/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil -*- */
/*
* Copyright (c) 2004-2005 The Trustees of Indiana University and Indiana
* University Research and Technology
* Corporation. All rights reserved.
* Copyright (c) 2004-2013 The University of Tennessee and The University
* of Tennessee Research Foundation. All rights
* reserved.
* Copyright (c) 2004-2005 High Performance Computing Center Stuttgart,
* University of Stuttgart. All rights reserved.
* Copyright (c) 2004-2005 The Regents of the University of California.
* All rights reserved.
* Copyright (c) 2006-2012 Cisco Systems, Inc. All rights reserved.
* Copyright (c) 2006-2010 University of Houston. All rights reserved.
* Copyright (c) 2009 Sun Microsystems, Inc. All rights reserved.
* Copyright (c) 2011-2013 Inria. All rights reserved.
* Copyright (c) 2011-2013 Universite Bordeaux 1
* Copyright (c) 2012-2013 Los Alamos National Security, LLC. All rights
* reserved.
* Copyright (c) 2014-2015 Intel, Inc. All rights reserved.
* Copyright (c) 2015 Research Organization for Information Science
* and Technology (RIST). All rights reserved.
* $COPYRIGHT$
*
* Additional copyrights may follow
*
* $HEADER$
*/
#ifndef OMPI_COMMUNICATOR_H
#define OMPI_COMMUNICATOR_H
#include "ompi_config.h"
#include "opal/class/opal_object.h"
#include "ompi/errhandler/errhandler.h"
#include "opal/threads/mutex.h"
#include "ompi/communicator/comm_request.h"
#include "mpi.h"
#include "ompi/group/group.h"
#include "ompi/mca/coll/coll.h"
#include "ompi/info/info.h"
#include "ompi/proc/proc.h"
BEGIN_C_DECLS
OMPI_DECLSPEC OBJ_CLASS_DECLARATION(ompi_communicator_t);
#define OMPI_COMM_INTER 0x00000001
#define OMPI_COMM_NAMEISSET 0x00000002
#define OMPI_COMM_INTRINSIC 0x00000004
#define OMPI_COMM_DYNAMIC 0x00000008
#define OMPI_COMM_ISFREED 0x00000010
#define OMPI_COMM_INVALID 0x00000020
#define OMPI_COMM_CART 0x00000100
#define OMPI_COMM_GRAPH 0x00000200
#define OMPI_COMM_DIST_GRAPH 0x00000400
#define OMPI_COMM_PML_ADDED 0x00001000
#define OMPI_COMM_EXTRA_RETAIN 0x00004000
/* some utility #defines */
#define OMPI_COMM_IS_INTER(comm) ((comm)->c_flags & OMPI_COMM_INTER)
#define OMPI_COMM_IS_INTRA(comm) (!((comm)->c_flags & OMPI_COMM_INTER))
#define OMPI_COMM_IS_CART(comm) ((comm)->c_flags & OMPI_COMM_CART)
#define OMPI_COMM_IS_GRAPH(comm) ((comm)->c_flags & OMPI_COMM_GRAPH)
#define OMPI_COMM_IS_DIST_GRAPH(comm) ((comm)->c_flags & OMPI_COMM_DIST_GRAPH)
#define OMPI_COMM_IS_INTRINSIC(comm) ((comm)->c_flags & OMPI_COMM_INTRINSIC)
#define OMPI_COMM_IS_FREED(comm) ((comm)->c_flags & OMPI_COMM_ISFREED)
#define OMPI_COMM_IS_DYNAMIC(comm) ((comm)->c_flags & OMPI_COMM_DYNAMIC)
#define OMPI_COMM_IS_INVALID(comm) ((comm)->c_flags & OMPI_COMM_INVALID)
#define OMPI_COMM_IS_PML_ADDED(comm) ((comm)->c_flags & OMPI_COMM_PML_ADDED)
#define OMPI_COMM_IS_EXTRA_RETAIN(comm) ((comm)->c_flags & OMPI_COMM_EXTRA_RETAIN)
#define OMPI_COMM_IS_TOPO(comm) (OMPI_COMM_IS_CART((comm)) || \
OMPI_COMM_IS_GRAPH((comm)) || \
OMPI_COMM_IS_DIST_GRAPH((comm)))
#define OMPI_COMM_SET_DYNAMIC(comm) ((comm)->c_flags |= OMPI_COMM_DYNAMIC)
#define OMPI_COMM_SET_INVALID(comm) ((comm)->c_flags |= OMPI_COMM_INVALID)
#define OMPI_COMM_SET_PML_ADDED(comm) ((comm)->c_flags |= OMPI_COMM_PML_ADDED)
#define OMPI_COMM_SET_EXTRA_RETAIN(comm) ((comm)->c_flags |= OMPI_COMM_EXTRA_RETAIN)
/* a set of special tags: */
/* to recognize an MPI_Comm_join in the comm_connect_accept routine. */
#define OMPI_COMM_ALLGATHER_TAG -31078
#define OMPI_COMM_BARRIER_TAG -31079
#define OMPI_COMM_ALLREDUCE_TAG -31080
/**
* Modes required for acquiring the new comm-id.
