More travis run speedups

- Using clang instead of gcc; compiles faster and with less memory,
meaning we can build in parallel.
- Caching more stuff so startup is faster. In particular, the Rust
toolchain.
- Using the ninja build tool which tends to be faster than Make.

.travis.yml

@@ -19,8 +19,8 @@ env:
   global:
     - MONO_THREADS_PER_CPU=2000
     - MONO_MANAGED_WATCHER=disabled
-    # Travis can run out of RAM when compiling if we don't prevent parallelization.
-    - YCM_CORES=1
+    # Travis can run out of RAM, so we need to be careful here.
+    - YCM_CORES=3
   matrix:
     # Don't forget to take the below matrix exclusions into account.
     - USE_CLANG_COMPLETER=true YCMD_PYTHON_VERSION=2.7
@@ -36,18 +36,31 @@ matrix:
     - os: linux
       env: USE_CLANG_COMPLETER=true YCMD_PYTHON_VERSION=2.7
 addons:
+  # If this doesn't make much sense to you, see the travis docs:
+  #    https://docs.travis-ci.com/user/migrating-from-legacy/
   apt:
     sources:
-     - ubuntu-toolchain-r-test
-     - deadsnakes
+     # The Travis apt source whitelist can be found here:
+     #   https://github.com/travis-ci/apt-source-whitelist/blob/master/ubuntu.json
+     - ubuntu-toolchain-r-test  # for new libstdc++
+     - llvm-toolchain-precise-3.7  # for clang
+     - deadsnakes  # for various versions of python
+     - kalakris-cmake # for a more recent version of cmake (needed for ninja-build)
     packages:
-     - g++-4.8
+     - cmake
+     - clang-3.7
+     - ninja-build
      - python2.6
      - python2.6-dev
      - python2.7
      - python2.7-dev
      - python-virtualenv
 cache:
   directories:
-    - $HOME/.cache/pip
-    - $HOME/.dnx/packages
+    - $HOME/.cache/pip  # Python packages from pip
+    - $HOME/.dnx/packages  # .Net packages?
+    - $HOME/multirust  # multirust itself
+    - $HOME/.multirust  # what multirust downloads
+    - $HOME/.cargo  # cargo package deps
+    - $HOME/clang_archives  # clang downloads
+    - $HOME/racerd/target/release  # compilation output

build.py

@@ -5,6 +5,7 @@
 import os.path as p
 import sys
 import shlex
+import distutils.dir_util
 
 major, minor = sys.version_info[ 0 : 2 ]
 if major != 2 or minor < 6:
@@ -172,9 +173,10 @@ def GetGenerator( args ):
     if ( not args.arch and platform.architecture()[ 0 ] == '64bit'
          or args.arch == 64 ):
       generator = generator + ' Win64'
-
     return generator
 
+  if PathToFirstExistingExecutable( ['ninja'] ):
+    return 'Ninja'
   return 'Unix Makefiles'
 
 
@@ -298,9 +300,25 @@ def BuildRacerd():
   if not FindExecutable( 'cargo' ):
     sys.exit( 'cargo is required for the rust completer' )
 
-  os.chdir( p.join( DIR_OF_THIRD_PARTY, 'racerd' ) )
+  # Building the dependencies of racerd takes a while, so for Travis, we copy
+  # the racerd source dir to ~/racerd (outside the repo) and build there. Then
+  # copy back. Having the dep build products outside the repo makes it possible
+  # to cache them (see .travis.yml).
+
+  orig_racerd_dir = p.join( DIR_OF_THIRD_PARTY, 'racerd' )
+  build_racerd_dir = orig_racerd_dir
+  if OnTravisOrAppVeyor():
+    cached_racerd_dir = os.path.expanduser( os.path.join( '~', 'racerd' ) )
+    distutils.dir_util.copy_tree( orig_racerd_dir, cached_racerd_dir )
+    build_racerd_dir = cached_racerd_dir
+
+  os.chdir( build_racerd_dir )
+  print( 'Compiling racerd in: ', build_racerd_dir )
   subprocess.check_call( [ 'cargo', 'build', '--release' ] )
 
+  if OnTravisOrAppVeyor():
+    distutils.dir_util.copy_tree( cached_racerd_dir, orig_racerd_dir )
+
 
 def SetUpTern():
   paths = {}

ci/travis/travis_install.linux.sh

@@ -1,13 +1,19 @@
 # Linux-specific installation
 
 # We can't use sudo, so we have to approximate the behaviour of the following:
-# $ sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-4.8 90
+# $ sudo update-alternatives --install /usr/bin/c++ c++ /usr/bin/clang++-3.7 100
 
 mkdir ${HOME}/bin
 
-ln -s /usr/bin/g++-4.8 ${HOME}/bin/g++
-ln -s /usr/bin/gcc-4.8 ${HOME}/bin/gcc
-ln -s ${HOME}/bin/g++ ${HOME}/bin/c++
+ln -s /usr/bin/clang++-3.7 ${HOME}/bin/clang++
+ln -s /usr/bin/clang-3.7 ${HOME}/bin/clang
+
+ln -s /usr/bin/clang++-3.7 ${HOME}/bin/c++
+ln -s /usr/bin/clang-3.7 ${HOME}/bin/cc
+
+# These shouldn't be necessary, but just in case.
+ln -s /usr/bin/clang++-3.7 ${HOME}/bin/g++
+ln -s /usr/bin/clang-3.7 ${HOME}/bin/gcc
 
 export PATH=${HOME}/bin:${PATH}
 

ci/travis/travis_install.osx.sh

@@ -5,6 +5,7 @@
 brew update || brew update
 brew install node.js || brew outdated node.js || brew upgrade node.js
 brew install go || brew outdated go || brew upgrade go
+brew install ninja
 
 # OS X comes with 2 versions of python by default, and a neat system
 # (versioner) to switch between them:

ci/travis/travis_install.sh

@@ -38,11 +38,17 @@ fi
 
 # Need rust available, but travis doesn't give it to you without language: rust
 pushd ${HOME}
-git clone --recursive https://github.com/brson/multirust
-cd multirust
-git reset --hard f3974f2b966476ad656afba311b50a9c23fe6d2e
-./build.sh
-./install.sh --prefix=${HOME}
+# Multirust might already exist if cached; see bottom of travis.yml
+if [ ! -f "$HOME/multirust/blastoff.sh" ]; then
+  git clone --recursive https://github.com/brson/multirust
+  cd multirust
+  git reset --hard f3974f2b966476ad656afba311b50a9c23fe6d2e
+  ./build.sh
+  ./install.sh --prefix=${HOME}
+else
+  cd multirust
+  ./install.sh --prefix=${HOME}
+fi
 popd
 
 multirust update stable