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<?php

/**

* 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 spanner_read_write_transaction]

use Google\Cloud\Spanner\SpannerClient;

use Google\Cloud\Spanner\Transaction;

use UnexpectedValueException;

/**

* Performs a read-write transaction to update two sample records in the

* database.

*

* This will transfer 200,000 from the `MarketingBudget` field for the second

* Album to the first Album. If the `MarketingBudget` for the second Album is

* too low, it will raise an exception.

*

* Before running this sample, you will need to run the `update_data` sample

* to populate the fields.

* Example:

* ```

* read_write_transaction($instanceId, $databaseId);

* ```

*

* @param string $instanceId The Spanner instance ID.

* @param string $databaseId The Spanner database ID.

*/

function read_write_transaction($instanceId, $databaseId)

{

$spanner = new SpannerClient();

$instance = $spanner->instance($instanceId);

$database = $instance->database($databaseId);

$database->runTransaction(function (Transaction $t) use ($spanner) {

$transferAmount = 200000;

// Read the second album's budget.

$secondAlbumKey = [2, 2];

$secondAlbumKeySet = $spanner->keySet(['keys' => [$secondAlbumKey]]);

$secondAlbumResult = $t->read(

'Albums',

$secondAlbumKeySet,

['MarketingBudget'],

['limit' => 1]

);

$firstRow = $secondAlbumResult->rows()->current();

$secondAlbumBudget = $firstRow['MarketingBudget'];

if ($secondAlbumBudget < $transferAmount) {

// Throwing an exception will automatically roll back the transaction.

throw new UnexpectedValueException(

'The second album\'s budget is lower than the transfer amount: ' . $transferAmount

);

}

$firstAlbumKey = [1, 1];

$firstAlbumKeySet = $spanner->keySet(['keys' => [$firstAlbumKey]]);

$firstAlbumResult = $t->read(

'Albums',

$firstAlbumKeySet,

['MarketingBudget'],

['limit' => 1]

);

// Read the first album's budget.

$firstRow = $firstAlbumResult->rows()->current();

$firstAlbumBudget = $firstRow['MarketingBudget'];

// Update the budgets.

$secondAlbumBudget -= $transferAmount;

$firstAlbumBudget += $transferAmount;

printf('Setting first album\'s budget to %s and the second album\'s ' .

'budget to %s.' . PHP_EOL, $firstAlbumBudget, $secondAlbumBudget);

// Update the rows.

$t->updateBatch('Albums', [

['SingerId' => 1, 'AlbumId' => 1, 'MarketingBudget' => $firstAlbumBudget],

['SingerId' => 2, 'AlbumId' => 2, 'MarketingBudget' => $secondAlbumBudget],

]);

// Commit the transaction!

$t->commit();

print('Transaction complete.' . PHP_EOL);

});

}

// [END spanner_read_write_transaction]

require_once __DIR__ . '/../../testing/sample_helpers.php';

\Google\Cloud\Samples\execute_sample(__FILE__, __NAMESPACE__, $argv);