/*
* 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 static org.apache.flink.util.Preconditions.checkNotNull;
/**
* {@code ConfigOptions} are used to build a {@link ConfigOption}.
* The option is typically built in one of the following pattern:
*
* <pre>{@code
* // simple string-valued option with a default value
* ConfigOption<String> tempDirs = ConfigOptions
* .key("tmp.dir")
* .defaultValue("/tmp");
*
* // simple integer-valued option with a default value
* ConfigOption<Integer> parallelism = ConfigOptions
* .key("application.parallelism")
* .defaultValue(100);
*
* // option with no default value
* ConfigOption<String> userName = ConfigOptions
* .key("user.name")
* .noDefaultValue();
*
* // option with deprecated keys to check
* ConfigOption<Double> threshold = ConfigOptions
* .key("cpu.utilization.threshold")
* .defaultValue(0.9).
* .withDeprecatedKeys("cpu.threshold");
* }</pre>
*/
@PublicEvolving
public class ConfigOptions {
/**
* Starts building a new {@link ConfigOption}.
*
* @param key The key for the config option.
* @return The builder for the config option with the given key.
*/
public static OptionBuilder key(String key) {
checkNotNull(key);
return new OptionBuilder(key);
}
// ------------------------------------------------------------------------
/**
* The option builder is used to create a {@link ConfigOption}.
* It is instantiated via {@link ConfigOptions#key(String)}.
*/
public static final class OptionBuilder {
/** The key for the config option */
private final String key;
/**
* Creates a new OptionBuilder.
* @param key The key for the config option
*/
OptionBuilder(String key) {
this.key = key;
}
/**
* Creates a ConfigOption with the given default value.
*
* <p>This method does not accept "null". For options with no default value, choose
* one of the {@code noDefaultValue} methods.
*
* @param value The default value for the config option
* @param <T> The type of the default value.
* @return The config option with the default value.
*/
public <T> ConfigOption<T> defaultValue(T value) {
checkNotNull(value);
return new ConfigOption<T>(key, value);
}
/**
* Creates a string-valued option with no default value.
* String-valued options are the only ones that can have no
* default value.
*
* @return The created ConfigOption.
*/
public ConfigOption<String> noDefaultValue() {
return new ConfigOption<>(key, null);
}
}
// ------------------------------------------------------------------------
/** Not intended to be instantiated */
private ConfigOptions() {}
}