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Free finalized Ethereum updates #159

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merged 14 commits into from
Jul 31, 2024
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@claravanstaden claravanstaden commented Jul 18, 2024

Allows free Ethereum finalized header updates if they larger or equal to the last interval within a certain interval.

  • Adds pallet config FreeHeadersInterval, to be set to 32.
  • All beacon headers equal to or more than 32 slots newer than the latest imported header will be free.
  • All valid sync committee updates are free.
  • Any extrinsic resulting in an error condition will be a paid transaction.

Resolves: https://linear.app/snowfork/issue/SNO-1053

@claravanstaden claravanstaden marked this pull request as ready for review July 18, 2024 18:38
@@ -281,10 +285,9 @@ pub mod pallet {
Ok(())
}

pub(crate) fn process_update(update: &Update) -> DispatchResult {
pub(crate) fn process_update(update: &Update) -> DispatchResultWithPostInfo {

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Non-blocking: Do you think this function is even necessary?

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Lol maybe not! I think its just to much the Ethereum consensus spec, which has a pattern of a "process" method, that does a "verify" and an "apply".

// If free headers are allowed and the latest finalized header is larger than the
// minimum slot interval, the header import transaction is free.
if let Some(free_headers_interval) = T::FreeHeadersInterval::get() {
if improved_by_slot >= latest_slot + free_headers_interval as u64 {

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So this is basically saying you get a free update if the update is far enough in the future?

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Yeah, seems follow the same pattern for the P->K bridge here with free update at a minimal interval.

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Exactly. It will be set to every 32 slots (so basically all the finalized updates), but if we ever need to make it less frequent we can.

@yrong
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yrong commented Jul 29, 2024

Maybe we can add a runtime test checking the balance of the relayer before and after the extrinsic, make sure that there is no fee charged actually.

IIUC set pays_fee flag to false does not mean it won't charge for the extrinsic, just the fee will be refunded to the caller. But I may not wrong here.

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+1

@claravanstaden
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Maybe we can add a runtime test checking the balance of the relayer before and after the extrinsic, make sure that there is no fee charged actually.

IIUC set pays_fee flag to false does not mean it won't charge for the extrinsic, just the fee will be refunded to the caller. But I may not wrong here.

@yrong that's a great suggestion, thanks. Added in c82647f.

@@ -83,6 +86,8 @@ pub mod pallet {
type RuntimeEvent: From<Event<Self>> + IsType<<Self as frame_system::Config>::RuntimeEvent>;
#[pallet::constant]
type ForkVersions: Get<ForkVersions>;
#[pallet::constant]
type FreeHeadersInterval: Get<Option<u32>>;
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Why does this need to be optional? Can't we just make free headers the default?

Comment on lines 670 to 672
if sync_committee_updated {
return Pays::No;
}
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This effectively is just returning the parameter of sync_committee_updated of mapped to Pays, which seems redundant.

And given my other comment above, I would advise restructuring as follows:

fn check_refundable(update: &Update, latest_slot: u64) -> Pays

@@ -464,13 +469,24 @@ pub mod pallet {
Self::deposit_event(Event::SyncCommitteeUpdated {
period: update_finalized_period,
});
sync_committee_updated = true;
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This sync_committee_updated flag seems redundant. Following the code, when sync_committee_updated=True, it follows that update.next_sync_committee_update == Some(...)

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@vgeddes thanks for the suggestions, fixed in e3281f8.

@claravanstaden claravanstaden requested a review from vgeddes July 30, 2024 18:13
@claravanstaden claravanstaden merged commit c7cbd99 into snowbridge Jul 31, 2024
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@claravanstaden claravanstaden deleted the free-finalized-updates branch July 31, 2024 12:30
claravanstaden added a commit that referenced this pull request Jul 31, 2024
* free finalized updates

* update comment

* fix check

* fixes

* tests

* fixes

* fmt

* finishing touches

* comments

* adds missing impl

* adds test

* fixes

* fix
github-merge-queue bot pushed a commit to paritytech/polkadot-sdk that referenced this pull request Sep 2, 2024
Allow free Snowbridge consensus updates, if the header interval is
larger than the configured value (set to 32, so once a epoch).

This PR also moves the Rococo Snowbridge pallet config into its own
module.

Original PR: Snowfork#159

---------

Co-authored-by: Francisco Aguirre <franciscoaguirreperez@gmail.com>
acatangiu pushed a commit to acatangiu/polkadot-sdk that referenced this pull request Sep 3, 2024
Allow free Snowbridge consensus updates, if the header interval is
larger than the configured value (set to 32, so once a epoch).

This PR also moves the Rococo Snowbridge pallet config into its own
module.

Original PR: Snowfork#159

---------

Co-authored-by: Francisco Aguirre <franciscoaguirreperez@gmail.com>
acatangiu added a commit to paritytech/polkadot-sdk that referenced this pull request Sep 3, 2024
Allow free Snowbridge consensus updates, if the header interval is
larger than the configured value (set to 32, so once a epoch).

This PR also moves the Rococo Snowbridge pallet config into its own
module.

Original PR: Snowfork#159

----------

Original `pr_5201.prdoc` is present but moved to release dir, ergo
`R0-Silent` for this backport PR.

---------

Co-authored-by: Clara van Staden <claravanstaden64@gmail.com>
Co-authored-by: Francisco Aguirre <franciscoaguirreperez@gmail.com>
x3c41a pushed a commit to paritytech/polkadot-sdk that referenced this pull request Sep 4, 2024
Allow free Snowbridge consensus updates, if the header interval is
larger than the configured value (set to 32, so once a epoch).

This PR also moves the Rococo Snowbridge pallet config into its own
module.

Original PR: Snowfork#159

---------

Co-authored-by: Francisco Aguirre <franciscoaguirreperez@gmail.com>
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4 participants