[mpiwg-tools] question about MPI_T_EVENT_SET_DROPPED_HANDLER

[Raffenetti, Kenneth J.]

On 1/25/21, 2:49 PM, "mpiwg-tools on behalf of Raffenetti,	Kenneth J. via mpiwg-tools" <mpiwg-tools-bounces at lists.mpi-forum.org on behalf of mpiwg-tools at lists.mpi-forum.org> wrote:

    On 1/25/21, 12:44 PM, "mpiwg-tools on behalf of Raffenetti,	Kenneth J. via mpiwg-tools" <mpiwg-tools-bounces at lists.mpi-forum.org on behalf of mpiwg-tools at lists.mpi-forum.org> wrote:
    
        On 1/25/21, 11:46 AM, "Marc-André Hermanns" <hermanns at itc.rwth-aachen.de> wrote:
           
            For me (although not explicitly defined in the text) that would imply
            that the dropped callback is only invoked once the library is in a
            state where a callback (and user_data) for the same level is defined
            and could be invoked.
            
            Does this make sense and clarify your concerns? Do you think this need
            more clarification in the text?
            
        I see. Yes, that makes sense for my implementation issue.
        
    I may have spoken too soon. I'm looking at pg 763, ln 37 (Handling Dropped Events):
    
       If an event occurs...[and] no callback function meeting the required callback safety level is registered, the event data may be dropped. To discover such data loss, the user can set a handler function for a specific event-registration handle.
    
    If a callback function meeting the required safety level is not registered, how do I decide which user buffer to provide to the dropped handler?
    
Oh, so if I am reading your clarification correctly above, you are saying I should not invoke the dropped handler until a callback for that safety level has been registered. It is possible then that I might never call the dropped handler. Should I be managing dropped event counts for all safety levels?

Ken