* The first (INTER/INTRA) indicates whether the
* input comm was an inter/intra-comm, the second
* whether the new communicator will be an inter/intra
* comm
*/
#define OMPI_COMM_CID_INTRA 0x00000020
#define OMPI_COMM_CID_INTER 0x00000040
#define OMPI_COMM_CID_INTRA_BRIDGE 0x00000080
#define OMPI_COMM_CID_INTRA_PMIX 0x00000100
#define OMPI_COMM_CID_GROUP 0x00000200
/**
* The block of CIDs allocated for MPI_COMM_WORLD
* and other communicators
*/
#define OMPI_COMM_BLOCK_WORLD 16
#define OMPI_COMM_BLOCK_OTHERS 8
/* A macro comparing two CIDs */
#define OMPI_COMM_CID_IS_LOWER(comm1,comm2) ( ((comm1)->c_contextid < (comm2)->c_contextid)? 1:0)
OMPI_DECLSPEC extern opal_pointer_array_t ompi_mpi_communicators;
OMPI_DECLSPEC extern opal_pointer_array_t ompi_comm_f_to_c_table;
struct ompi_communicator_t {
opal_object_t c_base;
opal_mutex_t c_lock; /* mutex for name and potentially
attributes */
char c_name[MPI_MAX_OBJECT_NAME];
uint32_t c_contextid;
int c_my_rank;
uint32_t c_flags; /* flags, e.g. intercomm,
topology, etc. */
int c_id_available; /* the currently available Cid for allocation
to a child*/
int c_id_start_index; /* the starting index of the block of cids
allocated to this communicator*/
ompi_group_t *c_local_group;
ompi_group_t *c_remote_group;
struct ompi_communicator_t *c_local_comm; /* a duplicate of the
local communicator in
case the comm is an
inter-comm*/
/* Attributes */
struct opal_hash_table_t *c_keyhash;
/**< inscribing cube dimension */
int c_cube_dim;
/* Standard information about the selected topology module (or NULL
if this is not a cart, graph or dist graph communicator) */
struct mca_topo_base_module_t* c_topo;
/* index in Fortran <-> C translation array */
int c_f_to_c_index;
#ifdef OMPI_WANT_PERUSE
/*
* Place holder for the PERUSE events.
*/
struct ompi_peruse_handle_t** c_peruse_handles;
#endif
/* Error handling. This field does not have the "c_" prefix so
that the OMPI_ERRHDL_* macros can find it, regardless of whether
it's a comm, window, or file. */
ompi_errhandler_t *error_handler;
ompi_errhandler_type_t errhandler_type;
/* Hooks for PML to hang things */
struct mca_pml_comm_t *c_pml_comm;
/* Collectives module interface and data */
mca_coll_base_comm_coll_t c_coll;
};
typedef struct ompi_communicator_t ompi_communicator_t;
/**
* Padded struct to maintain back compatibiltiy.
*
* The following ompi_predefined_xxx_t structure is used to maintain
* backwards binary compatibility for MPI applications compiled
* against one version of OMPI library but dynamically linked at
* runtime with another. The issue is between versions the actual
* structure may change in size (even between debug and optimized
* compilation -- the structure contents change, and therefore the
* overall size changes).
*
* This is problematic with predefined handles because the storage of
* the structure ends up being located to an application's BSS. This
* causes problems because if one version has the predefined as size X
* and then the application is dynamically linked with a version that
* has a size of Y (where X != Y) then the application will
* unintentionally overrun the memory initially allocated for the
* structure.
