malkusch\lock\mutex\MutexConcurrencyTest::provideTestHighContention PHP Метод

    public function provideTestHighContention()
    {
        $cases = array_map(function (array $mutexFactory) {
            $file = tmpfile();
            fputs($file, pack("i", 0));
            fflush($file);
            return [function ($increment) use($file) {
                fseek($file, 0);
                $data = fread($file, 4);
                $counter = unpack("i", $data)[1];
                $counter += $increment;
                fseek($file, 0);
                fwrite($file, pack("i", $counter));
                fflush($file);
                return $counter;
            }, $mutexFactory[0]];
        }, $this->provideMutexFactories());
        $addPDO = function ($dsn, $user, $vendor) use(&$cases) {
            $pdo = $this->getPDO($dsn, $user);
            $pdo->beginTransaction();
            $options = ["mysql" => "engine=InnoDB"];
            $option = isset($options[$vendor]) ? $options[$vendor] : "";
            $pdo->exec("CREATE TABLE IF NOT EXISTS counter(id INT PRIMARY KEY, counter INT) {$option}");
            $pdo->exec("DELETE FROM counter");
            $pdo->exec("INSERT INTO counter VALUES (1, 0)");
            $pdo->commit();
            $this->pdo = null;
            $cases[$vendor] = [function ($increment) use($dsn, $user) {
                // This prevents using a closed connection from a child.
                if ($increment == 0) {
                    $this->pdo = null;
                }
                $pdo = $this->getPDO($dsn, $user);
                $id = 1;
                $select = $pdo->prepare("SELECT counter FROM counter WHERE id = ? FOR UPDATE");
                $select->execute([$id]);
                $counter = $select->fetchColumn();
                $counter += $increment;
                $pdo->prepare("UPDATE counter SET counter = ? WHERE id = ?")->execute([$counter, $id]);
                return $counter;
            }, function ($timeout = 3) use($dsn, $user) {
                $this->pdo = null;
                $pdo = $this->getPDO($dsn, $user);
                return new TransactionalMutex($pdo, $timeout);
            }];
        };
        if (getenv("MYSQL_DSN")) {
            $dsn = getenv("MYSQL_DSN");
            $user = getenv("MYSQL_USER");
            $addPDO($dsn, $user, "mysql");
        }
        if (getenv("PGSQL_DSN")) {
            $dsn = getenv("PGSQL_DSN");
            $user = getenv("PGSQL_USER");
            $addPDO($dsn, $user, "postgres");
        }
        return $cases;
    }