<?php
/**
* Copyright © Magento, Inc. All rights reserved.
* See COPYING.txt for license details.
*/
declare(strict_types=1);

namespace Magento\Framework\Lock\Backend;

use Magento\Framework\App\DeploymentConfig;
use Magento\Framework\App\ResourceConnection;
use Magento\Framework\Config\ConfigOptionsListConstants;
use Magento\Framework\DB\ExpressionConverter;
use Magento\Framework\Exception\FileSystemException;
use Magento\Framework\Exception\RuntimeException;

/**
* Implementation of the lock manager on the basis of MySQL.
*/
class Database implements \Magento\Framework\Lock\LockManagerInterface
{
/**
* Max time for lock is 1 week
*
* MariaDB does not support negative timeout value to get infinite timeout,
* so we set 1 week for lock timeout
*/
private const MAX_LOCK_TIME = 604800;

/**
* @var ResourceConnection
*/
private $resource;

/**
* @var DeploymentConfig
*/
private $deploymentConfig;

/**
* @var string Lock prefix
*/
private $prefix;

/**
* @var string|false Holds current lock name if set, otherwise false
*/
private $currentLock = false;

/**
* @param ResourceConnection $resource
* @param DeploymentConfig $deploymentConfig
* @param string|null $prefix
*/
public function __construct(
ResourceConnection $resource,
DeploymentConfig $deploymentConfig,
string $prefix = null
) {
$this->resource = $resource;
$this->deploymentConfig = $deploymentConfig;
$this->prefix = $prefix;
}

/**
* Sets a lock for name
*
* @param string $name lock name
* @param int $timeout How long to wait lock acquisition in seconds, negative value means infinite timeout
* @return bool
* @throws FileSystemException
* @throws RuntimeException
* @throws \Zend_Db_Statement_Exception
*/
public function lock(string $name, int $timeout = -1): bool
{
if (!$this->deploymentConfig->isDbAvailable()) {
return true;
}
$name = $this->addPrefix($name);

$result = (bool)$this->resource->getConnection()->query(
"SELECT GET_LOCK(?, ?);",
[$name, $timeout < 0 ? self::MAX_LOCK_TIME : $timeout]
)->fetchColumn();

if ($result === true) {
$this->currentLock = $name;
}

return $result;
}

/**
* Releases a lock for name
*
* @param string $name lock name
* @return bool
* @throws \Zend_Db_Statement_Exception
*/
public function unlock(string $name): bool
{
if (!$this->deploymentConfig->isDbAvailable()) {
return true;
}

$name = $this->addPrefix($name);

$result = (bool)$this->resource->getConnection()->query(
"SELECT RELEASE_LOCK(?);",
[(string)$name]
)->fetchColumn();

if ($result === true) {
$this->currentLock = false;
}

return $result;
}

/**
* Tests of lock is set for name
*
* @param string $name lock name
* @return bool
* @throws \Zend_Db_Statement_Exception
*/
public function isLocked(string $name): bool
{
if (!$this->deploymentConfig->isDbAvailable()) {
return false;
}

$name = $this->addPrefix($name);

return (bool)$this->resource->getConnection()->query(
"SELECT IS_USED_LOCK(?);",
[$name]
)->fetchColumn();
}

/**
* Adds prefix and checks for max length of lock name
*
* Limited to 64 characters in MySQL.
*
* @param string $name
* @return string
*/
private function addPrefix(string $name): string
{
$prefix = $this->getPrefix() ? $this->getPrefix() . '|' : '';
$name = ExpressionConverter::shortenEntityName($prefix . $name, $prefix);

return $name;
}

/**
* Get installation specific lock prefix to avoid lock conflicts
*
* @return string lock prefix
*/
private function getPrefix(): string
{
if ($this->prefix === null) {
$this->prefix = (string)$this->deploymentConfig->get(
ConfigOptionsListConstants::CONFIG_PATH_DB_CONNECTION_DEFAULT
. '/'
. ConfigOptionsListConstants::KEY_NAME,
''
);
}

return $this->prefix;
}
}