Improve the flexibility of respondd providers about packages HOT 2 OPEN

I think we should generally avoid using Lua in daemons, as a garbage-collected scripting language will always use more RAM than C.

Having a DSL in C might be a good idea though - and we could even try to avoid using json-c and thus keeping JSON objects in RAM at all and directly write JSON out as we generate it.

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I think we should generally avoid using Lua in daemons, as a garbage-collected scripting language will always use more RAM than C.

The main idea was to improve the flexibility of this daemon. Often it is very useful that one can modify (or add) a provider by simply modifying files on the router while is online. If you need C skills and a build ready LEDE/gluon development environment, you will often leave out monitoring because it's to complicated to write new modules. Decreasing the memory footprint is a minor aspect of this thread, but would be also nice.

I do not have a lot experience in garbage collection, but can't we reach a negligible difference if the lua functions are short and do not use external lua libs?

Having a DSL in C might be a good idea though

The concept to use lua was caused by the idea to add some easy to write postprocessing functionality for the different data sources. I think the postprocessing is useful because we want to do complex stuff like parsing output of ubus calls or batman neigh tables. How would you solve this postprocessing in the DSL? Or should we drop support for postprocessing of the data sources?

and we could even try to avoid using json-c and thus keeping JSON objects in RAM at all and directly write JSON out as we generate it.

I'm not sure whether I got it. Did I understand it correctly, that you want to generate the json on demand while serving the requests? I'm not really sure if we can decrease the memory footprint with this change, since caching would be still necessary. Saving the whole response body as a string would consume more memory than before.

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