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/*
* Copyright (c) 2013 Google 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.
*/
package com.google.api.client.util.store;
import java.io.IOException;
import java.io.Serializable;
/**
* Factory for a store that manages serializable data, where the key is a string and the value is a
* {@link Serializable} object.
*
*
* Users should keep a single globally shared instance of the data store factory. Otherwise, some
* implementations may not share the internal copies of the data, and you'll end up with multiple
* data stores by the same IDs, each living in a separate implementation. Some implementations may
* also have some overhead, or may have caching implemented, and so multiple instances may defeat
* that. Finally, have multiple instances may defeat the thread-safety guarantee for some
* implementations.
*
*
*
* Implementation should store the data in a persistent storage such as a database. Implementation
* should be thread-safe. Read the JavaDoc of the implementation for those details.
*
*
* @see MemoryDataStoreFactory
* @see FileDataStoreFactory
* @author Yaniv Inbar
* @since 1.16
*/
public interface DataStoreFactory {
/**
* Returns a type-specific data store based on the given unique ID.
*
*
* If a data store by that ID does not already exist, it should be created now, stored for later
* access, and returned. Otherwise, if there is already a data store by that ID, it should be
* returned. The {@link DataStore#getId()} must match the {@code id} parameter from this method.
*
*
*
* The ID must be at least 1 and at most 30 characters long, and must contain only alphanumeric or
* underscore characters.
*
*
* @param id unique ID to refer to typed data store
* @param serializable type of the mapped value
*/
DataStore getDataStore(String id) throws IOException;
}