[Click] info about HandlerCall::call_read()

[Cliff Frey]

please always CC the mailing list in your replies.

You could probably do much of this with a script

Script(wait 1.0, print "the energy used in the last second was: " ${add
${control_a.energy} ${control_b.energy}, loop);

But, scripts are hard to use when there is a lot of logic that you want to
express.

So I advising that you make an element to do this calculation... the element
is something like  (please excuse my pseudo-code)

controlelement.hh defines a function
  int get_energy_usage();

energytracker.hh defines members
public:
  configure(...);
  element_name() ...;
  etc.

private:
  ControlElement *_control_a;
  ControlElement *_control_b;
}

then
energytracker.hh has
int EnergyTracker::configure(...) {
  Args(conf, this, errh)
    .read("CONTROL_A", ElementCastArg("ControlElement"), _control_a)
    .read("CONTROL_B", ElementCastArg("ControlElement"), _control_b)
    .complete();
}

String EnergyTracker::read_out_energy_handler(...) {
  EnergyTracker *et = (EnergyTracker *) e;
  return String(et->_control_a->get_energy_usage() +
et->_control_b->get_energy_usage());
}

good luck.

Cliff

On Tue, Oct 11, 2011 at 3:24 PM, Xavier Salip <saverione09 at gmail.com> wrote:

> Ok. I don't really get the option with the pointers. I'll try to explain
> better my situation:
>
> I have different CONTROL elements, one of them for each different element i
> have programmed (f.e: CONTROL_A will calculate energy consumption of an A
> element). To do that, the CONTROL element has a handler called "Energy",
> which i can eventually call on router execution to read the Energy
> consumption of a desired element. My purpose is to calculate the energy
> consumption of this desired element by calling the handler "time" (which is
> programmed in all my different kind of elements) and multiplying this "time"
> by a power formula.
> The problem is that i don't really know how to use* HandlerCall::call_read
> * to do that.
> For example, i would like to write *READ CONTROL_A.Energy* to get the
> energy consumption of an element called A.
> Despite my confusion, I hope you to understand what i mean.
>
> Thanks!
>
>
> On Tue, Oct 11, 2011 at 6:46 PM, Cliff Frey <cliff at meraki.com> wrote:
>
>> You can look at the HandlerCall interface if you really want to use
>> read-handlers.
>>
>> Often in cases like this, it is easier to actually pass a pointer from one
>> element to another through the config.  ARPQuerier can do this with
>> ARPTable, or etherswitch/spantree.cc does this as well.  Search for
>> ElementCastArg in the source.
>>
>> Cliff
>>
>> On Tue, Oct 11, 2011 at 7:54 AM, Xavier Salip <saverione09 at gmail.com>wrote:
>>
>>> Hi list,
>>>
>>> I have created an element called WC.
>>> In a configuration .click file i have a bank of 5 WC elements (WC1,
>>> WC2...WC5),  each one of them with a read handler called "energy".
>>> I would like to create a control element CONTROL which reads the handler
>>> "energy" on the desired WC and make some calculations with it.
>>> I'm trying with this function to call the handler, but i don't manage to
>>> find how to use it in a correct way:
>>>
>>> String <http://www.read.cs.ucla.edu/click/doxygen/class_string.html
>>> >HandlerCall::call_read
>>> ( Element <http://www.read.cs.ucla.edu/click/doxygen/class_element.html>
>>> *
>>> *e*,
>>>
>>> const String <
>>> http://www.read.cs.ucla.edu/click/doxygen/class_string.html>&
>>> *hname*,
>>>
>>> ErrorHandler<
>>> http://www.read.cs.ucla.edu/click/doxygen/class_error_handler.html>*
>>> *errh* = 0
>>>
>>> )
>>>
>>> Any ideas or suggestions?
>>>
>>> Thanks!
>>> _______________________________________________
>>> click mailing list
>>> click at amsterdam.lcs.mit.edu
>>> https://amsterdam.lcs.mit.edu/mailman/listinfo/click
>>>
>>
>>
>