topic Child task to access message queue in MQX Software Solutions

Child task to access message queue

CarlFST60L — Tue, 08 Sep 2009 08:17:28 GMT

Hi,

Is there an easy way to allow any child task to receive messages from a private message queue? The code was orginally written as if the queue ID was enough information to access the messages on the queue.

Example

'Main_Task' creates pool / queue to the task 'RXI_Task'

'Main_Task' calls various functions which get data via the message queue to 'RXI_Task'

'Main_Task' then creates several child tasks which can call the same functions called from 'Main_Task', these functions get the data via 'RXI_Task' queue. The problem is when these child tasks are created, the message queue ID is no longer enough to get the messages from 'RXI_Task', only 'Main_Task' can access those messages.

There is a mutex protecting the functions from multipule tasks trying to access the msgq.

Do i have to rewrite this? or is there some other way?

Re: Child task to access message queue

MQXuser — Tue, 08 Sep 2009 10:47:31 GMT

Hi Carl,

Are you closing(with your Main Task) and reopening the Message Queue with the child task trying to receive the message?

Remember that Only the task that opens a private message queue can receive messages from the queue.

And just a small question, if you are protecting the msgq with a mutex, should we protect message pools

with mutex too? I thought MQX protected this functions by default?

msg_ptr = (GENERIC_DATA_MSG_PTR)_msg_alloc(mp_QuadSPI);

If different priority tasks have calls to the instruction above, should we use Mutex to prevent simultaneous access?

Regards,

Re: Child task to access message queue

CarlFST60L — Tue, 08 Sep 2009 11:23:54 GMT

Maybe it makes no sense, but it would be nice if what ever task knows the queue ID could get messages with that queue ID. Or is there was a simple way you could change ownership of the message queue.