`specfem::MPI`¶

specfem::MPI is a static class that provides an interface to MPI functionality within SPECFEM++. It manages MPI initialization and finalization, and provides static access to the rank and size of the MPI communicator.

class MPI¶

Static MPI wrapper for SPECFEM++.

This class provides a static interface to MPI functionality, eliminating the need to pass MPI pointers throughout the codebase.

Key features:

Static rank and size members accessible globally
Context-managed lifecycle (only Context can initialize/finalize)
Safety checks to prevent use outside Context scope
Minimal API focused on essential MPI operations

Usage:

// After Context is initialized
int my_rank = specfem::MPI::get_rank();
int world_size = specfem::MPI::get_size();
specfem::MPI::sync();

Note

This class cannot be instantiated. All members are static.

Note

Only specfem::program::Context can initialize/finalize this class.

Public Static Functions

static inline void sync()¶

Synchronize all MPI processes (MPI_Barrier)

Throws:: Calls – MPI_Abort if called by an excluded rank

static inline void sync_all()¶

Synchronize all MPI processes (alias for sync())

Throws:: Exits – with error code 1 if called outside Context scope

static inline int get_rank()¶

Get MPI rank.

Throws:: Exits – with error code 1 if called outside Context scope
Returns:: int Current MPI rank

static inline int get_size()¶

Get MPI world size.

Throws:: Exits – with error code 1 if called outside Context scope
Returns:: int Total number of MPI processes

static inline MPI_Comm communicator()¶

Get active communicator for simulations.

Returns the active communicator, which may be a subset communicator (if initialized with nprocs) or MPI_COMM_WORLD (default initialization). For excluded ranks in subset initialization, returns MPI_COMM_NULL.

Throws:: Exits – with error code 1 if called outside Context scope
Returns:: MPI_Comm The active communicator for simulations

static inline bool main_proc()¶

Check if current process is the main process (rank 0)

Throws:: Exits – with error code 1 if called outside Context scope
Returns:: bool True if rank == 0

static inline bool is_active()¶

Format filename with processor number using dynamic zero-padding.

For multi-process runs, transforms “dir/stem.ext” into “dir/stem/proc_N.ext” where N is the zero-padded rank. For single-process runs, the filename is returned unchanged.

Examples (size=6, rank=2):

”foo/bar.bin” -> “foo/bar/proc_2.bin”
”foo/bar.bin” (size=100, rank=2) -> “foo/bar/proc_02.bin”
”bar.bin” -> “bar/proc_2.bin”

Check if this rank is part of the active communicator

Returns false for ranks excluded by subset initialization (i.e., ranks >= nprocs when initialized with nprocs). Safe to call on any rank without triggering exit.

Parameters:: filename – Input filename (can include directory path)
Throws:: Exits – with error code 1 if called outside Context scope
Returns:: std::string Formatted filename with processor number
Returns:: bool True if this rank holds a valid communicator

specfem::MPI¶

`specfem::MPI`¶