Test for correct memory mapping of a file that is growing.

When growing a store file, ensure that new regions at the end of the file are memory mapped, and there are no misses.

kernel/src/test/java/org/neo4j/kernel/impl/nioneo/store/TestGrowingFileMemoryMapping.java

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+/**
+ * Copyright (c) 2002-2012 "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.nioneo.store;
+
+import static org.junit.Assert.assertEquals;
+import static org.neo4j.graphdb.factory.GraphDatabaseSettings.nodestore_mapped_memory_size;
+import static org.neo4j.helpers.collection.MapUtil.stringMap;
+
+import java.io.File;
+
+import org.junit.Test;
+import org.neo4j.kernel.DefaultFileSystemAbstraction;
+import org.neo4j.kernel.DefaultIdGeneratorFactory;
+import org.neo4j.kernel.DefaultLastCommittedTxIdSetter;
+import org.neo4j.kernel.DefaultTxHook;
+import org.neo4j.kernel.configuration.Config;
+import org.neo4j.kernel.configuration.ConfigurationDefaults;
+import org.neo4j.kernel.impl.util.StringLogger;
+import org.neo4j.test.TargetDirectory;
+
+public class TestGrowingFileMemoryMapping
+{
+    private static final int MEGA = 1024 * 1024;
+
+    @Test
+    public void shouldGrowAFileWhileContinuingToMemoryMapNewRegions() throws Exception
+    {
+        // given
+        int NUMBER_OF_RECORDS = 1000000;
+
+        File storeDir = TargetDirectory.forTest( getClass() ).graphDbDir( true );
+        Config config = new Config( new ConfigurationDefaults( NodeStore.Configuration.class ).apply( stringMap(
+                nodestore_mapped_memory_size.name(), mmapSize( NUMBER_OF_RECORDS, NodeStore.RECORD_SIZE ),
+                NodeStore.Configuration.use_memory_mapped_buffers.name(), "true",
+                NodeStore.Configuration.store_dir.name(), storeDir.getPath(),
+                NodeStore.Configuration.neo_store.name(), new File( storeDir, NeoStore.DEFAULT_NAME ).getPath()
+        ) ) );
+        DefaultIdGeneratorFactory idGeneratorFactory = new DefaultIdGeneratorFactory();
+        StoreFactory storeFactory = new StoreFactory( config, idGeneratorFactory,
+                new DefaultFileSystemAbstraction(),
+                new DefaultLastCommittedTxIdSetter(), StringLogger.SYSTEM, new DefaultTxHook() );
+
+        String fileName = new File( storeDir, NeoStore.DEFAULT_NAME + ".nodestore.db" ).getPath();
+        storeFactory.createEmptyStore( fileName, storeFactory.buildTypeDescriptorAndVersion(
+                NodeStore.TYPE_DESCRIPTOR ) );
+
+        NodeStore nodeStore = new NodeStore( fileName, config, idGeneratorFactory,
+                new DefaultFileSystemAbstraction(), StringLogger.SYSTEM );
+
+        // when
+        for ( int i = 0; i < 2 * NUMBER_OF_RECORDS; i++ )
+        {
+            NodeRecord record = new NodeRecord( nodeStore.nextId(), 0, 0 );
+            record.setInUse( true );
+            nodeStore.updateRecord( record );
+        }
+
+        // then
+        WindowPoolStats stats = nodeStore.getWindowPoolStats();
+
+        nodeStore.close();
+
+        assertEquals( stats.toString(), 0, stats.getMissCount() );
+    }
+
+    private String mmapSize( int numberOfRecords, int recordSize )
+    {
+        int bytes = numberOfRecords * recordSize;
+        if (bytes < MEGA) {
+            throw new IllegalArgumentException( "too few records: " + numberOfRecords );
+        }
+        return bytes / MEGA + "M";
+    }
+}