Hello there!
I've decided to learn a bit of D, as I am currently Android Developer (mostly C++ <- JNI -> Java), I'm trying to create a D shared library which exports function (with extern (C)) for invocation from Java.
My .d file contains only a single function returning an int, .java calls this function several times.
This approach only works if d-function is trivial, e.g. it's not using any D functionality (I believe that it is related to GC and memory allocation).
For example, if my d-function just returns some constant integer, java side receives it. core.stdc.stdio also works and allows console output, but it's not the case with std.stdio.writeln and similar functions.
If I use any d-specific functions my program crashes while calling native code with some weird message like following:
"Invalid memory access of location 0x0 rip=addr".

It seems like D is not initialized at all, maybe there is some internal function like dinit() which I can call in order to activate everything?

Thanks.

On Wednesday, 16 October 2013 at 10:11:32 UTC, Andrew wrote:
> Hello there!
> I've decided to learn a bit of D, as I am currently Android Developer (mostly C++ <- JNI -> Java), I'm trying to create a D shared library which exports function (with extern (C)) for invocation from Java.
> My .d file contains only a single function returning an int, .java calls this function several times.
> This approach only works if d-function is trivial, e.g. it's not using any D functionality (I believe that it is related to GC and memory allocation).
> For example, if my d-function just returns some constant integer, java side receives it. core.stdc.stdio also works and allows console output, but it's not the case with std.stdio.writeln and similar functions.
> If I use any d-specific functions my program crashes while calling native code with some weird message like following:
> "Invalid memory access of location 0x0 rip=addr".
>
> It seems like D is not initialized at all, maybe there is some internal function like dinit() which I can call in order to activate everything?
>
> Thanks.


JNI requires (to some degree) compiler support.  This could be done in gdc as backend support is there because of g++ JNI interface to gcj. But it would be some magic module or change to the language to add the Java types to the language.

Regards
Iain.

On Wednesday, 16 October 2013 at 10:15:17 UTC, Iain Buclaw wrote:
> On Wednesday, 16 October 2013 at 10:11:32 UTC, Andrew wrote:
>> Hello there!
>> I've decided to learn a bit of D, as I am currently Android Developer (mostly C++ <- JNI -> Java), I'm trying to create a D shared library which exports function (with extern (C)) for invocation from Java.
>> My .d file contains only a single function returning an int, .java calls this function several times.
>> This approach only works if d-function is trivial, e.g. it's not using any D functionality (I believe that it is related to GC and memory allocation).
>> For example, if my d-function just returns some constant integer, java side receives it. core.stdc.stdio also works and allows console output, but it's not the case with std.stdio.writeln and similar functions.
>> If I use any d-specific functions my program crashes while calling native code with some weird message like following:
>> "Invalid memory access of location 0x0 rip=addr".
>>
>> It seems like D is not initialized at all, maybe there is some internal function like dinit() which I can call in order to activate everything?
>>
>> Thanks.
>
>
> JNI requires (to some degree) compiler support.  This could be done in gdc as backend support is there because of g++ JNI interface to gcj. But it would be some magic module or change to the language to add the Java types to the language.
>
> Regards
> Iain.

As far as I know, calling C from Java only requires is <jni.h> header. It can mimicked with mere D aliases. I'm currently not talking about calling Java from D, although it could be possible by writing C-wrapper library.

I just can't understand why D code compiled as a shared library does not work when called from Java. Why does it (does it?) work when called from C?

On Wednesday, 16 October 2013 at 10:11:32 UTC, Andrew wrote:
> Hello there!
> I've decided to learn a bit of D, as I am currently Android Developer (mostly C++ <- JNI -> Java), I'm trying to create a D shared library which exports function (with extern (C)) for invocation from Java.
> My .d file contains only a single function returning an int, .java calls this function several times.
> This approach only works if d-function is trivial, e.g. it's not using any D functionality (I believe that it is related to GC and memory allocation).
> For example, if my d-function just returns some constant integer, java side receives it. core.stdc.stdio also works and allows console output, but it's not the case with std.stdio.writeln and similar functions.
> If I use any d-specific functions my program crashes while calling native code with some weird message like following:
> "Invalid memory access of location 0x0 rip=addr".
>
> It seems like D is not initialized at all, maybe there is some internal function like dinit() which I can call in order to activate everything?
>
> Thanks.

Try using Runtime.init() from core.runtime

On Wednesday, 16 October 2013 at 10:41:35 UTC, John Colvin wrote:
> On Wednesday, 16 October 2013 at 10:11:32 UTC, Andrew wrote:
>> Hello there!
>> I've decided to learn a bit of D, as I am currently Android Developer (mostly C++ <- JNI -> Java), I'm trying to create a D shared library which exports function (with extern (C)) for invocation from Java.
>> My .d file contains only a single function returning an int, .java calls this function several times.
>> This approach only works if d-function is trivial, e.g. it's not using any D functionality (I believe that it is related to GC and memory allocation).
>> For example, if my d-function just returns some constant integer, java side receives it. core.stdc.stdio also works and allows console output, but it's not the case with std.stdio.writeln and similar functions.
>> If I use any d-specific functions my program crashes while calling native code with some weird message like following:
>> "Invalid memory access of location 0x0 rip=addr".
>>
>> It seems like D is not initialized at all, maybe there is some internal function like dinit() which I can call in order to activate everything?
>>
>> Thanks.
>
> Try using Runtime.init() from core.runtime

Wow, thanks! Now everything works, proving that my guess on uninitialized runtime was correct.
It's actually Runtime.initialize() according to documentation, by the way.

