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**\nurtHrtSubscriberSubscribe()\n

!include ../../functions.iuml

/'### PARAMETERS & RETURN ####################################################'/

note

  -- **subscriber** : urt_hrtsubscriber_t* --

  The HRT 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* --

  ""NULL"" terminated list of messages to contribute to the topic.

  Messages must not be associated to another topic.

  Once a message has been contributed, it cannot be removed later.

  May be ""NULL"" (no messages to contribute).

  -- **deadline** : urt_delay_t --

  Maximum latency to consume messages.

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

  -- **jitter** : urt_delay_t --

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

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

  -- **rate** : urt_delay_t --

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

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

  ====

  -- **return** : urt_status_t --

  Returns ""URT_STATUS_OK"" on success.

  Returns ""URT_STATUS_SUBSCRIBE_TOPICSET"" if the subscriber is already associated to a topic.

endnote

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

start

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

  stop

  note

    Returns ""URT_STATUS_SUBSCRIBE_TOPICSET"".

  endnote

else (no)

  fork

    :set topic;

  fork again

    #EEEEEE:initialize members;

    note #EEEEEE

      -- urt_basesubscriber_t --

      .. URT_CFG_PUBSUB_PROFILING == true ..

      * **sumLatencies** ← 0

      * **numMessagesReceived** ← 0

      -- urt_hrtsubscriber_t --

      .. URT_CFG_PUBSUB_QOS_DEADLINECHECKS == true ..

      * **deadlineOffset** ← deadline

      .. URT_CFG_PUBSUB_QOS_JITTERCHECKS == true ..

      * **maxJitter** ← jitter

      .. URT_CFG_PUBSUB_QOS_JITTERCHECKS == true || URT_CFG_PUBSUB_PROFILING == true ..

      * **minLatency** ← ""URT_DELAY_INFINITE""

      * **maxLatency** ← ""URT_DELAY_IMMEDIATE""

      .. URT_CFG_PUBSUB_QOS_RATECHECKS == true ..

      * **expectedRate** ← rate

    endnote

  endfork

  :lock topic;

  fork

    if (Messages to contribute?) then (yes)

      $contribute_messages()

    else (no)

    endif

  fork again

    fork

      :set message pointer to topic's latest message;

    fork again

      :copy timestamp from topic's latest message;

    endfork

  fork again

    :register to topic's event source;

  fork again

    fork

      partition "//URT_CFG_PUBSUB_QOS_RATECHECKS = true//" #EEEEEE {

        #EEEEEE:access first element of topic's list of HRT subscribers;

        while (Subscriber is not ""NULL""\nand its ""expectedRate"" is lower?) is (yes)

          #EEEEEE:proceed to next subscriber;

        endwhile (no)

        if (Current subscriber is ""NULL""?) then (yes)

          #EEEEEE:append self to topic's list of HRT subscribers;

        else (no)

          #EEEEEE:insert self in front of current HRT subscriber;

        endif

      }

    fork again

      :increment topic's counter of HRT subscribers;

    endfork

  fork again

    #EEEEEE:..//URT_CFG_PUBSUB_PROFILING == true//..\nincrement counter of subscribers (@topic);

  endfork

  :unlock topic;

  stop

  note

    Returns ""URT_STATUS_OK"".

  endnote

endif

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

@enduml