docs(samples): add undelete table (#611)

* docs(samples): add undelete table

* docs(samples): update code

Author: Praful Makani

samples/snippets/src/main/java/com/example/bigquery/UndeleteTable.java

@@ -0,0 +1,79 @@
+/*
+ * Copyright 2020 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.bigquery;
+
+// [START bigquery_undelete_table]
+import com.google.cloud.bigquery.BigQuery;
+import com.google.cloud.bigquery.BigQueryException;
+import com.google.cloud.bigquery.BigQueryOptions;
+import com.google.cloud.bigquery.CopyJobConfiguration;
+import com.google.cloud.bigquery.Job;
+import com.google.cloud.bigquery.JobInfo;
+import com.google.cloud.bigquery.TableId;
+import org.threeten.bp.Instant;
+
+// Sample to undeleting a table
+public class UndeleteTable {
+
+  public static void runUndeleteTable() {
+    // TODO(developer): Replace these variables before running the sample.
+    String datasetName = "MY_DATASET_NAME";
+    String tableName = "MY_TABLE_TABLE";
+    String recoverTableName = "MY_RECOVER_TABLE_TABLE";
+    undeleteTable(datasetName, tableName, recoverTableName);
+  }
+
+  public static void undeleteTable(String datasetName, String tableName, String recoverTableName) {
+    try {
+      // Initialize client that will be used to send requests. This client only needs to be created
+      // once, and can be reused for multiple requests.
+      BigQuery bigquery = BigQueryOptions.getDefaultInstance().getService();
+
+      // Record the current time.  We'll use this as the snapshot time
+      // for recovering the table.
+      long snapTime = Instant.now().toEpochMilli();
+
+      // "Accidentally" delete the table.
+      bigquery.delete(TableId.of(datasetName, tableName));
+
+      // Construct the restore-from tableID using a snapshot decorator.
+      String snapshotTableId = String.format("%s@%d", tableName, snapTime);
+
+      // Construct and run a copy job.
+      CopyJobConfiguration configuration =
+          CopyJobConfiguration.newBuilder(
+                  // Choose a new table ID for the recovered table data.
+                  TableId.of(datasetName, recoverTableName),
+                  TableId.of(datasetName, snapshotTableId))
+              .build();
+
+      Job job = bigquery.create(JobInfo.of(configuration));
+      job = job.waitFor();
+      if (job.isDone() && job.getStatus().getError() == null) {
+        System.out.println("Undelete table recovered successfully.");
+      } else {
+        System.out.println(
+            "BigQuery was unable to copy the table due to an error: \n"
+                + job.getStatus().getError());
+        return;
+      }
+    } catch (BigQueryException | InterruptedException e) {
+      System.out.println("Table not found. \n" + e.toString());
+    }
+  }
+}
+// [END bigquery_undelete_table]

samples/snippets/src/test/java/com/example/bigquery/UndeleteTableIT.java

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+/*
+ * Copyright 2020 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.bigquery;
+
+import static com.google.common.truth.Truth.assertThat;
+import static junit.framework.TestCase.assertNotNull;
+
+import com.google.cloud.bigquery.Schema;
+import java.io.ByteArrayOutputStream;
+import java.io.PrintStream;
+import java.util.UUID;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+public class UndeleteTableIT {
+
+  private String tableName;
+  private String recoverTableName;
+  private ByteArrayOutputStream bout;
+  private PrintStream out;
+
+  private static final String BIGQUERY_DATASET_NAME = System.getenv("BIGQUERY_DATASET_NAME");
+
+  private static void requireEnvVar(String varName) {
+    assertNotNull(
+        "Environment variable " + varName + " is required to perform these tests.",
+        System.getenv(varName));
+  }
+
+  @BeforeClass
+  public static void checkRequirements() {
+    requireEnvVar("BIGQUERY_DATASET_NAME");
+  }
+
+  @Before
+  public void setUp() {
+    bout = new ByteArrayOutputStream();
+    out = new PrintStream(bout);
+    System.setOut(out);
+
+    tableName = "UNDELETE_TABLE_TEST_" + UUID.randomUUID().toString().substring(0, 8);
+    recoverTableName = "RECOVER_DELETE_TABLE_TEST_" + UUID.randomUUID().toString().substring(0, 8);
+    // Create table in dataset for testing
+    CreateTable.createTable(BIGQUERY_DATASET_NAME, tableName, Schema.of());
+
+    bout = new ByteArrayOutputStream();
+    out = new PrintStream(bout);
+    System.setOut(out);
+  }
+
+  @After
+  public void tearDown() {
+    // Clean up
+    DeleteTable.deleteTable(BIGQUERY_DATASET_NAME, recoverTableName);
+    System.setOut(null);
+  }
+
+  @Test
+  public void testUndeleteTable() {
+    UndeleteTable.undeleteTable(BIGQUERY_DATASET_NAME, tableName, recoverTableName);
+    assertThat(bout.toString()).contains("Undelete table recovered successfully.");
+  }
+}