Binder prototype (aka. javaffi)

[Mikael Vidstedt]

All,

This year Santa brings a prototype implementation of the binder!

For some time now I and Henry have been working on a prototype of the 
binder, gluing together jextract (aka. "the groveler") with Vladimir's 
linkToNative functionality. The TL;DR of this is that with this 
prototype code we can now run the canonical test cases like getpid, 
printf (varargs) and qsort (callbacks), as well other complex function 
types.

Some disclaimers to set the mood:

The functionality in this prototype is in no way complete, nor is it 
stable. The implementation work has been focused exclusively on the sysv 
x64 ABI, meaning linux, osx and solaris only. Also, while the prototype 
does support enough types and function prototypes to hopefully make it 
interesting to look at and play around with, it is by no means providing 
complete support for all type marshaling, especially not for callbacks. 
If you actually run it you will also find that it can crash the VM 
relatively easily, so don't start putting this in production quite yet. :)

All that said, one of the most interesting test cases we have working is 
using the prototype binder for jextract itself - for binding the 
libclang API. The API includes functions with struct-by-value arguments 
and callbacks, so having it working is a good proof point that we've 
moved beyond the typical "simple" canonical examples. Not to mention the 
fact that it's fun to have a real world use case to work on.


I was hoping to have this in shape to push to the panama forest this 
week, but I'll need a few more days to get everything in place. 
Meanwhile, please have a look at the webrevs below and let me/us know 
what you think. Of specific interest may be the files in the jdk webrev 
under src/demo/share/panama/Panama. These "demos" outline roughly how 
this may be used, though spelling and exact syntax *will* change.

Webrev (top dir): 
http://cr.openjdk.java.net/~mikael/webrevs/panama/javaffi-20151224/webrev.00/top/webrev/
Webrev (jdk): 
http://cr.openjdk.java.net/~mikael/webrevs/panama/javaffi-20151224/webrev.00/jdk/webrev/
Webrev (hotspot): 
http://cr.openjdk.java.net/~mikael/webrevs/panama/javaffi-20151224/webrev.00/hotspot/webrev/

Happy holidays!

Cheers,
Mikael