automatically determine an appropriate number of jobs

.travis.yml

@@ -5,13 +5,37 @@
 os:
  - linux
 
+language: minimal
+
 branches.only:
  - docker
 
 services:
  - docker
 
-script:
-# - docker build -t "$DOCKER_USERNAME"/cxx-modules-sandbox:latest .
- - printf '%s' "$DOCKER_PASSWORD" | docker login -u "$DOCKER_USERNAME" --password-stdin
-# - docker push "$DOCKER_USERNAME"/cxx-modules-sandbox:latest
+script: |
+ set -eux &&
+ tag=cxx-modules-sandbox:latest
+
+ log=$(mktemp) # log to a file because travis rejects having big logs
+
+ # also, emit a message periodically otherwise travis thinks the build stalled and kills it
+ (while :; do sleep 5m; tail -n10 $log; done) &
+ log_pid=$!
+
+ # build the image
+ if ! docker image build -t "$DOCKER_USERNAME"/$tag . &> $log
+ then
+  # on failure, print tail of log before bailing out
+  error=$!
+  kill $log_pid
+  tail -c100000 $log
+  return $error
+ fi
+
+ # stop monitoring the log
+ kill $log_pid
+
+ # publish the image
+ printf '%s' "$DOCKER_PASSWORD" | docker login -u "$DOCKER_USERNAME" --password-stdin
+ docker image push "$DOCKER_USERNAME"/$tag

install_cmake.sh

@@ -9,14 +9,15 @@ readonly url="https://gitlab.kitware.com/ben.boeckel/cmake.git"
 readonly workdir="$HOME/misc/code/cmake"
 readonly srcdir="$workdir/cmake"
 readonly builddir="$workdir/build"
+readonly jobs=$(($(getconf _NPROCESSORS_ONLN) * 1))
 
 git clone "$url" "$srcdir"
 cd "$srcdir"
 git checkout "$cmake_version"
 mkdir -p "$builddir"
 cd "$builddir"
 "$srcdir/bootstrap" \
-    --parallel=14 \
+    --parallel=$jobs \
     --prefix="$HOME/misc/root/cmake"
 make -j14 install
 rm -rf "$workdir"

install_gcc.sh

@@ -9,6 +9,7 @@ readonly url="svn://gcc.gnu.org/svn/gcc/branches/c++-modules"
 readonly workdir="$HOME/misc/code/gcc"
 readonly srcdir="$workdir/gcc"
 readonly builddir="$workdir/build"
+readonly jobs=$(($(getconf _NPROCESSORS_ONLN) * 1))
 
 svn checkout "-r$revision" "$url" "$srcdir"
 cd "$srcdir"
@@ -18,6 +19,6 @@ cd "$builddir"
 "$srcdir/configure" \
     --disable-multilib \
     --prefix="$HOME/misc/root/gcc"
-make -j14
-make -j14 install
+make -j$jobs
+make -j$jobs install
 rm -rf "$workdir"