Set up database connection pool

core/build.gradle

@@ -221,6 +221,7 @@ dependencies {
   testCompile deps['org.seleniumhq.selenium:selenium-chrome-driver']
   testCompile deps['org.seleniumhq.selenium:selenium-java']
   testCompile deps['org.seleniumhq.selenium:selenium-remote-driver']
+  testCompile deps['org.testcontainers:postgresql']
   testCompile deps['org.testcontainers:selenium']
   compile deps['xerces:xmlParserAPIs']
   compile deps['xpp3:xpp3']

core/src/main/java/google/registry/config/RegistryConfig.java

@@ -1465,6 +1465,51 @@ public static Duration getBaseOfyRetryDuration() {
     return Duration.millis(CONFIG_SETTINGS.get().datastore.baseOfyRetryMillis);
   }
 
+  /** Returns the JDBC driver class name. */
+  public static String getDriverClassName() {
+    return CONFIG_SETTINGS.get().hibernate.driverClassName;
+  }
+
+  /** Returns the default database transaction isolation. */
+  public static String getHibernateConnectionIsolation() {
+    return CONFIG_SETTINGS.get().hibernate.connectionIsolation;
+  }
+
+  /** Returns true if hibernate.show_sql is enabled. */
+  public static String getHibernateShowSql() {
+    return CONFIG_SETTINGS.get().hibernate.showSql;
+  }
+
+  /** Returns true if schema modification is allowed. */
+  public static String getHibernateHbm2ddlAuto() {
+    return CONFIG_SETTINGS.get().hibernate.hbm2ddlAuto;
+  }
+
+  /** Returns the class name of the connection pool provider. */
+  public static String getHibernateConnectionProviderClass() {
+    return CONFIG_SETTINGS.get().hibernate.connectionProviderClass;
+  }
+
+  /** Returns the connection timeout for HikariCP. */
+  public static String getHibernateHikariConnectionTimeout() {
+    return CONFIG_SETTINGS.get().hibernate.hikariConnectionTimeout;
+  }
+
+  /** Returns the minimum idle connections for HikariCP. */
+  public static String getHibernateHikariMinimumIdle() {
+    return CONFIG_SETTINGS.get().hibernate.hikariMinimumIdle;
+  }
+
+  /** Returns the maximum pool size for HikariCP. */
+  public static String getHibernateHikariMaximumPoolSize() {
+    return CONFIG_SETTINGS.get().hibernate.hikariMaximumPoolSize;
+  }
+
+  /** Returns the idle timeout for HikariCP. */
+  public static String getHibernateHikariIdleTimeout() {
+    return CONFIG_SETTINGS.get().hibernate.hikariIdleTimeout;
+  }
+
   /** Returns the roid suffix to be used for the roids of all contacts and hosts. */
   public static String getContactAndHostRoidSuffix() {
     return CONFIG_SETTINGS.get().registryPolicy.contactAndHostRoidSuffix;

core/src/main/java/google/registry/config/RegistryConfigSettings.java

@@ -25,6 +25,7 @@ public class RegistryConfigSettings {
   public CredentialOAuth credentialOAuth;
   public RegistryPolicy registryPolicy;
   public Datastore datastore;
+  public Hibernate hibernate;
   public CloudDns cloudDns;
   public Caching caching;
   public IcannReporting icannReporting;
@@ -105,6 +106,19 @@ public static class Datastore {
     public int baseOfyRetryMillis;
   }
 
+  /** Configuration for Hibernate. */
+  public static class Hibernate {
+    public String connectionIsolation;
+    public String showSql;
+    public String hbm2ddlAuto;
+    public String driverClassName;
+    public String connectionProviderClass;
+    public String hikariConnectionTimeout;
+    public String hikariMinimumIdle;
+    public String hikariMaximumPoolSize;
+    public String hikariIdleTimeout;
+  }
+
   /** Configuration for Apache Beam (Cloud Dataflow). */
   public static class Beam {
     public String defaultJobZone;

core/src/main/java/google/registry/config/files/default-config.yaml

@@ -191,6 +191,31 @@ datastore:
   # doubles after each failure).
   baseOfyRetryMillis: 100
 
