XcmPaymentApi::query_weight_to_asset_fee simple common impl by mrshiposha · Pull Request #8281 · paritytech/polkadot-sdk

mrshiposha · 2025-04-18T09:34:22Z

Description

Add a common implementation for XcmPaymentApi::query_weight_to_asset_fee to pallet-xcm.

This PR is a simple alternative to #8202 (which could still be useful for other reasons).
It uses a workaround instead of a big refactoring.

The workaround is:
Computes the weight cost using the provided WeightTrader.
This function is supposed to be used ONLY in XcmPaymentApi::query_weight_to_asset_fee
Runtime API implementation, as it can introduce a massive change to the total issuance.
The provided WeightTrader must be the same as the one used in the XcmExecutor to ensure
uniformity in the weight cost calculation.

NOTE: Currently this function uses a workaround that should be good enough for all practical
uses: passes u128::MAX / 2 == 2^127 of the specified asset to the WeightTrader as
payment and computes the weight cost as the difference between this and the unspent amount.
Some weight traders could add the provided payment to some account's balance. However,
it should practically never result in overflow because even currencies with a lot of decimal digits
(say 18) usually have the total issuance of billions (x * 10^9) or trillions (x * 10^12) at max,
much less than 2^127 / 10^18 =~ 1.7 * 10^20 (170 billion billion). Thus, any account's balance
most likely holds less than 2^127, so adding 2^127 won't result in u128 overflow.

Integration

The Runtime builders can use the query_weight_to_asset_fee provided by pallet-xcm in
their XcmPaymentApi implementation.

mrshiposha · 2025-04-18T09:34:48Z

CC @acatangiu

acatangiu

I like the approach - using the Trader directly is the right way to go 👍

polkadot/xcm/pallet-xcm/src/lib.rs

acatangiu

Looks good! cc @franciscoaguirre to also have a look, but I think you can go ahead with fully implementing the PR.

polkadot/xcm/pallet-xcm/src/lib.rs

acatangiu

I tested the workaround locally using Westend Asset Hub. Is there a proper way to unit-test this?

Yes, I would add following tests:

generic test here using native DOT/KSM that can be called for all runtimes in their local unit-tests (e.g. here)
Asset Hub Westend unit test here that sets up a few pools then validates this call against a few assets (that have pools)

notes:

there is already a helper function available for setting up pools in the tests

polkadot/xcm/pallet-xcm/src/lib.rs

prdoc/pr_8281.prdoc

Co-authored-by: Adrian Catangiu <adrian@parity.io>

cumulus/parachains/runtimes/assets/asset-hub-rococo/tests/tests.rs

prdoc/pr_8281.prdoc

Co-authored-by: Adrian Catangiu <adrian@parity.io>

acatangiu · 2025-05-02T11:20:18Z

TRY 6 FAIL [ 0.209s] asset-hub-westend-integration-tests tests::swap::xcm_fee_querying_apis_work

some tests are failing

polkadot/xcm/pallet-xcm/src/lib.rs

acatangiu · 2025-05-05T14:19:02Z

cumulus/parachains/integration-tests/emulated/common/src/macros.rs

-				// We just created it, there's none.
-				assert_eq!(fee_in_usdt_fail, Err(XcmPaymentApiError::AssetNotFound));
+
+				// USDT is sufficient asset, so it passes even if there is not enough liquidity yet.


Since #8376 was merged recently, sufficient assets can no longer directly buy weight and also have to go through liquidity pool to work.

I'll revert this commit then. Merging master should fix the tests instead

acatangiu · 2025-05-05T14:19:45Z

also needs rebase and conflicts to resolve

This reverts commit 3bcd52e.

