[android] Replace libuv with Looper

[tmpsantos]

Looper ships with Android and can provide the same functionality.

[tmpsantos]

👀 @jfirebaugh @tobrun @zugaldia @bleege

This is a step towards #2909

[tmpsantos]

Marking as DO NOT MERGE because although it is apparently working just fine, I would feel more comfortable after getting the utests running on Android.

[zugaldia]

@tmpsantos thank you!

@tobrun let's schedule a new battery of tests on Monday?

[zugaldia]

Related: #3440

[tobrun]

@zugaldia we should look into those performance tests we did . These test should be able to give us some extra information about if it's less/more performant by using Traceview.

[jfirebaugh]

Also noting that we want to hold off merging this until after we branch for the 4.0.0 release.

[bleege]

Discussed with @tmpsantos in chat and will pick this up now. I'll build it locally to make sure the TestApp works as expected. From there I'll rebase and make sure CI is happy.

[bleege]

Local tests worked great! I'm going to rebase now and push back to the branch so that we can run the CI on it before merging back to master.

[bleege]

Rebased, but the only way to push to GitHub required a git pull first from the remote branch which created a merge commit. Everything appears to be as expected. Will wait for CI to playout before merging to master.

[bleege]

All CI save the Android build passed. Will explore.

[bleege]

Error turned out to be the following. Will try to resolve locally and push again for CI.

�[1m�[32m* Recreating project...�[0m
gyp: Undefined variable libuv_cflags in gyp/mbgl.gyp
make[1]: Leaving directory `/bitrise/src'
make[1]: *** [Makefile/__project__] Error 1
make: *** [android-lib] Error 2

[bleege]

As best I can tell some other C++ configs shifted between when @tmpsantos first wrote his 3 commits and now. To rule out a possible messed up rebase and merge, I created a new branch based off master today (commit 81261ca) and then tried cherrypicking @tmpsantos's original 3 commits from this PR on to it. I did this in a time sequential manor to mirror @tmpsantos original work and then ran make android after each cherrypick. The first two (Introduce and Attach RunLoop) both cherrypicked cleanly and executed make android just fine. However when the third commit (Replace libuv with Looper) was cherrypicked the make android command ended with the same error as above. Based on what I can see (see attached screenshot) it appears that the build script is still trying to build with libuv as indicated by the loop=uv print out.

• Introduce RunLoop ( a610d14 )
• Attach thread on RunLoop ( 9b15e6e )
• Replace libuv With Looper ( ea699ec )

Is loop=uv Still Being Used?

[jfirebaugh]

Give me a second and I'll be available to fix this up.

[bleege]

Forgot to mention that my test branch is called 3440-replace-libuv and is available for 👀 at:

https://github.com/mapbox/mapbox-gl-native/commits/3440-replace-libuv

[tmpsantos]

Got it fixed and merged!

[bleege]

Ah ha! Libuv had to also be turned off in defaults.mk Thanks again for making this happen @tmpsantos!