urtware / doc / activitydiagrams / subscriber / nrtsubscriber / urtNrtSubscriberFetchLatestMessage.uml @ 17d978fe
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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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|
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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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|
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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**\nurtNrtSubscriberFetchLatestMessage()\n |
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!include ../functions.iuml |
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/'### PARAMETERS & RETURN ####################################################'/ |
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note |
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-- **subscriber** : urt_nrtsubscriber_t* -- |
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The NRT subscriber that shall fetch the message. |
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Must not be ""NULL"". |
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-- **payload** : void* -- |
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Pointer where to copy the payload to. |
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May be ""NULL"" for messages without payload. |
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-- **bytes** : size_t -- |
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Payload size in bytes. |
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-- **latency** : urt_delay_t* -- |
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The latency can be returned by reference. |
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May be ""NULL"". |
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==== |
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-- **return** : urt_status_t -- |
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Returns ""URT_STATUS_OK"" on success. |
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Returns ""URT_STATUS_FETCH_NOTOPIC"" if the subscriber is not associated to a topic. |
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Retruns ""URT_STATUS_FETCH_NOMESSAGE"" if there is no new message to fetch. |
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endnote |
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/'### PROCEDURE ##############################################################'/ |
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start |
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if (Associated to a topic?) then (yes) |
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:lock topic; |
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$find_latest_message() |
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if (Timestamp equals local copy?) then (yes) |
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:unlock topic; |
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stop |
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note |
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Returns ""URT_STATUS_FETCH_NOMESSAGE"". |
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endnote |
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else (no) |
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fork |
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$fetch_message() |
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fork again |
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:calculate message latency; |
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note |
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Can be optimized in case all flags are disabled. |
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endnote |
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fork |
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#EEEEEE:..//URT_CFG_PUBSUB_PROFILING == true//..\naccumulate ""sumLatencies"" value; |
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fork again |
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partition "//URT_CFG_PUBSUB_PROFILING == true//" #EEEEEE {
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if (Latency is lower than ""minLatency""?) then (yes) |
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#EEEEEE:update ""minLatency"" value; |
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elseif (Latency is greater than ""maxLatency""?) then (yes) |
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#EEEEEE:update ""maxLatency"" value; |
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else (no) |
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endif |
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} |
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fork again |
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if (Optional ""latency"" output argument given?) then (yes) |
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:set ""latency"" value; |
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else (no) |
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endif |
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fork again |
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endfork |
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endfork |
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:unlock topic; |
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stop |
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note |
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Returns ""URT_STATUS_OK"". |
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endnote |
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endif |
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else (no) |
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stop |
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note |
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Returns ""URT_STATUS_FETCH_NOTOPIC"". |
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endnote |
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endif |
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/'### OUTRO ##################################################################'/ |
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@enduml |