More retry-resilient StringSchemaKey compare

As well as deduplication of some common native schema key initialization
code reseting flags and entityId.

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

@@ -30,7 +30,7 @@
  * {@link ValueMerger} which will merely detect conflict, not change any value if conflict, i.e. if the
  * key already exists. After this merge has been used in a call to {@link Writer#merge(Object, Object, ValueMerger)}
  * {@link #checkConflict(Value[])} can be called to check whether or not that call conflicted with
- * an existing key. A call to {@link #checkConflict(Value[])} will also clear the conflict flag.
+ * an existing key. A call to {@link #checkConflict(Value[])} will also initialize the conflict flag.
  *
  * @param <VALUE> type of values being merged.
  */

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

@@ -30,7 +30,7 @@
  */
 abstract class NativeSchemaKey<SELF extends NativeSchemaKey> extends ValueWriter.Adapter<RuntimeException>
 {
-    static final boolean DEFAULT_COMPARE_ID = true;
+    private static final boolean DEFAULT_COMPARE_ID = true;
 
     private long entityId;
     private boolean compareId = DEFAULT_COMPARE_ID;
@@ -64,12 +64,23 @@ void setEntityId( long entityId )
 
     final void from( long entityId, Value... values )
     {
-        compareId = DEFAULT_COMPARE_ID;
-        this.entityId = entityId;
+        initialize( entityId );
         // copy value state and store in this key instance
         assertValidValue( values ).writeTo( this );
     }
 
+    /**
+     * Initializes this key with entity id and resets other flags to default values.
+     * Doesn't touch value data.
+     *
+     * @param entityId entity id to set for this key.
+     */
+    void initialize( long entityId )
+    {
+        this.compareId = DEFAULT_COMPARE_ID;
+        this.entityId = entityId;
+    }
+
     private Value assertValidValue( Value... values )
     {
         if ( values.length > 1 )
@@ -94,17 +105,15 @@ String propertiesAsString()
 
     final void initAsLowest()
     {
-        compareId = DEFAULT_COMPARE_ID;
-        entityId = Long.MIN_VALUE;
+        initialize( Long.MIN_VALUE );
         initValueAsLowest();
     }
 
     abstract void initValueAsLowest();
 
     final void initAsHighest()
     {
-        compareId = DEFAULT_COMPARE_ID;
-        entityId = Long.MAX_VALUE;
+        initialize( Long.MAX_VALUE );
         initValueAsHighest();
     }
 

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

@@ -81,8 +81,7 @@ void initValueAsHighest()
     public void fromDerivedValue( long entityId, long derivedValue )
     {
         rawValueBits = derivedValue;
-        setEntityId( entityId );
-        setCompareId( DEFAULT_COMPARE_ID );
+        initialize( entityId );
     }
 
     /**

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

@@ -27,7 +27,6 @@
 import org.neo4j.values.storable.Values;
 
 import static java.lang.String.format;
-import static org.neo4j.values.storable.UTF8StringValue.codePointByteArrayCompare;
 
 /**
  * Includes value and entity id (to be able to handle non-unique values). A value can be any {@link String},
@@ -39,8 +38,6 @@ class StringSchemaKey extends NativeSchemaKey<StringSchemaKey>
 
     private boolean ignoreLength;
 
-    // TODO something better or?
-    // TODO this is UTF-8 bytes for now
     byte[] bytes;
 
     int size()
@@ -59,6 +56,13 @@ protected Value assertCorrectType( Value value )
         return value;
     }
 
+    @Override
+    void initialize( long entityId )
+    {
+        super.initialize( entityId );
+        ignoreLength = false;
+    }
+
     @Override
     public Value asValue()
     {
@@ -80,15 +84,15 @@ void initValueAsHighest()
     void initAsPrefixLow( String prefix )
     {
         writeString( prefix );
-        setEntityId( Long.MIN_VALUE );
-        setCompareId( DEFAULT_COMPARE_ID );
+        initialize( Long.MIN_VALUE );
+        // Don't set ignoreLength = true here since the "low" a.k.a. left side of the range should care about length.
+        // This will make the prefix lower than those that matches the prefix (their length is >= that of the prefix)
     }
 
     void initAsPrefixHigh( String prefix )
     {
         writeString( prefix );
-        setEntityId( Long.MAX_VALUE );
-        setCompareId( DEFAULT_COMPARE_ID );
+        initialize( Long.MAX_VALUE );
         ignoreLength = true;
     }
 
@@ -107,7 +111,6 @@ private boolean isHighest()
     @Override
     int compareValueTo( StringSchemaKey other )
     {
-        // TODO cover all cases of bytes == null and special tie breaker and document
         if ( bytes != other.bytes )
         {
             if ( bytes == null )
@@ -124,20 +127,10 @@ int compareValueTo( StringSchemaKey other )
             return 0;
         }
 
-        try
-        {
-            // TODO change to not throw
-            return codePointByteArrayCompare( bytes, other.bytes, ignoreLength || other.ignoreLength );
-        }
-        catch ( Exception e )
-        {
-            // We can not throw here because we will visit this method inside a pageCursor.shouldRetry() block.
-            // Just return a comparison that at least will be commutative.
-            return byteArrayCompare( bytes, other.bytes );
-        }
+        return byteArrayCompare( bytes, other.bytes, ignoreLength | other.ignoreLength );
     }
 
-    private static int byteArrayCompare( byte[] a, byte[] b )
+    private static int byteArrayCompare( byte[] a, byte[] b, boolean ignoreLength )
     {
         assert a != null && b != null : "Null arrays not supported.";
 
@@ -149,14 +142,14 @@ private static int byteArrayCompare( byte[] a, byte[] b )
         int length = Math.min( a.length, b.length );
         for ( int i = 0; i < length; i++ )
         {
-            int compare = Byte.compare( a[i], b[i] );
+            int compare = Short.compare( (short) (a[i] & 0xFF), (short) (b[i] & 0xFF) );
             if ( compare != 0 )
             {
                 return compare;
             }
         }
 
-        return Integer.compare( a.length, b.length );
+        return ignoreLength ? 0 : Integer.compare( a.length, b.length );
     }
 
     @Override