Re: [Ganglia-developers] Fwd: Getting started with developing a C++ DSO module

[Brad N. <BNI...@no...>]

>>> On 11/25/2009 at 11:12 AM, in message
<75f...@ma...>, Sylvester Steele
<syl...@gm...> wrote:
>>  I don't know why you would be getting a segfault on this line.  Gmond 
> expects the array to be NULL terminated so all you are doing is adding one 
> extra entry and filling it will NULLs.  With the array being NULL terminated, 
> gmond doesn't have to keep track of the metric count, it only has to look for 
> a NULL entry.
>>
> 
> 
> More modifications- and I can't figure out where the problem is.
> 
> I tried
> 
> gmi->name=NULL
> 
> that didn't work either
> 
> Then I thought I should remove the null metric and have only one metric 
> like:
> 
> 
> 
>     gmi = (Ganglia_25metric*)apr_array_push(metric_info);
> 
> gmi->name= apr_pstrdup (pool,"Random_Numbers_2");
> gmi->tmax=90;
> gmi->type=GANGLIA_VALUE_UNSIGNED_INT;
> gmi->msg_size= UDP_HEADER_SIZE+8;
> gmi->units= apr_pstrdup (pool,"Num");
> gmi->slope=apr_pstrdup (pool,"both");
> gmi->fmt=apr_pstrdup (pool,"%u");
> gmi->desc= apr_pstrdup (pool,"Example module metric (random numbers) 2");
> MMETRIC_INIT_METADATA(gmi, pool);
> MMETRIC_ADD_METADATA(gmi,MGROUP,"example_2");
> 
> printf ("\n First metric done");
> 
> /*
> gmi = (Ganglia_25metric*)apr_array_push(metric_info);
> printf ("\nStarted second metric..");
> 
> gmi->name= apr_pstrdup (pool,"Constant_Number_2");
> gmi->tmax=90;
> gmi->type=GANGLIA_VALUE_UNSIGNED_INT;
> gmi->msg_size= UDP_HEADER_SIZE+8;
> gmi->units= apr_pstrdup (pool,"Num");
> gmi->slope=apr_pstrdup (pool,"zero");
> gmi->fmt=apr_pstrdup (pool,"%u");
> gmi->desc= apr_pstrdup (pool,"Example module metric (constant number) 2");
> MMETRIC_INIT_METADATA(gmi, pool);
> MMETRIC_ADD_METADATA(gmi,MGROUP,"example_2");
> 
> printf ("\nSecond metric done");
> */
> //gmi = (Ganglia_25metric*)apr_array_push(metric_info);
> //printf ("\nStarted null metric");
> 
> //gmi->name= apr_pstrdup (pool,NULL);
> 
> //memset (gmi, 0, sizeof(*gmi));
> printf ("\nMetric initing done");
> return 0;
> 
> And this gives a segfault too! And here is the output:
> 
> In the ex_metric_init function
> Got first GMI
>  First metric done
> Segmentation fault
> 
> 
> ie there is a segfault between the last and second last printf
> statements! Any clues?
> 

Sorry, my only suggestion would be to run it in the debugger to get a better idea of what is happening.

Brad