Getting "UnsatisfiedLinkError" in io_uring for methods that were defined as "static inline" in the header

[Daniel Jarabek]

Not sure how helpful this is, but LWJGL recently implemented io_uring 
and liburing bindings. Maybe the bindings and demo code could serve as a 
reference for your experiments? The demo package includes 
samples/benchmarks using both the low level io_uring and high level 
liburing: 
https://github.com/LWJGL/lwjgl3/tree/master/modules/samples/src/test/java/org/lwjgl/demo/system/linux/liburing

-DJ

On 9/21/2022 6:39 PM, Gavin Ray wrote:
> Ahh okay, thank you.
>
> > In general inline functions (and function-like macros) are not true 
> library symbols, so there's not much the Linker can do for them.
>
> > If you need to access these, you would need a native library wrapper 
> which exposes them as regular symbols.
>
>
> That makes sense -- I will look at patching liburing with a dirty 
> one-liner that strips "static inline" from the definitions that have 
> them then, ty =)
>
> Do you anticipate any issues with using in/out-pointers as things get 
> passed back and forth from native to Java?
> I tried to write a draft of how I think the translation of a "hello 
> world" io_uring program should be:
>
> :https://gist.github.com/GavinRay97/8ea0997693c00f8df61968a98ba30135#file-io_uring-java
>
> (The C version at the bottom is canonical/definitely works)
>
>
> On Wed, Sep 21, 2022 at 5:13 PM Maurizio Cimadamore 
> <maurizio.cimadamore at oracle.com> wrote:
>
>     Hi Gavin,
>     thanks for the question - actually this might trip up others as
>     well, so it's always good to ask here.
>
>     I believe this has been fixed recently:
>
>     https://github.com/openjdk/jextract/pull/70
>
>     But the binary snapshots do not contain this fix.
>
>     In general inline functions (and function-like macros) are not
>     true library symbols, so there's not much the Linker can do for them.
>
>     If you need to access these, you would need a native library
>     wrapper which exposes them as regular symbols.
>
>     (we'd like, at some point, to automate the wrapper generation in
>     jextract).
>
>     Maurizio
>
>     On 21/09/2022 20:35, Gavin Ray wrote:
>>     I'm not super familiar with how linking and symbols work
>>
>>     The liburing header is weird, it contains a mix of definitions:
>>     https://github.com/axboe/liburing/blob/master/src/include/liburing.h
>>
>>     Some of them are traditional header defs, like:
>>
>>         int io_uring_queue_init(unsigned entries, struct io_uring
>>         *ring, unsigned flags);
>>
>>     But there are a lot of them which are defined like this:
>>
>>
>>         static inline int io_uring_wait_cqe(struct io_uring *ring,
>>         struct io_uring_cqe **cqe_ptr)
>>
>>     Using "objdump" on the ".so", I can see that none of these
>>     "static inline" functions appear
>>
>>     I have an almost-working test of using io_uring purely through
>>     Panama here, but it fails due to the above:
>>     https://github.com/GavinRay97/panama-liburing/blob/82f83a247bb78c26d787992fca28ea1b951dfd3c/lib/src/test/java/panama/liburing/LibraryTest.java#L25-L59
>>
>>     How are you meant to be able to use these from the Foreign Memory
>>     API?
>>     Do I need to write a second library and built it, that re-exports
>>     these?
>>
>>     Thanks, and sorry for so many newbie questions
>>
>>
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