- split/duplicate functionality
- rework inter-node/intra-node handling to allow selection of
splitting based on 'shared' or hostname (default).
- always creates node communicators at startup:
* commInterNode() - between nodes
* commLocalNode() - within a node
- world-comm is now always a duplicate of MPI_COMM_WORLD to provide
better separation from other processes.
NB:
the inter-node comm is a slight exception to other communicators
in that we always retain its list of (global) ranks, even if the
local process is not in that communicator.
This can help when constructing topology-aware patterns.
FIX: non-participating ranks still had knowledge of their potential siblings
- after create by group, the procIDs_ of non-participating ranks
should be empty (except for the inter-node exception)
- "buffered" corresponds to MPI_Bsend (buffered send),
whereas the old name "blocking" is misleading since the
regular MPI_Send also blocks until completion
(ie, buffer can be reused).
ENH: IPstream::read() returns std::streamsize instead of label (#3152)
- previously returned a 'label' but std::streamsize is consistent with
the input parameter and will help with later adjustments.
- use <label> instead of <int> for internal accounting of the message
size, for consistency with the underyling List<char> buffers used.
- improve handling for corner case of IPstream receive with
non-blocking, although this combination is not used anywhere
- can use UList signature since the routines do not resize the list
or attempt to broadcast it: useful for SubList handling.
ENH: add IPstream/OPstream send/recv static methods
- similar to UPstream::parRun(), the setter returns the previous value.
The accessors are prefixed with 'comm':
Eg, commGlobal(), commWarn(), commWorld(), commSelf().
This distinguishes them from any existing variables (eg, worldComm)
and arguably more similar to MPI_COMM_WORLD etc...
If demand-driven communicators are added in the future, the function
call syntax can help encapsulate that.
Previously:
const label oldWarnComm = UPstream::warnComm;
const label oldWorldComm = UPstream::worldComm;
UPstream::warnComm = myComm;
UPstream::worldComm = myComm;
...
UPstream::warnComm = oldWarnComm;
UPstream::worldComm = oldWorldComm;
Now:
const label oldWarnComm = UPstream::commWarn(myComm);
const label oldWorldComm = UPstream::commWorld(myComm);
...
UPstream::commWarn(oldWarnComm);
UPstream::commWorld(oldWorldComm);
STYLE: check (warnComm >= 0) instead of (warnComm != -1)
- UPstream::globalComm constant always refers to MPI_COMM_WORLD but
UPstream::worldComm could be MPI_COMM_WORLD (single world)
or a dedicated local communicator (for multi-world).
- provide a Pstream wrapped version of MPI_COMM_SELF,
references as UPstream::selfComm
- UPstream::isUserComm(label)
test for additional user-defined communicators
