The pugs framework

pugs stands for Parallel Unstructured Grid Solvers.

It aims at providing a collection of numerical methods and utilities that are assembled together by a user friendly language.

Building pugs

Requirements

For the most basic build, pugs only requires

• a C++-20 compiler.
  • g++-10 or higher versions
  • clang-11 or higher versions
• CMake (at least 3.19)

Warning:
Building pugs in its source directory is forbidden. Trying to do so will result in a failure. However it generally leaves some garbage files in the source directory, namely the CMakeCache.txt and the CMakeFiles directory. CMake itself is not able to remove them, to avoid the risk of compilation issues, one has to dot it manually...

In the build directory, one for instance launches

cmake path-to-pugs-source

and then

make -j nb_jobs

Specifying the compiler is done for instance as

CXX=g++ CC=gcc cmake path-to-pugs-source

When compilation is done, pugs binary is produce. Additionally, one can run unit tests by

make check

Optional packages

pugs can benefit from additional packages to gain more functionalities or development tools.

Optional numerical tools

MPI support

pugs integrates MPI support and should compile with any MPI-3 implementation. However in order to dispatch meshes on MPI processes pugs requires ParMETIS. Without, MPI support will be automatically deactivated.

The easiest way to enable MPI support on Debian-like systems is to run

apt install libparmetis-dev

PETSc

pugs can use PETSc to solve linear systems. In pugs the PETSc support requires MPI support.

To install PETSc on Debian-like systems

apt install petsc-dev

SLEPc

SLEPc is an eigenvalue problem solver based on PETSc. It requires PETSc.

To install SLEPc on Debian-like systems

apt install slepc-dev

Documentation

User documentation

To build documentation one requires emacs, gmsh and gnuplot, additionally since examples results are generated, the documentation can only be produced after the compilation of pugs itself.

To install emacs on Debian-like systems

apt install emacs

To install gmsh on Debian-like systems

apt install gmsh

To install gnuplot one can either use

apt install gnuplot-nox

or

apt install gnuplot-x11

Warning:
When building the documentation for the first time, a local emacs configuration is generated. This requires an internet connection.

These packages are enough to build the html documentation. To build the pdf documentation one requires a few more packages: pdflatex (actually a fresh texlive installation is probably necessary) and pygmentize

On Debian-like systems these two packages are installed after

apt install texlive-full

Running the command

make doc

produces both the html and pdf documentation. Additional targets are

• userdoc, userdoc-pdf and userdoc-html.

Warning:
The documentation building should not be run in parallel. Generation uses similar temporary files. A generation race can produce corrupted documentations.

doxygen documentation

Development tools

clang-format

If clang-format is found, a new compilation target is defined which allows to run

make clang-format

This allows to run clang-format on the entire code. This should never be run on non main development branches since clang-format versions may experience unpleasant compatibility issues.

Static analysis

scan-build

To install scan-build

apt install clang-tools

It is fairly simple to use. First launch

scan-build cmake path-to-pugs-source -DCMAKE_BUILD_TYPE=Debug

Observe that the code is built in debug mode to reduce false positives.

Then compile pugs

scan-build make -j nb-jobs pugs

One can use any other generator such as Ninja for instance. Here we only build pugs's binary, which is generally enough.

At the end of the compilation, an hint such as

scan-build: Run 'scan-view /tmp/scan-build-XXXX-XX-XX-XXXXXX-XXXXX-X' to examine bug reports.

is produced. Running this command opens the report in the default browser.

scan-build is a precious tool but may unfortunately produce false positives.

clang-tidy

We do not give details here about clang-tidy. It is a much more complex tool and should be used by more experienced developers since it requires fine tuning and produces a lot of false positive.

clazy

clazy is another great static-analysis tool. It checks constructions and gives some performances hints. It can be install by

apt install clazy

When clazy is installed a new target is defined and one just has to run

make clazy-standalone

Warning:
Since some generated sources files are required, one must first run a classic compilation in the same build directory.

This is a special homemade compilation procedure: specifying jobs has no effect. Each file is checked serially.

CMake building options

In this section we give specific options that can be used to modify the way pugs is built.

Optimization options

• Coverage is a special compilation mode. It forces the run of unit tests and produces coverage reports. See below for coverage instructions.
• OpenMP, PThread and Serial builds are mutually exclusive. OpenMP support is automatically enabled as soon as the C++ compiler supports it.

Additional packages support

Code coverage build

To enable coverage more, one requires the following tools:

• lcov
• gcov
• and fastcov when using g++ as a compiler.

To install these tools

apt install lcov gcov python3-pip

then to install fastcov, as the user do

pip3 install fastcov

Then to get coverage reports one can do

CXX=g++ CC=gcc cmake path-to-pugs-source -DCMAKE_BUILD_TYPE=Coverage

and

make -j nb-jobs

This produces a text report summary and a detailed html report is produced in the coverage directory.

One can also use clang but the production of the report is much slower (does not use fastcov).