JNA VS panama-foreign

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.

Going to copy my Reddit comment over to HN because I think it's valuable:

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One of the coolest things that's been worked on (by this same author, no less!) isn't even in the article!

Per has written a pretty-printer for MemorySegments and ByteBuffers that can hex-dump memory or render memory/buffers as their "struct" representations given some MemoryLayout.

You can also customize it with your own printers, it's wicked cool and helps so much to debug buffers when working with them.

https://github.com/openjdk/panama-foreign/pull/695

What do I mean by that? Have a look at this comment for an image of a raw memory structure layout I represented with MemoryLayout, and the pretty-print rendering of it:

https://github.com/openjdk/panama-foreign/pull/695#issuecomm...

[Here's the project github](https://github.com/openjdk/panama-foreign)

I am not using any special flag (is there one?) but the overhead seems quite high, especially considering the explanation on how these methods are compiled https://github.com/openjdk/panama-foreign/blob/foreign-jextract/doc/panama_ffi.md

https://github.com/openjdk/panama-foreign/blob/foreign-jextract/doc/panama_jextract.md ..look at these examples

I found the full context for the change written up here https://github.com/openjdk/panama-foreign/pull/554

Incentive for JVM devs? We know that C interoperability, malloc, free, structs are already supported on JVM natively since Java 14 with project panama's foreign-memory-api without JNI. I've been using sun.misc.Unsafe since Java8 and also LWJGL's C API.