Send scheme procedure as callback to foreign thread.

Send scheme procedure as callback to foreign thread.

[Zhu Zihao]

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In Guile FFI programming, we have procedure->pointer, which makes a
Scheme procedure a foreign callback. And foreign library call use this
callback.

However, if this callback is called in a another foreign thread. The scheme
context is not properly setup, It may cause crash or UB.

IIUC, the procedure invoker "invoke_closure" defined in foreign.c
doesn't use scm_with_guile. If we use scm_with_guile to make a foreign
callback, would it be OK to execute Scheme procedure in multithreading context?
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Zihao

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Re: Send scheme procedure as callback to foreign thread.

[Ludovic Courtès]

Hi,

Zhu Zihao <all_but_last@163.com> skribis:

> In Guile FFI programming, we have procedure->pointer, which makes a
> Scheme procedure a foreign callback. And foreign library call use this
> callback.
>
> However, if this callback is called in a another foreign thread. The scheme
> context is not properly setup, It may cause crash or UB.
>
> IIUC, the procedure invoker "invoke_closure" defined in foreign.c
> doesn't use scm_with_guile. If we use scm_with_guile to make a foreign
> callback, would it be OK to execute Scheme procedure in multithreading context?

Yes, it should be.

Could you come up with a minimal reproducer and maybe even a fix, now
that you likely found the solution?  :-)

Thanks in advance,
Ludo’.

PS: It may be best to use bug-guile to reduce the chances that the issue
    gets lost.

Re: Send scheme procedure as callback to foreign thread.

[Zhu Zihao]

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Thanks for your help!

I submit a more detailed report to https://debbugs.gnu.org/cgi/bugreport.cgi?bug=58498.
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