[chain] Multidimensional Fees + FIFO Mempool

[patrick-ogrady]

Resolves: #96
Resolves: #73

TODO

• Allow transactions to emit multiple Outputs: [chain] Allow Transactions to output Multiple Outputs #359
• Add metric for each unit price as gauge
• Limit auth unit usage to prevent DoS: [auth] Limit Unit Usage to Prevent RPC DoS #382
• Add multiple fee dimensions
• Store fee data in state instead of in block
• Differentiate between storage read from disk or from cache already loaded form block?: Cold/Warm-Based Fees #365
• Charge storage by byte: Size-Based Storage Fees #366
• add MaxFee option to spam
• Make mempool FIFO: [mempool] FIFO #383
• add README item for "multi-dimensional fee pricing" to optimize resource usage
• Ensure txs only added to mempool if not too far in advance

[deuszx]

Hey @patrick-ogrady . I haven't read the whole PR (and its dependants) but how (if at all) do you enforce that every validator uses a FIFO for its mempool? Theoretically, I can fork the code and change my mempool algo to something else than FIFO and it still will work properly?

[patrick-ogrady]

Hey @patrick-ogrady . I haven't read the whole PR (and its dependants) but how (if at all) do you enforce that every validators uses a FIFO for its mempool? Theoretically, I can fork the code and change my mempool algo to something else than FIFO and it still will work properly?

That's correct. It was not a design goal to "enforce" FIFO (I'm not sure enforcing some mempool behavior is even theoretically possible without a TEE and trusted broadcast). You could replace FIFO with any mempool algo you want and the on-chain fees would still work as expected (they update independently of any off-chain knowledge/behavior -> they more or less perform an on-chain auction for resources, how flow is provided to that auction is up to the builder but using non-FIFO won't break it).