GRAS flow control from work function

addis_a · July 15, 2013, 11:44pm

Hi,

I’m using gras for my application and my custom block needs to be able
to do a blocking read to get data from an external source. With the
standard scheduler I used a non blocking read in a polling loop with an
interruptable sleep and this worked Ok. Do I need to do it this way with
gras or can I get away with with blocking?

Another thing my block must do is stop the flow graph if its external
source has signaled that it is done. I did this with the standard
scheduler by returning WORK_DONE. How should this be done with gras?

Thanks.

casper_the_ghost · July 15, 2013, 11:49pm

On 07/15/2013 05:43 PM, [email protected] wrote:

Hi,

I’m using gras for my application and my custom block needs to be
able to do a blocking read to get data from an external source. With
the standard scheduler I used a non blocking read in a polling loop
with an interruptable sleep and this worked Ok. Do I need to do it
this way with gras or can I get away with with blocking?

Basically, you want to avoid stealing away the work() thread for too
long. So I recommend polling with a small timeout and return if there is
nothing. Work will get called again.

Relevant discussion:
http://lists.gnu.org/archive/html/discuss-gnuradio/2013-05/msg00124.html

Another thing my block must do is stop the flow graph if its external
source has signaled that it is done. I did this with the standard
scheduler by returning WORK_DONE. How should this be done with gras?

Use this->mark_done()

github.com

guruofquality/gras/blob/master/include/gras/block.hpp#L213


      
           * Direct buffer access API
           ******************************************************************/
          
          
/*!
           * Get access to the underlying reference counted input buffer.
           * This is the same buffer pointed to by input_items[which].
           * This function must be called during the call to work().
           * Use this function to implement passive work-flows.
           *
           * \param which_input the input port index
           * \return a reference counted copy of the buffer
           */
          SBuffer get_input_buffer(const size_t which_input) const;
          
          
/*!
           * Get access to the underlying reference counted output buffer.
           * This is the same buffer pointed to by output_items[which].
           * This function must be called during the call to work().
           * Use this to get a pool of buffers for datagram message ports.
           *
           * \param which_output the output port index

-josh