+hibernate:
+  # Make 'SERIALIZABLE' the default isolation level to ensure correctness.
+  #
+  #	Entities that are never involved in multi-table transactions may use optimistic
+  #	locks and a less strict isolation level. We may lower individual transaction's
+  #	isolation level using a framework-dependent method.
+  #
+  #	Alternatively, if a use case calls for, we may also use a lower isolation level
+  # but lock tables explicitly, either using framework-dependent API, or execute
+  # "select table for update" statements directly.
+  connectionIsolation: TRANSACTION_SERIALIZABLE
+  # Whether to log all SQL queries. Overridable at runtime.
+  showSql: false
+  # Never modify the schema. May use 'none' or 'validate'
+  hbm2ddlAuto: none
+  # JDBC driver class name for PostgreSQL
+  driverClassName: org.postgresql.Driver
+
+  # Connection pool configurations.
+  connectionProviderClass: org.hibernate.hikaricp.internal.HikariCPConnectionProvider
+  hikariConnectionTimeout: 20000
+  hikariMinimumIdle: 0
+  hikariMaximumPoolSize: 20
+  hikariIdleTimeout: 300000
+
 cloudDns:
   # Set both properties to null in Production.
   # The root url for the Cloud DNS API.  Set this to a non-null value to

core/src/main/java/google/registry/model/transaction/EntityManagerFactoryProvider.java

@@ -0,0 +1,65 @@
+// Copyright 2019 The Nomulus Authors. 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.
+
+package google.registry.model.transaction;
+
+import static google.registry.config.RegistryConfig.getDriverClassName;
+import static google.registry.config.RegistryConfig.getHibernateConnectionIsolation;
+import static google.registry.config.RegistryConfig.getHibernateConnectionProviderClass;
+import static google.registry.config.RegistryConfig.getHibernateHbm2ddlAuto;
+import static google.registry.config.RegistryConfig.getHibernateHikariConnectionTimeout;
+import static google.registry.config.RegistryConfig.getHibernateHikariIdleTimeout;
+import static google.registry.config.RegistryConfig.getHibernateHikariMaximumPoolSize;
+import static google.registry.config.RegistryConfig.getHibernateHikariMinimumIdle;
+import static google.registry.config.RegistryConfig.getHibernateShowSql;
+
+import com.google.common.collect.ImmutableMap;
+import javax.persistence.EntityManagerFactory;
+import javax.persistence.Persistence;
+import org.hibernate.cfg.Environment;
+
+/** Factory class to provide {@link EntityManagerFactory} instance. */
+public class EntityManagerFactoryProvider {
+  // This name must be same to the one defined in persistence.xml.
+  public static final String PERSISTENCE_UNIT_NAME = "nomulus";
+  public static final String HIKARI_CONNECTION_TIMEOUT = "hibernate.hikari.connectionTimeout";
+  public static final String HIKARI_MINIMUM_IDLE = "hibernate.hikari.minimumIdle";
+  public static final String HIKARI_MAXIMUM_POOL_SIZE = "hibernate.hikari.maximumPoolSize";
+  public static final String HIKARI_IDLE_TIMEOUT = "hibernate.hikari.idleTimeout";
+
+  private static ImmutableMap<String, String> getDefaultProperties() {
+    ImmutableMap.Builder<String, String> properties = ImmutableMap.builder();
+    properties.put(Environment.DRIVER, getDriverClassName());
+    properties.put(Environment.ISOLATION, getHibernateConnectionIsolation());
+    properties.put(Environment.SHOW_SQL, getHibernateShowSql());
+    properties.put(Environment.HBM2DDL_AUTO, getHibernateHbm2ddlAuto());
+    properties.put(Environment.CONNECTION_PROVIDER, getHibernateConnectionProviderClass());
+    properties.put(HIKARI_CONNECTION_TIMEOUT, getHibernateHikariConnectionTimeout());
+    properties.put(HIKARI_MINIMUM_IDLE, getHibernateHikariMinimumIdle());
+    properties.put(HIKARI_MAXIMUM_POOL_SIZE, getHibernateHikariMaximumPoolSize());
+    properties.put(HIKARI_IDLE_TIMEOUT, getHibernateHikariIdleTimeout());
+    return properties.build();
+  }
+
+  /** Constructs the {@link EntityManagerFactory} instance. */
+  public static EntityManagerFactory create(String jdbcUrl, String username, String password) {
+    ImmutableMap.Builder<String, String> properties = ImmutableMap.builder();
+    properties.putAll(getDefaultProperties());
+    properties.put(Environment.URL, jdbcUrl);
+    properties.put(Environment.USER, username);
+    properties.put(Environment.PASS, password);
+    return Persistence.createEntityManagerFactory(PERSISTENCE_UNIT_NAME, properties.build());
+  }
+
+}

