Add schema and DAO for cursors in cloudsql (#370)

* Add schema for Cursor

* Add CursorDao and CursorDaoTest

* Fix comment on getTld

* Change tld column to scope

* Fix cursorTime to be converted to DateTime internally and other small fixes

* Add a CursorType enum and a createGlobal constructor for Cursor

* Rename flyway file

* Use cursorType from common/Cursor.java and add null checks

core/src/main/java/google/registry/schema/cursor/Cursor.java

@@ -0,0 +1,116 @@
+// 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.schema.cursor;
+
+import static com.google.appengine.api.search.checkers.Preconditions.checkNotNull;
+
+import google.registry.model.ImmutableObject;
+import google.registry.model.UpdateAutoTimestamp;
+import google.registry.model.common.Cursor.CursorType;
+import google.registry.schema.cursor.Cursor.CursorId;
+import google.registry.util.DateTimeUtils;
+import java.io.Serializable;
+import java.time.ZonedDateTime;
+import javax.persistence.Column;
+import javax.persistence.Entity;
+import javax.persistence.EnumType;
+import javax.persistence.Enumerated;
+import javax.persistence.Id;
+import javax.persistence.IdClass;
+import javax.persistence.Table;
+import org.joda.time.DateTime;
+
+/**
+ * Shared entity for date cursors. This uses a compound primary key as defined in {@link CursorId}.
+ */
+@Entity
+@Table
+@IdClass(CursorId.class)
+public class Cursor {
+
+  @Enumerated(EnumType.STRING)
+  @Column(nullable = false)
+  @Id
+  private CursorType type;
+
+  @Column @Id private String scope;
+
+  @Column(nullable = false)
+  private ZonedDateTime cursorTime;
+
+  @Column(nullable = false)
+  private UpdateAutoTimestamp lastUpdateTime = UpdateAutoTimestamp.create(null);
+
+  /** The scope of a global cursor. A global cursor is a cursor that is not specific to one tld. */
+  public static final String GLOBAL = "GLOBAL";
+
+  private Cursor(CursorType type, String scope, DateTime cursorTime) {
+    this.type = type;
+    this.scope = scope;
+    this.cursorTime = DateTimeUtils.toZonedDateTime(cursorTime);
+  }
+
+  // Hibernate requires a default constructor.
+  private Cursor() {}
+
+  /** Constructs a {@link Cursor} object. */
+  public static Cursor create(CursorType type, String scope, DateTime cursorTime) {
+    checkNotNull(
+        scope, "Scope cannot be null. To create a global cursor, use the createGlobal method");
+    return new Cursor(type, scope, cursorTime);
+  }
+
+  /** Constructs a {@link Cursor} object with a {@link GLOBAL} scope. */
+  public static Cursor createGlobal(CursorType type, DateTime cursorTime) {
+    return new Cursor(type, GLOBAL, cursorTime);
+  }
+
+  /** Returns the type of the cursor. */
+  public CursorType getType() {
+    return type;
+  }
+
+  /**
+   * Returns the scope of the cursor. The scope will typically be the tld the cursor is referring
+   * to. If the cursor is a global cursor, the scope will be {@link GLOBAL}.
+   */
+  public String getScope() {
+    return scope;
+  }
+
+  /** Returns the time the cursor is set to. */
+  public DateTime getCursorTime() {
+    return DateTimeUtils.toJodaDateTime(cursorTime);
+  }
+
+  /** Returns the last time the cursor was updated. */
+  public DateTime getLastUpdateTime() {
+    return lastUpdateTime.getTimestamp();
+  }
+
+  static class CursorId extends ImmutableObject implements Serializable {
+
+    public CursorType type;
+
+    public String scope;
+
+    private CursorId() {}
+
+    public CursorId(CursorType type, String scope) {
+      this.type = type;
+      this.scope = scope;
+    }
+  }
+}

core/src/main/java/google/registry/schema/cursor/CursorDao.java

@@ -0,0 +1,70 @@
+// 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.schema.cursor;
+
+import static com.google.appengine.api.search.checkers.Preconditions.checkNotNull;
+import static google.registry.model.transaction.TransactionManagerFactory.jpaTm;
+
+import google.registry.model.common.Cursor.CursorType;
+import google.registry.schema.cursor.Cursor.CursorId;
+import java.util.List;
+
+/** Data access object class for {@link Cursor}. */
+public class CursorDao {
+
+  public static void save(Cursor cursor) {
+    jpaTm()
+        .transact(
+            () -> {
+              jpaTm().getEntityManager().merge(cursor);
+            });
+  }
+
+  public static Cursor load(CursorType type, String scope) {
+    checkNotNull(scope, "The scope of the cursor to load cannot be null");
+    checkNotNull(type, "The type of the cursor to load must be specified");
+    return jpaTm()
+        .transact(() -> jpaTm().getEntityManager().find(Cursor.class, new CursorId(type, scope)));
+  }
+
+  /** If no scope is given, use {@link Cursor.GLOBAL} as the scope. */
+  public static Cursor load(CursorType type) {
+    checkNotNull(type, "The type of the cursor to load must be specified");
+    return load(type, Cursor.GLOBAL);
+  }
+
+  public static List<Cursor> loadAll() {
+    return jpaTm()
+        .transact(
+            () ->
+                jpaTm()
+                    .getEntityManager()
+                    .createQuery("SELECT cursor FROM Cursor cursor", Cursor.class)
+                    .getResultList());
+  }
+
+  public static List<Cursor> loadByType(CursorType type) {
+    checkNotNull(type, "The type of the cursors to load must be specified");
+    return jpaTm()
+        .transact(
+            () ->
+                jpaTm()
+                    .getEntityManager()
+                    .createQuery(
+                        "SELECT cursor FROM Cursor cursor WHERE cursor.type = :type", Cursor.class)
+                    .setParameter("type", type)
+                    .getResultList());
+  }
+}

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

@@ -22,6 +22,7 @@
     <class>google.registry.model.domain.DomainBase</class>
     <class>google.registry.schema.domain.RegistryLock</class>
     <class>google.registry.schema.tmch.ClaimsList</class>
+    <class>google.registry.schema.cursor.Cursor</class>
     <class>google.registry.model.transfer.BaseTransferObject</class>
     <class>google.registry.schema.tld.PremiumList</class>
     <class>google.registry.schema.tld.ReservedList</class>