Basic implementation of native schema string indexing layer

Much of the changes in here are about making test classes and utilities
generic to value type as well as copy type-specific indexing code from
number schema index classes.

Here's also a basic, non-optimized implementation of the string schema
index accessor, string layout and friends which focuses on getting the
functionality in place first and foremost.

community/kernel-api/src/main/java/org/neo4j/internal/kernel/api/IndexQuery.java

@@ -514,6 +514,11 @@ public String from()
             return (String)from.asObject();
         }
 
+        public Value fromAsValue()
+        {
+            return from;
+        }
+
         public boolean fromInclusive()
         {
             return fromInclusive;
@@ -524,6 +529,11 @@ public String to()
             return (String)to.asObject();
         }
 
+        public Value toAsValue()
+        {
+            return to;
+        }
+
         public boolean toInclusive()
         {
             return toInclusive;

community/kernel/pom.xml

@@ -254,6 +254,13 @@ the relevant Commercial Agreement.
       <type>test-jar</type>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>org.neo4j</groupId>
+      <artifactId>neo4j-values</artifactId>
+      <version>${project.version}</version>
+      <type>test-jar</type>
+      <scope>test</scope>
+    </dependency>
     <dependency>
       <groupId>org.apache.commons</groupId>
       <artifactId>commons-compress</artifactId>

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

@@ -0,0 +1,105 @@
+/*
+ * Copyright (c) 2002-2018 "Neo Technology,"
+ * Network Engine for Objects in Lund AB [http://neotechnology.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * Neo4j is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.neo4j.kernel.impl.index.schema;
+
+import org.neo4j.index.internal.gbptree.Layout;
+import org.neo4j.io.pagecache.PageCursor;
+
+import static java.lang.String.format;
+
+import static org.neo4j.kernel.impl.index.schema.StringSchemaKey.ENTITY_ID_SIZE;
+
+/**
+ * {@link Layout} for numbers where numbers doesn't need to be unique.
+ */
+abstract class StringLayout extends Layout.Adapter<StringSchemaKey,NativeSchemaValue>
+{
+    @Override
+    public StringSchemaKey newKey()
+    {
+        return new StringSchemaKey();
+    }
+
+    @Override
+    public StringSchemaKey copyKey( StringSchemaKey key, StringSchemaKey into )
+    {
+        // TODO when we have reuse of byte[] take that into consideration here too
+        into.bytes = key.bytes.clone();
+        into.setEntityId( key.getEntityId() );
+        into.setEntityIdIsSpecialTieBreaker( key.getEntityIdIsSpecialTieBreaker() );
+        return into;
+    }
+
+    @Override
+    public NativeSchemaValue newValue()
+    {
+        return NativeSchemaValue.INSTANCE;
+    }
+
+    @Override
+    public int keySize( StringSchemaKey key )
+    {
+        return key.size();
+    }
+
+    @Override
+    public int valueSize( NativeSchemaValue value )
+    {
+        return NativeSchemaValue.SIZE;
+    }
+
+    @Override
+    public void writeKey( PageCursor cursor, StringSchemaKey key )
+    {
+        cursor.putLong( key.getEntityId() );
+        cursor.putBytes( key.bytes );
+    }
+
+    @Override
+    public void writeValue( PageCursor cursor, NativeSchemaValue value )
+    {
+    }
+
+    @Override
+    public void readKey( PageCursor cursor, StringSchemaKey into, int keySize )
+    {
+        // TODO consider reusing byte[] instances somehow
+        into.setEntityId( cursor.getLong() );
+        into.bytes = new byte[keySize - ENTITY_ID_SIZE];
+        cursor.getBytes( into.bytes );
+    }
+
+    @Override
+    public void readValue( PageCursor cursor, NativeSchemaValue into, int valueSize )
+    {
+    }
+
+    @Override
+    public boolean fixedSize()
+    {
+        return false;
+    }
+
+    @Override
+    public String toString()
+    {
+        return format( "%s[version:%d.%d, identifier:%d]", getClass().getSimpleName(), majorVersion(), minorVersion(), identifier() );
+    }
+}