core/src/main/resources/META-INF/persistence.xml

@@ -0,0 +1,27 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence
+          http://xmlns.jcp.org/xml/ns/persistence/persistence_2_2.xsd"
+    version="2.2">
+  <persistence-unit name="nomulus" transaction-type="RESOURCE_LOCAL">
+    <description>
+      Persistence unit for the Nomulus Cloud SQL database.
+    </description>
+    <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
+
+    <!--
+      All JPA entities must be enumerated here. JPA does not support auto detection.
+
+      Note that Hibernate's auto detection functionality (hibernate.archive.autodection)
+      does not meet our needs. It only scans archives, not the 'classes' folders. So we
+      are left with two options:
+      *  Move tests to another (sub)project. This is not a big problem, but feels unnatural.
+      *  Use Hibernate's ServiceRegistry for bootstrapping (not JPA-compliant)
+    -->
+    <!-- <class>google.registry.schema.tmch.ClaimsList</class> -->
+
+    <!-- TODO(weiminyu): check out application-layer validation. -->
+    <validation-mode>NONE</validation-mode>
+  </persistence-unit>
+</persistence>

core/src/test/java/google/registry/model/transaction/EntityManagerFactoryProviderTest.java

@@ -0,0 +1,58 @@
+// Copyright 2019 The Nomulus Authors. 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.
+
+package google.registry.model.transaction;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import javax.persistence.EntityManager;
+import javax.persistence.EntityManagerFactory;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+import org.testcontainers.containers.PostgreSQLContainer;
+
+/** Unit tests for {@link EntityManagerFactoryProvider}. */
+@RunWith(JUnit4.class)
+public class EntityManagerFactoryProviderTest {
+  @Rule
+  public PostgreSQLContainer database = new PostgreSQLContainer();
+
+  private EntityManagerFactory emf;
+
+  @Before
+  public void init() {
+    emf = EntityManagerFactoryProvider.create(
+        database.getJdbcUrl(),
+        database.getUsername(),
+        database.getPassword()
+    );
+  }
+
+  @After
+  public void destroy() {
+    emf.close();
+    emf = null;
+  }
+
+  @Test
+  public void testConnectToDatabase_success() {
+    EntityManager em = emf.createEntityManager();
+    assertThat(em.isOpen()).isTrue();
+    em.close();
+  }
+}

dependencies.gradle

@@ -125,6 +125,7 @@ ext {
       'org.seleniumhq.selenium:selenium-chrome-driver:3.141.59',
       'org.seleniumhq.selenium:selenium-java:3.141.59',
       'org.seleniumhq.selenium:selenium-remote-driver:3.141.59',
+      'org.testcontainers:postgresql:1.11.3',
       'org.testcontainers:selenium:1.10.7',
       'org.yaml:snakeyaml:1.17',
       'xerces:xmlParserAPIs:2.6.2',