MPI_T_event_callback_set_info(3)

✨ MPI_T_event_callback_set_info ✨

okay bestie, so this is the tea: MPI_T_event_callback_set_info is the MPI tool-interface girly whose whole job is updating the hints of the callback function you already registered 💅 and like, specifically the callback registered for the callback safety level that cb_safety picks out, on the event-registration handle that goes with event_registration. it's giving "change of plans, bestie" energy, and honestly? we love that for her 🎀

this page lives in the MPI manual, section 3 🦋

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🌸 SYNOPSIS 🌸

int MPI_T_event_callback_set_info(MPI_T_event_registration event_registration,
       MPI_T_cb_safety cb_safety, MPI_Info info)

like, that's the whole summoning ritual, no cap ✨

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💖 INPUT PARAMETERS 💖

• event_registration — the event registration, aka a handle 🫶
• cb_safety — the callback safety level, and she's an integer babe 🔢
• info — the info object, which is also a handle 📋

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🧵 THREAD AND INTERRUPT SAFETY 🧵

okay so this routine is thread-safe, periodt 💅 that means multiple threads can use it at the same time and you do not need to bring your own user-provided thread locks, she handles herself fr fr 🫶

but 😭 she is not interrupt safe. and the reason is typically giving memory allocation routines — stuff like malloc, or other non-MPICH runtime routines — which are themselves not interrupt-safe. so like, don't be out here interrupting her mid-glow-up, iykyk 💀

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💀 ERRORS 💀

okay so all MPI routines (except MPI_Wtime and MPI_Wtick) return an error value — C routines hand it back as the value of the function, and Fortran routines put it in the last argument 📌 before that value comes back, the current MPI error handler gets called. and by default, that error handler aborts the MPI job 😭 dramatic much?

the error handler can be changed with MPI_Comm_set_errhandler (for communicators), MPI_File_set_errhandler (for files), and MPI_Win_set_errhandler (for RMA windows) ✨ the MPI-1 routine MPI_Errhandler_set may be used but its use is deprecated — so like, she's retired bestie, don't 👑 the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned 🫶

note that MPI does not guarantee that an MPI program can continue past an error; however, MPI implementations will attempt to continue whenever possible. so, fingers crossed 🍓

here's the full error roster, no skipping any of them, we don't do that here:

• MPI_SUCCESS — no error; the MPI routine completed successfully 🎉 slay.
• MPI_ERR_INFO — invalid Info 🙈
• MPI_T_ERR_INVALID_HANDLE — the handle is invalid 💀
• MPI_T_ERR_NOT_INITIALIZED — the MPI tool information interface is not initialized 😭
• MPI_ERR_OTHER — other error; use MPI_Error_string to get more information about this error code 🧚

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that's the whole page bestie, you ate this 🍽️✨

mwah 💖 this was the MPI implementation's manual page, version date 4/10/2026, filed under section 3 as MPI_T_event_callback_set_info(3) — go forth and set those callback infos, queen 👑