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StringSchemaKey.java
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StringSchemaKey.java
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/*
* Copyright (c) 2002-2018 "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.index.schema;
import java.util.Arrays;
import org.neo4j.index.internal.gbptree.GBPTree;
import org.neo4j.string.UTF8;
import org.neo4j.values.storable.Value;
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},
* or rather any string that {@link GBPTree} can handle.
*/
class StringSchemaKey extends NativeSchemaKey
{
static final int ENTITY_ID_SIZE = Long.BYTES;
private boolean ignoreLength;
// TODO something better or?
// TODO this is UTF-8 bytes for now
byte[] bytes;
int size()
{
return ENTITY_ID_SIZE + bytes.length;
}
@Override
protected Value assertCorrectType( Value value )
{
if ( !Values.isTextValue( value ) )
{
throw new IllegalArgumentException(
"Key layout does only support strings, tried to create key from " + value );
}
return value;
}
@Override
public Value asValue()
{
return bytes == null ? Values.NO_VALUE : Values.utf8Value( bytes );
}
@Override
void initValueAsLowest()
{
bytes = null;
}
@Override
void initValueAsHighest()
{
bytes = null;
}
void initAsPrefixLow( String prefix )
{
writeString( prefix );
setEntityId( Long.MIN_VALUE );
setCompareId( DEFAULT_COMPARE_ID );
}
void initAsPrefixHigh( String prefix )
{
writeString( prefix );
setEntityId( Long.MAX_VALUE );
setCompareId( DEFAULT_COMPARE_ID );
ignoreLength = true;
}
private boolean isHighest()
{
return getCompareId() && getEntityId() == Long.MAX_VALUE && bytes == null;
}
/**
* Compares the value of this key to that of another key.
* This method is expected to be called in scenarios where inconsistent reads may happen (and later retried).
*
* @param other the {@link StringSchemaKey} to compare to.
* @return comparison against the {@code other} {@link StringSchemaKey}.
*/
int compareValueTo( StringSchemaKey other )
{
// TODO cover all cases of bytes == null and special tie breaker and document
if ( bytes != other.bytes )
{
if ( bytes == null )
{
return isHighest() ? 1 : -1;
}
if ( other.bytes == null )
{
return other.isHighest() ? -1 : 1;
}
}
else
{
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 );
}
}
private static int byteArrayCompare( byte[] a, byte[] b )
{
assert a != null && b != null : "Null arrays not supported.";
if ( a == b )
{
return 0;
}
int length = Math.min( a.length, b.length );
for ( int i = 0; i < length; i++ )
{
int compare = Byte.compare( a[i], b[i] );
if ( compare != 0 )
{
return compare;
}
}
return Integer.compare( a.length, b.length );
}
@Override
public String toString()
{
return format( "value=%s,entityId=%d,bytes=%s", asValue(), getEntityId(), Arrays.toString( bytes ) );
}
@Override
public void writeString( String value )
{
bytes = UTF8.encode( value );
}
@Override
public void writeString( char value )
{
writeString( String.valueOf( value ) );
}
}