[mpiwg-tools] ticket 405: MPI_CHAR as string

Sat Feb 15 06:47:28 CST 2014

+1

I under stand the null-terminating character as "the character doing the
null termination". As only the null character can do that, the text is
clearer now.

Cheers,
Marc-Andre

On 15.02.14 13:42, Jeff Squyres (jsquyres) wrote:
> Sorry -- nit-picking on my own text:
> 
> -----
> The use of the datatype MPI_CHAR in the MPI tool information interface implies a null-terminated character array, i.e., a string in the C language. If a variable has type MPI_CHAR, the value of the count parameter returned by MPI_T_CVAR_HANDLE_ALLOC and MPI_T_PVAR_HANDLE_ALLOC must be large enough to include any valid value, including its null-terminating character. The contents of returned MPI_CHAR arrays are only defined from index 0 through the location of the first null-terminating character.
> -----
> 
> In the 2nd and 3rd sentence, we refer to the "null-terminating character".  Is that correct?  Isn't it just a "null character"?
> 
> We use "null-terminated character array" in the first sentence, and that seems fine. But "null-terminated character" means "a character terminated by a null", which doesn't seem to make sense.
> 
> In 14.3.3 ("Convention for Returning Strings"), we refer to the "null terminator" and "terminating null character").  
> 
> I therefore think we should slightly change the last 2 sentences to:
> 
> -----
> The use of the datatype MPI_CHAR in the MPI tool information interface implies a null-terminated character array, i.e., a string in the C language. If a variable has type MPI_CHAR, the value of the count parameter returned by MPI_T_CVAR_HANDLE_ALLOC and MPI_T_PVAR_HANDLE_ALLOC must be large enough to include any valid value, including its ***terminating null*** character. The contents of returned MPI_CHAR arrays are only defined from index 0 through the location of the first ***null*** character.
> -----
> 
> 
> 
> 
> On Feb 14, 2014, at 6:16 PM, "Mohror, Kathryn" <mohror1 at llnl.gov> wrote:
> 
>> Thanks for the feedback. I have attached a new draft for this ticket and incorporated your changes. Please give me any additional comments by the start of business Monday.
>>
>> Kathryn
>>
>> On Feb 14, 2014, at 7:23 AM, Dave Goodell (dgoodell) <dgoodell at cisco.com> wrote:
>>
>>> +1 to almost everything that Jeff said.  My only quibble would be to change the last sentence in his text from:
>>>
>>> The contents of returned MPI_CHAR values are only defined from index 0 through the location of the first null-terminating character.
>>>
>>> To:
>>>
>>> The contents of returned MPI_CHAR ***arrays*** are only defined from index 0 through the location of the first null-terminating character.
>>>
>>> -Dave
>>>
>>> On Feb 14, 2014, at 7:27 AM, Jeff Squyres (jsquyres) <jsquyres at cisco.com> wrote:
>>>
>>>> Here's the new text:
>>>>
>>>> -----
>>>> The use of the datatype MPI_CHAR in the MPI tool information interface implies a null-terminated character array, i.e. a string in the C language. If a variable has type MPI_CHAR, the value of the count parameter returned by MPI_T_CVAR_HANDLE_ALLOC and MPI_T_PVAR_HANDLE_ALLOC will include the null-terminating character. The value returned in count must be large enough to contain any valid value for the given variable. Arrays of type MPI_CHAR are only valid to the first null character.
>>>> -----
>>>>
>>>> There's a missing "," after "i.e." -- it should be "i.e.,"
>>>>
>>>> I'd make some other minor changes:
>>>>
>>>> The use of the datatype MPI_CHAR in the MPI tool information interface implies a null-terminated character array, i.e., a string in the C language. If a variable has type MPI_CHAR, the value of the count parameter returned by MPI_T_CVAR_HANDLE_ALLOC and MPI_T_PVAR_HANDLE_ALLOC ***must be large enough to include any valid value, including its null-terminating character.***  ***The contents of returned MPI_CHAR values are only defined from index 0 through the location of the first null-terminating character.***
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On Feb 13, 2014, at 3:24 PM, Kathryn Mohror <kathryn at llnl.gov> wrote:
>>>>
>>>>> Hi all,
>>>>>
>>>>> Please have a look at this since we  have to decide if it's ready for a reading, and submit it to the forum for review on Monday if we do.
>>>>>
>>>>> Kathryn
>>>>>
>>>>> On Feb 7, 2014, at 1:05 PM, "Mohror, Kathryn" <mohror1 at llnl.gov> wrote:
>>>>>
>>>>>> Hi all,
>>>>>>
>>>>>> As we discussed in our call, I have drafted new text for ticket 405 which clarifies our intent for the MPI_CHAR datatype to represent strings in the tools interface. Please take a look at the red text for ticket 405 in the attached document and send your comments.
>>>>>>
>>>>>> Kathryn
>>>>>>
>>>>>>
>>>>>> _________________________________________________________________
>>>>>> Kathryn Mohror, kathryn at llnl.gov, http://scalability.llnl.gov/
>>>>>> Scalability Team @ Lawrence Livermore National Laboratory, Livermore, CA, USA
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> <tools-3.pdf>_______________________________________________
>>>>>> mpiwg-tools mailing list
>>>>>> mpiwg-tools at lists.mpi-forum.org
>>>>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-tools
>>>>>
>>>>> _________________________________________________________________
>>>>> Kathryn Mohror, kathryn at llnl.gov, http://scalability.llnl.gov/
>>>>> Scalability Team @ Lawrence Livermore National Laboratory, Livermore, CA, USA
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> mpiwg-tools mailing list
>>>>> mpiwg-tools at lists.mpi-forum.org
>>>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-tools
>>>>
>>>>
>>>> -- 
>>>> Jeff Squyres
>>>> jsquyres at cisco.com
>>>> For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/
>>>>
>>>> _______________________________________________
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>>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-tools
>>>
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>>
>> _________________________________________________________________
>> Kathryn Mohror, kathryn at llnl.gov, http://scalability.llnl.gov/
>> Scalability Team @ Lawrence Livermore National Laboratory, Livermore, CA, USA
>>
>>
>>
>>
>>
>>
>>
>>
>> <tools-3.pdf>_______________________________________________
>> mpiwg-tools mailing list
>> mpiwg-tools at lists.mpi-forum.org
>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-tools
> 
> 

-- 
Marc-Andre Hermanns
German Research School for
Simulation Sciences GmbH
c/o Laboratory for Parallel Programming
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