[Click] how do I dynamically create an element ?

[Eddie Kohler]

Bart,

Click is not built to do this.  I will not help you do this.  CERTAINLY not when 
you have not even measured how slow hotswapping is for your application.  How 
many configuration changes do you want a second?  10000?

Eddie


bartvdb wrote:
> Hi all
> 
> 
> I fear the configuration will probably need to be "hotswapped" too
> often.  I've tried a bit to create elements dynamically anyway in the
> C++ code of a custom element, and that seems to work up to a certain
> level, but now the router.cc code gives me a SIGABORT signal...
> 
> 
> Could anyone tell me please why this doesn't work and how I could make
> it to work:
> ##############
> int Valve::configure(Vector<String> &conf, ErrorHandler *errh)
> {   
>     int result;
>     Vector<String> v;
>     v.push_back("1000");
>     queue->configure(v,errh);
>     queue->initialize(errh);
>     _errh=errh;
>     //fill hashmap with dummy value;
>     unsigned hash=hashcode("255.255.255.255");
>     Usershaper *ushaper=new Usershaper();
>     ushaper->usershaper=new BandwidthShaper();
>     ushaper->userqueue=new SimpleQueue();
> 
>     Vector<String> vqueue;
>     vqueue.push_back("1000");
>     result = ushaper->userqueue->configure(vqueue,_errh);
>     click_chatter("result: %i", result);
> 
>     Vector<String> tempv;
>     tempv.push_back("56000bps");
>     result = ushaper->usershaper->configure(tempv,_errh);
>     click_chatter("result: %i", result);
> 
>     // cf.     
> http://www.pdos.lcs.mit.edu/click/doc/progman.html#Initialization%20Phases
>     //                  First configure, then connect ports, then initialize
>     //  cf.     $CLICKDIR/lib/router.cc: "Router::set_connections()"
>     //                  First connect output port then input port
>     int *input_codes, *output_codes;
>     ushaper->userqueue->processing_vector(input_codes, output_codes, _errh);
>     ushaper->userqueue->initialize_ports(input_codes, output_codes);
>     ushaper->usershaper->processing_vector(input_codes, output_codes,
> _errh);
>     ushaper->usershaper->initialize_ports(input_codes, output_codes);
>     result = ushaper->userqueue->connect_output(0,ushaper->usershaper,0);
>     click_chatter("result: %i", result);
>     result = ushaper->usershaper->connect_input(0,ushaper->userqueue,0);
>     click_chatter("result: %i", result);
>     result = ushaper->userqueue->initialize(_errh);
>     click_chatter("result: %i", result);
>     result = ushaper->usershaper->initialize(_errh);
>     click_chatter("result: %i", result);
> 
>     _shapermap.insert(hash, ushaper);
>     
>     return 0;
> }
> ##############
> 
> 
> Starting a configuration with this element in userlevel Click returns
> this on the command line:
> ##############
> result: 0
> result: 0
> result: -1
> result: 0
> result: 0
> result: 0
> Segmentation fault
> ##############
> 
> 
> All seems very much OK, up till the segmentation fault.  As mentioned
> before, the segmentation fault corresponds to a SIGABORT signal (as seen
> when debugging the code with DDD) when the configuration of this element
> finishes and the code of router.cc resumes executing.  Some memory
> address cannot be accessed and it seems the "this" pointer has changed...
> 
> 
> Thanks in advance
> Bart
> 
> 
> 
> 
>>Hi Bart,
>>
>>Click doesn't yet support this directly, but it is possible to 
>>"hotswap" a new configuration.  State from the old config will be 
>>inserted into the new.
>>
>>Eddie
>>
>>
>>On Mar 16, 2005, at 6:08 AM, Bart Van Keyenberg wrote:
>>
>>
>>>Hi,
>>>
>>>I want to create a click configuration where I don't know how much 
>>>elements of a certain kind I will need beforehand (number of elements 
>>>depends on number of users).  Can I dynamically create an element 
>>>(e.g. from within another element), and if so, how do I handle this 
>>>kind of thing?
>>>
>>>Kind Regards
>>>
>>>Bart
> 
> 
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