com.avanza.astrix.config.DynamicProperty Maven / Gradle / Ivy
/*
* Copyright 2014 Avanza Bank AB
*
* 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 com.avanza.astrix.config;
/**
* A property that can change state even after it is read
* from a {@link DynamicConfigSource}.
*
* DynamicProperty instances are designed to be lightweight with no dependencies
* to the underlying configuration sources, thereby keeping consumers of DynamicProperty
* instances decoupled from the underlying configuration sources.
*
* @author Elias Lindholm (elilin)
*
* @param
*/
public interface DynamicProperty {
/**
* Adds a given listener to the underlying property. The listener
* will be notified each time the property value changes.
*
* Events are not guaranteed to be received in the same order
* as the underlying property is set.
*
* The listener will be notified synchronously on the same thread
* that mutates the underlying property, so don't do any long-running
* work on the thread thats notifies the {@link DynamicPropertyListener}.
*
* @param listener
*/
void addListener(DynamicPropertyListener listener);
/**
* Removes a given listener. After remove the given listener will
* not receive events when this property is changed.
*
* @param listener
*/
void removeListener(DynamicPropertyListener listener);
/**
* Returns the current value of this DynamicPropery. For primitive
* types the boxed version is returned (never null).
*
* @return
*/
T getCurrentValue();
/**
* Sets the value of this DynamicProperty. If the underlying
* property is a primitive type then this method throws
* {@link NullPointerException} when passing a null argument. All
* other DynamicPropery types accepts null as a value.
* @param value
*/
void setValue(T value);
}