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Neo4j kernel is a lightweight, embedded Java database designed to store data structured as graphs rather than tables. For more information, see http://neo4j.org.

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/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [https://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.index.schema;

import java.util.ArrayList;
import java.util.Collection;
import org.neo4j.kernel.api.exceptions.index.IndexEntryConflictException;
import org.neo4j.kernel.api.index.IndexUpdater;
import org.neo4j.storageengine.api.IndexEntryUpdate;

/**
 * Collects updates from {@link #process(IndexEntryUpdate)} and passes them to the {@link Applier} on {@link #close()}.
 */
public class CollectingIndexUpdater implements IndexUpdater {
    private final Applier applier;

    private boolean closed;
    private final Collection> updates = new ArrayList<>();

    public CollectingIndexUpdater(Applier applier) {
        this.applier = applier;
    }

    @Override
    public void process(IndexEntryUpdate update) {
        assertOpen();
        updates.add(update);
    }

    @Override
    public void close() throws IndexEntryConflictException {
        assertOpen();
        try {
            applier.accept(updates);
        } finally {
            closed = true;
        }
    }

    private void assertOpen() {
        if (closed) {
            throw new IllegalStateException("Updater has been closed");
        }
    }

    public interface Applier {
        void accept(Collection> updates) throws IndexEntryConflictException;
    }
}