Lazily instantiate jpaTm (#491)

* Lazily load jpaTm

This fixes an exception we were seeing in production where commands that only
implemented CommandWithRemoteApi (and that had nothing to do with Cloud SQL)
were nevertheless trying to initialize a JPA TM instance, and then failing.
That stacktrace looked like:

com.google.api.client.http.HttpResponseException: 400 Bad Request
{
  "error": "invalid_grant",
  "error_description": "Bad Request"
}
at com.google.api.client.http.HttpRequest.execute(HttpRequest.java:1113)
at com.google.auth.oauth2.UserCredentials.refreshAccessToken(UserCredentials.java:193)
at com.google.auth.oauth2.OAuth2Credentials.refresh(OAuth2Credentials.java:165)
at com.google.auth.oauth2.OAuth2Credentials.getRequestMetadata(OAuth2Credentials.java:151)
at com.google.auth.http.HttpCredentialsAdapter.initialize(HttpCredentialsAdapter.java:96)
at com.google.api.client.http.HttpRequestFactory.buildRequest(HttpRequestFactory.java:88)
at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.buildHttpRequest(AbstractGoogleClientRequest.java:423)
at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.executeUnparsed(AbstractGoogleClientRequest.java:542)
at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.executeUnparsed(AbstractGoogleClientRequest.java:475)
at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.execute(AbstractGoogleClientRequest.java:592)
at google.registry.keyring.kms.KmsConnectionImpl.attemptDecrypt(KmsConnectionImpl.java:163)
at google.registry.keyring.kms.KmsConnectionImpl.lambda$decrypt$0(KmsConnectionImpl.java:148)
at google.registry.util.Retrier.callWithRetry(Retrier.java:153)
at google.registry.util.Retrier.callWithRetry(Retrier.java:130)
at google.registry.util.Retrier.callWithRetry(Retrier.java:95)
at google.registry.keyring.kms.KmsConnectionImpl.decrypt(KmsConnectionImpl.java:147)
at google.registry.keyring.kms.KmsKeyring.getDecryptedData(KmsKeyring.java:209)
at google.registry.keyring.kms.KmsKeyring.getString(KmsKeyring.java:178)
at google.registry.keyring.kms.KmsKeyring.getToolsCloudSqlPassword(KmsKeyring.java:100)
at google.registry.persistence.PersistenceModule.providesNomulusToolJpaTm(PersistenceModule.java:124)
at google.registry.persistence.PersistenceModule_ProvidesNomulusToolJpaTmFactory.proxyProvidesNomulusToolJpaTm(PersistenceModule_ProvidesNomulusToolJpaTmFactory.java:61)
at google.registry.persistence.PersistenceModule_ProvidesNomulusToolJpaTmFactory.get(PersistenceModule_ProvidesNomulusToolJpaTmFactory.java:39)
at google.registry.persistence.PersistenceModule_ProvidesNomulusToolJpaTmFactory.get(PersistenceModule_ProvidesNomulusToolJpaTmFactory.java:12)
at dagger.internal.DoubleCheck.get(DoubleCheck.java:47)
at google.registry.persistence.DaggerPersistenceComponent.nomulusToolJpaTransactionManager(DaggerPersistenceComponent.java:168)
at google.registry.persistence.transaction.TransactionManagerFactory.createJpaTransactionManager(TransactionManagerFactory.java:38)
at google.registry.persistence.transaction.TransactionManagerFactory.<clinit>(TransactionManagerFactory.java:29)
at google.registry.model.registry.Registries.lambda$createFreshCache$2(Registries.java:60)
at com.google.common.base.Suppliers$ExpiringMemoizingSupplier.get(Suppliers.java:243)
at google.registry.model.registry.Registries.getTlds(Registries.java:85)
at google.registry.model.registry.Registries.assertTldsExist(Registries.java:112)
at google.registry.tools.CountDomainsCommand.run(CountDomainsCommand.java:41)
at google.registry.tools.RegistryCli.runCommand(RegistryCli.java:243)
at google.registry.tools.RegistryCli.run(RegistryCli.java:168)
at google.registry.tools.RegistryTool.main(RegistryTool.java:127)

The TL;DR is that RegistryCli was over-eagerly creating the jpaTm, because
there's no reason the Registries cache (which is Datastore-only) should ever
need it, but because this cache is using the Datastore transaction manager, the
other one was being created too.

core/src/main/java/google/registry/persistence/transaction/TransactionManagerFactory.java

@@ -17,16 +17,23 @@ package google.registry.persistence.transaction;
 import com.google.appengine.api.utils.SystemProperty;
 import com.google.appengine.api.utils.SystemProperty.Environment.Value;
 import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Suppliers;
 import google.registry.model.ofy.DatastoreTransactionManager;
 import google.registry.persistence.DaggerPersistenceComponent;
 import google.registry.tools.RegistryToolEnvironment;
+import google.registry.util.NonFinalForTesting;
+import java.util.function.Supplier;
 
 /** Factory class to create {@link TransactionManager} instance. */
 // TODO: Rename this to PersistenceFactory and move to persistence package.
 public class TransactionManagerFactory {
 
   private static final TransactionManager TM = createTransactionManager();
-  @VisibleForTesting static JpaTransactionManager jpaTm = createJpaTransactionManager();
+
+  /** Supplier for jpaTm so that it is initialized only once, upon first usage. */
+  @NonFinalForTesting
+  private static Supplier<JpaTransactionManager> jpaTm =
+      Suppliers.memoize(TransactionManagerFactory::createJpaTransactionManager);
 
   private TransactionManagerFactory() {}
 
@@ -68,6 +75,11 @@ public class TransactionManagerFactory {
 
   /** Returns {@link JpaTransactionManager} instance. */
   public static JpaTransactionManager jpaTm() {
-    return jpaTm;
+    return jpaTm.get();
+  }
+
+  @VisibleForTesting
+  static void setJpaTmForTesting(JpaTransactionManager newJpaTm) {
+    jpaTm = Suppliers.ofInstance(newJpaTm);
   }
 }

core/src/main/java/google/registry/tools/RegistryCli.java

@@ -237,7 +237,7 @@ final class RegistryCli implements AutoCloseable, CommandRunner {
       // Enable Cloud SQL for command that needs remote API as they will very likely use
       // Cloud SQL after the database migration. Note that the DB password is stored in Datastore
       // and it is already initialized above.
-      RegistryToolEnvironment.get().enableJpaTm();
+      RegistryToolEnvironment.enableJpaTm();
     }
 
     command.run();

core/src/test/java/google/registry/persistence/transaction/JpaTransactionManagerRule.java

@@ -132,13 +132,13 @@ abstract class JpaTransactionManagerRule extends ExternalResource {
             properties,
             extraEntityClasses);
     JpaTransactionManagerImpl txnManager = new JpaTransactionManagerImpl(emf, clock);
-    cachedTm = TransactionManagerFactory.jpaTm;
+    cachedTm = TransactionManagerFactory.jpaTm();
-    TransactionManagerFactory.jpaTm = txnManager;
+    TransactionManagerFactory.setJpaTmForTesting(txnManager);
   }
 
   @Override
   public void after() {
-    TransactionManagerFactory.jpaTm = cachedTm;
+    TransactionManagerFactory.setJpaTmForTesting(cachedTm);
     if (emf != null) {
       emf.close();
       emf = null;