[vtkusers] FindCell in multithreaded application

[Jim Peterson]

John Haiducek wrote:
> On Sat, 2010-10-30 at 14:39 -0400, Jim Peterson wrote:
>   
>> John,
>>
>> Just curious, where did you get the original premise that protecting the 
>> first call to FindCell would make all calls threadsafe? Was that in a 
>> VTK usage recomendation or document somewhere?
>>
>> Thanks,
>> Jim
>>     
>
> In the documentation for vtkDataSet it says: THIS METHOD IS THREAD SAFE
> IF FIRST CALLED FROM A SINGLE THREAD AND THE DATASET IS NOT MODIFIED.
> That's for the second version of FindCell, which takes a vtkGenericCell
> as a parameter. I may be misunderstanding it, but I thought the text in
> all caps meant that it's thread-safe as long as the first call is
> protected.
>
> John
>
>
>   
John,
Thanks for that, I think the part that needs clarification to me is what 
exactly is intended by the phrase "If first called from a single thread".

To anyone who can illuminate this threadsafe reference:
Can someone explain how there can be a first call not from a single 
thread? Single threaded use does not constitute "Thread Safe" to me, in 
fact, if all calls must be from a single thread, I would call it "Not 
Thread Safe" personally. Are all subsequent calls supposed to specify 
the same vtkGenericCell? Is the suggestion of "thread safe" suggesting 
the generated logic may result in multiple threads?

HTH,
Jim

HTH,
Jim