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Introduction

Cloud Spanner’s Java package was already instrumented for:

Tracing with OpenCensus
Metrics with OpenCensus by way of gRPC metrics

This guide makes use of a couple of APIs

API	Guided codelab
Spanner	Spanner codelab
Stackdriver	Stackdriver codelab

Packages to import

For tracing and metrics on Spanner, we’ll import a couple of packages

Package Name	Package link
The Cloud Spanner Java package	com.google.cloud.spanner
The OpenCensus trace package	io.opencensus.trace
The OpenCensus stats package	io.opencensus.stats
The OpenCensus Java gRPC views	io.opencensus.contrib.grpc.metrics.RpcViews

And when imported in code:

import com.google.cloud.spanner;
import io.opencensus.contrib.grpc.metrics.RpcViews;
import io.opencensus.trace.Tracing;

Enable metric reporting

To enable metric reporting/exporting, we need to enable a metrics exporter, but before that we’ll need to register and enable the views that match the metrics to collect. For a complete list of the available views available please visit io.opencensus.contrib.grpc.metrics.RpcViews

Finally, we’ll register all the views

Register gRPC views

RpcViews.registerAllGrpcViews();

Exporting traces and metrics

The last step is to enable trace and metric exporting. For that we’ll use say Stackdriver Exporter or any of the Java exporters

End to end code sample

With all the steps combined, we’ll finally have this code snippet

package com.opencensus.tutorials;

import com.google.cloud.spanner.DatabaseClient;
import com.google.cloud.spanner.DatabaseId;
import com.google.cloud.spanner.Key;
import com.google.cloud.spanner.Mutation;
import com.google.cloud.spanner.Spanner;
import com.google.cloud.spanner.SpannerOptions;
import io.opencensus.common.Scope;
import io.opencensus.contrib.grpc.metrics.RpcViews;
import io.opencensus.exporter.stats.stackdriver.StackdriverStatsExporter;
import io.opencensus.exporter.trace.stackdriver.StackdriverTraceConfiguration;
import io.opencensus.exporter.trace.stackdriver.StackdriverTraceExporter;
import io.opencensus.trace.Tracing;
import io.opencensus.trace.samplers.Samplers;
import java.util.Arrays;
import java.util.List;

public class SpannerOpenCensusTutorial {
  private DatabaseClient dbClient;
  private Spanner spanner;

  private static final String parentSpanName = "create-players";

  public SpannerOpenCensusTutorial(String instanceId, String databaseId) throws Exception {
    // Instantiate the client.
    SpannerOptions options = SpannerOptions.getDefaultInstance();
    spanner = options.getService();

    // And then create the Spanner database client.
    String projectId = options.getProjectId();
    dbClient = spanner.getDatabaseClient(DatabaseId.of(projectId, instanceId, databaseId));

    // Next up let's  install the exporter for Stackdriver tracing.
    StackdriverTraceExporter.createAndRegister(
        StackdriverTraceConfiguration.builder().setProjectId(projectId).build());

    Tracing.getExportComponent()
        .getSampledSpanStore()
        .registerSpanNamesForCollection(Arrays.asList(parentSpanName));

    // Then the exporter for Stackdriver monitoring/metrics.
    StackdriverStatsExporter.createAndRegister();

    // Finally register the gRPC views to give us metrics.
    RpcViews.registerAllGrpcViews();
  }

  public void close() {
    spanner.close();
  }

  public void warmUpRead() {
    dbClient.singleUse().readRow("Players", Key.of("foo@gmail.com"), Arrays.asList("email"));
  }

  public static void main(String... args) throws Exception {
    if (args.length < 2) {
      System.err.println("Usage: ZeuSports <instance_id> <database_id>");
      return;
    }

    try {
      SpannerOpenCensusTutorial zdb = new SpannerOpenCensusTutorial(args[0], args[1]);
      // Warm up the spanner client session. In normal usage
      // you'd have hit this point after the first operation.
      zdb.warmUpRead();

      for (int i = 0; i < 3; i++) {
        String up = i + "-" + (System.currentTimeMillis() / 1000) + ".";
        List<Mutation> mutations =
            Arrays.asList(
                playerMutation(
                    "Poke",
                    "Mon",
                    up + "poke.mon@example.org",
                    "f1578551-eb4b-4ecd-aee2-9f97c37e164e"),
                playerMutation(
                    "Go",
                    "Census",
                    up + "go.census@census.io",
                    "540868a2-a1d8-456b-a995-b324e4e7957a"),
                playerMutation(
                    "Quick",
                    "Sort",
                    up + "q.sort@gmail.com",
                    "2b7e0098-a5cc-4f32-aabd-b978fc6b9710"));

