flink-core/src/main/java/org/apache/flink/configuration/ReadableConfig.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.flink.configuration;

import org.apache.flink.annotation.PublicEvolving;

import java.util.Optional;

/**
 * Read access to a configuration object. Allows reading values described with meta information
 * included in {@link ConfigOption}.
 */
@PublicEvolving
public interface ReadableConfig {

    /**
     * Reads a value using the metadata included in {@link ConfigOption}. Returns the {@link
     * ConfigOption#defaultValue()} if value key not present in the configuration.
     *
     * @param option metadata of the option to read
     * @param <T> type of the value to read
     * @return read value or {@link ConfigOption#defaultValue()} if not found
     * @see #getOptional(ConfigOption)
     */
    <T> T get(ConfigOption<T> option);

    /**
     * Reads a value using the metadata included in {@link ConfigOption}. In contrast to {@link
     * #get(ConfigOption)} returns {@link Optional#empty()} if value not present.
     *
     * @param option metadata of the option to read
     * @param <T> type of the value to read
     * @return read value or {@link Optional#empty()} if not found
     * @see #get(ConfigOption)
     */
    <T> Optional<T> getOptional(ConfigOption<T> option);
}