samples: adds samples for commit stats (#899)

* samples: adds commit stats samples

Adds samples for commit stats. Shows has to get the mutation count from
a write.

* test: adds tests for commit stats samples

* samples: refactors samples for get commit stats

* samples: reformats samples for commit stats

* samples: addresses PR comments

* test: fixes tests for get commit stats samples

* test: addresses pr comments

Throws an error if the instance is not set. Fixes the format database id
name function.

samples/snippets/src/main/java/com/example/spanner/GetCommitStatsSample.java

@@ -0,0 +1,70 @@
+/*
+ * Copyright 2021 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
+ *
+ *       http://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.spanner;
+
+// [START spanner_get_commit_stats]
+
+import com.google.cloud.spanner.CommitResponse;
+import com.google.cloud.spanner.DatabaseClient;
+import com.google.cloud.spanner.DatabaseId;
+import com.google.cloud.spanner.Mutation;
+import com.google.cloud.spanner.Options;
+import com.google.cloud.spanner.Spanner;
+import com.google.cloud.spanner.SpannerOptions;
+import java.util.Arrays;
+
+public class GetCommitStatsSample {
+
+  static void getCommitStats() {
+    // TODO(developer): Replace these variables before running the sample.
+    final String projectId = "my-project";
+    final String instanceId = "my-instance";
+    final String databaseId = "my-database";
+
+    try (Spanner spanner =
+        SpannerOptions.newBuilder().setProjectId(projectId).build().getService()) {
+      final DatabaseClient databaseClient = spanner
+          .getDatabaseClient(DatabaseId.of(projectId, instanceId, databaseId));
+      getCommitStats(databaseClient);
+    }
+  }
+
+  static void getCommitStats(DatabaseClient databaseClient) {
+    final CommitResponse commitResponse = databaseClient.writeWithOptions(Arrays.asList(
+        Mutation.newInsertOrUpdateBuilder("Albums")
+            .set("SingerId")
+            .to("1")
+            .set("AlbumId")
+            .to("1")
+            .set("MarketingBudget")
+            .to("200000")
+            .build(),
+        Mutation.newInsertOrUpdateBuilder("Albums")
+            .set("SingerId")
+            .to("2")
+            .set("AlbumId")
+            .to("2")
+            .set("MarketingBudget")
+            .to("400000")
+            .build()
+    ), Options.commitStats());
+
+    System.out.println(
+        "Updated data with " + commitResponse.getCommitStats().getMutationCount() + " mutations.");
+  }
+}
+// [END spanner_get_commit_stats]

samples/snippets/src/test/java/com/example/spanner/GetCommitStatsSampleIT.java

@@ -0,0 +1,146 @@
+/*
+ * Copyright 2021 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
+ *
+ *       http://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.spanner;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.cloud.spanner.DatabaseAdminClient;
+import com.google.cloud.spanner.DatabaseClient;
+import com.google.cloud.spanner.DatabaseId;
+import com.google.cloud.spanner.KeySet;
+import com.google.cloud.spanner.Mutation;
+import com.google.cloud.spanner.Spanner;
+import com.google.cloud.spanner.SpannerOptions;
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableList;
+import java.io.ByteArrayOutputStream;
+import java.io.PrintStream;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.UUID;
+import org.junit.After;
+import org.junit.AfterClass;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/**
+ * Integration tests for {@link GetCommitStatsSample}
+ */
+@RunWith(JUnit4.class)
+public class GetCommitStatsSampleIT {
+
+  private static String instanceId = System.getProperty("spanner.test.instance");
+  private static String databaseId = formatForTest(
+      System.getProperty("spanner.sample.database", "commitstatssample"));
+  private static DatabaseId dbId;
+  private static DatabaseAdminClient dbClient;
+  private static Spanner spanner;
+
+  @BeforeClass
+  public static void createTestDatabase() throws Exception {
+    Preconditions.checkState(instanceId != null, "No instance id set");
+    final SpannerOptions options =
+        SpannerOptions.newBuilder().setAutoThrottleAdministrativeRequests().build();
+    spanner = options.getService();
+    dbClient = spanner.getDatabaseAdminClient();
+    dbId = DatabaseId.of(options.getProjectId(), instanceId, databaseId);
+    dbClient.dropDatabase(dbId.getInstanceId().getInstance(), dbId.getDatabase());
+    dbClient
+        .createDatabase(
+            instanceId,
+            databaseId,
+            ImmutableList.of(
+                "CREATE TABLE Singers ("
+                    + "  SingerId   INT64 NOT NULL,"
+                    + "  FirstName  STRING(1024),"
+                    + "  LastName   STRING(1024),"
+                    + "  SingerInfo BYTES(MAX)"
+                    + ") PRIMARY KEY (SingerId)",
+                "CREATE TABLE Albums ("
+                    + "  SingerId        INT64 NOT NULL,"
+                    + "  AlbumId         INT64 NOT NULL,"
+                    + "  AlbumTitle      STRING(MAX),"
+                    + "  MarketingBudget INT64"
+                    + ") PRIMARY KEY (SingerId, AlbumId),"
+                    + "  INTERLEAVE IN PARENT Singers ON DELETE CASCADE"))
+        .get();
+  }
+
+  @AfterClass
+  public static void dropTestDatabase() {
+    dbClient.dropDatabase(dbId.getInstanceId().getInstance(), dbId.getDatabase());
+    spanner.close();
+  }
+
+  @Before
+  public void insertTestData() {
+    final DatabaseClient client = spanner.getDatabaseClient(dbId);
+    client.write(Arrays.asList(
+        Mutation.newInsertBuilder("Singers")
+            .set("SingerId")
+            .to(1L)
+            .set("FirstName")
+            .to("first name 1")
+            .set("LastName")
+            .to("last name 1")
+            .build(),
+        Mutation.newInsertBuilder("Singers")
+            .set("SingerId")
+            .to(2L)
+            .set("FirstName")
+            .to("first name 2")
+            .set("LastName")
+            .to("last name 2")
+            .build()
+    ));
+  }
+
+  @After
+  public void removeTestData() {
+    final DatabaseClient client = spanner.getDatabaseClient(dbId);
+    client.write(Collections.singletonList(Mutation.delete("Singers", KeySet.all())));
+  }
+
+  @Test
+  public void testGetCommitStatsSample() {
+    final DatabaseClient client = spanner.getDatabaseClient(dbId);
+    final String out = runExample(client);
+
+    assertThat(out).contains("Updated data with 6 mutations.");
+  }
+
+  private String runExample(DatabaseClient client) {
+    PrintStream stdOut = System.out;
+    ByteArrayOutputStream bout = new ByteArrayOutputStream();
+    PrintStream out = new PrintStream(bout);
+    System.setOut(out);
+    GetCommitStatsSample.getCommitStats(client);
+    System.setOut(stdOut);
+    return bout.toString();
+  }
+
+  private static String formatForTest(String name) {
+    return (
+        name
+            + "-"
+            + UUID.randomUUID().toString().replaceAll("-", "")
+    ).substring(0, 30);
+  }
+}