org.neo4j.kernel.impl.context.TransactionVersionContextSupplier Maven / Gradle / Ivy

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/*
 * Copyright (c) 2018-2020 "Graph Foundation,"
 * Graph Foundation, Inc. [https://graphfoundation.org]
 *
 * This file is part of ONgDB.
 *
 * ONgDB 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 .
 */
/*
 * Copyright (c) 2002-2020 "Neo4j,"
 * Neo4j Sweden AB [http://neo4j.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 .
 */
package org.neo4j.kernel.impl.context;

import java.util.function.LongSupplier;

import org.neo4j.io.pagecache.tracing.cursor.context.EmptyVersionContext;
import org.neo4j.io.pagecache.tracing.cursor.context.VersionContext;
import org.neo4j.io.pagecache.tracing.cursor.context.VersionContextSupplier;

/**
 * {@link VersionContextSupplier} that supplier thread bound version context that should be used in a context of
 * transaction(Committing or reading).
 */
public class TransactionVersionContextSupplier implements VersionContextSupplier
{
    protected ThreadLocal cursorContext;

    @Override
    public void init( LongSupplier lastClosedTransactionIdSupplier )
    {
        this.cursorContext = ThreadLocal.withInitial( () -> new TransactionVersionContext( lastClosedTransactionIdSupplier ) );
    }

    @Override
    public VersionContext getVersionContext()
    {
        return cursorContext == null ? EmptyVersionContext.EMPTY : cursorContext.get();
    }

}