Add by-repo-id method to RegistryLockDao (#344)

* Add by-repo-id method to RegistryLockDao

When we create new registry lock objects on user request, we will want
to make sure that there are no pending lock/unlock actions on this
domain. In order to do that, we will need to know what lock actions
there have been for this domain.

* Inline the query into a single statement

* whoops

* comments

core/src/main/java/google/registry/model/registry/RegistryLockDao.java

@@ -19,6 +19,7 @@ import static google.registry.model.transaction.TransactionManagerFactory.jpaTm;
 
 import com.google.common.collect.ImmutableList;
 import google.registry.schema.domain.RegistryLock;
+import java.util.Optional;
 import javax.persistence.EntityManager;
 
 /** Data access object for {@link google.registry.schema.domain.RegistryLock}. */
@@ -47,6 +48,7 @@ public final class RegistryLockDao {
             });
   }
 
+  /** Returns all lock objects that this registrar has created. */
   public static ImmutableList<RegistryLock> getByRegistrarId(String registrarId) {
     return jpaTm()
         .transact(
@@ -62,6 +64,26 @@ public final class RegistryLockDao {
                         .getResultList()));
   }
 
+  /**
+   * Returns the most recent lock object for a given repo ID (i.e. a domain) or empty if this domain
+   * hasn't been locked before.
+   */
+  public static Optional<RegistryLock> getMostRecentByRepoId(String repoId) {
+    return jpaTm()
+        .transact(
+            () ->
+                jpaTm()
+                    .getEntityManager()
+                    .createQuery(
+                        "SELECT lock FROM RegistryLock lock WHERE lock.repoId = :repoId"
+                            + " ORDER BY lock.revisionId DESC",
+                        RegistryLock.class)
+                    .setParameter("repoId", repoId)
+                    .setMaxResults(1)
+                    .getResultStream()
+                    .findFirst());
+  }
+
   public static RegistryLock save(RegistryLock registryLock) {
     checkNotNull(registryLock, "Null registry lock cannot be saved");
     return jpaTm().transact(() -> jpaTm().getEntityManager().merge(registryLock));

core/src/test/java/google/registry/model/registry/RegistryLockDaoTest.java

@@ -120,6 +120,26 @@ public final class RegistryLockDaoTest {
     assertThat(RegistryLockDao.getByRegistrarId("nonexistent")).isEmpty();
   }
 
+  @Test
+  public void testLoad_byRepoId() {
+    RegistryLock completedLock =
+        createLock().asBuilder().setCompletionTimestamp(jpaTmRule.getTxnClock().nowUtc()).build();
+    RegistryLockDao.save(completedLock);
+
+    jpaTmRule.getTxnClock().advanceOneMilli();
+    RegistryLock inProgressLock = createLock();
+    RegistryLockDao.save(inProgressLock);
+
+    Optional<RegistryLock> mostRecent = RegistryLockDao.getMostRecentByRepoId("repoId");
+    assertThat(mostRecent.isPresent()).isTrue();
+    assertThat(mostRecent.get().isVerified()).isFalse();
+  }
+
+  @Test
+  public void testLoad_byRepoId_empty() {
+    assertThat(RegistryLockDao.getMostRecentByRepoId("nonexistent").isPresent()).isFalse();
+  }
+
   private RegistryLock createLock() {
     return new RegistryLock.Builder()
         .setRepoId("repoId")