Some small feedback regading jextract as a user
sundararajan.athijegannathan at oracle.com
sundararajan.athijegannathan at oracle.com
Fri Nov 13 02:02:29 UTC 2020
Hi,
jextract -J-Djextract.debug=true <other options>
prints stack trace on runtime exceptions.
-Sundar
On 13/11/20 5:03 am, Jerven Tjalling Bolleman wrote:
> Hi Jorn,
>
> I got it you where on commit 9cf693a0ddb33357f35b02e79f9b3fa848e9cca9
> Where jextract works with your build.rs fix.
> I was on commit 9cb2fbcc257b5e7665a57a036ec170a0f8c67333
> where it does not with the error I showed earlier (also with your
> build.rs fix).
>
> I will investigate a bit more tomorrow.
>
> Again thank you very much for your help.
>
> Regards,
> Jerven
>
> On 2020-11-13 00:08, Jorn Vernee wrote:
>> Hi Jerven,
>>
>> No, I did not do anything special, I just followed your instructions
>> in your reply to Maurizio (running `cargo build` with the modified
>> build.rs was all I did).
>>
>> FWIW, the file I get out of cbindgen does not include 'HashGraph'
>> anywhere, and the line 13 that supposedly throws the error is empty in
>> my file [1].
>>
>> Jorn
>>
>> [1] :
>>
>> #include <stdarg.h>
>> #include <stdbool.h>
>> #include <stdint.h>
>> #include <stdlib.h>
>>
>> typedef struct CGraph CGraph;
>>
>> typedef struct EdgesIter EdgesIter;
>>
>> typedef struct HandlesIter HandlesIter;
>>
>> typedef struct PathsIter PathsIter;
>> // <-- line 13
>> typedef struct {
>> uint64_t left;
>> uint64_t right;
>> } EdgeHolder;
>>
>> CGraph *load_hashgraph(const uint8_t *file_name, uintptr_t
>> file_name_len);
>>
>> void free_hashgraph(CGraph *graph);
>>
>> HandlesIter *graph_handles(const CGraph *graph);
>>
>> void free_handles_iter(HandlesIter *handles);
>>
>> uint64_t handles_next(HandlesIter *handles);
>>
>> bool handles_has_next(HandlesIter *handles);
>>
>> EdgesIter *graph_edges(const CGraph *graph);
>>
>> void free_edges_iter(EdgesIter *handles);
>>
>> EdgeHolder edges_next(EdgesIter *edges);
>>
>> bool edges_has_next(EdgesIter *edges);
>>
>> PathsIter *graph_paths(const CGraph *graph);
>>
>> void free_paths_iter(PathsIter *paths);
>>
>> int64_t paths_next(PathsIter *paths);
>>
>> bool paths_has_next(PathsIter *paths);
>>
>> On 12/11/2020 23:50, Jerven Tjalling Bolleman wrote:
>>> Hi Jorn,
>>>
>>> Thank you so much for pointing that out.
>>>
>>> That said I am still getting a
>>>
>>> java.lang.RuntimeException: libhandlegraph-ffi-c.h:13:3: error:
>>> unknown type name 'HashGraph'
>>>
>>> The libhandlegraph-ffi-c.h is now a C file, so that part worked.
>>> Did you do anything special regarding your cargo build?
>>> Sorry to ask, after you have been super helpful already!
>>>
>>> Regards,
>>> Jerven
>>>
>>> On 2020-11-12 23:26, Jorn Vernee wrote:
>>>> Hi,
>>>>
>>>> On 12/11/2020 21:47, Jerven Tjalling Bolleman wrote:
>>>>> Dear panama-devs,
>>>>>
>>>>> I hope this feedback is in the useful category. My feedback is
>>>>> regarding the jextract tool and ffi. Most of it is trivial but I
>>>>> hope it is still useful.
>>>>>
>>>>> No --version or -v option to quickly get the exact version of
>>>>> jextract (would make future feedback easier to pinpoint).
>>>>>
>>>>> Assume the jextract user has minimal or no knowledge (like me) of
>>>>> how the library they want to wrap was built. For example the first
>>>>> error I ran into was “fatal error: 'cstdarg' file not found” which
>>>>> required “-C -x -C c++” to be added to the command. This was not
>>>>> intuitive and certainly not the first thing I tried (I started
>>>>> with trying different -I combinations. Specifically, I am trying
>>>>> to wrap a rust library with a header generated by rust cbindgen.
>>>>> So thinking of needing to add clang options to jextract was not
>>>>> high on my lists of things to do.
>>>> The problem here seems that cbindgen produces a C++ header file, not a
>>>> C file, and then exports a bunch of functions with C linkage (i.e.
>>>> extern "C"). Note that jextract currently only handles C well, so
>>>> parsing C++ will likely fail (e.g. with an NPE).
