Build Payout Plugin System #43
Description
This is highly motivated by this PR #42 and others including @rkuester requesting ways to modify payout and accounting mechanisms.
The goals of the Plugin system are:
- Users should be able to write independent crates in Rust to handle accounting and/or payouts.
- Users should be able to point their payout/accounting crate in Cargo.toml or drop .so file in plugins/ directory. Then activate the plugin in hydrapool's config.toml.
- Users should have access to well defined and well documented traits to make it clear what they need to do to implement in their plugins.
- Users should get access to read/write to rocksdb that hydrapool is using to save shares, read back shares etc. We need a clean API for this - cleaner than what we have, with a limited subset exposed to plugin authors. Some plugins might not need access to this store at all.
- We should write a score based pplns payout as a plugin and make it the default for hydrapool. We should also move the existing simple_pplns crate into a plugin. This lets us dog food our plugin system with this.
- We should also provide an implementation of the system @keegreil is using in the above mentioned PR, so he can easily switch. Least we can do for him showing us the way!