Future Swap limitation

[Bushstar]

Summary

• Limits the amount that can be swapped from loan token to DUSD to 10% of the 28 day average liquidity of that loan token in its DUSD pool. Actual percentage and period is configurable, but defaults to the values above.
• Average liquidity will only populate on a Future Swap event if there is enough liquidity data present, which there should be as long as the limitation has been enabled for the full 28 days period before the event.
• If there is no average liquidity present then Future Swap will behave as normal without any limits.
• Implements DFIP-2211-F: Limit FutureSwap volume dfips#238

RPCs

• listloantokenliquidity returns a list of all present average liquidity.

Implications

• Storage

  • Database reindex required
  • Database reindex optional
  • Database reindex not required
  • None

• Consensus

  • Network upgrade required
  • Includes backward compatible changes
  • Includes consensus workarounds
  • Includes consensus refactors
  • None

[kuegi]

small comment, rest looks good to me

[prasannavl]

The cost of doing these calc at every block concerns me. This is going to stall the chain esp. on sync catch-up at this block range, which cannot be fixed after the fact as well.

We might likely want to just to do the calc at periodic intervals. I don't think accuracy is necessary here.

[kuegi]

The cost of doing these calc at every block concerns me. This is going to stall the chain esp. on sync catch-up at this block range, which cannot be fixed after the fact as well.

We might likely want to just to do the calc at periodic intervals. I don't think accuracy is necessary here.

valid point. how about doing it every price block (so every 120 blocks)?

[prasannavl]

Indeed, that would be perfect. We'll add var that makes the time period changeable.