src/PEAR/Registry.php
function mirrorExists($channel, $mirror)
    {
        if (PEAR::isError($e = $this->_lock(LOCK_SH))) {
            return $e;
        }

        $ret = $this->_mirrorExists($channel, $mirror);
        $this->_unlock();
        return $ret;
    }
function mirrorExists($channel, $mirror)
    {
        if (PEAR::isError($e = $this->_lock(LOCK_SH))) {
            return $e;
        }

        $ret = $this->_mirrorExists($channel, $mirror);
        $this->_unlock();
        return $ret;
    }
@param string channel name mirror is in
@param string mirror name

@return bool