On Wednesday, 16 October 2013 at 10:15:17 UTC, Iain Buclaw wrote:
> On Wednesday, 16 October 2013 at 10:11:32 UTC, Andrew wrote:
>> Hello there!
>> I've decided to learn a bit of D, as I am currently Android Developer (mostly C++ <- JNI -> Java), I'm trying to create a D shared library which exports function (with extern (C)) for invocation from Java.
>> My .d file contains only a single function returning an int, .java calls this function several times.
>> This approach only works if d-function is trivial, e.g. it's not using any D functionality (I believe that it is related to GC and memory allocation).
>> For example, if my d-function just returns some constant integer, java side receives it. core.stdc.stdio also works and allows console output, but it's not the case with std.stdio.writeln and similar functions.
>> If I use any d-specific functions my program crashes while calling native code with some weird message like following:
>> "Invalid memory access of location 0x0 rip=addr".
>>
>> It seems like D is not initialized at all, maybe there is some internal function like dinit() which I can call in order to activate everything?
>>
>> Thanks.
>
>
> JNI requires (to some degree) compiler support.  This could be done in gdc as backend support is there because of g++ JNI interface to gcj. But it would be some magic module or change to the language to add the Java types to the language.
>
> Regards
> Iain.

I was talking about calling D from Java in following fashion:
https://gist.github.com/DieHertz/7005898

Java calls dinit in static initializer after loading shader library and then proceeds with calling dget.

On Wednesday, 16 October 2013 at 10:53:28 UTC, Andrew wrote:
> On Wednesday, 16 October 2013 at 10:41:35 UTC, John Colvin wrote:
>> On Wednesday, 16 October 2013 at 10:11:32 UTC, Andrew wrote:
>>> Hello there!
>>> I've decided to learn a bit of D, as I am currently Android Developer (mostly C++ <- JNI -> Java), I'm trying to create a D shared library which exports function (with extern (C)) for invocation from Java.
>>> My .d file contains only a single function returning an int, .java calls this function several times.
>>> This approach only works if d-function is trivial, e.g. it's not using any D functionality (I believe that it is related to GC and memory allocation).
>>> For example, if my d-function just returns some constant integer, java side receives it. core.stdc.stdio also works and allows console output, but it's not the case with std.stdio.writeln and similar functions.
>>> If I use any d-specific functions my program crashes while calling native code with some weird message like following:
>>> "Invalid memory access of location 0x0 rip=addr".
>>>
>>> It seems like D is not initialized at all, maybe there is some internal function like dinit() which I can call in order to activate everything?
>>>
>>> Thanks.
>>
>> Try using Runtime.init() from core.runtime
>
> Wow, thanks! Now everything works, proving that my guess on uninitialized runtime was correct.

No problem.

> It's actually Runtime.initialize() according to documentation, by the way.

Ah yeah, sorry I misremembered.

On 2013-10-16 12:53, Andrew wrote:

> Wow, thanks! Now everything works, proving that my guess on
> uninitialized runtime was correct.
> It's actually Runtime.initialize() according to documentation, by the way.

If you're calling it from C it might be more correct to call this function:

https://github.com/D-Programming-Language/druntime/blob/master/src/rt/dmain2.d#L161

It's what Runtime.initialize calls.

-- 
/Jacob Carlborg

On Wednesday, 16 October 2013 at 11:01:33 UTC, Jacob Carlborg wrote:
> On 2013-10-16 12:53, Andrew wrote:
>
>> Wow, thanks! Now everything works, proving that my guess on
>> uninitialized runtime was correct.
>> It's actually Runtime.initialize() according to documentation, by the way.
>
> If you're calling it from C it might be more correct to call this function:
>
> https://github.com/D-Programming-Language/druntime/blob/master/src/rt/dmain2.d#L161
>
> It's what Runtime.initialize calls.

Agreed. You can't call Runtime.initialize from outside D due to name mangling (and maybe ABI, depending on your system).

However, other than that it really makes no difference which you call, Runtime.initialize is just a no-op wrapper around rt_init.

On Wednesday, 16 October 2013 at 11:01:33 UTC, Jacob Carlborg wrote:
> On 2013-10-16 12:53, Andrew wrote:
>
>> Wow, thanks! Now everything works, proving that my guess on
>> uninitialized runtime was correct.
>> It's actually Runtime.initialize() according to documentation, by the way.
>
> If you're calling it from C it might be more correct to call this function:
>
> https://github.com/D-Programming-Language/druntime/blob/master/src/rt/dmain2.d#L161
>
> It's what Runtime.initialize calls.

Thanks for advice, I'll use it when I'm interfacing C with D :-)
For now I can't use it directly because a native function called from java requires a name with "Java_" prefix, so I'd have to write a wrapper with such prefix anyway.