Why InPort.registerConsumerEvent don't establish a precedence between InPort >> Consumer ?

[myhwz]

hi, viewing the code from sparta/ports/port.cpp:

1. from the OutPort.bind(...), there is a comment:
   // ,--------------------------------------------------.
   // | V
   // producer -> [ inport internal delivery ]* -> consumer
   The inport -> consumer precedence is established during the consumer registration from a call to:
   InPort::registerConsumerEvent()

2. but in Inport.registerConsumerEvent(...):
   I can't find the code to establish the precedence of: InPort >> Consumer.
   What's the considerations in here ?

   thanks a lot.

[klingaard]

The call to registerConsumerEvent() places the given event into a list called port_consumers_ on the InPort:

map/sparta/sparta/ports/Port.hpp

Line 378 in 3092846

port_consumers_.push_back(&consumer);

That list is used in binding here:

map/sparta/sparta/ports/Port.hpp

Line 619 in 3092846

for(auto & cons : inp->port_consumers_) {

The actual precedence is made during the call setProducerPrecedence_ here:

map/sparta/sparta/ports/Port.hpp

Line 630 in 3092846

inp->setProducerPrecedence_(pd);

and eventually established to the internal event (Payload for example) here:

map/sparta/sparta/ports/DataPort.hpp

Line 458 in 3092846

void setProducerPrecedence_(Scheduleable * pd) override final {

Hope this clarifies how this works.

[myhwz]

Sorry to ask the question in the improper place, and thanks for you answer.
In OutPort.bind(...):

if((inp->getPortDelay() == 0) && presume_zero_delay_) {
    for(auto & pd : port_producers_)
    {
        for(auto & cons : inp->port_consumers_) {
            if(pd->getSchedulingPhase() == cons->getSchedulingPhase()) {
                pd->precedes(cons, reason);

                // Here just add a precedence between:  Producer >> Consumers
                // the Consumers are saved in: registerConsumerEvent()
            }
        }
        inp->setProducerPrecedence_(pd);

        // Here just add a precedence between:  Producer >> Inport.InnerEvent
    }
}

So after Bind, the DAG is:

graph LR
1(Producer) --> 2(Consumers)
1 --> 3("InPort's InnerEvent")
3 -.-x 2

Loading

My question is:
Why not establish a precedence between: InPort's InnerEvent >> Consumers ?

thanks a lot.

[klingaard]

Good question! And you had me stumped for a minute. 😆 I thought that this was possibly an oversight until I realized I forgot tell you about the last bit of binding activity that occurs in the port.

After the port consumers are "connected" to the port producers (mostly for, and only needed for, 0-cycle delay ports), a call to the InPort's internal bind_ is called;

map/sparta/sparta/ports/Port.hpp

Line 635 in 3092846

inp->bind_(this);

And in that function the inner event is preceded to the consumers:

map/sparta/sparta/ports/DataPort.hpp

Lines 478 to 484 in 3092846

	for(auto & consumer : port_consumers_)
	{
	if(consumer->getSchedulingPhase() == user_payload_delivery_->getSchedulingPhase()) {
	user_payload_delivery_->getScheduleable().precedes(consumer, "Port::bind(" + getName() + "->" + outp->getName() + "),'"
	+ consumer->getLabel() + "' is registered consumer");
	}
	}