Read stale data sample for spanner. (GoogleCloudPlatform#434)

Author: SurferJeffAtGoogle

spanner/composer.json

@@ -21,7 +21,8 @@
       "src/read_data_with_storing_index.php",
       "src/create_storing_index.php",
       "src/query_data_with_new_column.php",
-      "src/read_only_transaction.php"
+      "src/read_only_transaction.php",
+      "src/read_stale_data.php"
     ]
   }
 }

spanner/spanner.php

@@ -81,6 +81,17 @@
     })
 );
 
+// Read stale data command
+$application->add((new Command('read-stale-data'))
+    ->setDefinition($inputDefinition)
+    ->setDescription('Reads sample data from the database, with a maximum staleness of 3 seconds.')
+    ->setCode(function ($input, $output) {
+        read_stale_data(
+            $input->getArgument('instance_id'),
+            $input->getArgument('database_id')
+        );
+    })
+);
 // Add column command
 $application->add((new Command('add-column'))
     ->setDefinition($inputDefinition)

spanner/src/read_stale_data.php

@@ -0,0 +1,61 @@
+
+/**
+ * Copyright 2016 Google Inc.
+ *
+ * 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.
+ */
+
+/**
+ * For instructions on how to run the full sample:
+ *
+ * @see https://github.com/GoogleCloudPlatform/php-docs-samples/tree/master/spanner/README.md
+ */
+
+namespace Google\Cloud\Samples\Spanner;
+
+// [START read_stale_data]
+use Google\Cloud\Spanner\Duration;
+use Google\Cloud\Spanner\SpannerClient;
+
+/**
+ * Reads sample data from the database.  The data is exactly 10 seconds stale.
+ * Example:
+ * ```
+ * read_stale_data
+ *($instanceId, $databaseId);
+ * ```
+ *
+ * @param string $instanceId The Spanner instance ID.
+ * @param string $databaseId The Spanner database ID.
+ */
+function read_stale_data($instanceId, $databaseId)
+{
+    $spanner = new SpannerClient();
+    $instance = $spanner->instance($instanceId);
+    $database = $instance->database($databaseId);
+    // maxStaleness and minReadTimestamp are only available in single-use transactions.
+    $snapshot = $database->snapshot();
+    $keySet = $spanner->keySet(['all' => true]);
+    $results = $snapshot->read(
+        'Albums',
+        $keySet,
+        ['SingerId', 'AlbumId', 'AlbumTitle'],
+        ['exactStaleness' => new Duration(10)]
+    );
+
+    foreach ($results->rows() as $row) {
+        printf('SingerId: %s, AlbumId: %s, AlbumTitle: %s' . PHP_EOL,
+            $row['SingerId'], $row['AlbumId'], $row['AlbumTitle']);
+    }
+}
+// [END read_stale_data]

spanner/test/spannerTest.php

@@ -24,15 +24,18 @@
 
 class spannerTest extends \PHPUnit_Framework_TestCase
 {
-    /* @var string instanceId */
+    /** @var string instanceId */
     protected static $instanceId;
 
-    /* @var string databaseId */
+    /** @var string databaseId */
     protected static $databaseId;
 
-    /* @var $instance Instance */
+    /** @var $instance Instance */
     protected static $instance;
 
+    /** @var $lastUpdateData int */
+    protected static $lastUpdateDataTimestamp;
+
     public static function setUpBeforeClass()
     {
         if (!getenv('GOOGLE_APPLICATION_CREDENTIALS')) {
@@ -116,6 +119,7 @@ public function testAddColumn()
     public function testUpdateData()
     {
         $output = $this->runCommand('update-data');
+        self::$lastUpdateDataTimestamp = time();
         $this->assertEquals('Updated data.' . PHP_EOL, $output);
     }
 
@@ -212,6 +216,25 @@ public function testReadOnlyTransaction()
         $this->assertContains('SingerId: 2, AlbumId: 3, AlbumTitle: Terrified', $output);
     }
 
+    /**
+     * @depends testUpdateData
+     */
+    public function testReadStaleData()
+    {
+        // read-stale-data reads data that is exactly 10 seconds old.  So, make sure 10 seconds
+        // have elapsed since testUpdateData().
+        $elapsed = time() - self::$lastUpdateDataTimestamp;
+        if ($elapsed < 11) {
+            sleep(11 - $elapsed);
+        }
+        $output = $this->runCommand('read-stale-data');
+        $this->assertContains('SingerId: 1, AlbumId: 1, AlbumTitle: Go, Go, Go', $output);
+        $this->assertContains('SingerId: 1, AlbumId: 2, AlbumTitle: Total Junk', $output);
+        $this->assertContains('SingerId: 2, AlbumId: 1, AlbumTitle: Green', $output);
+        $this->assertContains('SingerId: 2, AlbumId: 2, AlbumTitle: Forever Hold Your Peace', $output);
+        $this->assertContains('SingerId: 2, AlbumId: 3, AlbumTitle: Terrified', $output);
+    }
+
     private function runCommand($commandName)
     {
         $application = require __DIR__ . '/../spanner.php';