Notes 2019 01 17

Participants

Remove MPI_T_CB_REQUIRE_MPI_RESTRICTED
- Higher safety levels may actually make it harder to support specific functions in a callback.
- Implementation is allowed to return an error code
- Implementation is allowed to support more if it wants to
New hierarchy of safety requirement levels only contains:
- MPI_T_CB_REQUIRE_NONE
- MPI_T_CB_REQUIRE_THREAD_SAFE
- MPI_T_CB_REQUIRE_ASYNC_SIGNAL_SAFE
List of functions required to be supported in callbacks:
- (P)MPI_T_EVENT_HANDLE_ALLOC
- (P)MPI_T_EVENT_HANDLE_FREE
- (P)MPI_T_EVENT_READ
- (P)MPI_T_EVENT_COPY
- (P)MPI_T_EVENT_GET_TIMESTAMP
- (P)MPI_T_EVENT_GET_SOURCE
- (P)MPI_T_PVAR_READ
- (P)MPI_T_PVAR_READRESET
- (P)MPI_T_PVAR_WRITE
- (P)MPI_T_PVAR_START
- (P)MPI_T_PVAR_STOP
- (P)MPI_T_PVAR_RESET
- (P)MPI_T_SOURCE_GET_NUM
- (P)MPI_T_SOURCE_GET_TIMESTAMP
- (P)MPI_T_SOURCE_GET_INFO
Calls may still return an error code (e.g., MPI_T_ERR_NOT_ACCESSIBLE), it just has to be safe to call them.
No MPI_T event calls should be allowed as macros
- Flexibility of interception weighs higher than speed gained from macro implementation

Be explicit with how info objects are handled:
- MPI_T_EVENT_GET_INFO will return MPI_INFO_NULL before MPI initialization and after MPI finalization.
- MPI_T_EVENT_HANDLE_ALLOC will not evaluate info_object argument before MPI initialization and after MPI finalization.