AMiRo-OS

/'

µRtWare is a lightweight publish/subscribe middleware for real-time

applications. It was developed as part of the software habitat for the

Autonomous Mini Robot [1] (AMiRo) but can be used for other purposes as well.

Copyright (C) 2018..2020  Thomas Schöpping et al.

This program is free software: you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation, either version 3 of the License, or

(at your option) any later version.

This program is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

GNU General Public License for more details.

You should have received a copy of the GNU General Public License

along with this program.  If not, see <http://www.gnu.org/licenses/>.

'/

/'### INTRO ##################################################################'/

@startuml

title **µRtWare**\nurtSubscriberFrt()\n

!include ../../functions.iuml

/'### PARAMETERS & START #####################################################'/

start

note

  -- ""**subscriber** : urt_subscriber_t*"" --

  The subscriber which shall subscribe to a topic.

  Must not be ""NULL"".

  -- ""**topic** : urt_topic_t*"" --

  The topic to subscribe to.

  Must not be ""NULL"".

  -- ""**messages** : urt_message_t*"" --

  List of messages to be contributed to the topic.

  Those messages must not be associated to another topic.

  Once a message was contributed, it cannot be removed from the topic anymore.

  -- ""**deadline** : urt_delay_t"" --

  Maximum latency to consume messages.

  A value of 0 indicates, that latency is of no concern.

  -- ""**rate** : urt_delay_t_t"" --

  Expected minimum rate of new messages (= mamximum time between consecutive messages).

  A value of 0 indicates, that rate is of no concern.

  -- ""**jitter** : urt_delay_t_t"" --

  Maximum allowed jitter (difference between maximum and minimum latency) when consuming messages.

  A value of 0 indicates, that jitter is of no concern.

end note

/'### PROCEDURE ##############################################################'/

if (Is topic already set?) then (yes)

  :return ""URT_STATUS_ERROR"";

else (no)

  fork

    :set FRT data;

  fork again

    :set topic;

  endfork

  fork

    :lock topic;

    fork

      if (Messages to contribute?) then (yes)

        partition "contribute messages" {

          :set next pointer of topic's latest message to first message to contribute;

          :set next pointer of last message to contribute to the message after the topic's latest message;

        }

      else (no)

      endif

    fork again

      :set message pointer to topic's latest message;

    endfork

    :unlock topic;

  fork again

    :register to topic's event source;

  endfork

  :return ""URT_STATUS_OK"";

endif

/'### STOP & RETURN ##########################################################'/

stop

note

  -- **return** ""urt_status_t"" --

  Returns ""URT_STATUS_ERROR"" if the subscriber was already associated to a topic.

end note

/'### OUTRO ##################################################################'/

@enduml