*
* The solution we are using below creates a parent structure
* (ompi_predefined_xxx_t) that contains the base structure
* (ompi_xxx_t) followed by a character padding that is the size of
* the total size we choose to preallocate for the structure minus the
* amount used by the base structure. In this way, we've normalized
* the size of each predefined handle across multiple versions and
* configurations of Open MPI (e.g., MPI_COMM_WORLD will refer to a
* back-end struct that is X bytes long, even if we change the
* back-end ompi_communicator_t between version A.B and version C.D in
* Open MPI). When we come close to filling up the the padding we can
* add a pointer at the back end of the base structure to point to an
* extension of the type. Or we can just increase the padding and
* break backwards binary compatibility.
*
* The above method was decided after several failed attempts
* described below.
*
* - Original implementation - suffered that the base structure seemed
* to always change in size between Open MPI versions and/or
* configurations (e.g., optimized vs. debugging build).
*
* - Convert all predefined handles to run-time-assigned pointers
* (i.e., global variables) - This worked except in cases where an MPI
* application wanted to assign the predefined handle value to a
* global variable -- we could not guarantee to have the global
* variable filled until MPI_INIT was called (recall that MPI
* predefined handles must be assignable before MPI_INIT; e.g.,
* "MPI_Comm foo = MPI_COMM_WORLD").
*
* - union of struct and padding - Similar to current implementation
* except using a union for the parent. This worked except in cases
* where the compilers did not support C99 union static initalizers.
* It would have been a pain to convert a bunch of the code to use
* non-static initializers (e.g., MPI datatypes).
*/
/* Define for the preallocated size of the predefined handle.
* Note that we are using a pointer type as the base memory chunk
* size so when the bitness changes the size of the handle changes.
* This is done so we don't end up needing a structure that is
* incredibly larger than necessary because of the bitness.
*/
#define PREDEFINED_COMMUNICATOR_PAD (sizeof(void*) * 192)
struct ompi_predefined_communicator_t {
struct ompi_communicator_t comm;
char padding[PREDEFINED_COMMUNICATOR_PAD - sizeof(ompi_communicator_t)];
};
typedef struct ompi_predefined_communicator_t ompi_predefined_communicator_t;
OMPI_DECLSPEC extern ompi_communicator_t *ompi_mpi_comm_parent;
OMPI_DECLSPEC extern ompi_predefined_communicator_t ompi_mpi_comm_world;
OMPI_DECLSPEC extern ompi_predefined_communicator_t ompi_mpi_comm_self;
OMPI_DECLSPEC extern ompi_predefined_communicator_t ompi_mpi_comm_null;
/*
* These variables are for the MPI F03 bindings (F03 must bind Fortran
* varaiables to symbols; it cannot bind Fortran variables to the
* address of a C variable).
*/
OMPI_DECLSPEC extern ompi_predefined_communicator_t *ompi_mpi_comm_world_addr;
OMPI_DECLSPEC extern ompi_predefined_communicator_t *ompi_mpi_comm_self_addr;
OMPI_DECLSPEC extern ompi_predefined_communicator_t *ompi_mpi_comm_null_addr;
/**
* Is this a valid communicator? This is a complicated question.
* :-)
*
* According to MPI-1:5.2.4 (p137):
*
* "The predefined constant MPI_COMM_NULL is the value used for
* invalid communicator handles."
*
* Hence, MPI_COMM_NULL is not valid. However, MPI-2:4.12.4 (p50)
* clearly states that the MPI_*_C2F and MPI_*_F2C functions
* should treat MPI_COMM_NULL as a valid communicator -- it
* distinctly differentiates between "invalid" handles and
* "MPI_*_NULL" handles. Some feel that the MPI-1 definition
* still holds for all other MPI functions; others feel that the
* MPi-2 definitions trump the MPI-1 definition. Regardless of
* who is right, there is ambiguity here. So we have left
* ompi_comm_invalid() as originally coded -- per the MPI-1
* definition, where MPI_COMM_NULL is an invalid communicator.
* The MPI_Comm_c2f() function, therefore, calls
* ompi_comm_invalid() but also explictily checks to see if the
* handle is MPI_COMM_NULL.
