REVIEW add support for incremental build

[Egor18]

Moved from #1816

Hi, this is my new implementation of the incremental build.

A few words about performance.
On my machine spoon model for RxJava project builds in about 15 minutes, but I can get cached model in less than 1 minute. So, on some projects cache itself could be quite useful.
I added BufferedOutputStream and BufferedInputStream to SerializationModelStreamer because they drastically increase model serialization/deserialization speed (dozens of times or even more).
However, it's possible that reference resolution part for incremental build could be rewritten in a more effective way (as I mentioned here).

So what do you think about this incremental launcher?

[msteinbeck]

Is it really necessary to make the factory protected?

[Egor18]

I can replace that with super(oldFactory), but I would like to avoid undesirable call of processArguments() in the Launcher constructor. Alternatively, I can add another protected constructor to the Launcher, which does not call processArguments().

[surli]

I'm not really sure why you created a new Launcher for that feature: why not creating a class managing the serialization that you can use in the current Launcher if a specific option is given? And maybe adding a new property in environment to manage the cache directory.

My point is your new IncrementalLauncher is breaking the current behaviour of Launcher: what if I create an IncrementalLauncher and add resources in the environment after it?

[monperrus]

Before adding new code, could you, in a first PR, remove the code related to the old and broken 'build-outdated' feature? Thanks!

[Egor18]

@surli Ok, so what API do you suggest?
Something like that?

Launcher launcher = new Launcher();
launcher.addInputResources(....);
launcher.getEnvironment.setClasspath(....);
launcher.getEnvironment().setCacheEnabled(true);
launcher.getEnvironment().setCacheDir(....);
launcher.setIncremental(true);
launcher.build();

I think, I can refactor it this way.

[surli]

Actually you could even put the setIncremental inside the environment: we might need this value in other classes for specific treatments.

And isn't the cache directory mandatory in case of incremental build?

So I suggest this kind of API then:

Launcher launcher = new Launcher();
launcher.addInputResources(....);
launcher.getEnvironment.setClasspath(....);
launcher.getEnvironment().setIncremental(true);
launcher.getEnvironment().setCacheDir(....); // optional: a default value should be available
launcher.build();

WDYT?

[Egor18]

Ok. I'll try to implement this API.

[surli]

Any news on this one @Egor18 ?

[Egor18]

@surli I'll do that as soon, as I can.

[mehdi-kaytoue]

Any news? I am very interested in this feature, it looks quite related to #1983

Would be happy to help

Cheers,
Mehdi

[monperrus]

just restarted Travis

[monperrus]

Thanks a lot for the contribution!