Reduce the number of build jobs

Many configuration options of NEST are actually independent.
This means we don't have to run the full matrix, but just a
minimal job, a maximal job, and some jobs for dependent options.

This commit simplifies the matrix from 8 runs to 4 runs while
also adding a new option for builds with and without threading.

.travis.yml

@@ -7,14 +7,13 @@ dist: trusty
 
 env:
   matrix:
-    - xGSL=0 xMPI=0 xPYTHON=1 xSTATIC_ANALYSIS=1 CACHE_NAME=JOB
-    - xGSL=0 xMPI=0 xPYTHON=0 xSTATIC_ANALYSIS=1 CACHE_NAME=JOB
-    - xGSL=0 xMPI=1 xPYTHON=0 xSTATIC_ANALYSIS=1 CACHE_NAME=JOB
-    - xGSL=0 xMPI=1 xPYTHON=1 xSTATIC_ANALYSIS=1 CACHE_NAME=JOB
-    - xGSL=1 xMPI=0 xPYTHON=0 xSTATIC_ANALYSIS=1 CACHE_NAME=JOB
-    - xGSL=1 xMPI=0 xPYTHON=1 xSTATIC_ANALYSIS=1 CACHE_NAME=JOB
-    - xGSL=1 xMPI=1 xPYTHON=0 xSTATIC_ANALYSIS=1 CACHE_NAME=JOB
-    - xGSL=1 xMPI=1 xPYTHON=1 xSTATIC_ANALYSIS=1 CACHE_NAME=JOB
+    # We don't have to run a full matrix here, because most of the options are
+    # independent. This means that we can test them together in the full build.
+    # See also https://docs.travis-ci.com/user/caching/#Caches-and-build-matrices
+    - xTHREADING=0 xMPI=0 xGSL=0 xPYTHON=0 xSTATIC_ANALYSIS=1 CACHE_NAME=JOB   # minimal
+    - xTHREADING=0 xMPI=1 xGSL=0 xPYTHON=0 xSTATIC_ANALYSIS=1 CACHE_NAME=JOB   # only MPI
+    - xTHREADING=1 xMPI=0 xGSL=0 xPYTHON=0 xSTATIC_ANALYSIS=1 CACHE_NAME=JOB   # only threading
+    - xTHREADING=1 xMPI=1 xGSL=1 xPYTHON=1 xSTATIC_ANALYSIS=1 CACHE_NAME=JOB   # full
 matrix:
   # do notify immediately about it when a job of a build fails.
   fast_finish: true

build.sh

@@ -17,14 +17,18 @@ set -e
 
 mkdir -p $HOME/.matplotlib
 cat > $HOME/.matplotlib/matplotlibrc <<EOF
-    # ZYV
     backend : svg
 EOF
 
+if [ "$xTHREADING" = "1" ] ; then
+    CONFIGURE_THREADING="-Dwith-openmp=ON"
+else
+    CONFIGURE_THREADING="-Dwith-openmp=OFF"
+fi
+
 if [ "$xMPI" = "1" ] ; then
 
 cat > $HOME/.nestrc <<EOF
-    % ZYV: NEST MPI configuration
     /mpirun
     [/integertype /stringtype]
     [/numproc     /slifile]
@@ -233,6 +237,7 @@ cmake \
   -DCMAKE_INSTALL_PREFIX="$NEST_RESULT" \
   -Dwith-optimize=ON \
   -Dwith-warning=ON \
+  $CONFIGURE_THREADING \
   $CONFIGURE_MPI \
   $CONFIGURE_PYTHON \
   $CONFIGURE_GSL \