*/
static inline int ompi_comm_invalid(ompi_communicator_t* comm)
{
if ((NULL == comm) || (MPI_COMM_NULL == comm) ||
(OMPI_COMM_IS_FREED(comm)) || (OMPI_COMM_IS_INVALID(comm)) )
return true;
else
return false;
}
/**
* rank w/in the communicator
*/
static inline int ompi_comm_rank(ompi_communicator_t* comm)
{
return comm->c_my_rank;
}
/**
* size of the communicator
*/
static inline int ompi_comm_size(ompi_communicator_t* comm)
{
return comm->c_local_group->grp_proc_count;
}
/**
* size of the remote group for inter-communicators.
* returns zero for an intra-communicator
*/
static inline int ompi_comm_remote_size(ompi_communicator_t* comm)
{
return (comm->c_flags & OMPI_COMM_INTER ? comm->c_remote_group->grp_proc_count : 0);
}
/**
* Context ID for the communicator, suitable for passing to
* ompi_comm_lookup for getting the communicator back
*/
static inline uint32_t ompi_comm_get_cid(ompi_communicator_t* comm)
{
return comm->c_contextid;
}
/* return pointer to communicator associated with context id cid,
* No error checking is done*/
static inline ompi_communicator_t *ompi_comm_lookup(uint32_t cid)
{
/* array of pointers to communicators, indexed by context ID */
return (ompi_communicator_t*)opal_pointer_array_get_item(&ompi_mpi_communicators, cid);
}
static inline struct ompi_proc_t* ompi_comm_peer_lookup(ompi_communicator_t* comm, int peer_id)
{
#if OPAL_ENABLE_DEBUG
if(peer_id >= comm->c_remote_group->grp_proc_count) {
opal_output(0, "ompi_comm_peer_lookup: invalid peer index (%d)", peer_id);
return (struct ompi_proc_t *) NULL;
}
#endif
/*return comm->c_remote_group->grp_proc_pointers[peer_id];*/
return ompi_group_peer_lookup(comm->c_remote_group,peer_id);
}
static inline bool ompi_comm_peer_invalid(ompi_communicator_t* comm, int peer_id)
{
if(peer_id < 0 || peer_id >= comm->c_remote_group->grp_proc_count) {
return true;
}
return false;
}
/**
* Initialise MPI_COMM_WORLD and MPI_COMM_SELF
*/
int ompi_comm_init(void);
OMPI_DECLSPEC int ompi_comm_link_function(void);
/**
* extract the local group from a communicator
*/
OMPI_DECLSPEC int ompi_comm_group (ompi_communicator_t *comm, ompi_group_t **group);
/**
* create a communicator based on a group
*/
int ompi_comm_create (ompi_communicator_t* comm, ompi_group_t *group,
ompi_communicator_t** newcomm);
/**
* Non-collective create communicator based on a group
*/
int ompi_comm_create_group (ompi_communicator_t *comm, ompi_group_t *group, int tag,
ompi_communicator_t **newcomm);
/**
* Take an almost complete communicator and reserve the CID as well
* as activate it (initialize the collective and the topologies).
*/
int ompi_comm_enable(ompi_communicator_t *old_comm,
ompi_communicator_t *new_comm,
int new_rank,
int num_procs,
ompi_proc_t** topo_procs);
/**
* Back end of MPI_DIST_GRAPH_CREATE_ADJACENT
*/
int ompi_topo_dist_graph_create_adjacent(ompi_communicator_t *old_comm,
int indegree, int sources[],
int sourceweights[], int outdegree,
int destinations[], int destweights[],
MPI_Info info, int reorder,
MPI_Comm *comm_dist_graph);
/**
* split a communicator based on color and key. Parameters
* are identical to the MPI-counterpart of the function.
*
* @param comm: input communicator
* @param color
* @param key
*
* @
*/
OMPI_DECLSPEC int ompi_comm_split (ompi_communicator_t *comm, int color, int key,
ompi_communicator_t** newcomm, bool pass_on_topo);
/**
* split a communicator based on type and key. Parameters
* are identical to the MPI-counterpart of the function.
*
* @param comm: input communicator
* @param color
* @param key
*
* @
*/
OMPI_DECLSPEC int ompi_comm_split_type(ompi_communicator_t *comm,
int split_type, int key,
struct ompi_info_t *info,
ompi_communicator_t** newcomm);
/**
* dup a communicator. Parameter are identical to the MPI-counterpart
* of the function. It has been extracted, since we need to be able
* to dup a communicator internally as well.