        zdb.insertPlayers(mutations);
      }

      zdb.close();
    } catch (Exception e) {
      System.out.printf("Exception while adding player: " + e);
    } finally {
      System.out.println("Bye!");
    }
  }

  public static Mutation playerMutation(
      String firstName, String lastName, String email, String uuid) {
    return Mutation.newInsertBuilder("Players")
        .set("first_name")
        .to(firstName)
        .set("last_name")
        .to(lastName)
        .set("uuid")
        .to(uuid)
        .set("email")
        .to(email)
        .build();
  }

  public void insertPlayers(List<Mutation> players) throws Exception {
    try (Scope ss =
        Tracing.getTracer()
            .spanBuilderWithExplicitParent(parentSpanName, null)
            // Enable the trace sampler.
            //  We are always sampling for demo purposes only: this is a very high sampling
            // rate, but sufficient for the purpose of this quick demo.
            // More realistically perhaps tracing 1 in 10,000 might be more useful
            .setSampler(Samplers.alwaysSample())
            .startScopedSpan()) {

      dbClient.write(players);
    } finally {
    }
  }
}

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.opencensus.tutorials</groupId>
  <artifactId>opencensus-tutorials</artifactId>
  <packaging>jar</packaging>
  <version>1.0-SNAPSHOT</version>
  <name>opencensus-examples</name>
  <url>http://maven.apache.org</url>

  <properties>
    <maven.compiler.target>1.8</maven.compiler.target>
    <maven.compiler.source>1.8</maven.compiler.source>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <opencensus.version>0.18.0</opencensus.version>
    <spanner.version>1.5.0</spanner.version>
  </properties>

  <dependencies>
    <dependency>
      <groupId>com.google.cloud</groupId>
      <artifactId>google-cloud-spanner</artifactId>
      <version>${spanner.version}</version>
      <exclusions>
	<exclusion>
	  <groupId>com.google.guava</groupId>
	  <artifactId>guava-jdk5</artifactId>
	</exclusion>
	<exclusion>
	  <groupId>io.opencensus</groupId>
	  <artifactId>opencensus-api</artifactId>
	</exclusion>
      </exclusions>
    </dependency>

    <dependency>
      <groupId>com.google.guava</groupId>
      <artifactId>guava</artifactId>
      <version>20.0</version>
    </dependency>

    <dependency>
      <groupId>io.opencensus</groupId>
      <artifactId>opencensus-api</artifactId>
      <version>${opencensus.version}</version>
    </dependency>

    <dependency>
      <groupId>io.opencensus</groupId>
      <artifactId>opencensus-exporter-stats-stackdriver</artifactId>
      <version>${opencensus.version}</version>
    </dependency>

    <dependency>
      <groupId>io.opencensus</groupId>
      <artifactId>opencensus-exporter-trace-stackdriver</artifactId>
      <version>${opencensus.version}</version>
    </dependency>

    <dependency>
      <groupId>io.opencensus</groupId>
      <artifactId>opencensus-contrib-grpc-metrics</artifactId>
      <version>${opencensus.version}</version>
    </dependency>


    <dependency>
      <groupId>io.opencensus</groupId>
      <artifactId>opencensus-impl</artifactId>
      <version>${opencensus.version}</version>
      <scope>runtime</scope>
    </dependency>

  </dependencies>

  <build>
    <plugins>
      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>exec-maven-plugin</artifactId>
        <version>1.4.0</version>
        <configuration>
            <mainClass>com.opencensus.tutorials.SpannerOpenCensusTutorial</mainClass>
            <cleanupDaemonThreads>false</cleanupDaemonThreads>
        </configuration>
      </plugin>
    </plugins>
  </build>

</project>

Maven install

Saving the file

Please save the Java source code in your current working directory under src/main/java/com/opencensus/tutorials/SpannerOpenCensusTutorial.java. Also save the pom.xml file in the same current working directory.

Your current working directory’s structure should then look like this.

pom.xml
src/
  |-main
    |-java
      |-com
        |-opencensus
          |-tutorials
            |-SpannerOpenCensusTutorial.java

Running it

mvn install && \
mvn exec:java \
-Dexec.mainClass=com.opencensus.tutorials.SpannerOpenCensusTutorial \
-Dexec.args="census-demos demo1"

Viewing your metrics

Please visit https://console.cloud.google.com/monitoring

Viewing your traces

Please visit https://console.cloud.google.com/traces/traces