From a0878fd14f14e444ce98c4d8660ff853bb6fb3bf Mon Sep 17 00:00:00 2001
From: Dave Cameron <dcameron@digitalocean.com>
Date: Sun, 12 Aug 2018 09:37:37 -0400
Subject: [PATCH] Faster builds by limiting visible CPUs

As described in this elm compiler issue:
https://github.com/elm/compiler/issues/1473
---
 .travis.yml                            | 11 ++++++++++-
 install_sysconfcpus                    | 13 +++++++++++++
 protoc-gen-elm/elm_tests/run_elm_tests |  8 +++++++-
 3 files changed, 30 insertions(+), 2 deletions(-)
 create mode 100755 install_sysconfcpus

diff --git a/.travis.yml b/.travis.yml
index 093c78b..ed30fa3 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -10,11 +10,17 @@ addons:
 env:
   - TRAVIS_NODE_VERSION="v7.2.1"
 
+cache:
+  directories:
+    - sysconfcpus
+    - protoc
+
 before_install:
   - rm -rf ~/.nvm && git clone https://github.com/creationix/nvm.git ~/.nvm && (cd ~/.nvm && git checkout `git describe --abbrev=0 --tags`) && source ~/.nvm/nvm.sh && nvm install $TRAVIS_NODE_VERSION
+  - ./install_sysconfcpus
+  - ./install_protobuf
 
 install:
-  - ./install_protobuf
   - export PATH=$PATH:$PWD/protoc/bin
   - go get -t -v ./protoc-gen-elm
   - protoc --version
@@ -22,5 +28,8 @@ install:
   - npm --version
   - npm install -g elm
   - npm install -g elm-test
+  - mv $(npm config get prefix)/bin/elm-make $(npm config get prefix)/bin/elm-make-old
+  - printf '%s\n\n' '#!/bin/bash' 'echo "Running elm-make with sysconfcpus -n 2"' '$TRAVIS_BUILD_DIR/sysconfcpus/bin/sysconfcpus -n 2 elm-make-old "$@"' > $(npm config get prefix)/bin/elm-make
+  - chmod +x $(npm config get prefix)/bin/elm-make
 
 script: ./run_tests
diff --git a/install_sysconfcpus b/install_sysconfcpus
new file mode 100755
index 0000000..efc0a2a
--- /dev/null
+++ b/install_sysconfcpus
@@ -0,0 +1,13 @@
+#!/bin/bash
+
+set -ex
+
+echo "Install libsysconfcpus to compensate for slow elm builds"
+# More at: https://github.com/elm/compiler/issues/1473
+if [ ! -d sysconfcpus/bin ]; then
+    git clone https://github.com/obmarg/libsysconfcpus.git
+    cd libsysconfcpus
+    ./configure --prefix=$TRAVIS_BUILD_DIR/sysconfcpus
+    make && make install
+    cd ..
+fi
diff --git a/protoc-gen-elm/elm_tests/run_elm_tests b/protoc-gen-elm/elm_tests/run_elm_tests
index 898ce69..4d230fb 100755
--- a/protoc-gen-elm/elm_tests/run_elm_tests
+++ b/protoc-gen-elm/elm_tests/run_elm_tests
@@ -11,5 +11,11 @@ readonly ROOT="$(dirname "$0")"
 
 (
   cd ${ROOT}
-  elm-test
+  # If sysconfcpus is on path, as on travis, then limit the number of
+  # visible CPUs to 1 to work around the elm problems with many CPUs.
+  if [ -x "$(command -v sysconfcpus)" ]; then
+      sysconfcpus -n 1 elm-test
+  else
+      elm-test
+  fi
 )