chore(spanner): multi use transaction benchmarking (#3075)

* chore(spanner): add multi use RO benchmarking for mutiplexed session

* chore(spanner): code refactor

* chore(spanner): 3 read operation per multi use txn

* chore(spanner): code refactor

* chore(spanner): code refactor

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

* chore(spanner): update dependency version

---------

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: harshachinta

README.md

@@ -57,13 +57,13 @@ implementation 'com.google.cloud:google-cloud-spanner'
 If you are using Gradle without BOM, add this to your dependencies:
 
 ```Groovy
-implementation 'com.google.cloud:google-cloud-spanner:6.65.1'
+implementation 'com.google.cloud:google-cloud-spanner:6.66.0'
 ```
 
 If you are using SBT, add this to your dependencies:
 
 ```Scala
-libraryDependencies += "com.google.cloud" % "google-cloud-spanner" % "6.65.1"
+libraryDependencies += "com.google.cloud" % "google-cloud-spanner" % "6.66.0"
 ```
 <!-- {x-version-update-end} -->
 
@@ -651,7 +651,7 @@ Java is a registered trademark of Oracle and/or its affiliates.
 [kokoro-badge-link-5]: http://storage.googleapis.com/cloud-devrel-public/java/badges/java-spanner/java11.html
 [stability-image]: https://img.shields.io/badge/stability-stable-green
 [maven-version-image]: https://img.shields.io/maven-central/v/com.google.cloud/google-cloud-spanner.svg
-[maven-version-link]: https://central.sonatype.com/artifact/com.google.cloud/google-cloud-spanner/6.65.1
+[maven-version-link]: https://central.sonatype.com/artifact/com.google.cloud/google-cloud-spanner/6.66.0
 [authentication]: https://github.com/googleapis/google-cloud-java#authentication
 [auth-scopes]: https://developers.google.com/identity/protocols/oauth2/scopes
 [predefined-iam-roles]: https://cloud.google.com/iam/docs/understanding-roles#predefined_roles

benchmarks/pom.xml

@@ -92,7 +92,7 @@
     <dependency>
       <groupId>com.google.cloud</groupId>
       <artifactId>google-cloud-spanner</artifactId>
-      <version>6.65.1</version>
+      <version>6.66.0</version>
     </dependency>
     <dependency>
       <groupId>commons-cli</groupId>

benchmarks/src/main/java/com/google/cloud/spanner/benchmark/BenchmarkRunner.java

@@ -22,6 +22,7 @@
 public interface BenchmarkRunner {
   enum TransactionType {
     READ_ONLY_SINGLE_USE,
+    READ_ONLY_MULTI_USE,
     READ_WRITE
   }
 

benchmarks/src/main/java/com/google/cloud/spanner/benchmark/JavaClientRunner.java

@@ -20,6 +20,7 @@
 import com.google.cloud.opentelemetry.trace.TraceExporter;
 import com.google.cloud.spanner.DatabaseClient;
 import com.google.cloud.spanner.DatabaseId;
+import com.google.cloud.spanner.ReadOnlyTransaction;
 import com.google.cloud.spanner.ResultSet;
 import com.google.cloud.spanner.SessionPoolOptions;
 import com.google.cloud.spanner.SessionPoolOptionsHelper;
@@ -161,7 +162,10 @@ private Duration executeTransaction(
     Stopwatch watch = Stopwatch.createStarted();
     switch (transactionType) {
       case READ_ONLY_SINGLE_USE:
-        executeReadOnlyTransaction(client);
+        executeSingleUseReadOnlyTransaction(client);
+        break;
+      case READ_ONLY_MULTI_USE:
+        executeMultiUseReadOnlyTransaction(client);
         break;
       case READ_WRITE:
         executeReadWriteTransaction(client);
@@ -172,7 +176,7 @@ private Duration executeTransaction(
     return elapsedTime;
   }
 
-  private void executeReadOnlyTransaction(DatabaseClient client) {
+  private void executeSingleUseReadOnlyTransaction(DatabaseClient client) {
     try (ResultSet resultSet = client.singleUse().executeQuery(getRandomisedReadStatement())) {
       while (resultSet.next()) {
         for (int i = 0; i < resultSet.getColumnCount(); i++) {
@@ -186,6 +190,34 @@ private void executeReadOnlyTransaction(DatabaseClient client) {
     }
   }
 
+  private void executeMultiUseReadOnlyTransaction(DatabaseClient client) {
+    try (ReadOnlyTransaction transaction = client.readOnlyTransaction()) {
+      ResultSet resultSet = transaction.executeQuery(getRandomisedReadStatement());
+      iterateResultSet(resultSet);
+
+      ResultSet resultSet1 = transaction.executeQuery(getRandomisedReadStatement());
+      iterateResultSet(resultSet1);
+
+      ResultSet resultSet2 = transaction.executeQuery(getRandomisedReadStatement());
+      iterateResultSet(resultSet2);
+
+      ResultSet resultSet3 = transaction.executeQuery(getRandomisedReadStatement());
+      iterateResultSet(resultSet3);
+    }
+  }
+
+  private void iterateResultSet(ResultSet resultSet) {
+    while (resultSet.next()) {
+      for (int i = 0; i < resultSet.getColumnCount(); i++) {
+        if (resultSet.isNull(i)) {
+          numNullValues++;
+        } else {
+          numNonNullValues++;
+        }
+      }
+    }
+  }
+
   private void executeReadWriteTransaction(DatabaseClient client) {
     client
         .readWriteTransaction()