private function packHeader(int $id, int $offset, int $size, int $flags = 0): string
    {
        return pack('SSQI', $id, $offset, $size, $flags);
    }
private function packHeader(int $id, int $offset, int $size, int $flags = 0): string
    {
        return pack('SSQI', $id, $offset, $size, $flags);
    }
private function packHeader ( int $ id , int $ offset , int $ size , int $ flags = 0 ) : string { return pack ( 'SSQI' , $ id , $ offset , $ size , $ flags ) ; }
Blocking method, writes process result state to state file

@param int $id
@param int $offset
@param int $size
@param int $flags

@return string binary data
sizes: 2 (ushort) + 2 (ushort) + 8(ulong long) + 4(uint) bytes, order - machine-dependent
@see SharedMemoryManager::F_SERIALIZED and other flags
Blocking method writes process result state to state file