>>>>
>>>> It looks like cbindgen supports generating C headers as well [1]. And,
>>>> after some changes to your build.rs [2], jextract works with the
>>>> following command:
>>>>
>>>> jextract -l rs_handlegraph_ffi -t rs.handlegraph -d out
>>>> libhandlegraph-ffi-c.h
>>>>
>>>> (Note that -l takes a library name, not a path). Producing the
>>>> following files:
>>>>
>>>> out
>>>> └───rs
>>>> └───handlegraph
>>>> C.class
>>>> libhandlegraph_ffi_c_h$atexit$x0.class
>>>> libhandlegraph_ffi_c_h$at_quick_exit$x0.class
>>>> libhandlegraph_ffi_c_h$bsearch$_CompareFunction.class
>>>> libhandlegraph_ffi_c_h$bsearch_s$_CompareFunction.class
>>>> libhandlegraph_ffi_c_h$constants$0.class
>>>> libhandlegraph_ffi_c_h$div_t.class
>>>> libhandlegraph_ffi_c_h$EdgeHolder.class
>>>> libhandlegraph_ffi_c_h$ldiv_t.class
>>>> libhandlegraph_ffi_c_h$lfind$_CompareFunction.class
>>>> libhandlegraph_ffi_c_h$lldiv_t.class
>>>> libhandlegraph_ffi_c_h$lsearch$_CompareFunction.class
>>>> libhandlegraph_ffi_c_h$mbstate_t.class
>>>> libhandlegraph_ffi_c_h$onexit$_Func.class
>>>> libhandlegraph_ffi_c_h$qsort$_CompareFunction.class
>>>> libhandlegraph_ffi_c_h$qsort_s$_CompareFunction.class
>>>> libhandlegraph_ffi_c_h$_CRT_DOUBLE.class
>>>> libhandlegraph_ffi_c_h$_CRT_FLOAT.class
>>>> libhandlegraph_ffi_c_h$_div_t.class
>>>> libhandlegraph_ffi_c_h$_LDBL12.class
>>>> libhandlegraph_ffi_c_h$_ldiv_t.class
>>>> libhandlegraph_ffi_c_h$_LDOUBLE.class
>>>> libhandlegraph_ffi_c_h$_lfind$_CompareFunction.class
>>>> libhandlegraph_ffi_c_h$_lfind_s$_CompareFunction.class
>>>> libhandlegraph_ffi_c_h$_lldiv_t.class
>>>> libhandlegraph_ffi_c_h$_LONGDOUBLE.class
>>>> libhandlegraph_ffi_c_h$_lsearch$_CompareFunction.class
>>>> libhandlegraph_ffi_c_h$_lsearch_s$_CompareFunction.class
>>>> libhandlegraph_ffi_c_h$_Mbstatet.class
>>>> libhandlegraph_ffi_c_h$_onexit$_Func.class
>>>> libhandlegraph_ffi_c_h$_set_invalid_parameter_handler$_Handler.class
>>>> libhandlegraph_ffi_c_h$_set_purecall_handler$_Handler.class
>>>> libhandlegraph_ffi_c_h$_set_thread_local_invalid_parameter_handler$_Handler.class
>>>> libhandlegraph_ffi_c_h.class
>>>> libhandlegraph_ffi_c_h.class
>>>> libhandlegraph_ffi_c_h.class
>>>> RuntimeHelper$VarargsInvoker.class
>>>> RuntimeHelper.class
>>>>
>>>> HTH,
>>>> Jorn
>>>>
>>>>>
>>>>> Having fixed that I ran into a null pointer exception. i.e.
>>>>> WARNING: Using incubator modules: jdk.incubator.jextract,
>>>>> jdk.incubator.foreign
>>>>> java.lang.NullPointerException
>>>>>
>>>>> While we might dislike stack traces. I think a bug report (to
>>>>> myself regarding the C code) or to you would be easier to work on
>>>>> when you have a stack trace.
>>>>>
>>>>> When generating the helloworld example I needed to compile with
>>>>> -fPIC. Which the document at
>>>>> https://urldefense.com/v3/__https://github.com/openjdk/panama-foreign/blob/foreign-jextract/doc/panama_jextract.md*jextract-a-jar-file-for-helloworldh__;Iw!!GqivPVa7Brio!ORVvc0YKf1IezH9e1ZzHs3kEoc7rXWUi_45S5WOZw9LQeW859IDHJq7ySlh27tcF$
>>>>> claims generates a jar file but actually generates a directory
>>>>> with class files. The example worked fine with clang 10.0.1 but my
>>>>> fedora 10.2.1 gcc needed -fPIC.
>>>>>
>>>>> Regarding the FFI interface, I would love to see more examples
>>>>> regarding the group layout functionality.
>>>>>
>>>>> Otherwise with jextract I quite quickly ran into error: unknown
>>>>> type name without much of a suggestion why a certain type was not
>>>>> known. The libraries added to the command line should have had the
>>>>> types. And I am still working on this one.
>>>>>
>>>>> That said the tools have lots of promise and please keep working
>>>>> on them!
>>>>>
>>>>> Regards,
>>>>> Jerven
>>>>
>>>> [1] :
>>>> https://urldefense.com/v3/__https://github.com/eqrion/cbindgen*quick-start__;Iw!!GqivPVa7Brio!ORVvc0YKf1IezH9e1ZzHs3kEoc7rXWUi_45S5WOZw9LQeW859IDHJq7ySlzVd6-F$
>>>> [2] :
>>>>
>>>> diff --git a/build.rs b/build.rs
>>>> index 2dd7493..02b36e6 100644
>>>> --- a/build.rs
>>>> +++ b/build.rs
>>>> @@ -7,6 +7,7 @@ fn main() {
>>>>
>>>> cbindgen::Builder::new()
>>>> .with_crate(crate_dir)
>>>> + .with_language(cbindgen::Language::C)
>>>> .generate()
>>>> .expect("Unable to generate bindings")
>>>> .write_to_file("libhandlegraph-ffi-c.h");
>>>
>
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