.Adapter<RuntimeException>
+abstract class NativeSchemaKey<SELF extends NativeSchemaKey> extends ValueWriter.Adapter<RuntimeException>
 {
     static final boolean DEFAULT_COMPARE_ID = true;
 
@@ -109,4 +109,13 @@ final void initAsHighest()
     }
 
     abstract void initValueAsHighest();
+
+    /**
+     * Compares the value of this key to that of another key.
+     * This method is expected to be called in scenarios where inconsistent reads may happen (and later retried).
+     *
+     * @param other the key to compare to.
+     * @return comparison against the {@code other} key.
+     */
+    abstract int compareValueTo( SELF other );
 }

community/kernel/src/main/java/org/neo4j/kernel/impl/index/schema/NumberIndexProvider.java

@@ -54,15 +54,18 @@ public NumberIndexProvider( PageCache pageCache, FileSystemAbstraction fs,
     }
 
     @Override
-    protected NumberLayoutUnique layoutUnique()
+    Layout<NumberSchemaKey,NativeSchemaValue> layout( SchemaIndexDescriptor descriptor )
     {
-        return new NumberLayoutUnique();
-    }
-
-    @Override
-    protected NumberLayoutNonUnique layoutNonUnique()
-    {
-        return new NumberLayoutNonUnique();
+        // split like this due to legacy reasons, there are old stores out there with these different identifiers
+        switch ( descriptor.type() )
+        {
+        case GENERAL:
+            return new NumberLayoutNonUnique();
+        case UNIQUE:
+            return new NumberLayoutUnique();
+        default:
+            throw new IllegalArgumentException( "Unknown index type " + descriptor.type() );
+        }
     }
 
     @Override

community/kernel/src/main/java/org/neo4j/kernel/impl/index/schema/NumberLayout.java

@@ -27,9 +27,9 @@
  */
 abstract class NumberLayout extends SchemaLayout<NumberSchemaKey>
 {
-    NumberLayout( long identifier, int majorVersion, int minorVersion )
+    NumberLayout( String identifierName, int majorVersion, int minorVersion )
     {
-        super( identifier, majorVersion, minorVersion );
+        super( identifierName, majorVersion, minorVersion );
     }
 
     @Override