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digitalmars.D.learn - Shared library loading and static constructor

reply Sobaya <sobaya007 gmail.com> writes:
I fail to load the shared library created in a specific 
situation, but I do not know the cause.

---- a.d
import b.d
----

---- b.d
static this() {}
----

for above 2 files, I created shared library by following command.

dmd a.d -shared -of=a.so

And I ran below code, but the library is not loaded.

--- main.d
void main() {
     import core.runtime;
     auto lib = Runtime.loadLibrary(a.so)
     assert(lib !is null);
}
---

Please tell me why. Thanks.
Mar 22 2019
parent reply Andre Pany <andre s-e-a-p.de> writes:
On Friday, 22 March 2019 at 10:51:58 UTC, Sobaya wrote:

 I fail to load the shared library created in a specific 
 situation, but I do not know the cause.

 ---- a.d
 import b.d
 ----

 ---- b.d
 static this() {}
 ----

 for above 2 files, I created shared library by following 
 command.

 dmd a.d -shared -of=a.so

 And I ran below code, but the library is not loaded.

 --- main.d
 void main() {
     import core.runtime;
     auto lib = Runtime.loadLibrary(a.so)
     assert(lib !is null);
 }
 ---

 Please tell me why. Thanks.


As far as I know different to windows, linus will not search 
current working directory for a.so. if this is the issue here, 
you have different possibilities. You could determine the current 
working directory and use std.path: buildPath to create an 
absolute path to a.so.
This path you can then use for Runtime.loadLibrary.

Or you can set the environment variable LD_LIBRARY_PATH.

I do not know what is the correct way on linux.

Kind regards
Andre
Mar 22 2019
parent reply Sobaya <sobaya007 gmail.com> writes:
On Friday, 22 March 2019 at 11:00:32 UTC, Andre Pany wrote:

 On Friday, 22 March 2019 at 10:51:58 UTC, Sobaya wrote:

 [...]


 As far as I know different to windows, linus will not search 
 current working directory for a.so. if this is the issue here, 
 you have different possibilities. You could determine the 
 current working directory and use std.path: buildPath to create 
 an absolute path to a.so.
 This path you can then use for Runtime.loadLibrary.

 Or you can set the environment variable LD_LIBRARY_PATH.

 I do not know what is the correct way on linux.

 Kind regards
 Andre


This is not a problem of path, I think.

Because when I do not write static constructor in b.d, that code 
works.

This problem occurs only when static constructor is used.
Mar 22 2019
parent reply Andre Pany <andre s-e-a-p.de> writes:
On Friday, 22 March 2019 at 17:52:34 UTC, Sobaya wrote:

 On Friday, 22 March 2019 at 11:00:32 UTC, Andre Pany wrote:

 On Friday, 22 March 2019 at 10:51:58 UTC, Sobaya wrote:

 [...]


 As far as I know different to windows, linus will not search 
 current working directory for a.so. if this is the issue here, 
 you have different possibilities. You could determine the 
 current working directory and use std.path: buildPath to 
 create an absolute path to a.so.
 This path you can then use for Runtime.loadLibrary.

 Or you can set the environment variable LD_LIBRARY_PATH.

 I do not know what is the correct way on linux.

 Kind regards
 Andre


 This is not a problem of path, I think.

 Because when I do not write static constructor in b.d, that 
 code works.

 This problem occurs only when static constructor is used.


Did you noticed this thread?
https://forum.dlang.org/post/eumnxgxtjrvvkhxpwjug forum.dlang.org

The author has an example for shared static this and it seems it 
works for him although he has some other issues with gc.

Kind regards
Andre
Mar 23 2019
parent reply Sobaya <sobaya007 gmail.com> writes:
On Saturday, 23 March 2019 at 09:37:16 UTC, Andre Pany wrote:

 On Friday, 22 March 2019 at 17:52:34 UTC, Sobaya wrote:

 On Friday, 22 March 2019 at 11:00:32 UTC, Andre Pany wrote:

 On Friday, 22 March 2019 at 10:51:58 UTC, Sobaya wrote:

 [...]


 As far as I know different to windows, linus will not search 
 current working directory for a.so. if this is the issue 
 here, you have different possibilities. You could determine 
 the current working directory and use std.path: buildPath to 
 create an absolute path to a.so.
 This path you can then use for Runtime.loadLibrary.

 Or you can set the environment variable LD_LIBRARY_PATH.

 I do not know what is the correct way on linux.

 Kind regards
 Andre


 This is not a problem of path, I think.

 Because when I do not write static constructor in b.d, that 
 code works.

 This problem occurs only when static constructor is used.


 Did you noticed this thread?
 https://forum.dlang.org/post/eumnxgxtjrvvkhxpwjug forum.dlang.org

 The author has an example for shared static this and it seems 
 it works for him although he has some other issues with gc.

 Kind regards
 Andre


I read his code(https://github.com/tchaloupka/dlangsharedlib).

But in his code the static constructor is written directly in 
worker.d.
Such code works just fine with me.

What I am saying is that it can not be read when a code importing 
(a.d) a code including the static constructor (b.d)  is compiled 
into shared library.
Mar 23 2019
parent reply tchaloupka <chalucha gmail.com> writes:
On Saturday, 23 March 2019 at 15:58:07 UTC, Sobaya wrote:

 What I am saying is that it can not be read when a code 
 importing (a.d) a code including the static constructor (b.d)  
 is compiled into shared library.


Hi. I've tried to add your case to the repository and at it seems 
to be working for me.
At least with dmd-2.085.0.

When run with `make dynamicd`:

```
main shared static this
+main()
utils shared static this
worker shared static this
libworker.so is loaded
entry_point1() function is found
entry_point2() function is found
...
-main()
unloading libworker.so
worker shared static ~this
utils shared static ~this
main shared static ~this
```
Mar 23 2019
parent Sobaya <sobaya007 gmail.com> writes:
On Saturday, 23 March 2019 at 16:56:28 UTC, tchaloupka wrote:

 On Saturday, 23 March 2019 at 15:58:07 UTC, Sobaya wrote:

 What I am saying is that it can not be read when a code 
 importing (a.d) a code including the static constructor (b.d)  
 is compiled into shared library.


 Hi. I've tried to add your case to the repository and at it 
 seems to be working for me.
 At least with dmd-2.085.0.

 When run with `make dynamicd`:

 ```
 main shared static this
 +main()
 utils shared static this
 worker shared static this
 libworker.so is loaded
 entry_point1() function is found
 entry_point2() function is found
 ...
 -main()
 unloading libworker.so
 worker shared static ~this
 utils shared static ~this
 main shared static ~this
 ```


I understand the cause.
Solved by passing b.d to dmd.
Sorry for the stupid question.
Mar 23 2019