# Description Add a common implementation for `XcmPaymentApi::query_weight_to_asset_fee` to `pallet-xcm`. This PR is a simple alternative to #8202 (which could still be useful for other reasons). It uses a workaround instead of a big refactoring. The workaround is: Computes the weight cost using the provided `WeightTrader`. This function is supposed to be used ONLY in `XcmPaymentApi::query_weight_to_asset_fee` Runtime API implementation, as it can introduce a massive change to the total issuance. The provided `WeightTrader` must be the same as the one used in the XcmExecutor to ensure uniformity in the weight cost calculation. NOTE: Currently this function uses a workaround that should be good enough for all practical uses: passes `u128::MAX / 2 == 2^127` of the specified asset to the `WeightTrader` as payment and computes the weight cost as the difference between this and the unspent amount. Some weight traders could add the provided payment to some account's balance. However, it should practically never result in overflow because even currencies with a lot of decimal digits (say 18) usually have the total issuance of billions (`x * 10^9`) or trillions (`x * 10^12`) at max, much less than `2^127 / 10^18 =~ 1.7 * 10^20` (170 billion billion). Thus, any account's balance most likely holds less than `2^127`, so adding `2^127` won't result in `u128` overflow. ## Integration The Runtime builders can use the `query_weight_to_asset_fee` provided by `pallet-xcm` in their XcmPaymentApi implementation. --------- Co-authored-by: Adrian Catangiu <adrian@parity.io>

@kianenigma

This brings in `stable2506` Polkadot SDK, and integrates many new features. Integrated breaking changes to be verified by the original authors: - [x] ~paritytech/polkadot-sdk#8127 @kianenigma @Ank4n~ This will come in with AHM, and not before. - [x] paritytech/polkadot-sdk#7597 @gui1117 - [x] paritytech/polkadot-sdk#8254 @bkchr - [x] paritytech/polkadot-sdk#7592 @bkontur - [x] paritytech/polkadot-sdk#8382 @UtkarshBhardwaj007 - [x] paritytech/polkadot-sdk#8021 @serban300 - [x] paritytech/polkadot-sdk#8344 @serban300 - [x] paritytech/polkadot-sdk#8262 @athei - [x] paritytech/polkadot-sdk#8584 @athei - [x] paritytech/polkadot-sdk#8299 @skunert - [x] paritytech/polkadot-sdk#8652 @pgherveou - [x] paritytech/polkadot-sdk#8554 @pgherveou - [x] paritytech/polkadot-sdk#8281 @mrshiposha - [x] paritytech/polkadot-sdk#7730 @franciscoaguirre - [x] paritytech/polkadot-sdk#8599 @yrong @claravanstaden - [x] paritytech/polkadot-sdk#8531 @bkontur - [x] paritytech/polkadot-sdk#8409 @kianenigma - [x] paritytech/polkadot-sdk#9137 @franciscoaguirre - [x] paritytech/polkadot-sdk#7944 @bkontur - [x] paritytech/polkadot-sdk#8179 @bkontur - [x] paritytech/polkadot-sdk#8037 @yrong --------- Co-authored-by: GitHub Action <action@github.com> Co-authored-by: claravanstaden <claravanstaden64@gmail.com> Co-authored-by: Branislav Kontur <bkontur@gmail.com> Co-authored-by: Bastian Köcher <git@kchr.de> Co-authored-by: Alain Brenzikofer <alain@integritee.network> Co-authored-by: kianenigma <kian@parity.io> Co-authored-by: Francisco Aguirre <franciscoaguirreperez@gmail.com> Co-authored-by: ron <yrong1997@gmail.com> Co-authored-by: joe petrowski <25483142+joepetrowski@users.noreply.github.com> Co-authored-by: Overkillus <maciej.zyszkiewicz@parity.io>

# Description Add a common implementation for `XcmPaymentApi::query_weight_to_asset_fee` to `pallet-xcm`. This PR is a simple alternative to #8202 (which could still be useful for other reasons). It uses a workaround instead of a big refactoring. The workaround is: Computes the weight cost using the provided `WeightTrader`. This function is supposed to be used ONLY in `XcmPaymentApi::query_weight_to_asset_fee` Runtime API implementation, as it can introduce a massive change to the total issuance. The provided `WeightTrader` must be the same as the one used in the XcmExecutor to ensure uniformity in the weight cost calculation. NOTE: Currently this function uses a workaround that should be good enough for all practical uses: passes `u128::MAX / 2 == 2^127` of the specified asset to the `WeightTrader` as payment and computes the weight cost as the difference between this and the unspent amount. Some weight traders could add the provided payment to some account's balance. However, it should practically never result in overflow because even currencies with a lot of decimal digits (say 18) usually have the total issuance of billions (`x * 10^9`) or trillions (`x * 10^12`) at max, much less than `2^127 / 10^18 =~ 1.7 * 10^20` (170 billion billion). Thus, any account's balance most likely holds less than `2^127`, so adding `2^127` won't result in `u128` overflow. ## Integration The Runtime builders can use the `query_weight_to_asset_fee` provided by `pallet-xcm` in their XcmPaymentApi implementation. --------- Co-authored-by: Adrian Catangiu <adrian@parity.io>

