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| Re: Receiving exernal event on genfb (ex.: subscribe) [message #1863970 is a reply to message #1863578] |
Fri, 08 March 2024 12:18  |
 paulo nunes
Messages: 10
Registered: January 2024 |
Junior Member |
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after some reading about external events on this forum, i still don't know what the best approach is. i'm creating a generated block subscriber for a layer 2 OSI protocol from a library that already has its functions implemented, i simply integrated the library into FORTE. i already tested the function that subscribes to data from layer 2 inside 4diac and it's working.
what i'm not being able to do is receive an external event inside the same block, and still don't know if it's the right way, as the data can arrive multiple times in a short time interval and i've read in some posts that i can't simply output an event into 4diac, i must generate an external event and receive inside the block so that it may be thread-safe.
Edit: After some time experimenting with external events, i was able to start and receive an external event on a generated block.
For anyone with the same problem: the generated block class inherits from "CGenFunctionBlock<CEventSourceFB>" similar to "basecommfb" header and source, and has every setting of a generated block. Also, it's necessary to create a handler class that will inherit from "CExternalEventHandler" and "CThread". I created the handler based on the way they are used on any protocol of the "com" folders (like MQTT):
I - a CSyncObject is created to enter the critical region when creating the external event.
II - a CSinglyLinkedList<"generated_block_class_here"*> object is created to hold the instances of the generated blocks during runtime (the instance will be added to the list during the creation of the generated block). For that, it's necessary to include the generated block header into the handler header.
III - two new functions on the handler: one will register the instance (example: mlayers.pushback of "mqtt" source) and the other will create the external event (example:
::getexternalevhandler(instance)...Startneweventchain(instance) also in "mqtt" source).
in the generated block source, you will include the handler header and will create a handler object that will call the register function with the pointer "this" and everytime you need to create the external event, call the event creation function from the same handler object with some parameter that identify the instance you are trying to generate an external event on (example: i created a handler function that passes a string as parameter to compare with a instance variable through a loop on the singlylinkedlist, that also is on the "mqtt" source).
[Updated on: Tue, 19 March 2024 19:13] Report message to a moderator |
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