Bridging fees are calculated using a static ETH/DOT exchange rate that
can deviate significantly from the real-world exchange rate. We
therefore need to add a safety margin to the fee so that users almost
aways cover the cost of relaying.
# FAQ
> Why introduce a `multiplier` parameter instead of configuring an
exchange rate which already has a safety factor applied?
When converting from ETH to DOT, we need to _divide_ the multiplier by
the exchange rate, and to convert from DOT to ETH we need to _multiply_
the multiplier by the exchange rate.
> Other input parameters to the fee calculation can also deviate from
real-world values. These include substrate weights, gas prices, and so
on. Why does the multiplier introduced here not adjust those?
A single scalar multiplier won't be able to accommodate the different
volatilities efficiently. For example, gas prices are much more volatile
than exchange rates, and substrate weights hardly ever change.
So the pricing config relating to weights and gas prices should already
have some appropriate safety margin pre-applied.
# Detailed Changes:
* Added `multiplier` field to `PricingParameters`
* Outbound-queue fee is multiplied by `multiplier`
* This `multiplier` is synced to the Ethereum side
* Improved Runtime API for calculating outbound-queue fees. This API
makes it much easier to for configure parts of the system in preparation
for launch.
* Improve and clarify code documentation
Upstreamed from https://github.com/Snowfork/polkadot-sdk/pull/127
---------
Co-authored-by: Clara van Staden <claravanstaden64@gmail.com>
Co-authored-by: Adrian Catangiu <adrian@parity.io>
While adding runtime tests to
https://github.com/polkadot-fellows/runtimes/pull/130, I noticed the
Ethereum chain ID was hardcoded. For Kusama + Polkadot, the Ethereum
chain ID should 1 (Mainnet), whereas on Rococo it is 11155111 (Sepolia).
This PR also updates the Snowbridge crates versions to the current
versions on crates.io.
---------
Co-authored-by: claravanstaden <Cats 4 life!>
Removes the `bridges/snowbridge/parachain` directory and moves
everything up to under `snowbridge` directly. We are cleaning up our
local dev env after merging our crates into the polkadot-sdk.
---------
Co-authored-by: claravanstaden <Cats 4 life!>
Branislav Kontur