modules/indexing/src/main/java/org/apache/ignite/internal/processors/query/h2/twostep/GridMergeIndexUnsorted.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.ignite.internal.processors.query.h2.twostep;

import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.TimeUnit;
import javax.cache.CacheException;
import org.h2.index.Cursor;
import org.h2.index.IndexType;
import org.h2.result.Row;
import org.h2.result.SearchRow;
import org.h2.table.IndexColumn;
import org.h2.value.Value;
import org.jetbrains.annotations.Nullable;

/**
 * Unsorted merge index.
 */
public class GridMergeIndexUnsorted extends GridMergeIndex {
    /** */
    private final BlockingQueue<GridResultPage> queue = new LinkedBlockingQueue<>();

    /**
     * @param tbl  Table.
     * @param name Index name.
     */
    public GridMergeIndexUnsorted(GridMergeTable tbl, String name) {
        super(tbl, name, IndexType.createScan(false), IndexColumn.wrap(tbl.getColumns()));
    }

    /**
     * @return Dummy index instance.
     */
    public static GridMergeIndexUnsorted createDummy() {
        return new GridMergeIndexUnsorted();
    }

    /**
     *
     */
    private GridMergeIndexUnsorted() {
        // No-op.
    }

    /** {@inheritDoc} */
    @Override protected void addPage0(GridResultPage page) {
        assert page.rowsInPage() > 0 || page.isLast() || page.isFail();

        queue.add(page);
    }

    /** {@inheritDoc} */
    @Override protected Cursor findAllFetched(List<Row> fetched, @Nullable SearchRow first, @Nullable SearchRow last) {
        return new IteratorCursor(fetched.iterator());
    }

    /** {@inheritDoc} */
    @Override protected Cursor findInStream(@Nullable SearchRow first, @Nullable SearchRow last) {
        return new FetchingCursor(new Iterator<Row>() {
            /** */
            Iterator<Value[]> iter = Collections.emptyIterator();

            @Override public boolean hasNext() {
                while (!iter.hasNext()) {
                    GridResultPage page;

                    for (;;) {
                        try {
                            page = queue.poll(500, TimeUnit.MILLISECONDS);
                        }
                        catch (InterruptedException e) {
                            throw new CacheException("Query execution was interrupted.", e);
                        }

                        if (page != null)
                            break;

                        ((GridMergeTable)table).checkSourceNodesAlive();
                    }

                    if (page.isLast())
                        return false; // We are done.

                    fetchNextPage(page);

                    iter = page.rows();
                }

                return true;
            }

            @Override public Row next() {
                return new Row(iter.next(), 0);
            }

            @Override public void remove() {
                throw new UnsupportedOperationException();
            }
        });
    }
}