archaius-core/src/main/java/com/netflix/config/DynamicPropertyFactory.java
public DynamicDoubleProperty getDoubleProperty(String propName, double defaultValue, final Runnable propertyChangeCallback) {
        checkAndWarn(propName);
        DynamicDoubleProperty property = new DynamicDoubleProperty(propName, defaultValue);
        addCallback(propertyChangeCallback, property);
        return property;
    }
public DynamicDoubleProperty getDoubleProperty(String propName, double defaultValue, final Runnable propertyChangeCallback) {
        checkAndWarn(propName);
        DynamicDoubleProperty property = new DynamicDoubleProperty(propName, defaultValue);
        addCallback(propertyChangeCallback, property);
        return property;
    }
Create a new property whose value is a double and subject to change on-the-fly.

@param propName               property name
@param defaultValue           default value if the property is not defined in underlying configuration
@param propertyChangeCallback a Runnable to be called when the property is changed