| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You 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 org.apache.tuweni.kv |
| |
| import kotlin.jvm.Throws |
| import kotlinx.coroutines.Dispatchers |
| |
| import java.io.IOException |
| import java.util.function.Function |
| import java.util.function.Supplier |
| import java.util.stream.Stream |
| import javax.persistence.EntityManager |
| import kotlin.coroutines.CoroutineContext |
| |
| class EntityManagerKeyValueStore<K, V> |
| @Throws(IOException::class) |
| constructor( |
| private val entityManagerProvider: () -> EntityManager, |
| private val entityClass: Class<V>, |
| private val idAccessor: (V) -> K, |
| override val coroutineContext: CoroutineContext = Dispatchers.IO |
| ) : KeyValueStore<K, V> { |
| |
| companion object { |
| /** |
| * Open a relational database backed key-value store using a JPA entity manager. |
| * |
| * @param entityManagerProvider The supplier of entity manager to operate. |
| * @return A key-value store. |
| * @throws IOException If an I/O error occurs. |
| */ |
| @JvmStatic |
| @Throws(IOException::class) |
| fun <K, V> open( |
| entityManagerProvider: Supplier<EntityManager>, |
| entityClass: Class<V>, |
| idAccessor: Function<V, K> |
| ) = EntityManagerKeyValueStore<K, V>(entityManagerProvider::get, entityClass, idAccessor::apply) |
| } |
| |
| override suspend fun get(key: K): V? { |
| val em = entityManagerProvider() |
| em.transaction.begin() |
| try { |
| return em.find(entityClass, key) |
| } finally { |
| em.transaction.commit() |
| em.close() |
| } |
| } |
| |
| override suspend fun put(key: K, value: V) { |
| val em = entityManagerProvider() |
| em.transaction.begin() |
| try { |
| em.merge(value) |
| } finally { |
| em.transaction.commit() |
| em.close() |
| } |
| } |
| |
| override suspend fun keys(): Iterable<K> { |
| val em = entityManagerProvider() |
| val query = em.createQuery(em.criteriaBuilder.createQuery(entityClass)) |
| val resultStream: Stream<V> = query.resultStream |
| return Iterable { resultStream.map(idAccessor).iterator() } |
| } |
| |
| override fun close() { |
| } |
| } |