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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * This code is free software; you can redistribute it and/or modify it

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 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 * 

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 * 

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 * 

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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package jdk.incubator.sql2;

import java.time.Duration;

import java.util.concurrent.CompletionStage;

import java.util.function.BiConsumer;

import java.util.function.Consumer;

import java.util.function.Function;

/**

 * A multi-operation is an {@link Operation} that returns one or more results in

 * addition to the out result defined by the {@link Operation}. Each result is

 * processed by an Operation. The Operations can be created by calling rowOperation,

 * rowProcessorOperation, or countOperation if the kind of results is known. These

 * results are processed in the order the Operations are submitted. Any results

 * not processed by an explicit Operation is processed by calling the appropriate

 * handler specified by onRows or onCount. If any result is an error that error

 * is processed by calling the handler specified by onError. If the appropriate

 * handler is not specified that result is ignored, including errors.

 * 

 * ISSUE: Should this have a collector?

 *

 * @param <T> The type of the result of this {@link Operation}

 */

public interface MultiOperation<T> extends OutOperation<T> {

  /**

   * Returns a {@link RowOperation} to process a row sequence result. The

   * {@link Operation}s are executed in the order they are submitted. If a

   * result is of the wrong type for the next submitted {@link Operation} the

   * {@link MultiOperation} is completed with

   * {@link IllegalStateException}.

   *

   * @return a {@link RowOperation} that is part of this {@link MultiOperation}

   */

  public RowOperation<T> rowOperation();

  /**

   * Returns a {@link RowProcessorOperation} to process a row sequence result. The

   * {@link Operation}s are executed in the order they are submitted. If a

   * result is of the wrong type for the next submitted {@link Operation} the

   * {@link MultiOperation} is completed with

   * {@link IllegalStateException}.

   *

   * @return a {@link RowProcessorOperation} that is part of this {@link MultiOperation}

   */

  public RowProcessorOperation<T> rowProcessorOperation();

  /**

   * Returns a {@link CountOperation} to process a count result. The {@link Operation}s

   * are executed in the order they are submitted. If a result is of the wrong

   * type for the next submitted Operation the {@link MultiOperation} is completed

   * with {@link IllegalStateException}.

   *

   * @return a {@link CountOperation} that is part of this {@link MultiOperation}

   */

  public CountOperation<T> countOperation();

  /**

   * Provides a handler for trailing count results. The provided handler is called for

   * each count result not processed by CountOperation. When called the first argument is the number of results

   * that preceeded the current result. The second argument is a

   * {@link CountOperation} that will process the current result. This

   * {@link CountOperation} has not been configured in any way nor has it been

   * submitted. The handler configures the {@link CountOperation} and submits

   * it. The count result is processed when the {@link CountOperation} is

   * submitted. If the {@link CountOperation} is not submitted when the handler

   * returns the count result is ignored.

   * 

   * If this method is not called any trailing count results are ignored.

   *

   * @param handler not null

   * @return this MultiOperation

   * @throws IllegalStateException if this method was called previously

   */

  public MultiOperation<T> onCount(BiConsumer<Integer, CountOperation<T>> handler);

  /**

   * Provides a handler for trailing row sequence results. The provided handler is called

   * for each row sequence result not processed by a RowOperation. When called the first argument is the number

   * of results that preceeded the current result. The second argument is a

   * {@link RowOperation} that will process the current result. This

   * {@link RowOperation} has not been configured in any way nor has it been

   * submitted. The handler configures the {@link RowOperation} and submits it.

   * The row sequence result is processed when the {@link RowOperation} is

   * submitted. If the {@link RowOperation} is not submitted when the handler

   * returns, the row sequence result is ignored.

   * 

   * If this method is not called any trailing row sequence results are ignored.

   * 

   * ISSUE: Should there be a version of this method that provides 

   * RowProcessorOperations? If so only one of that method or this one can be called.

   *

   * @param handler

   * @return This MultiOperation

   * @throws IllegalStateException if this method was called previously

   */

  public MultiOperation<T> onRows(BiConsumer<Integer, RowOperation<T>> handler);

  /**

   * Provides an error handler for this {@link Operation}. The provided handler 

   * is called for each error that occurs. When called the first argument is the 

   * number of results, including errors, that preceeded the current error. The

   * second argument is a {@link Throwable} corresponding to the error. When the

   * handler returns processing of the MultiOperation results continues. 

   * Only one onError method may be called.

   * 

   * @param handler a BiConsumer that handles an error

   * @return this MultiOperation

   * @throws IllegalStateException if this method was called previously

   */

  public MultiOperation<T> onError(BiConsumer<Integer, Throwable> handler);

  // Covariant overrides

  /**

   * This handler is called if the execution fails completely. If the execution

   * returns any individual results, even if any or all of those results are

   * errors, this handler is not called.

   * 

   * @param handler

   * @return 

   */

  @Override

  public MultiOperation<T> onError(Consumer<Throwable> handler);

  @Override

  public MultiOperation<T> apply(Function<Result.OutParameterMap, ? extends T> processor);

  @Override

  public MultiOperation<T> outParameter(String id, SqlType type);

  @Override

  public MultiOperation<T> set(String id, Object value, SqlType type);

  @Override

  public MultiOperation<T> set(String id, Object value);

  @Override

  public MultiOperation<T> set(String id, CompletionStage<?> source, SqlType type);

  @Override

  public MultiOperation<T> set(String id, CompletionStage<?> source);

  @Override

  public MultiOperation<T> timeout(Duration minTime);

}