Copyright 2016 Netflix, Inc.

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.
/**
 * Copyright 2016 Netflix, Inc.
 * <p/>
 * 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
 * <p/>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p/>
 * 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 com.netflix.hystrix.strategy.properties;

import java.util.ServiceLoader;

A hystrix plugin (SPI) for resolving dynamic configuration properties. This SPI allows for varying configuration sources. The HystrixPlugin singleton will load only one implementation of this SPI throught the ServiceLoader mechanism. 
Author:
agentgt/**
 * A hystrix plugin (SPI) for resolving dynamic configuration properties. This
 * SPI allows for varying configuration sources.
 * 
 * The HystrixPlugin singleton will load only one implementation of this SPI
 * throught the {@link ServiceLoader} mechanism.
 * 
 * @author agentgt
 *
 */
public interface HystrixDynamicProperties {
    
    
Requests a property that may or may not actually exist.
Params:
name – property name, never null
fallback – default value, maybe null
Returns:
never null/**
     * Requests a property that may or may not actually exist.
     * @param name property name, never <code>null</code>
     * @param fallback default value, maybe <code>null</code>
     * @return never <code>null</code>
     */
    public HystrixDynamicProperty<String> getString(String name, String fallback);
    
Requests a property that may or may not actually exist.
Params:
name – property name, never null
fallback – default value, maybe null
Returns:
never null/**
     * Requests a property that may or may not actually exist.
     * @param name property name, never <code>null</code>
     * @param fallback default value, maybe <code>null</code>
     * @return never <code>null</code>
     */
    public HystrixDynamicProperty<Integer> getInteger(String name, Integer fallback);
    
Requests a property that may or may not actually exist.
Params:
name – property name, never null
fallback – default value, maybe null
Returns:
never null/**
     * Requests a property that may or may not actually exist.
     * @param name property name, never <code>null</code>
     * @param fallback default value, maybe <code>null</code>
     * @return never <code>null</code>
     */
    public HystrixDynamicProperty<Long> getLong(String name, Long fallback);
    
Requests a property that may or may not actually exist.
Params:
name – property name
fallback – default value
Returns:
never null/**
     * Requests a property that may or may not actually exist.
     * @param name property name
     * @param fallback default value
     * @return never <code>null</code>
     */
    public HystrixDynamicProperty<Boolean> getBoolean(String name, Boolean fallback);
    
    
@ExcludeFromJavadoc
/**
     * @ExcludeFromJavadoc
     */
    public static class Util {
        
A convenience method to get a property by type (Class).
Params:
properties – never null
name – never null
fallback – maybe null
type – never null
Returns:
a dynamic property with type T./**
         * A convenience method to get a property by type (Class).
         * @param properties never <code>null</code>
         * @param name never <code>null</code>
         * @param fallback maybe <code>null</code>
         * @param type never <code>null</code>
         * @return a dynamic property with type T.
         */
        @SuppressWarnings("unchecked")
        public static <T> HystrixDynamicProperty<T> getProperty(
                HystrixDynamicProperties properties, String name, T fallback, Class<T> type) {
            return (HystrixDynamicProperty<T>) doProperty(properties, name, fallback, type);
        }
        
        private static HystrixDynamicProperty<?> doProperty(
                HystrixDynamicProperties delegate, 
                String name, Object fallback, Class<?> type) {
            if(type == String.class) {
                return delegate.getString(name, (String) fallback);
            }
            else if (type == Integer.class) {
                return delegate.getInteger(name, (Integer) fallback);
            }
            else if (type == Long.class) {
                return delegate.getLong(name, (Long) fallback);
            }
            else if (type == Boolean.class) {
                return delegate.getBoolean(name, (Boolean) fallback);
            }
            throw new IllegalStateException();
        }
    }
    
}