*
* @param comm: input communicator
* @param newcomm: the new communicator or MPI_COMM_NULL if any error is detected.
*/
OMPI_DECLSPEC int ompi_comm_dup (ompi_communicator_t *comm, ompi_communicator_t **newcomm);
/**
* dup a communicator (non-blocking). Parameter are identical to the MPI-counterpart
* of the function. It has been extracted, since we need to be able
* to dup a communicator internally as well.
*
* @param comm: input communicator
* @param newcomm: the new communicator or MPI_COMM_NULL if any error is detected.
*/
OMPI_DECLSPEC int ompi_comm_idup (ompi_communicator_t *comm, ompi_communicator_t **newcomm, ompi_request_t **request);
/**
* dup a communicator with info. Parameter are identical to the MPI-counterpart
* of the function. It has been extracted, since we need to be able
* to dup a communicator internally as well.
*
* @param comm: input communicator
* @param newcomm: the new communicator or MPI_COMM_NULL if any error is detected.
*/
OMPI_DECLSPEC int ompi_comm_dup_with_info (ompi_communicator_t *comm, ompi_info_t *info, ompi_communicator_t **newcomm);
/**
* dup a communicator (non-blocking) with info.
* of the function. It has been extracted, since we need to be able
* to dup a communicator internally as well.
*
* @param comm: input communicator
* @param newcomm: the new communicator or MPI_COMM_NULL if any error is detected.
*/
OMPI_DECLSPEC int ompi_comm_idup_with_info (ompi_communicator_t *comm, ompi_info_t *info, ompi_communicator_t **newcomm, ompi_request_t **req);
/**
* compare two communicators.
*
* @param comm1,comm2: input communicators
*
*/
int ompi_comm_compare(ompi_communicator_t *comm1, ompi_communicator_t *comm2, int *result);
/**
* free a communicator
*/
OMPI_DECLSPEC int ompi_comm_free (ompi_communicator_t **comm);
/**
* allocate a new communicator structure
* @param local_group_size
* @param remote_group_size
*
* This routine allocates the structure, the according local and
* remote groups, the proc-arrays in the local and remote group.
* It furthermore sets the fortran index correctly,
* and sets all other elements to zero.
*/
ompi_communicator_t* ompi_comm_allocate (int local_group_size,
int remote_group_size);
/**
* allocate new communicator ID
* @param newcomm: pointer to the new communicator
* @param oldcomm: original comm
* @param bridgecomm: bridge comm for intercomm_create
* @param mode: combination of input
* OMPI_COMM_CID_INTRA: intra-comm
* OMPI_COMM_CID_INTER: inter-comm
* OMPI_COMM_CID_INTRA_BRIDGE: 2 intracomms connected by
* a bridge comm. local_leader
* and remote leader are in this
* case an int (rank in bridge-comm).
* OMPI_COMM_CID_INTRA_PMIX: 2 intracomms, leaders talk
* through PMIx. lleader and rleader
* are the required contact information.
* @param send_first: to avoid a potential deadlock for
* the OOB version.
* This routine has to be thread safe in the final version.
*/
OMPI_DECLSPEC int ompi_comm_nextcid ( ompi_communicator_t* newcomm,
ompi_communicator_t* oldcomm,
ompi_communicator_t* bridgecomm,
void* local_leader,
void* remote_leader,
int mode,
int send_first);
/**
* allocate new communicator ID (non-blocking)
* @param newcomm: pointer to the new communicator
* @param oldcomm: original comm
* @param bridgecomm: bridge comm for intercomm_create
* @param mode: combination of input
* OMPI_COMM_CID_INTRA: intra-comm
* OMPI_COMM_CID_INTER: inter-comm
* This routine has to be thread safe in the final version.
*/
OMPI_DECLSPEC int ompi_comm_nextcid_nb (ompi_communicator_t* newcomm,
ompi_communicator_t* comm,
ompi_communicator_t* bridgecomm,
int mode, ompi_request_t **req);
/**
* shut down the communicator infrastructure.
*/
int ompi_comm_finalize (void);
/**
* This is THE routine, where all the communicator stuff
* is really set.
