How to use the rucio.common.exception.RucioException function in rucio

except Exception as error:
                raise RucioException('Failed to execute aria2c!', error)

            # if port is in use aria should fail to start so give it some time
            time.sleep(2)

            # did it fail?
            if rpcproc.poll() is not None:
                (out, err) = rpcproc.communicate()
                logger.debug('Failed to start aria2c with port: %d' % port)
                logger.debug('aria2c output: %s' % out)
            else:
                break

        if rpcproc.poll() is not None:
            raise RucioException('Failed to start aria2c rpc server!')

        try:
            aria_rpc = RPCServerProxy('http://localhost:%d/rpc' % port)
        except Exception as error:
            rpcproc.kill()
            raise RucioException('Failed to initialise rpc proxy!', error)
        return (rpcproc, aria_rpc)

:param session:    Database session to use.
    """

    try:
        for request_id in transfers:
            rowcount = session.query(models.Request)\
                              .filter_by(id=request_id)\
                              .filter(models.Request.state == RequestState.SUBMITTING)\
                              .update({'state': transfers[request_id]['state'],
                                       'external_id': transfers[request_id]['external_id'],
                                       'external_host': transfers[request_id]['external_host'],
                                       'source_rse_id': transfers[request_id]['src_rse_id'],
                                       'submitted_at': submitted_at},
                                      synchronize_session=False)
            if rowcount == 0:
                raise RucioException("Failed to set requests %s tansfer %s: request doesn't exist or is not in SUBMITTING state" % (request_id, transfers[request_id]))

            request_type = transfers[request_id].get('request_type', None)
            msg = {'request-id': request_id,
                   'request-type': str(request_type).lower() if request_type else request_type,
                   'scope': transfers[request_id]['scope'].external,
                   'name': transfers[request_id]['name'],
                   'src-rse-id': transfers[request_id]['metadata'].get('src_rse_id', None),
                   'src-rse': transfers[request_id]['metadata'].get('src_rse', None),
                   'dst-rse-id': transfers[request_id]['metadata'].get('dst_rse_id', None),
                   'dst-rse': transfers[request_id]['metadata'].get('dst_rse', None),
                   'state': str(transfers[request_id]['state']),
                   'activity': transfers[request_id]['metadata'].get('activity', None),
                   'file-size': transfers[request_id]['metadata'].get('filesize', None),
                   'bytes': transfers[request_id]['metadata'].get('filesize', None),
                   'checksum-md5': transfers[request_id]['metadata'].get('md5', None),
                   'checksum-adler': transfers[request_id]['metadata'].get('adler32', None),

:param request_id:  Request-ID as a 32 character hex string.
    :param session:     Database session to use.
    :returns:           Request as a dictionary.
    """

    try:
        tmp = session.query(models.Request).filter_by(id=request_id).first()

        if not tmp:
            return
        else:
            tmp = dict(tmp)
            tmp.pop('_sa_instance_state')
            return tmp
    except IntegrityError as error:
        raise RucioException(error.args)

if not self.renaming:
            params.strict_copy = True

        try:
            if transfer_timeout:
                watchdog.start()
            ret = ctx.filecopy(params, str(src), str(dest))
            if transfer_timeout:
                watchdog.cancel()
            return ret
        except gfal2.GError as error:  # pylint: disable=no-member
            if transfer_timeout:
                watchdog.cancel()
            if error.code == errno.ENOENT or 'No such file' in str(error):
                raise exception.SourceNotFound(error)
            raise exception.RucioException(error)

client.store_registration_info(client_reg)
            # setting public_key cache timeout to 'keytimeout' seconds
            keybundles = client.keyjar.issuer_keys[client.issuer]
            for keybundle in keybundles:
                keybundle.cache_time = keytimeout
            clients[issuer] = client
            # doing the same to store a Rucio Admin client
            # which has client credential flow allowed
            client_secret = client_secrets[iss]["SCIM"]
            client = Client(client_authn_method=CLIENT_AUTHN_METHOD)
            client.provider_config(issuer)
            client_reg = RegistrationResponse(**client_secret)
            client.store_registration_info(client_reg)
            admin_clients[issuer] = client
        except Exception as error:
            raise RucioException(error.args)
    return (clients, admin_clients)

if not existing_content or (scope, name, file['scope'], file['name']) not in existing_content:
                contents.append(existing_files[did_tag])

    # insert into archive_contents
    try:
        new_files and session.bulk_insert_mappings(models.DataIdentifier, new_files)
        if existing_files_condition:
            for chunk in chunks(existing_files_condition, 20):
                session.query(models.DataIdentifier).\
                    with_hint(models.DataIdentifier, "INDEX(DIDS DIDS_PK)", 'oracle').\
                    filter(models.DataIdentifier.did_type == DIDType.FILE).\
                    filter(or_(*chunk)).update({'constituent': True})
        contents and session.bulk_insert_mappings(models.ConstituentAssociation, contents)
        session.flush()
    except IntegrityError as error:
        raise exception.RucioException(error.args)

"""

        space_token = ''
        if self.attributes['extended_attributes'] is not None and 'space_token' in list(self.attributes['extended_attributes'].keys()):
            space_token = '--dst %s' % self.attributes['extended_attributes']['space_token']

        try:
            cmd = 'lcg-cp $LCGVO -v -b --srm-timeout 3600 -D srmv2 %s %s %s' % (space_token, path, new_path)
            status, out, err = execute(cmd)
            if status:
                raise exception.RucioException(err)

            cmd = 'lcg-del $LCGVO -v -b -l --srm-timeout 600 -D srmv2 %s' % (path)
            status, out, err = execute(cmd)
            if status:
                raise exception.RucioException(err)
        except Exception as error:
            raise exception.ServiceUnavailable(error)

'bytes': transfers[request_id]['metadata'].get('filesize', None),
                   'checksum-md5': transfers[request_id]['metadata'].get('md5', None),
                   'checksum-adler': transfers[request_id]['metadata'].get('adler32', None),
                   'external-id': transfers[request_id]['external_id'],
                   'external-host': transfers[request_id]['external_host'],
                   'queued_at': str(submitted_at)}

            if msg['request-type']:
                transfer_status = '%s-%s' % (msg['request-type'], msg['state'])
            else:
                transfer_status = 'transfer-%s' % msg['state']
            transfer_status = transfer_status.lower()
            message_core.add_message(transfer_status, msg, session=session)

    except IntegrityError as error:
        raise RucioException(error.args)

if not os.path.exists(source_url):
            raise exception.SourceNotFound()

        space_token = ''
        if self.attributes['extended_attributes'] is not None and 'space_token' in list(self.attributes['extended_attributes'].keys()):
            space_token = '--dst %s' % self.attributes['extended_attributes']['space_token']

        timeout_option = ''
        if transfer_timeout:
            timeout_option = '--sendreceive-timeout %s' % transfer_timeout

        try:
            cmd = 'lcg-cp $LCGVO -v -b --srm-timeout 3600 %s -D srmv2 %s file:%s %s' % (timeout_option, space_token, source_url, target)
            status, out, err = execute(cmd)
            if status:
                raise exception.RucioException(err)
        except Exception as error:
            raise exception.ServiceUnavailable(error)