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 *  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
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 *  Unless required by applicable law or agreed to in writing,
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package org.apache.cayenne.access;

import java.util.List;

import org.apache.cayenne.ObjectId;
import org.apache.cayenne.ResultIterator;
import org.apache.cayenne.query.Query;

/**
 * Defines a set of callback methods that allow {@link QueryEngine} to pass back query
 * results and notify caller about exceptions.
 */
public interface OperationObserver extends OperationHints {

    /**
     * Callback method invoked after an updating query is executed.
     */
    void nextCount(Query query, int resultCount);

    /**
     * Callback method invoked after a batch update is executed.
     */
    void nextBatchCount(Query query, int[] resultCount);

    /**
     * Callback method invoked for each processed ResultSet.
     * 
     * @since 3.0
     */
    void nextRows(Query query, List<?> dataRows);

    /**
     * Callback method invoked for each opened ResultIterator. If this observer requested
     * results to be returned as a ResultIterator, this method is invoked instead of
     * {@link #nextRows(Query, List)}.
     * 
     * @since 3.0
     */
    void nextRows(Query q, ResultIterator<?> it);

    /**
     * Callback method invoked after each batch of generated values is read during an
     * update.
     * 
     * @since 4.0
     */
    void nextGeneratedRows(Query query, ResultIterator<?> keys, ObjectId idToUpdate);

    /**
     * Callback method invoked on exceptions that happen during an execution of a specific
     * query.
     */
    public void nextQueryException(Query query, Exception ex);

    /**
     * Callback method invoked on exceptions that are not tied to a specific query
     * execution, such as JDBC connection exceptions, etc.
     */
    public void nextGlobalException(Exception ex);
}