JNA VS SWIG

As far as I understand it, with JNA, all calls into C code go through libffi: https://github.com/java-native-access/jna/blob/master/www/Fu...

This means that every call sets up some libffi data structures and libffi uses this information to perform the native call. Likewise in the other direction for return values. With JNI (and Panama), Hotspot can directly emit the argument/return code a the call, not too dissimilar from what a C or C++ compiler would do. There is still some overhead from maintaining JVM invariants. For example, I think a thread blocked in an FFI call can still participate in a safepoint. But that applies to JNI as well.

If you were prepared to go to the JVM you might try JNA. https://github.com/java-native-access/jna

Other good example, but for Java platform is JNA library. Do not mix it with Java's JNI, which is a bad example of how it could be done.

In case you haven't used it (assuming that you already know about JNI, for comparison) - https://github.com/java-native-access/jna is about as easy as it gets for native interop. Also, as mentioned in another comment, with the Java FFM (Foreign Function and Memory) API already in preview mode, pretty soon, there will be no external dependencies at all, and Java should be able to interop with any language that can talk to C.

The complexity of JNI has given rise to some community-driven libraries that make it simpler to do FFI in Java. Java Native Access (JNA) is one of them. It's built on top of JNI and at least makes FFI easier to use, especially as it removes the need to write any C binding code manually and reduces the chances of memory safety issues. Still, it has some of the disadvantages of being JNI-based and is slightly slower than JNI in many cases. However, JNA is widely used and battle-tested, so definitely a better option than using JNI directly.

This is about calling into any native operating system APIs, as long as they are callable via C or C++ (which these days means "all" operating system APIs).

JNI is somewhat harder to use, because you need custom glue on both sides of the border: Some custom classes in Java and some custom code on the C (and C++) side.

This proposal would remove the need for the glue on the C side and would allow a pure java solution.

Something like this has existed in third-party form for a while as JNA (https://github.com/java-native-access/jna), but now it's going to be built into the JRE itself (if the proposal passes through review)

I use JNA https://github.com/java-native-access/jna , as you can write the entire interface in Java faster as well as easier without the need of messing with the complexities of JNI.

How is this any different than a mature tool such as SWIG (https://www.swig.org/)?

I've used SWIG extensively with Python to call C code and import C headers for testing/tooling purposes.

For pure C, CGO. For C++ they are likely creating shims with Swig: https://www.swig.org/

I mostly write in C and C++ so for language bindings I use Swig a lot. Say Im creating a machine learning library in C++, its very easy to create a Python API that can call the C++ classes and methods using Swig. iirc, I am using the same swig interface file to create bindings for Python, OCaml, R and even Fortran. Feel free to DM me if you got any more questions or anything!

Swig can make c++ types and functions available to python.

The likes of SWIG is often used to link C library-like code to 11-ish other widely used languages.

Maybe you could use swig to create a wrapper for Java.

But, you might find these links interesting: * https://github.com/swig/swig/issues/918 * https://github.com/kaby76/swigged.llvm