feat: allow Spanner and Datastore Transaction Manager in same project (…

…#1412)

Fixes #944 

Conditional for Spanner is based on missing beans of type SpannerTransactionManager instead of PlatformTransactionManager, this way it always gets created if Spanner libs are pulled in 

Conditional for Datastore is based on missing beans of type DatastoreTransactionManager instead of PlatformTransactionManager, this way it gets created if Datastore libs are pulled in.

It is the user's responsibility to designate the transaction's right transaction manager:

```
@transactional(transactionManager = "spannerTransactionManager")
```

```
@transactional(transactionManager = "datastoreTransactionManager")
```

docs/src/main/asciidoc/datastore.adoc

@@ -854,6 +854,13 @@ This feature requires a bean of `DatastoreTransactionManager`, which is provided
 If a method annotated with `@Transactional` calls another method also annotated, then both methods will work within the same transaction.
 `performTransaction` cannot be used in `@Transactional` annotated methods because Cloud Datastore does not support transactions within transactions.
 
+Other Google Cloud database-related integrations like Spanner and Firestore can introduce `PlatformTransactionManager` beans, and can interfere with Datastore Transaction Manager. To disambiguate, explicitly specify the name of the transaction manager bean for such `@Transactional` methods. Example:
+
+[source,java]
+----
+@Transactional(transactionManager = "datastoreTransactionManager")
+----
+
 ==== Read-Write Support for Maps
 
 You can work with Maps of type `Map<String, ?>` instead of with entity objects by directly reading and writing them to and from Cloud Datastore.

docs/src/main/asciidoc/spanner.adoc

@@ -956,6 +956,14 @@ This feature requires a bean of `SpannerTransactionManager`, which is provided w
 If a method annotated with `@Transactional` calls another method also annotated, then both methods will work within the same transaction.
 `performReadOnlyTransaction` and `performReadWriteTransaction` cannot be used in `@Transactional` annotated methods because Cloud Spanner does not support transactions within transactions.
 
+Other Google Cloud database-related integrations like Spanner and Firestore can introduce `PlatformTransactionManager` beans, and can interfere with Datastore Transaction Manager. To disambiguate, explicitly specify the name of the transaction manager bean for such `@Transactional` methods. Example:
+
+[source,java]
+----
+@Transactional(transactionManager = "spannerTransactionManager")
+----
+
+
 ==== DML Statements
 
 `SpannerTemplate` supports https://cloud.google.com/spanner/docs/dml-tasks:[DML] `Statements`.

docs/src/main/md/datastore.md

@@ -944,6 +944,15 @@ same transaction. `performTransaction` cannot be used in
 `@Transactional` annotated methods because Cloud Datastore does not
 support transactions within transactions.
 
+Other Google Cloud database-related integrations like Spanner and Firestore can
+introduce `PlatformTransactionManager` beans, and can interfere with Datastore
+Transaction Manager. To disambiguate, explicitly specify the name of the
+transaction manager bean for such `@Transactional` methods. Example:
+
+```java
+@Transactional(transactionManager = "datastoreTransactionManager")
+```
+
 #### Read-Write Support for Maps
 
 You can work with Maps of type `Map<String, ?>` instead of with entity

docs/src/main/md/spanner.md

@@ -1123,6 +1123,15 @@ same transaction. `performReadOnlyTransaction` and
 annotated methods because Cloud Spanner does not support transactions
 within transactions.
 
+Other Google Cloud database-related integrations like Spanner and Firestore can
+introduce `PlatformTransactionManager` beans, and can interfere with Datastore
+Transaction Manager. To disambiguate, explicitly specify the name of the
+transaction manager bean for such `@Transactional` methods. Example:
+
+```java
+@Transactional(transactionManager = "spannerTransactionManager")
+```
+
 #### DML Statements
 
 `SpannerTemplate` supports

spring-cloud-gcp-autoconfigure/src/main/java/com/google/cloud/spring/autoconfigure/datastore/DatastoreTransactionManagerAutoConfiguration.java

@@ -26,7 +26,6 @@
 import org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration;
 import org.springframework.boot.autoconfigure.transaction.TransactionManagerCustomizers;
 import org.springframework.context.annotation.Bean;
-import org.springframework.transaction.PlatformTransactionManager;
 
 /**
  * Auto-configuration for {@link DatastoreTransactionManager}.
@@ -59,7 +58,7 @@ static class DatastoreTransactionManagerConfiguration {
     }
 
     @Bean
-    @ConditionalOnMissingBean(PlatformTransactionManager.class)
+    @ConditionalOnMissingBean
     public DatastoreTransactionManager datastoreTransactionManager() {
       DatastoreTransactionManager transactionManager =
           new DatastoreTransactionManager(this.datastore);

spring-cloud-gcp-autoconfigure/src/main/java/com/google/cloud/spring/autoconfigure/spanner/SpannerTransactionManagerAutoConfiguration.java

