| // Copyright 2010 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.gwtorm.nosql.generic; |
| |
| import com.google.gwtorm.nosql.NoSqlDatabase; |
| import com.google.gwtorm.nosql.NoSqlSchema; |
| import com.google.gwtorm.server.OrmException; |
| import com.google.gwtorm.server.Schema; |
| import java.util.concurrent.TimeUnit; |
| |
| /** |
| * Base class for generic NoSQL typed databases. |
| * |
| * <p>The generic types provide basic NoSQL implementation assuming a handful of primitive |
| * operations are available inside of the implementation's extension of {@link GenericSchema}. All |
| * relations are stored within the same key space, using the relation name as a prefix for the row's |
| * primary or secondary key. |
| * |
| * <p>Applications should use the database class to create instances of their Schema extension |
| * interface, and thus open and connect to the data store. |
| * |
| * <p>Creating a new database instance is expensive, due to the type analysis and code generation |
| * performed to implement the Schema and Access interfaces. Applications should create and cache |
| * their database instance for the life of the application. |
| * |
| * <p>Database instances are thread-safe, but returned Schema instances are not. |
| * |
| * <p>This class must be further extended by the NoSQL implementation to configure the connectivity |
| * with the data store and supply the correct subclass of {@link NoSqlSchema} that knows how to |
| * interact with the data store. |
| * |
| * @param <T> type of the application's Schema. |
| * @param <S> type of the implementation's base for Schema implementations. |
| * @param <A> type of the implementation's base for Access implementations. |
| */ |
| @SuppressWarnings("rawtypes") |
| public abstract class GenericDatabase< |
| T extends Schema, S extends GenericSchema, A extends GenericAccess> |
| extends NoSqlDatabase<T, S, A> { |
| private static final long DEFAULT_FOSSIL_AGE = TimeUnit.MILLISECONDS.convert(5, TimeUnit.MINUTES); |
| |
| /** |
| * Initialize a new database and generate the implementation. |
| * |
| * @param schemaBaseType class that the generated Schema implementation should extend in order to |
| * provide data store connectivity. |
| * @param accessBaseType class that the generated Access implementations should extend in order to |
| * provide single-relation access for each schema instance. |
| * @param appSchema the application schema interface that must be implemented and constructed on |
| * demand. |
| * @throws OrmException the schema cannot be created because of an annotation error in the |
| * interface definitions. |
| */ |
| protected GenericDatabase( |
| final Class<S> schemaBaseType, final Class<A> accessBaseType, final Class<T> appSchema) |
| throws OrmException { |
| super(schemaBaseType, accessBaseType, appSchema); |
| } |
| |
| /** |
| * Default number of milliseconds a transaction can appear to be open. |
| * |
| * <p>Secondary index rows that don't match their primary data object and that are older than this |
| * age are removed from the system during a scan. |
| * |
| * @return milliseconds before considering a fossil index record is garbage and should be pruned. |
| * By default, 5 minutes. |
| */ |
| public long getMaxFossilAge() { |
| return DEFAULT_FOSSIL_AGE; |
| } |
| } |