Event Callback Registration for Stratum Server

[bladedoyle]

Is your feature request related to a problem? Please describe.
Pools need to get information from the built-in stratum server - for example to know when a block is found. The current options are:

1. parse the stratum server log message - This isnt a great option because when changes are made to the log message format, or the content of the messages it breaks things.
2. Use a modified version of the stratum server - This isnt a great option since it requires manual merge of code for each upstream change.

Describe the solution you'd like
I would like the built-in stratum server to support event hooks with callback registration api. This will allow a pool operator to write custom code that is called when events they care about occur.

[hendi]

👍 from grin-pool.org here (using 2. currently)

Events I'd like to see hooks for:

• miner submits a solution
• solution rejected, and why
• solution accepted
• block found
• new job
• new block
• block found

[hashmap]

For my education - I heard all pools have some proxies on top of grin stratum, can it intercept requests and gets most of this info (not sure how stratum is chatty about reasons etc)?

[hendi]

Yes, proxies can get most of the info. For the stuff they can't, we need to

a) modify grin-server to send us the information we need

and

b) write some logic within the proxy to remove that info/to not pass it along to miners

[hashmap]

Sounds reasonable. Do you mean in-process API (Rust) or smth like websocket or both?

[bladedoyle]

Not websockets. I prefer in-process for performance. I would like to be able to build my custom code into a shared library, and the grin-server would load that and call the methods I define. The simplest (though not cleanest) way is for grin-server to include a "default implementation" (just empty functions) in an external shared library, which could be replaced by the custom library I write.

[edit] the zeromq idea in #2321 also seems fine

[0xmichalis]

Can this issue be closed now that we have webhooks? @bladedoyle @mcdallas

[hashmap]

Closing, feel free to reopen if needed