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IndexDirectoryStructure.java
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IndexDirectoryStructure.java
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/*
* Copyright (c) 2002-2017 "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.api.index;
import java.io.File;
import org.neo4j.kernel.api.index.SchemaIndexProvider.Descriptor;
import static org.neo4j.io.fs.FileUtils.path;
/**
* Dictates how directory structure looks for a {@link SchemaIndexProvider} and its indexes. Generally there's a
* {@link #rootDirectory() root directory} which contains all index directories in some shape and form.
* For getting a directory (which must be a sub-directory to the root directory) for a particular index there's the
* {@link #directoryForIndex(long)} method.
*
* These instances are created from a {@link Factory} which typically gets passed into a {@link SchemaIndexProvider} constructor,
* which then a {@link IndexDirectoryStructure} given its {@link Descriptor}.
*/
public abstract class IndexDirectoryStructure
{
/**
* Creates an {@link IndexDirectoryStructure} for a {@link Descriptor} for a {@link SchemaIndexProvider}.
*/
public interface Factory
{
IndexDirectoryStructure forProvider( SchemaIndexProvider.Descriptor descriptor );
}
private static class SubDirectoryByIndexId extends IndexDirectoryStructure
{
private final File providerRootFolder;
private SubDirectoryByIndexId( File providerRootFolder )
{
this.providerRootFolder = providerRootFolder;
}
@Override
public File rootDirectory()
{
return providerRootFolder;
}
@Override
public File directoryForIndex( long indexId )
{
return path( providerRootFolder, String.valueOf( indexId ) );
}
}
/**
* Returns the base schema index directory, i.e.
*
* <pre>
* <db>/schema/index/
* </pre>
*
* @param databaseStoreDir database store directory, i.e. {@code db} in the example above, where e.g. {@code nodestore} lives.
* @return the base directory of schema indexing.
*/
static final File baseSchemaIndexFolder( File databaseStoreDir )
{
return path( databaseStoreDir, "schema", "index" );
}
/**
* @param databaseStoreDir store directory of database, i.e. {@code db} in the example above.
* @return {@link Factory} for creating {@link IndexDirectoryStructure} returning directories looking something like:
*
* <pre>
* <db>/schema/index/<providerKey>/<indexId>/
* </pre>
*/
public static Factory directoriesByProviderKey( File databaseStoreDir )
{
return descriptor -> new SubDirectoryByIndexId(
path( baseSchemaIndexFolder( databaseStoreDir ), fileNameFriendly( descriptor.getKey() ) ) );
}
/**
* @param databaseStoreDir store directory of database, i.e. {@code db} in the example above.
* @return {@link Factory} for creating {@link IndexDirectoryStructure} returning directories looking something like:
*
* <pre>
* <db>/schema/index/<providerKey>-<providerVersion>/<indexId>/
* </pre>
*/
public static Factory directoriesByProvider( File databaseStoreDir )
{
return descriptor -> new SubDirectoryByIndexId(
path( baseSchemaIndexFolder( databaseStoreDir ), fileNameFriendly( descriptor ) ) );
}
/**
* @param directoryStructure existing {@link IndexDirectoryStructure}.
* @return a {@link Factory} returning an already existing {@link IndexDirectoryStructure}.
*/
public static Factory given( IndexDirectoryStructure directoryStructure )
{
return descriptor -> directoryStructure;
}
/**
* Useful when combining multiple {@link SchemaIndexProvider} into one.
*
* @param parentStructure {@link IndexDirectoryStructure} of the parent.
* @return {@link Factory} creating {@link IndexDirectoryStructure} looking something like:
*
* <pre>
* <db>/schema/index/.../<indexId>/<childProviderKey>-<childProviderVersion>/
* </pre>
*/
public static Factory directoriesBySubProvider( IndexDirectoryStructure parentStructure )
{
return new Factory()
{
@Override
public IndexDirectoryStructure forProvider( Descriptor descriptor )
{
return new IndexDirectoryStructure()
{
@Override
public File rootDirectory()
{
return parentStructure.rootDirectory();
}
@Override
public File directoryForIndex( long indexId )
{
return path( parentStructure.directoryForIndex( indexId ), fileNameFriendly( descriptor ) );
}
};
}
};
}
private static String fileNameFriendly( String name )
{
return name.replaceAll( "\\+", "_" );
}
private static String fileNameFriendly( Descriptor descriptor )
{
return fileNameFriendly( descriptor.getKey() + "-" + descriptor.getVersion() );
}
private static final IndexDirectoryStructure NO_DIRECTORY_STRUCTURE = new IndexDirectoryStructure()
{
@Override
public File rootDirectory()
{
return null; // meaning there's no persistent storage
}
@Override
public File directoryForIndex( long indexId )
{
return null; // meaning there's no persistent storage
}
};
/**
* Useful for some in-memory index providers or similar.
*/
public static final Factory NONE = descriptor -> NO_DIRECTORY_STRUCTURE;
/**
* Returns root directory. Must be above all sub-directories returned from {@link #directoryForIndex(long)}.
* Returns something equivalent to:
*
* <pre>
* <db>/schema/index/<provider>/
* </pre>
*
* @return {@link File} denoting root directory for this provider.
* May return {@code null} if there's no root directory, i.e. no persistent storage at all.
*/
public abstract File rootDirectory();
/**
* Returns a sub-directory (somewhere under {@link #rootDirectory()}) for a specific index id, looking something equivalent to:
*
* <pre>
* <db>/schema/index/<provider>/<indexId>/
* </pre>
*
* I.e. the root of the schema indexes for this specific provider.
*
* @param indexId index id to return directory for.
* @return {@link File} denoting directory for the specific {@code indexId} for this provider.
* May return {@code null} if there's no root directory, i.e. no persistent storage at all.
*/
public abstract File directoryForIndex( long indexId );
}