openfoam/applications/test/parallel-broadcast/Test-parallel-broadcast.C
Mark Olesen c086f22298 ENH: extend/improve broadcast handling
- 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
2022-03-04 17:49:23 +00:00

159 lines
3.8 KiB
C

/*---------------------------------------------------------------------------*\
========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration |
\\ / A nd | www.openfoam.com
\\/ M anipulation |
-------------------------------------------------------------------------------
Copyright (C) 2022 OpenCFD Ltd.
-------------------------------------------------------------------------------
License
This file is part of OpenFOAM.
OpenFOAM is free software: you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with OpenFOAM. If not, see <http://www.gnu.org/licenses/>.
Application
Test-parallel-broadcast
Description
Test for various broadcast routines.
\*---------------------------------------------------------------------------*/
#include "List.H"
#include "argList.H"
#include "Time.H"
#include "vector.H"
#include "IPstream.H"
#include "OPstream.H"
#include "IOstreams.H"
using namespace Foam;
template<class T>
void printPre(const T& value)
{
Info<< nl << "is_contiguous:" << is_contiguous<T>::value << endl;
Pout<< "pre-broadcast: " << value << endl;
}
template<class T>
void printPost(const T& value)
{
Pout<< "post-broadcast: " << value << endl;
}
template<class T>
void testBroadcast(T& value)
{
printPre(value);
Pstream::broadcast(value);
printPost(value);
}
template<class T>
void testBroadcast(List<T>& values)
{
Info<< nl << "is_contiguous:" << is_contiguous<T>::value << endl;
Pout<< "pre-broadcast: " << flatOutput(values) << endl;
Pstream::broadcast(values);
Pout<< "post-broadcast: " << flatOutput(values) << endl;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
int main(int argc, char *argv[])
{
argList::noCheckProcessorDirectories();
#include "setRootCase.H"
#include "createTime.H"
{
label value = -1;
if (Pstream::master())
{
value = UPstream::nProcs();
}
testBroadcast(value);
}
{
labelList values;
if (Pstream::master())
{
values = identity(UPstream::nProcs());
}
testBroadcast(values);
}
{
word value;
if (Pstream::master())
{
value = args.executable();
}
printPre(value);
UPstream::broadcast(value); // Low-level UPstream broadcast
printPost(value);
}
{
wordList values;
if (Pstream::master())
{
values.resize(UPstream::nProcs());
forAll(values, i)
{
values[i] = "value_" + Foam::name(i);
}
}
testBroadcast(values);
}
{
vector values(vector::uniform(-1));
if (Pstream::master())
{
values = vector(1,2,3);
}
testBroadcast(values);
}
{
FixedList<vector, 3> values(vector::uniform(-1));
if (Pstream::master())
{
values = vector(1,2,3);
scalar mult = 1;
for (auto& v : values)
{
v *= mult;
mult += 1;
}
}
testBroadcast(values);
}
Info<< "End\n" << endl;
return 0;
}
// ************************************************************************* //