workaround: weight to selected currency fee Runtime API common impl

8096676

mrshiposha changed the title ~~workaround: XcmPaymentApi::query_weight_to_asset_fee common impl~~ workaround: XcmPaymentApi::query_weight_to_asset_fee simple common impl Apr 18, 2025

acatangiu reviewed Apr 18, 2025

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polkadot/xcm/pallet-xcm/src/lib.rs Outdated Show resolved Hide resolved

fix: use with_transaction to compute weight cost

3d30d31

acatangiu reviewed Apr 18, 2025

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polkadot/xcm/pallet-xcm/src/lib.rs Outdated Show resolved Hide resolved

mrshiposha added 3 commits April 18, 2025 19:55

fix: create trader under transaction

6ddc956

feat: use common query_weight_to_asset_fee impl in all chains

a97ad8f

chore: add prdoc

7d49bf2

mrshiposha marked this pull request as ready for review April 21, 2025 15:09

mrshiposha requested a review from a team as a code owner April 21, 2025 15:09

acatangiu changed the title ~~workaround: XcmPaymentApi::query_weight_to_asset_fee simple common impl~~ XcmPaymentApi::query_weight_to_asset_fee simple common impl Apr 23, 2025

acatangiu reviewed Apr 23, 2025

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polkadot/xcm/pallet-xcm/src/lib.rs Outdated Show resolved Hide resolved

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mrshiposha and others added 5 commits April 28, 2025 13:54

Update polkadot/xcm/pallet-xcm/src/lib.rs

12801c5

Co-authored-by: Adrian Catangiu <adrian@parity.io>

Update prdoc/pr_8281.prdoc

34a4765

Co-authored-by: Adrian Catangiu <adrian@parity.io>

test(XcmPaymentApi): check computed weight fee (native + in-pool)

d66524c

test(XcmPaymentApi): check computed weight foreign asset fee

a901399

test: query_weight_to_asset_fee storage noop

2bb0a7a

acatangiu approved these changes Apr 29, 2025

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cumulus/parachains/runtimes/assets/asset-hub-rococo/tests/tests.rs Outdated Show resolved Hide resolved

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mrshiposha and others added 3 commits April 29, 2025 15:50

Update prdoc/pr_8281.prdoc

4cd5e5d

Co-authored-by: Adrian Catangiu <adrian@parity.io>

refactor: move common test stuff to asset_test_utils

1a0521f

fix: clippy

4c574eb

acatangiu approved these changes May 2, 2025

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franciscoaguirre approved these changes May 2, 2025

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x3c41a approved these changes May 5, 2025

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mrshiposha added 3 commits May 5, 2025 16:07

fix: integration tests

3bcd52e

fix: restore usage comment

1d628c2

Merge branch 'master' into workaround/weight-to-fee-common-impl

c2d25a6

acatangiu reviewed May 5, 2025

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mrshiposha added 2 commits May 5, 2025 16:49

fix: after master merge

04b6d30

Revert "fix: integration tests"

920ba3a

This reverts commit 3bcd52e.

acatangiu approved these changes May 6, 2025

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acatangiu added this pull request to the merge queue May 6, 2025

github-merge-queue bot removed this pull request from the merge queue due to failed status checks May 6, 2025

acatangiu added this pull request to the merge queue May 6, 2025

Merged via the queue into paritytech:master with commit 5802306 May 6, 2025
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al3mart mentioned this pull request May 6, 2025

refactor: consider using common impl of XcmPaymentApi::query_weight_to_asset_fee in runtimes. r0gue-io/pop-node#560

Open

acatangiu mentioned this pull request Jul 16, 2025

Upgrade to Polkadot-SDK stable2506 polkadot-fellows/runtimes#817

Merged

21 tasks

franciscoaguirre mentioned this pull request Jul 28, 2025

Add the common query_weight_to_asset_fee for relays acatangiu/runtimes#8

Merged

franciscoaguirre mentioned this pull request Sep 22, 2025

update XcmPaymentApi query_delivery_fees to return the fee based on V… #8297

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pgherveou added this to [preview] release tracker Mar 23, 2026

github-project-automation bot moved this to Done in [preview] release tracker Mar 23, 2026

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