Fix/travis timeout

[dellaert]

I refactored slightly, to use more direct configuration of cmake.
I also disabled unstable for gcc tests build, it comes in right under 50 mins ....

One possible speedup is using the gold linker, see http://www.bitsnbites.eu/faster-c-builds/

[ghost]

Btw, is ccache actually working? Looking at the last few builds on develop of gcc + examples, they all took 24+ minutes, which is not what I would expect. For example, the build after you merged PR #40 should have gone much faster because it didn't have to rebuild base, geometry, etc.

[dellaert]

I don’t think we enabled ccache yet, is described here. I can add it to this PR. Otherwise ok?

[dellaert]

https://docs.travis-ci.com/user/caching/

[dellaert]

By the way, caching will only help for small changes, right? I think we still have to make sure that a full rebuild fits within 50 minutes.

[dellaert]

OK,

• I saw ccache was enable by Jose, nice
• I added Mac OS install
• it seems ccache also needs "Build pushed branches" ON, which I did.

[chrisbeall]

Hmm, I thought it was enabled because we have:

gtsam/.travis.yml

Lines 1 to 2 in 823c8bd

	language: cpp
	cache: ccache

That's exactly what https://docs.travis-ci.com/user/caching says to do. Our cmake config does pick it up, and says it will use it.
Correct, it'll only help with small changes. As long as you're not touching base and geometry, speedup is huge.

[chrisbeall]

Just fyi: As far as gtsam is concerned, ccache is turned on by default if we detect it (unless we're on Windows or generate an Xcode project):

gtsam/CMakeLists.txt

Lines 71 to 73 in 823c8bd

	if(NOT MSVC AND NOT XCODE_VERSION)
	option(GTSAM_BUILD_WITH_CCACHE "Use ccache compiler cache" ON)
	endif()

[chrisbeall]

Ah, there's an easy way to check whether cache was used. At the end of shell script, run ccache -s to print statistics.

[dellaert]

It seems to be used after I enabled branches. First two builds were 3/4 mins only!
I'll add ccache -s and remove the forcing flag, making sure to check whether it actually works.

[dellaert]

PS, brew update takes almost 5 mins all by itself. Are we sure it's needed, @jlblancoc ?

[jlblancoc]

Hmm... we normally use another setup (CircleCI+docker), so can't recall the details in Travis, but it looks like a problem in its file cache across matrix configurations, doesn't it? Worth a careful read: https://docs.travis-ci.com/user/caching/#caches-and-build-matrices

[chrisbeall]

Looks like it definitely worked on Linux, but mac is still slow.
If I understand the documentation correctly, I don't think we run the risk of poisoning the cache between configurations, because we have unique OS, compiler, and environment variables in each build.

[chrisbeall]

But we get two sets of builds now; that's not good :-(

[jlblancoc]

But we get two sets of builds now; that's not good :-(

That's actually normal in travis: to build each branch, and also prs. You can disable branch builds if so desired in travis project settings.

[dellaert]

Finally the clang one passed on Mac and wrote the cache. This story is not yet over I think, but I will merge for now.