Update the persist service to ignore multiple start/stop calls, so it matches its javadoc. Fixes #1214, fixes #972, fixes #598.

PiperOrigin-RevId: 525538767

Author: sameb

extensions/persist/src/com/google/inject/persist/jpa/JpaPersistService.java

@@ -103,7 +103,9 @@ synchronized void start(EntityManagerFactory emFactory) {
 
   @Override
   public synchronized void start() {
-    Preconditions.checkState(null == emFactory, "Persistence service was already initialized.");
+    if (null != emFactory) {
+      return;
+    }
 
     if (null != persistenceProperties) {
       this.emFactory =
@@ -115,8 +117,9 @@ public synchronized void start() {
 
   @Override
   public synchronized void stop() {
-    Preconditions.checkState(emFactory.isOpen(), "Persistence service was already shut down.");
-    emFactory.close();
+    if (null != emFactory && emFactory.isOpen()) {
+      emFactory.close();
+    }
   }
 
   @Singleton

extensions/persist/test/com/google/inject/persist/jpa/JpaWorkManagerTest.java

@@ -29,7 +29,9 @@
 import junit.framework.TestCase;
 import org.hibernate.HibernateException;
 
-/** @author Dhanji R. Prasanna ([email protected]) */
+/**
+ * @author Dhanji R. Prasanna ([email protected])
+ */
 
 public class JpaWorkManagerTest extends TestCase {
   private Injector injector;
@@ -41,9 +43,6 @@ public class JpaWorkManagerTest extends TestCase {
   @Override
   public void setUp() {
     injector = Guice.createInjector(new JpaPersistModule("testUnit"));
-
-    //startup persistence
-    injector.getInstance(PersistService.class).start();
   }
 
   @Override
@@ -56,6 +55,7 @@ public void tearDown() {
   }
 
   public void testWorkManagerInSession() {
+    injector.getInstance(PersistService.class).start();
     injector.getInstance(UnitOfWork.class).begin();
     try {
       injector.getInstance(TransactionalObject.class).runOperationInTxn();
@@ -89,15 +89,24 @@ public void testWorkManagerInSession() {
     }
   }
 
+  public void testStartMoreThanOnce() {
+    injector.getInstance(PersistService.class).start();
+    // No exception is thrown on subsequent start.
+    injector.getInstance(PersistService.class).start();
+  }
+
   public void testCloseMoreThanOnce() {
+    injector.getInstance(PersistService.class).start();
+    injector.getInstance(PersistService.class).stop();
+    // No exception is thrown on subsequent stop.
     injector.getInstance(PersistService.class).stop();
+  }
 
-    try {
-      injector.getInstance(PersistService.class).stop();
-      fail();
-    } catch (IllegalStateException e) {
-      // Ignored.
-    }
+  public void testCloseWithoutStart() {
+    // No exception.
+    injector.getInstance(PersistService.class).stop();
+    // (but also start it so we can have one tearDown that unconditionally stops started things)
+    injector.getInstance(PersistService.class).start();
   }
 
   public static class TransactionalObject {