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urtware / doc / activitydiagrams / service / urtServiceDispatch.uml @ 0de5bed8

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/'
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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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/'### INTRO ##################################################################'/
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@startuml
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title **µRtWare**\nurtServiceDispatch()\n
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/'### PARAMETERS & RETURN ####################################################'/
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note
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  -- **service** : urt_service_t* --
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  The service to dispatch a request for.
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  Must not be ""NULL"".
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  -- **payload** : void* --
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  Pointer where to store the payload (if any).
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  May be ""NULL"" if the service expects no payload.
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  -- **bytes** : size_t --
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  Size of the payload in bytes.
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  Must be 0 if the service expects no payload.
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  ====
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  -- **return** : urt_baserequest_t* --
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  Pointer to the request to be processed next.
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  May be ""NULL"" if there are no pending requests.
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endnote
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/'### PROCEDURE ##############################################################'/
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start
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:lock service;
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if (Request list empty?) then (no)
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  :access first request (""requestQueue_front"");
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  note
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    No need to lock the request because it is enqueued at this point.
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    Enqueued requests must not be altered without the according service to be locked.
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    Since the service has been locked, no enqueued requests will be modified externally.
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  endnote
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  :proceed ""requestQueue_front"" pointer;
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  fork
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    if (This was the last request (pointer became ""NULL"")?) then (yes)
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      :set ""requestQueue_back"" to ""NULL"";
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    else (no)
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      :set request ""next"" pointer to ""NULL"";
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    endif
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  fork again
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    if (This was the last HRT request?) then (yes)
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      :set ""requestQueue_hrtBack"" to ""NULL"";
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    elseif (This was the last FRT/SRT request?) then (yes)
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      :set ""requestQueue_fsrtBack"" to ""NULL"";
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    else (no)
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    endif
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  fork again
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    :copy payload from request to argument;
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  endfork
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  :unlock service;
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  stop
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  note
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    Returns pointer to the dispatched request.
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  endnote
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else (yes)
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endif
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:unlock service;
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stop
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note
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  Returns ""NULL"".
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endnote
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/'### OUTRO ##################################################################'/
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@enduml