<?php

namespace Drupal\KernelTests\Core\Database;

use Drupal\Component\Utility\Environment;
use Drupal\Core\Database\Database;
use Drupal\Core\Database\DatabaseException;

/**
 * Tests handling of large queries.
 *
 * @group Database
 */
class LargeQueryTest extends DatabaseTestBase {

  /**
   * Tests truncation of messages when max_allowed_packet exception occurs.
   */
  public function testMaxAllowedPacketQueryTruncating() {
    // This test only makes sense if we are running on a MySQL database.
    // Test if we are.
    $database = Database::getConnectionInfo('default');
    if ($database['default']['driver'] == 'mysql') {
      // The max_allowed_packet value is configured per database instance.
      // Retrieve the max_allowed_packet value from the current instance and
      // check if PHP is configured with sufficient allowed memory to be able
      // to generate a query larger than max_allowed_packet.
      $max_allowed_packet = db_query('SELECT @@global.max_allowed_packet')->fetchField();
      if (Environment::checkMemoryLimit($max_allowed_packet + (16 * 1024 * 1024))) {
        $long_name = str_repeat('a', $max_allowed_packet + 1);
        try {
          db_query('SELECT name FROM {test} WHERE name = :name', [':name' => $long_name]);
          $this->fail("An exception should be thrown for queries larger than 'max_allowed_packet'");
        }
        catch (DatabaseException $e) {
          // Close and re-open the connection. Otherwise we will run into error
          // 2006 "MySQL server had gone away" afterwards.
          Database::closeConnection();
          Database::getConnection();
          $this->assertEqual($e->getPrevious()->errorInfo[1], 1153, "Got a packet bigger than 'max_allowed_packet' bytes exception thrown.");
          // Use strlen() to count the bytes exactly, not the unicode chars.
          $this->assertTrue(strlen($e->getMessage()) <= $max_allowed_packet, "'max_allowed_packet' exception message truncated.");
        }
      }
      else {
        $this->verbose('The configured max_allowed_packet exceeds the php memory limit. Therefore the test is skipped.');
      }
    }
    else {
      $this->verbose('The test requires MySQL. Therefore the test is skipped.');
    }
  }

}