io.vertx.sqlclient.Cursor.java Source code

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Here is the source code for io.vertx.sqlclient.Cursor.java

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/*
 * Copyright (C) 2017 Julien Viet
 *
 * Licensed 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 io.vertx.sqlclient;

import io.vertx.codegen.annotations.VertxGen;
import io.vertx.core.AsyncResult;
import io.vertx.core.Handler;

/**
 * A cursor that reads progressively rows from the database, it is useful for reading very large result sets.
 */
@VertxGen
public interface Cursor {

    /**
     * Read rows from the cursor, the result is provided asynchronously to the {@code handler}.
     *
     * @param count the amount of rows to read
     * @param handler the handler for the result
     */
    void read(int count, Handler<AsyncResult<RowSet<Row>>> handler);

    /**
     * Returns {@code true} when the cursor has results in progress and the {@link #read} should be called to retrieve
     * them.
     *
     * @return whether the cursor has more results,
     */
    boolean hasMore();

    /**
     * Release the cursor.
     * <p/>
     * It should be called for prepared queries executed with a fetch size.
     */
    default void close() {
        close(ar -> {
        });
    }

    /**
     * Like {@link #close()} but with a {@code completionHandler} called when the cursor has been released.
     */
    void close(Handler<AsyncResult<Void>> completionHandler);

}