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urtware / doc / activitydiagrams / subscriber / functions.iuml @ e87bd7c7

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1 e87bd7c7 Thomas Schöpping
/'
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µRtWare is a lightweight publish/subscribe middleware for real-time
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applications. It was developed as part of the software habitat for the
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Autonomous Mini Robot [1] (AMiRo) but can be used for other purposes as well.
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Copyright (C) 2018..2020  Thomas Schöpping et al.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program.  If not, see <http://www.gnu.org/licenses/>.
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'/
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/' Fetch a message and update/copy all data. '/
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!function $fetch_message()
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  partition "fetch message" {
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    fork
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      :update message pointer;
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    fork again
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        :copy timestamp of message;
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    fork again
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      :copy message payload;
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    fork again
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      if (Optional output argument ""latency"" given?) then (yes)
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        :set ""latency"" value (now - message origin time);
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      else (no)
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      endif
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    endfork
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  }
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!endfunction
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/' Find the latest message in the circular message buffer. '/
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!function $find_latest_message()
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  partition "find latest message" {
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    :access last read message;
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    while (Timestamp of next message is younger?) is (yes)
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      :proceed to next message;
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    endwhile (no)
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  }
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!endfunction
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/' Find the oldest message in the circular message buffer. '/
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!function $find_oldest_message()
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  partition "find oldest valid message" {
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    if (Timestamp of last read message euqals local copy?) then (yes)
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    else (no)
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      while (Timestamp of next message is younger?) is (yes)
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        :proceed to next message;
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      endwhile (no)
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    endif
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    :proceed to next message;
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  }
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!endfunction