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

@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2002-2018 "Neo Technology,"
+ * Network Engine for Objects in Lund AB [http://neotechnology.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * Neo4j is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.neo4j.kernel.impl.index.schema;
+
+import org.neo4j.index.internal.gbptree.Layout;
+
+public class StringLayoutNonUnique extends StringLayout
+{
+    private static final String IDENTIFIER_NAME = "NUSI";
+    static final int MAJOR_VERSION = 0;
+    static final int MINOR_VERSION = 1;
+    static long IDENTIFIER = Layout.namedIdentifier( IDENTIFIER_NAME, NativeSchemaValue.SIZE );
+
+    @Override
+    public long identifier()
+    {
+        return IDENTIFIER;
+    }
+
+    @Override
+    public int majorVersion()
+    {
+        return MAJOR_VERSION;
+    }
+
+    @Override
+    public int minorVersion()
+    {
+        return MINOR_VERSION;
+    }
+
+    @Override
+    public int compare( StringSchemaKey o1, StringSchemaKey o2 )
+    {
+        int comparison = o1.compareValueTo( o2 );
+        return comparison != 0 ? comparison : Long.compare( o1.getEntityId(), o2.getEntityId() );
+    }
+}

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

@@ -0,0 +1,66 @@
+/*
+ * Copyright (c) 2002-2018 "Neo Technology,"
+ * Network Engine for Objects in Lund AB [http://neotechnology.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * Neo4j is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.neo4j.kernel.impl.index.schema;
+
+import org.neo4j.index.internal.gbptree.Layout;
+
+/**
+ * {@link Layout} for numbers where numbers need to be unique.
+ */
+class StringLayoutUnique extends StringLayout
+{
+    private static final String IDENTIFIER_NAME = "USI";
+    static final int MAJOR_VERSION = 0;
+    static final int MINOR_VERSION = 1;
+    static long IDENTIFIER = Layout.namedIdentifier( IDENTIFIER_NAME, NativeSchemaValue.SIZE );
+
+    @Override
+    public long identifier()
+    {
+        return IDENTIFIER;
+    }
+
+    @Override
+    public int majorVersion()
+    {
+        return MAJOR_VERSION;
+    }
+
+    @Override
+    public int minorVersion()
+    {
+        return MINOR_VERSION;
+    }
+
+    @Override
+    public int compare( StringSchemaKey o1, StringSchemaKey o2 )
+    {
+        int comparison = o1.compareValueTo( o2 );
+        if ( comparison == 0 )
+        {
+            // This is a special case where we need also compare entityId to support inclusive/exclusive
+            if ( o1.getEntityIdIsSpecialTieBreaker() || o2.getEntityIdIsSpecialTieBreaker() )
+            {
+                return Long.compare( o1.getEntityId(), o2.getEntityId() );
+            }
+        }
+        return comparison;
+    }
+}

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

@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2002-2018 "Neo Technology,"
+ * Network Engine for Objects in Lund AB [http://neotechnology.com]
+ *
+ * This file is part of Neo4j.
+ *
+ * Neo4j is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.neo4j.kernel.impl.index.schema;
+
+import java.io.File;
+import java.io.IOException;
+
+import org.neo4j.index.internal.gbptree.Layout;
+import org.neo4j.index.internal.gbptree.RecoveryCleanupWorkCollector;
+import org.neo4j.io.fs.FileSystemAbstraction;
+import org.neo4j.io.pagecache.PageCache;
+import org.neo4j.kernel.api.index.SchemaIndexProvider;
+import org.neo4j.kernel.api.schema.index.IndexDescriptor;
+import org.neo4j.kernel.impl.api.index.sampling.IndexSamplingConfig;
+import org.neo4j.storageengine.api.schema.IndexReader;
+
+public class StringSchemaIndexAccessor<KEY extends StringSchemaKey, VALUE extends NativeSchemaValue>
+        extends NativeSchemaIndexAccessor<KEY,VALUE>
+{
+    StringSchemaIndexAccessor(
+            PageCache pageCache,
+            FileSystemAbstraction fs,
+            File storeFile,
+            Layout<KEY,VALUE> layout,
+            RecoveryCleanupWorkCollector recoveryCleanupWorkCollector,
+            SchemaIndexProvider.Monitor monitor,
+            IndexDescriptor descriptor,
+            long indexId,
+            IndexSamplingConfig samplingConfig ) throws IOException
+    {
+        super( pageCache, fs, storeFile, layout, recoveryCleanupWorkCollector, monitor, descriptor, indexId, samplingConfig );
+    }
+
+    @Override
+    public IndexReader newReader()
+    {
+        assertOpen();
+        return new StringSchemaIndexReader<>( tree, layout, samplingConfig, descriptor );
+    }
+}