- additional startup guard for inter-node/local-node queries (UPstream)
- impose linear communication tree for inter-node/local-node
communicators. Was previously defaulted to a basic tree, but more
consistent to have flat addressing for these types of connections.
- demand-driven UPstream::interNode_offsets() for walking
inter-node ranges instead of creating it manually in various places.
- (style): List<int> instead of labelList for internal commsStruct
since the communication structures are tied to MPI sizes
and not to the OpenFOAM label sizes
- reduce the number of intermediate buffer allocations within
gatherList, scatterList.
- using the List containers, and not their low-level data_bytes(),
size_bytes() methods is more convenient and allows future
adjustments to be centralized
ENH: trivial intptr_t wrapper for MPI_Win
STYLE: minor adjustments to mpirunDebug
- 'if constexpr (...)'
* instead of std::enable_if
* terminate template recursion
* compile-time elimination of code
- use C++14 '_t', '_v' versions,
eg, std::is_integral_v<T> instead of std::is_integral<T>::value
- std::begin, std::end, std::void_t instead of prev stdFoam versions
- provide is_contiguous_v<..> as short form of is_contiguous<..>::value
with the additional benefit of removing any cv qualifiers.
ENH: include is_rotational_vectorspace trait
- tests for vector-space and nComponents > 1 (ie, not sphericalTensor)
ENH: improve robustness of pTraits_.. tests by removing cv qualifiers
- 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
- the old Pstream::scatter routines (which were largely a misnomer)
have been superseded by various broadcast routines, but were left in
the code with #ifndef/#ifdef Foam_Pstream_scatter_nobroadcast
guards. Now noisily deprecate them, and remove the old manual tree
communication in favour of MPI broadcast and/or
serialize/de-serialize with wrapped Pstream::broadcast
- consolidate various gather methods to include the communication
structure directly. No functional change, but reduces the number of
methods.
ENH: add parallel guard to UPstream::whichCommunication() method
- returns List::null() as the schedule for non-parallel instead
of an inappropriate linear or tree schedule
ENH: Pstream::listGatherValues, Pstream::listScatterValues
- like the existing UPstream versions but supporting non-contiguous
- these are primarily when encountering sparse (eg, inter-host)
communicators. Additional UPstream convenience methods:
is_rank(comm)
=> True if process corresponds to a rank in the communicators.
Can be a master rank or a sub-rank.
is_parallel(comm)
=> True if parallel algorithm or exchange is used on the process.
same as
(parRun() && (nProcs(comm) > 1) && is_rank(comm))
- bundles frequently used 'gather/scatter' patterns more consistently.
- combineAllGather -> combineGather + broadcast
- listCombineAllGather -> listCombineGather + broadcast
- mapCombineAllGather -> mapCombineGather + broadcast
- allGatherList -> gatherList + scatterList
- reduce -> gather + broadcast (ie, allreduce)
- The allGatherList currently wraps gatherList/scatterList, but may be
replaced with a different algorithm in the future.
STYLE: PstreamCombineReduceOps.H is mostly unneeded now
- split off a Pstream::genericBroadcast() which uses UOPBstream during
serialization and UOPBstream during de-serialization.
This function will not normally be used directly by callers, but
provides a base layer for higher-level broadcast calls.
- low-level UPstream broadcast of string content.
Since std::string has length and contiguous content, it is possible
to handle directly by the following:
1. broadcast size
2. resize
3. broadcast content when size != 0
Although this is a similar amount of communication as the generic
streaming version (min 1, max 2 broadcasts) it is more efficient
by avoiding serialization/de-serialization overhead.
- handle broadcast of List content distinctly.
Allows an optimized path for contiguous data, similar to how
std::string is handled (broadcast size, resize container, broadcast
content when size != 0), but can revert to genericBroadcast (streamed)
for non-contiguous data.
- make various scatter variants simple aliases for broadcast, since
that is what they are doing behind the scenes anyhow:
* scatter()
* combineScatter()
* listCombineScatter()
* mapCombineScatter()
Except scatterList() which remains somewhat different.
Beyond the additional (size == nProcs) check, the only difference to
using broadcast(List<T>&) or a regular scatter(List<T>&) is that
processor-local data is skipped. So leave this variant as-is.
STYLE: rename/prefix implementation code with 'Pstream'
- better association with its purpose and provides a unique name
