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ReferenceTest.java
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ReferenceTest.java
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/*
* 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 Affero 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.neo4j.kernel.impl.store.format.busted;
import org.junit.Rule;
import org.junit.Test;
import java.io.IOException;
import java.nio.ByteBuffer;
import org.neo4j.io.pagecache.StubPageCursor;
import org.neo4j.kernel.impl.store.format.busted.Reference;
import org.neo4j.test.RandomRule;
import static org.junit.Assert.assertEquals;
import static org.neo4j.kernel.impl.store.format.busted.Reference.PAGE_CURSOR_ADAPTER;
public class ReferenceTest
{
public final @Rule RandomRule random = new RandomRule();
private final ByteBuffer buffer = ByteBuffer.allocateDirect( 100 );
private final StubPageCursor cursor = new StubPageCursor( 0, buffer );
@Test
public void shouldEncodeRandomLongs() throws Exception
{
// WHEN/THEN
long mask = numberOfBits( 58 );
for ( int i = 0; i < 100_000_000; i++ )
{
long reference = limit( random.nextLong(), mask );
assertDecodedMatchesEncoded( reference );
}
}
private long numberOfBits( int count )
{
long result = 0;
for ( int i = 0; i < count; i++ )
{
result = (result << 1) | 1;
}
return result;
}
/**
* The current scheme only allows us to use 58 bits for a reference. Adhere to that limit here.
*/
private long limit( long reference, long mask )
{
boolean positive = true;
if ( reference < 0 )
{
positive = false;
reference = ~reference;
}
reference &= mask;
if ( !positive )
{
reference = ~reference;
}
return reference;
}
private void assertDecodedMatchesEncoded( long reference ) throws IOException
{
cursor.setOffset( 0 );
Reference.encode( reference, cursor, PAGE_CURSOR_ADAPTER );
cursor.setOffset( 0 );
long read = Reference.decode( cursor, PAGE_CURSOR_ADAPTER );
assertEquals( reference, read );
}
}