Add microbenchmark for stateless queries.

This adds a Java Microbenchmark Harness (JMH) benchmark that compares
a small query with and without job creation.

Documentation on running the microbenchmark can be found in its
class' Javadoc.

A small query with job creation takes almost twice as long as one
with optional job creation.

pom.xml

@@ -142,6 +142,18 @@
       <version>1.19.0</version>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>org.openjdk.jmh</groupId>
+      <artifactId>jmh-core</artifactId>
+      <version>1.37</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.openjdk.jmh</groupId>
+      <artifactId>jmh-generator-annprocess</artifactId>
+      <version>1.37</version>
+      <scope>test</scope>
+    </dependency>
     <!-- END TEST DEPENDENCIES -->
   </dependencies>
   <build>
@@ -221,8 +233,29 @@
           </java>
         </configuration>
       </plugin>
+      <plugin>
+        <groupId>org.codehaus.mojo</groupId>
+        <artifactId>exec-maven-plugin</artifactId>
+        <version>3.1.0</version>
+        <executions>
+          <execution>
+            <id>benchmark-stateless-small</id>
+            <goals><goal>exec</goal></goals>
+            <configuration>
+              <classpathScope>test</classpathScope>
+              <executable>java</executable>
+              <arguments>
+                <argument>-classpath</argument>
+                <classpath/>
+                <argument>org.openjdk.jmh.Main</argument>
+                <argument>
+                  net.starschema.clouddb.jdbc.StatelessSmallQueryBenchmark
+                </argument>
+              </arguments>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
     </plugins>
   </build>
-
-
 </project>

src/test/java/net/starschema/clouddb/jdbc/ConnectionFromResources.java

@@ -0,0 +1,44 @@
+package net.starschema.clouddb.jdbc;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.SQLException;
+import java.util.Properties;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/** Utility class to enable BigQuery connections from properties resources. */
+public class ConnectionFromResources {
+  private static final Logger logger = LoggerFactory.getLogger(ConnectionFromResources.class);
+
+  /**
+   * Connect to a BigQuery project as described in a properties file
+   *
+   * @param propertiesFilePath the path to the properties in file in src/test/resources
+   * @param extraUrl extra URL arguments to add; must start with &
+   * @return A {@link BQConnection} connected to the given database
+   * @throws IOException if the properties file cannot be read
+   * @throws SQLException if the configuration can't connect to BigQuery
+   */
+  public static BQConnection connect(String propertiesFilePath, String extraUrl)
+      throws IOException, SQLException {
+    final Properties properties = new Properties();
+    final ClassLoader loader = ConnectionFromResources.class.getClassLoader();
+    try (InputStream stream = loader.getResourceAsStream(propertiesFilePath)) {
+      properties.load(stream);
+    }
+    final StringBuilder jdcbUrlBuilder =
+        new StringBuilder(BQSupportFuncts.constructUrlFromPropertiesFile(properties));
+    if (extraUrl != null) {
+      jdcbUrlBuilder.append(extraUrl);
+    }
+    final String jdbcUrl = jdcbUrlBuilder.toString();
+
+    final Connection connection = DriverManager.getConnection(jdbcUrl, properties);
+    final BQConnection bqConnection = (BQConnection) connection;
+    logger.info("Created connection from {} to {}", propertiesFilePath, bqConnection.getURLPART());
+    return bqConnection;
+  }
+}

src/test/java/net/starschema/clouddb/jdbc/StatelessSmallQueryBenchmark.java

@@ -0,0 +1,84 @@
+package net.starschema.clouddb.jdbc;
+
+import java.io.IOException;
+import java.sql.Connection;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+import org.assertj.core.api.Assertions;
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Level;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.annotations.TearDown;
+import org.openjdk.jmh.annotations.Threads;
+
+/**
+ * Performance microbenchmark for stateless queries. This uses the example query from {@link
+ * StatelessQuery}, same as the tests.
+ *
+ * <p>Run with mvn exec:exec@benchmark-stateless - note that mvn install must have been run at least
+ * once before.
+ */
+@Fork(1)
+@Threads(10)
+@BenchmarkMode(Mode.Throughput)
+public class StatelessSmallQueryBenchmark {
+  private static final String CONNECTION_PROPERTIES = "installedaccount1.properties";
+
+  @State(Scope.Thread)
+  public static class RequiredJob {
+    private BQConnection connection;
+
+    @Setup(Level.Trial)
+    public void connect() throws SQLException, IOException {
+      connection = ConnectionFromResources.connect(CONNECTION_PROPERTIES, null);
+    }
+
+    @TearDown
+    public void disconnect() throws SQLException {
+      connection.close();
+    }
+  }
+
+  @State(Scope.Thread)
+  public static class OptionalJob {
+    private BQConnection connection;
+
+    @Setup(Level.Trial)
+    public void connect() throws SQLException, IOException {
+      connection =
+          ConnectionFromResources.connect(
+              CONNECTION_PROPERTIES, "&jobcreationmode=JOB_CREATION_OPTIONAL");
+    }
+
+    @TearDown
+    public void disconnect() throws SQLException {
+      connection.close();
+    }
+  }
+
+  private String[][] benchmarkSmallQuery(final Connection connection) throws SQLException {
+    final Statement statement = connection.createStatement();
+    final ResultSet results = statement.executeQuery(StatelessQuery.exampleQuery());
+    final String[][] rows = BQSupportMethods.GetQueryResult(results);
+    Assertions.assertThat(rows).isEqualTo(StatelessQuery.exampleValues());
+    return rows;
+  }
+
+  @Benchmark
+  public String[][] benchmarkSmallQueryRequiredJob(final RequiredJob requiredJob)
+      throws SQLException {
+    return benchmarkSmallQuery(requiredJob.connection);
+  }
+
+  @Benchmark
+  public String[][] benchmarkSmallQueryOptionalJob(final OptionalJob optionalJob)
+      throws SQLException {
+    return benchmarkSmallQuery(optionalJob.connection);
+  }
+}