Keith Yeung
3dece311be
Combination of paritytech/polkadot#7005, its addon PR paritytech/polkadot#7585 and its companion paritytech/cumulus#2433. This PR introduces a new XcmFeesToAccount struct which implements the `FeeManager` trait, and assigns this struct as the `FeeManager` in the XCM config for all runtimes. The struct simply deposits all fees handled by the XCM executor to a specified account. In all runtimes, the specified account is configured as the treasury account. XCM __delivery__ fees are now being introduced (unless the root origin is sending a message to a system parachain on behalf of the originating chain). # Note for reviewers Most file changes are tests that had to be modified to account for the new fees. Main changes are in: - cumulus/pallets/xcmp-queue/src/lib.rs <- To make it track the delivery fees exponential factor - polkadot/xcm/xcm-builder/src/fee_handling.rs <- Added. Has the FeeManager implementation - All runtime xcm_config files <- To add the FeeManager to the XCM configuration # Important note After this change, instructions that create and send a new XCM (Query*, Report*, ExportMessage, InitiateReserveWithdraw, InitiateTeleport, DepositReserveAsset, TransferReserveAsset, LockAsset and RequestUnlock) will require the corresponding origin account in the origin register to pay for transport delivery fees, and the onward message will fail to be sent if the origin account does not have the required amount. This delivery fee is on top of what we already collect as tx fees in pallet-xcm and XCM BuyExecution fees! Wallet UIs that want to expose the new delivery fee can do so using the formula: ``` delivery_fee_factor * (base_fee + encoded_msg_len * per_byte_fee) ``` where the delivery fee factor can be obtained from the corresponding pallet based on which transport you are using (UMP, HRMP or bridges), the base fee is a constant, the encoded message length from the message itself and the per byte fee is the same as the configured per byte fee for txs (i.e. `TransactionByteFee`). --------- Co-authored-by: Branislav Kontur <bkontur@gmail.com> Co-authored-by: joe petrowski <25483142+joepetrowski@users.noreply.github.com> Co-authored-by: Giles Cope <gilescope@gmail.com> Co-authored-by: command-bot <> Co-authored-by: Francisco Aguirre <franciscoaguirreperez@gmail.com> Co-authored-by: Liam Aharon <liam.aharon@hotmail.com> Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>
xcm-emulator
XCM-Emulator is a tool to emulate XCM program execution using pre-configured runtimes, including those used to run on live networks, such as Kusama, Polkadot, Asset Hubs, et cetera. This allows for testing cross-chain message passing and verifying outcomes, weights, and side-effects. It is faster than spinning up a zombienet and as all the chains are in one process debugging using Clion is easy.
Limitations
As the messages do not physically go through the same messaging infrastructure there is some code that is not being tested compared to using slower E2E tests. In future it may be possible to run these XCM emulated tests as E2E tests (without changes).
As well as the XCM message transport being mocked out, so too are areas around consensus, in particular things like disputes, staking and iamonline events can't be tested.
Alternatives
If you just wish to test execution of various XCM instructions
against the XCM VM then the xcm-simulator (in the Polkadot
repo) is the perfect tool for this.