R4R: Update gas costs to more reasonable numbers for GoS

[jaekwon]

TODO: Create a new issue to unify gas constants in one place, and improve tests.

Recommended best-guess estimates for gas for GoS:

50,000 bytes per block.
1,500,000 gas per block.

50,000 bytes being written x 30 gas/byte-written ~= 1,500,000 gas
750 writes to store x 2000 gas/store-set ~= 1,500,000 gas

• Targeted PR against correct branch (see CONTRIBUTING.md)

• Linked to github-issue with discussion and accepted design OR link to spec that describes this work.

• Wrote tests

• Updated relevant documentation (docs/)

• Added entries in PENDING.md with issue #

• rereviewed Files changed in the github PR explorer

[ValarDragon]

Would be cool to have 3 app-set constants, gas per nanosecond of computation, gas per byte read, and gas per p2p byte, and then derive gas numbers from there.

[jaekwon]

Sounds like it could be a good solution in the long run... the storage system should evolve to return some values upon operations that return the above kinds of values, and then compute the overall gas from those figures though, sounds useful. I'm not convinced that we need manage cpu costs, at least for the hub.

[jaekwon]

Merging this in early for sake of release. Lets still discuss here though.

[cwgoes]

Code changes look fine to me. We might want to set a non-zero default minimum fee for GoS.

[cwgoes]

This is only efficacious if ctx.MinimumFees() is nonzero, maybe we should set that for GoS

[alexanderbez]

How do we set this if it's set per validator? Simply state a recommendation?

[cwgoes]

Just set a non-zero default. I think @zmanian will mention it in the docs, which works too