Mutex.php

Go to the documentation of this file.

<?php
 
namespace Elgg\Database;
 
use Elgg\Database;
use Elgg\Exceptions\InvalidArgumentException;
use Elgg\Traits\Loggable;
 
class Mutex {
 
    use Loggable;
 
    public function __construct(protected Database $db) {
    }
 
    public function lock(string $namespace): bool {
        $this->assertNamespace($namespace);
 
        if (!$this->isLocked($namespace)) {
            // Lock it
            $this->db->getConnection('write')->executeStatement("CREATE TABLE {$this->db->prefix}{$namespace}_lock (id INT)");
 
            $this->getLogger()->info("Locked mutex for {$namespace}");
            return true;
        }
 
        $this->getLogger()->warning("Cannot lock mutex for {$namespace}: already locked.");
        return false;
    }
 
    public function unlock(string $namespace): void {
        $this->assertNamespace($namespace);
 
        $this->db->getConnection('write')->executeStatement("DROP TABLE {$this->db->prefix}{$namespace}_lock");
 
        $this->getLogger()->notice("Mutex unlocked for {$namespace}.");
    }
 
    public function isLocked(string $namespace): bool {
        $this->assertNamespace($namespace);
 
        $result = $this->db->getConnection('read')->executeQuery("SHOW TABLES LIKE '{$this->db->prefix}{$namespace}_lock'");
        return $result->rowCount() > 0;
    }
 
    protected function assertNamespace(string $namespace): void {
        if (!ctype_alpha($namespace)) {
            throw new InvalidArgumentException('Mutex namespace can only have characters [A-Za-z].');
        }
    }
}