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/*
* Copyright 2006-2010 Amazon Technologies, Inc. or its affiliates.
* Amazon, Amazon.com and Carbonado are trademarks or registered trademarks
* of Amazon Technologies, Inc. or its affiliates. All rights reserved.
*
* 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.
*/
/**
* Support for recording the evolution of a storable's layout, used internally
* by some repositories. This allows storable's to evolve. Enough information
* is recorded in the {@link com.amazon.carbonado.layout.Layout layout} such
* that an older generation can be reconstructed, allowing it to be decoded
* from persistent storage.
*
* <p>A storable generation is different than a storable {@link
* com.amazon.carbonado.Version version}. The version increases with each
* update of an <i>instance</i>, whereas the generation increases when the
* storable type definition changes. The version number is stored with each
* instance, and the generation is stored via the classes in this package.
*
* <p>Whenever a property is added or removed from a storable, the storable
* layout is assigned a new generation value. If the storable layout reverts to
* a previous generation's layout, no new generation value is created. Instead,
* the generation value of the current storable will match the previous
* generation.
*
* @see com.amazon.carbonado.layout.LayoutFactory
*/
package com.amazon.carbonado.layout;
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