First draft of off-heap PageList implementation

community/io/src/main/java/org/neo4j/io/fs/DefaultFileSystemAbstraction.java

@@ -85,13 +85,13 @@ public InputStream openAsInputStream( File fileName ) throws IOException
     @Override
     public Reader openAsReader( File fileName, Charset charset ) throws IOException
     {
-        return new InputStreamReader( new FileInputStream( fileName ), charset );
+        return new InputStreamReader( openAsInputStream( fileName ), charset );
     }
 
     @Override
     public Writer openAsWriter( File fileName, Charset charset, boolean append ) throws IOException
     {
-        return new OutputStreamWriter( new FileOutputStream( fileName, append ), charset );
+        return new OutputStreamWriter( openAsOutputStream( fileName, append ), charset );
     }
 
     @Override

community/io/src/main/java/org/neo4j/io/pagecache/impl/muninn/MuninnPage.java

@@ -33,7 +33,7 @@
 
 import static java.lang.String.format;
 
-final class MuninnPage extends SequenceLock implements Page
+final class MuninnPage extends OnHeapSequenceLock implements Page
 {
     private static final long usageStampOffset = UnsafeUtil.getFieldOffset( MuninnPage.class, "usageStamp" );
 

community/io/src/main/java/org/neo4j/io/pagecache/impl/muninn/MuninnPageCache.java

@@ -224,6 +224,9 @@ public MuninnPageCache( PageSwapperFactory swapperFactory, int maxPages, int cac
         long expectedMaxMemory = ((long) maxPages) * cachePageSize; // cast to long prevents overflow
         MemoryManager memoryManager = new MemoryManager( expectedMaxMemory, alignment );
         this.victimPage = VictimPageReference.getVictimPage( cachePageSize );
+
+//        PageList pages = new PageList( maxPages, cachePageSize, memoryManager, victimPage );
+
         Object pageList = null;
         int pageIndex = maxPages;
         while ( pageIndex-- > 0 )

community/io/src/main/java/org/neo4j/io/pagecache/impl/muninn/OnHeapSequenceLock.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2002-2016 "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.io.pagecache.impl.muninn;
+
+import org.neo4j.unsafe.impl.internal.dragons.UnsafeUtil;
+
+/**
+ * This is a {@link SequenceLock} lock implementation that keeps its state on-heap in a field.
+ */
+public class OnHeapSequenceLock extends SequenceLock
+{
+    private static final long STATE = UnsafeUtil.getFieldOffset( OnHeapSequenceLock.class, "state" );
+
+    @SuppressWarnings( "unused" ) // accessed via unsafe
+    private volatile long state;
+
+    @Override
+    protected long getState()
+    {
+        return state;
+    }
+
+    @Override
+    protected boolean compareAndSetState( long expect, long update )
+    {
+        return UnsafeUtil.compareAndSwapLong( this, STATE, expect, update );
+    }
+
+    @Override
+    protected void unconditionallySetState( long update )
+    {
+        state = update;
+    }
+}