*
* @param[out] newcomm new ompi communicator object
* @param[in] oldcomm old communicator
* @param[in] local_size size of local_ranks array
* @param[in] local_ranks local ranks (not used if local_group != NULL)
* @param[in] remote_size size of remote_ranks array
* @param[in] remote_ranks remote ranks (intercomm) (not used if remote_group != NULL)
* @param[in] attr attributes (can be NULL)
* @param[in] errh error handler
* @param[in] copy_topocomponent whether to copy the topology
* @param[in] local_group local process group (may be NULL if local_ranks array supplied)
* @param[in] remote_group remote process group (may be NULL)
*/
OMPI_DECLSPEC int ompi_comm_set ( ompi_communicator_t** newcomm,
ompi_communicator_t* oldcomm,
int local_size,
int *local_ranks,
int remote_size,
int *remote_ranks,
opal_hash_table_t *attr,
ompi_errhandler_t *errh,
bool copy_topocomponent,
ompi_group_t *local_group,
ompi_group_t *remote_group );
/**
* This is THE routine, where all the communicator stuff
* is really set. Non-blocking version.
*
* @param[out] newcomm new ompi communicator object
* @param[in] oldcomm old communicator
* @param[in] local_size size of local_ranks array
* @param[in] local_ranks local ranks (not used if local_group != NULL)
* @param[in] remote_size size of remote_ranks array
* @param[in] remote_ranks remote ranks (intercomm) (not used if remote_group != NULL)
* @param[in] attr attributes (can be NULL)
* @param[in] errh error handler
* @param[in] copy_topocomponent whether to copy the topology
* @param[in] local_group local process group (may be NULL if local_ranks array supplied)
* @param[in] remote_group remote process group (may be NULL)
* @param[out] req ompi_request_t object for tracking completion
*/
OMPI_DECLSPEC int ompi_comm_set_nb ( ompi_communicator_t **ncomm,
ompi_communicator_t *oldcomm,
int local_size,
int *local_ranks,
int remote_size,
int *remote_ranks,
opal_hash_table_t *attr,
ompi_errhandler_t *errh,
bool copy_topocomponent,
ompi_group_t *local_group,
ompi_group_t *remote_group,
ompi_request_t **req );
/**
* This is a short-hand routine used in intercomm_create.
* The routine makes sure, that all processes have afterwards
* a list of ompi_proc_t pointers for the remote group.
*/
struct ompi_proc_t **ompi_comm_get_rprocs ( ompi_communicator_t *local_comm,
ompi_communicator_t *bridge_comm,
int local_leader,
int remote_leader,
int tag,
int rsize);
/**
* This routine verifies, whether local_group and remote group are overlapping
* in intercomm_create
*/
int ompi_comm_overlapping_groups (int size, struct ompi_proc_t ** lprocs,
int rsize, struct ompi_proc_t ** rprocs);
/**
* This is a routine determining whether the local or the
* remote group will be first in the new intra-comm.
* Just used from within MPI_Intercomm_merge.
*/
int ompi_comm_determine_first ( ompi_communicator_t *intercomm,
int high );
OMPI_DECLSPEC int ompi_comm_activate ( ompi_communicator_t** newcomm,
ompi_communicator_t* comm,
ompi_communicator_t* bridgecomm,
void* local_leader,
void* remote_leader,
int mode,
int send_first );
OMPI_DECLSPEC int ompi_comm_activate_nb (ompi_communicator_t **newcomm,
ompi_communicator_t *comm,
ompi_communicator_t *bridgecomm,
int mode, ompi_request_t **req);
/**
* a simple function to dump the structure
*/
int ompi_comm_dump ( ompi_communicator_t *comm );
/* setting name */
int ompi_comm_set_name (ompi_communicator_t *comm, const char *name );
/*
* these are the init and finalize functions for the comm_reg
* stuff. These routines are necessary for handling multi-threading
* scenarious in the communicator_cid allocation
*/
void ompi_comm_reg_init(void);
void ompi_comm_reg_finalize(void);
/* global variable to save the number od dynamic communicators */
extern int ompi_comm_num_dyncomm;
/* check whether any of the processes has requested support for
MPI_THREAD_MULTIPLE. Note, that this produces global
information across MPI_COMM_WORLD, in contrary to the local
flag ompi_mpi_thread_provided
*/
OMPI_DECLSPEC int ompi_comm_cid_init ( void );
END_C_DECLS
#endif /* OMPI_COMMUNICATOR_H */