[erlang-questions] Accessing private data in a NIF C module

[zambal]

I could not found any information about if one needs to do any manual
locking when accessing data via enif_get_data(env) in an exported NIF
function. Does anybody know if this is needed?

thanks,
vincent

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[Sverker Eriksson]

zambal wrote:
> I could not found any information about if one needs to do any manual
> locking when accessing data via enif_get_data(env) in an exported NIF
> function. Does anybody know if this is needed?
>

Yes, you need to do your own locking on any data structures that you
introduce yourself and access either through enif_get_data() or static
variables. The callbacks load, reload, upgrade and unload are however
thread safe.

I will add more about this in the erl_nif documentation for next release.

/Sverker, Erlang/OTP Ericsson

[zambal]

Thanks for the info. So using NIF is a bit dangerous indeed ;-) but I
guess it's mainly intended for small side-effect free functions.

-
vincent