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>
This MR is the merge of
https://github.com/paritytech/substrate/pull/14414 and
https://github.com/paritytech/substrate/pull/14275. It implements
[RFC#13](https://github.com/polkadot-fellows/RFCs/pull/13), closes
https://github.com/paritytech/polkadot-sdk/issues/198.
-----
This Merge request introduces three major topicals:
1. Multi-Block-Migrations
1. New pallet `poll` hook for periodic service work
1. Replacement hooks for `on_initialize` and `on_finalize` in cases
where `poll` cannot be used
and some more general changes to FRAME.
The changes for each topical span over multiple crates. They are listed
in topical order below.
# 1.) Multi-Block-Migrations
Multi-Block-Migrations are facilitated by creating `pallet_migrations`
and configuring `System::Config::MultiBlockMigrator` to point to it.
Executive picks this up and triggers one step of the migrations pallet
per block.
The chain is in lockdown mode for as long as an MBM is ongoing.
Executive does this by polling `MultiBlockMigrator::ongoing` and not
allowing any transaction in a block, if true.
A MBM is defined through trait `SteppedMigration`. A condensed version
looks like this:
```rust
/// A migration that can proceed in multiple steps.
pub trait SteppedMigration {
type Cursor: FullCodec + MaxEncodedLen;
type Identifier: FullCodec + MaxEncodedLen;
fn id() -> Self::Identifier;
fn max_steps() -> Option<u32>;
fn step(
cursor: Option<Self::Cursor>,
meter: &mut WeightMeter,
) -> Result<Option<Self::Cursor>, SteppedMigrationError>;
}
```
`pallet_migrations` can be configured with an aggregated tuple of these
migrations. It then starts to migrate them one-by-one on the next
runtime upgrade.
Two things are important here:
- 1. Doing another runtime upgrade while MBMs are ongoing is not a good
idea and can lead to messed up state.
- 2. **Pallet Migrations MUST BE CONFIGURED IN `System::Config`,
otherwise it is not used.**
The pallet supports an `UpgradeStatusHandler` that can be used to notify
external logic of upgrade start/finish (for example to pause XCM
dispatch).
Error recovery is very limited in the case that a migration errors or
times out (exceeds its `max_steps`). Currently the runtime dev can
decide in `FailedMigrationHandler::failed` how to handle this. One
follow-up would be to pair this with the `SafeMode` pallet and enact
safe mode when an upgrade fails, to allow governance to rescue the
chain. This is currently not possible, since governance is not
`Mandatory`.
## Runtime API
- `Core`: `initialize_block` now returns `ExtrinsicInclusionMode` to
inform the Block Author whether they can push transactions.
### Integration
Add it to your runtime implementation of `Core` and `BlockBuilder`:
```patch
diff --git a/runtime/src/lib.rs b/runtime/src/lib.rs
@@ impl_runtime_apis! {
impl sp_block_builder::Core<Block> for Runtime {
- fn initialize_block(header: &<Block as BlockT>::Header) {
+ fn initialize_block(header: &<Block as BlockT>::Header) -> RuntimeExecutiveMode {
Executive::initialize_block(header)
}
...
}
```
# 2.) `poll` hook
A new pallet hook is introduced: `poll`. `Poll` is intended to replace
mostly all usage of `on_initialize`.
The reason for this is that any code that can be called from
`on_initialize` cannot be migrated through an MBM. Currently there is no
way to statically check this; the implication is to use `on_initialize`
as rarely as possible.
Failing to do so can result in broken storage invariants.
The implementation of the poll hook depends on the `Runtime API` changes
that are explained above.
# 3.) Hard-Deadline callbacks
Three new callbacks are introduced and configured on `System::Config`:
`PreInherents`, `PostInherents` and `PostTransactions`.
These hooks are meant as replacement for `on_initialize` and
`on_finalize` in cases where the code that runs cannot be moved to
`poll`.
The reason for this is to make the usage of HD-code (hard deadline) more
explicit - again to prevent broken invariants by MBMs.
# 4.) FRAME (general changes)
## `frame_system` pallet
A new memorize storage item `InherentsApplied` is added. It is used by
executive to track whether inherents have already been applied.
Executive and can then execute the MBMs directly between inherents and
transactions.
The `Config` gets five new items:
- `SingleBlockMigrations` this is the new way of configuring migrations
that run in a single block. Previously they were defined as last generic
argument of `Executive`. This shift is brings all central configuration
about migrations closer into view of the developer (migrations that are
configured in `Executive` will still work for now but is deprecated).
- `MultiBlockMigrator` this can be configured to an engine that drives
MBMs. One example would be the `pallet_migrations`. Note that this is
only the engine; the exact MBMs are injected into the engine.
- `PreInherents` a callback that executes after `on_initialize` but
before inherents.
- `PostInherents` a callback that executes after all inherents ran
(including MBMs and `poll`).
- `PostTransactions` in symmetry to `PreInherents`, this one is called
before `on_finalize` but after all transactions.
A sane default is to set all of these to `()`. Example diff suitable for
any chain:
```patch
@@ impl frame_system::Config for Test {
type MaxConsumers = ConstU32<16>;
+ type SingleBlockMigrations = ();
+ type MultiBlockMigrator = ();
+ type PreInherents = ();
+ type PostInherents = ();
+ type PostTransactions = ();
}
```
An overview of how the block execution now looks like is here. The same
graph is also in the rust doc.
<details><summary>Block Execution Flow</summary>
<p>
</p>
</details>
## Inherent Order
Moved to https://github.com/paritytech/polkadot-sdk/pull/2154
---------------
## TODO
- [ ] Check that `try-runtime` still works
- [ ] Ensure backwards compatibility with old Runtime APIs
- [x] Consume weight correctly
- [x] Cleanup
---------
Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>
Co-authored-by: Liam Aharon <liam.aharon@hotmail.com>
Co-authored-by: Juan Girini <juangirini@gmail.com>
Co-authored-by: command-bot <>
Co-authored-by: Francisco Aguirre <franciscoaguirreperez@gmail.com>
Co-authored-by: Gavin Wood <gavin@parity.io>
Co-authored-by: Bastian Köcher <git@kchr.de>
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!>
- Adds a test to check the correct digest for Snowbridge outbound
messages. For the correct digest to be in the block, the the
MessageQueue pallet should be configured after the EthereumOutbound
queue pallet. The added test fails if the EthereumOutbound is configured
after the MessageQueue pallet.
- Adds a helper method `run_to_block_with_finalize` to simulate the
block finalizing. The existing `run_to_block` method does not finalize
and so it cannot successfully test this condition.
Closes: https://github.com/paritytech/polkadot-sdk/issues/3208
---------
Co-authored-by: claravanstaden <Cats 4 life!>
Changes (partial https://github.com/paritytech/polkadot-sdk/issues/994):
- Set log to `0.4.20` everywhere
- Lift `log` to the workspace
Starting with a simpler one after seeing
https://github.com/paritytech/polkadot-sdk/pull/2065 from @jsdw.
This sets the `default-features` to `false` in the root and then
overwrites that in each create to its original value. This is necessary
since otherwise the `default` features are additive and its impossible
to disable them in the crate again once they are enabled in the
workspace.
I am using a tool to do this, so its mostly a test to see that it works
as expected.
---------
Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>
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