Testing for create new version of node on write if stable and Pointer…

…Checking update

Add checkSiblingPointer to PointerChecking
Use checkSiblingPointer and checkChildPointer whenever a child or sibling pointer is read.
Testing for PointerChecking

PageAwareByteArrayCursor now support openLinkedCursor.

community/index/src/main/java/org/neo4j/index/gbptree/ByteArrayPageCursor.java

@@ -210,7 +210,7 @@ public long getCurrentPageId()
     @Override
     public int getCurrentPageSize()
     {
-        throw new UnsupportedOperationException();
+        return buffer.capacity();
     }
 
     @Override

community/index/src/main/java/org/neo4j/index/gbptree/IdSpace.java

@@ -27,8 +27,20 @@ public class IdSpace
      */
     static final long META_PAGE_ID = 0L;
 
+    /**
+     * State page with IDs such as free-list, highId, rootId and more. There are two such pages alternating
+     * between checkpoints, this is the first.
+     */
+    static final long STATE_PAGE_A = 1L;
+
+    /**
+     * State page with IDs such as free-list, highId, rootId and more. There are two such pages alternating
+     * between checkpoints, this is the second.
+     */
+    static final long STATE_PAGE_B = 2L;
+
     /**
      * Min value allowed as tree node id.
      */
-    static final long MIN_TREE_NODE_ID = 1L;
+    static final long MIN_TREE_NODE_ID = 3L;
 }

community/index/src/main/java/org/neo4j/index/gbptree/InternalTreeLogic.java

@@ -231,6 +231,7 @@ private void splitInternal( PageCursor cursor, StructurePropagation<KEY> structu
     {
         long current = cursor.getCurrentPageId();
         long oldRight = bTreeNode.rightSibling( cursor, stableGeneration, unstableGeneration );
+        PointerChecking.checkSiblingPointer( oldRight );
         long newRight = idProvider.acquireNewId();
 
         // Find position to insert new key
@@ -386,6 +387,7 @@ private void splitLeaf( PageCursor cursor, StructurePropagation<KEY> structurePr
 
         long current = cursor.getCurrentPageId();
         long oldRight = bTreeNode.rightSibling( cursor, stableGeneration, unstableGeneration );
+        PointerChecking.checkSiblingPointer( oldRight );
         long newRight = idProvider.acquireNewId();
 
         // BALANCE KEYS AND VALUES
@@ -529,6 +531,7 @@ VALUE remove( PageCursor cursor, StructurePropagation<KEY> structurePropagation,
 
         long currentId = cursor.getCurrentPageId();
         long childId = bTreeNode.childAt( cursor, pos, stableGeneration, unstableGeneration );
+        PointerChecking.checkChildPointer( childId );
         bTreeNode.goTo( cursor, childId, stableGeneration, unstableGeneration );
 
         VALUE result = remove( cursor, structurePropagation, key, into, stableGeneration, unstableGeneration );
@@ -619,6 +622,10 @@ private void createUnstableVersionIfNeeded( PageCursor cursor, StructurePropagat
         long newGenId = idProvider.acquireNewId();
         try ( PageCursor newGenCursor = cursor.openLinkedCursor( newGenId ) )
         {
+            if ( !newGenCursor.next() )
+            {
+                throw new IllegalStateException( "Could not go to new node " + newGenId );
+            }
             cursor.copyTo( 0, newGenCursor, 0, cursor.getCurrentPageSize() );
             bTreeNode.setGen( newGenCursor, unstableGeneration );
         }
@@ -640,7 +647,9 @@ private void createUnstableVersionIfNeeded( PageCursor cursor, StructurePropagat
         //              v                                     v                                      v
         // (leftSiblingOfStableNode) -[rightSibling]-> (newUnstableNode) <-[leftSibling]- (rightSiblingOfStableNode)
         long leftSibling = bTreeNode.leftSibling( cursor, stableGeneration, unstableGeneration );
+        PointerChecking.checkSiblingPointer( leftSibling );
         long rightSibling = bTreeNode.rightSibling( cursor, stableGeneration, unstableGeneration );
+        PointerChecking.checkSiblingPointer( rightSibling );
         if ( leftSibling != TreeNode.NO_NODE_FLAG )
         {
             bTreeNode.goTo( cursor, leftSibling, stableGeneration, unstableGeneration );

community/index/src/main/java/org/neo4j/index/gbptree/PointerChecking.java

@@ -42,4 +42,17 @@ static void checkChildPointer( long result )
                                              IdSpace.MIN_TREE_NODE_ID );
         }
     }
+
+    static void checkSiblingPointer( long result )
+    {
+        if ( !GenSafePointerPair.isSuccess( result ) )
+        {
+            throw new IllegalStateException( GenSafePointerPair.failureDescription( result ) );
+        }
+        if ( result < IdSpace.MIN_TREE_NODE_ID && result != TreeNode.NO_NODE_FLAG )
+        {
+            throw new IllegalStateException( "Pointer to id " + result + " not allowed. Minimum node id allowed is " +
+                    IdSpace.MIN_TREE_NODE_ID );
+        }
+    }
 }