@@ -28,7 +28,6 @@
 import org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration;
 import org.springframework.boot.autoconfigure.transaction.TransactionManagerCustomizers;
 import org.springframework.context.annotation.Bean;
-import org.springframework.transaction.PlatformTransactionManager;
 
 /**
  * Auto-configuration for {@link SpannerTransactionManager}.
@@ -61,7 +60,7 @@ static class DatabaseClientTransactionManagerConfiguration {
     }
 
     @Bean
-    @ConditionalOnMissingBean(PlatformTransactionManager.class)
+    @ConditionalOnMissingBean
     public SpannerTransactionManager spannerTransactionManager() {
       SpannerTransactionManager transactionManager =
           new SpannerTransactionManager(this.databaseClientProvider);

spring-cloud-gcp-samples/spring-cloud-gcp-data-multi-sample/README.adoc

@@ -1,6 +1,7 @@
 = Spring Framework on Google Cloud Cloud Spanner and Datastore Combined Usage Example
 
 This code sample demonstrates how to use both link:../../spring-cloud-gcp-starters/spring-cloud-gcp-starter-data-spanner[Spring Data Cloud Spanner] and link:../../spring-cloud-gcp-starters/spring-cloud-gcp-starter-data-datastore[Spring Data Cloud Datastore] using the Spring Data Cloud Datastore modules in a single Spring application.
+This sample also demonstrates usage of transactions with both modules.
 
 == Running the example
 

spring-cloud-gcp-samples/spring-cloud-gcp-data-multi-sample/src/main/java/com/example/MultipleDataModuleExample.java

@@ -26,11 +26,11 @@
 @SpringBootApplication
 public class MultipleDataModuleExample {
 
-  // A Spring Data Datastore repository
-  @Autowired PersonRepository personRepository;
+  // Internally uses a Spring Data Datastore repository
+  @Autowired private PersonService personService;
 
-  // A Spring Data Cloud Spanner repository
-  @Autowired TraderRepository traderRepository;
+  // Internally uses a Spring Data Cloud Spanner repository
+  @Autowired private TraderService traderService;
 
   public static void main(String[] args) {
     SpringApplication.run(MultipleDataModuleExample.class, args);
@@ -41,19 +41,19 @@ ApplicationRunner applicationRunner() {
     return args -> {
       System.out.println("Deleting all entities.");
 
-      this.personRepository.deleteAll();
-      this.traderRepository.deleteAll();
+      this.personService.deleteAll();
+      this.traderService.deleteAll();
 
-      System.out.println("The number of Person entities is now: " + this.personRepository.count());
-      System.out.println("The number of Trader entities is now: " + this.traderRepository.count());
+      System.out.println("The number of Person entities is now: " + this.personService.count());
+      System.out.println("The number of Trader entities is now: " + this.traderService.count());
 
       System.out.println("Saving one entity with each repository.");
 
-      this.traderRepository.save(new Trader("id1", "trader", "one"));
-      this.personRepository.save(new Person(1L, "person1"));
+      this.traderService.save(new Trader("id1", "trader", "one"));
+      this.personService.save(new Person(1L, "person1"));
 
-      System.out.println("The number of Person entities is now: " + this.personRepository.count());
-      System.out.println("The number of Trader entities is now: " + this.traderRepository.count());
+      System.out.println("The number of Person entities is now: " + this.personService.count());
+      System.out.println("The number of Trader entities is now: " + this.traderService.count());
     };
   }
 }

spring-cloud-gcp-samples/spring-cloud-gcp-data-multi-sample/src/main/java/com/example/PersonService.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2023 Google LLC
+ *
+ * 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
+ *
+ *      https://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 com.example;
+
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+@Service
+@Transactional(transactionManager = "spannerTransactionManager")
+public class PersonService {
+
+  private final PersonRepository personRepository;
+
+  public PersonService(PersonRepository personRepository) {
+    this.personRepository = personRepository;
+  }
+
+  public Person save(Person person) {
+    return this.personRepository.save(person);
+  }
+
+  public void deleteAll() {
+    this.personRepository.deleteAll();
+  }
+
+  public Long count() {
+    return this.personRepository.count();
+  }
+}

spring-cloud-gcp-samples/spring-cloud-gcp-data-multi-sample/src/main/java/com/example/TraderService.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2023 Google LLC
+ *
+ * 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
+ *
+ *      https://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 com.example;
+
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+@Service
+@Transactional(transactionManager = "datastoreTransactionManager")
+public class TraderService {
+
+  private final TraderRepository traderRepository;
+
+  public TraderService(TraderRepository traderRepository) {
+    this.traderRepository = traderRepository;
+  }
+
+  public Trader save(Trader trader) {
+    return this.traderRepository.save(trader);
+  }
+
+  public void deleteAll() {
+    this.traderRepository.deleteAll();
+  }
+
+  public Long count() {
+    return this.traderRepository.count();
+  }
+}