/*
 * 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.sql.engine.exec.rel;

import java.util.List;
import org.apache.calcite.rel.type.RelDataType;
import org.apache.ignite.internal.sql.engine.exec.ExecutionContext;

/**
 * Represents a node of execution tree.
 *
 * <b>Note</b>: except several cases (like consumer node and mailboxes), {@link Node#request(int)}, {@link Node#close()},
 * {@link Downstream#push(Object)} and {@link Downstream#end()} methods should be used from one single thread.
 */
public interface Node<RowT> extends AutoCloseable {
    /**
     * Returns runtime context allowing access to the tables in a database.
     *
     * @return Execution context.
     */
    ExecutionContext<RowT> context();

    /**
     * Returns logical node output row type.
     *
     * @return Logical node output row type.
     */
    RelDataType rowType();

    /**
     * Returns node downstream.
     *
     * @return Node downstream.
     */
    Downstream<RowT> downstream();

    /**
     * Registers node sources.
     *
     * @param sources Sources collection.
     */
    void register(List<Node<RowT>> sources);

    /**
     * Returns registered node sources.
     *
     * @return Node sources.
     */
    List<Node<RowT>> sources();

    /**
     * Registers downstream.
     *
     * @param downstream Downstream.
     */
    void onRegister(Downstream<RowT> downstream);

    /**
     * Requests next bunch of rows.
     */
    void request(int rowsCnt) throws Exception;

    /**
     * Rewinds upstream.
     */
    void rewind();
}
