Message Queue as DMP and XCMP dispatch queue (#1246)
(imported from https://github.com/paritytech/cumulus/pull/2157) ## Changes This MR refactores the XCMP, Parachains System and DMP pallets to use the [MessageQueue](https://github.com/paritytech/substrate/pull/12485) for delayed execution of incoming messages. The DMP pallet is entirely replaced by the MQ and thereby removed. This allows for PoV-bounded execution and resolves a number of issues that stem from the current work-around. All System Parachains adopt this change. The most important changes are in `primitives/core/src/lib.rs`, `parachains/common/src/process_xcm_message.rs`, `pallets/parachain-system/src/lib.rs`, `pallets/xcmp-queue/src/lib.rs` and the runtime configs. ### DMP Queue Pallet The pallet got removed and its logic refactored into parachain-system. Overweight message management can be done directly through the MQ pallet. Final undeployment migrations are provided by `cumulus_pallet_dmp_queue::UndeployDmpQueue` and `DeleteDmpQueue` that can be configured with an aux config trait like: ```rust parameter_types! { pub const DmpQueuePalletName: &'static str = \"DmpQueue\" < CHANGE ME; pub const RelayOrigin: AggregateMessageOrigin = AggregateMessageOrigin::Parent; } impl cumulus_pallet_dmp_queue::MigrationConfig for Runtime { type PalletName = DmpQueuePalletName; type DmpHandler = frame_support::traits::EnqueueWithOrigin<MessageQueue, RelayOrigin>; type DbWeight = <Runtime as frame_system::Config>::DbWeight; } // And adding them to your Migrations tuple: pub type Migrations = ( ... cumulus_pallet_dmp_queue::UndeployDmpQueue<Runtime>, cumulus_pallet_dmp_queue::DeleteDmpQueue<Runtime>, ); ``` ### XCMP Queue pallet Removed all dispatch queue functionality. Incoming XCMP messages are now either: Immediately handled if they are Signals, enqueued into the MQ pallet otherwise. New config items for the XCMP queue pallet: ```rust /// The actual queue implementation that retains the messages for later processing. type XcmpQueue: EnqueueMessage<ParaId>; /// How a XCM over HRMP from a sibling parachain should be processed. type XcmpProcessor: ProcessMessage<Origin = ParaId>; /// The maximal number of suspended XCMP channels at the same time. #[pallet::constant] type MaxInboundSuspended: Get<u32>; ``` How to configure those: ```rust // Use the MessageQueue pallet to store messages for later processing. The `TransformOrigin` is needed since // the MQ pallet itself operators on `AggregateMessageOrigin` but we want to enqueue `ParaId`s. type XcmpQueue = TransformOrigin<MessageQueue, AggregateMessageOrigin, ParaId, ParaIdToSibling>; // Process XCMP messages from siblings. This is type-safe to only accept `ParaId`s. They will be dispatched // with origin `Junction::Sibling(…)`. type XcmpProcessor = ProcessFromSibling< ProcessXcmMessage< AggregateMessageOrigin, xcm_executor::XcmExecutor<xcm_config::XcmConfig>, RuntimeCall, >, >; // Not really important what to choose here. Just something larger than the maximal number of channels. type MaxInboundSuspended = sp_core::ConstU32<1_000>; ``` The `InboundXcmpStatus` storage item was replaced by `InboundXcmpSuspended` since it now only tracks inbound queue suspension and no message indices anymore. Now only sends the most recent channel `Signals`, as all prio ones are out-dated anyway. ### Parachain System pallet For `DMP` messages instead of forwarding them to the `DMP` pallet, it now pushes them to the configured `DmpQueue`. The message processing which was triggered in `set_validation_data` is now being done by the MQ pallet `on_initialize`. XCMP messages are still handed off to the `XcmpMessageHandler` (XCMP-Queue pallet) - no change here. New config items for the parachain system pallet: ```rust /// Queues inbound downward messages for delayed processing. /// /// Analogous to the `XcmpQueue` of the XCMP queue pallet. type DmpQueue: EnqueueMessage<AggregateMessageOrigin>; ``` How to configure: ```rust /// Use the MQ pallet to store DMP messages for delayed processing. type DmpQueue = MessageQueue; ``` ## Message Flow The flow of messages on the parachain side. Messages come in from the left via the `Validation Data` and finally end up at the `Xcm Executor` on the right.  ## Further changes - Bumped the default suspension, drop and resume thresholds in `QueueConfigData::default()`. - `XcmpQueue::{suspend_xcm_execution, resume_xcm_execution}` errors when they would be a noop. - Properly validate the `QueueConfigData` before setting it. - Marked weight files as auto-generated so they wont auto-expand in the MR files view. - Move the `hypothetical` asserts to `frame_support` under the name `experimental_hypothetically` Questions: - [ ] What about the ugly `#[cfg(feature = \"runtime-benchmarks\")]` in the runtimes? Not sure how to best fix. Just having them like this makes tests fail that rely on the real message processor when the feature is enabled. - [ ] Need a good weight for `MessageQueueServiceWeight`. The scheduler already takes 80% so I put it to 10% but that is quite low. TODO: - [x] Remove c&p code after https://github.com/paritytech/polkadot/pull/6271 - [x] Use `HandleMessage` once it is public in Substrate - [x] fix `runtime-benchmarks` feature https://github.com/paritytech/polkadot/pull/6966 - [x] Benchmarks - [x] Tests - [ ] Migrate `InboundXcmpStatus` to `InboundXcmpSuspended` - [x] Possibly cleanup Migrations (DMP+XCMP) - [x] optional: create `TransformProcessMessageOrigin` in Substrate and replace `ProcessFromSibling` - [ ] Rerun weights on ref HW --------- Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> Co-authored-by: Liam Aharon <liam.aharon@hotmail.com> Co-authored-by: joe petrowski <25483142+joepetrowski@users.noreply.github.com> Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com> Co-authored-by: command-bot <>
NOTE: We have recently made significant changes to our repository structure. In order to streamline our development process and foster better contributions, we have merged three separate repositories Cumulus, Substrate and Polkadot into this repository. Read more about the changes here.
Polkadot SDK
The Polkadot SDK repository provides all the resources needed to start building on the Polkadot network, a multi-chain blockchain platform that enables different blockchains to interoperate and share information in a secure and scalable way. The Polkadot SDK comprises three main pieces of software:
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Implementation of a node for the https://polkadot.network in Rust, using the Substrate framework. This directory
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Substrate is the primary blockchain SDK used by developers to create the parachains that make up the Polkadot network. Additionally, it allows for the development of self-sovereign blockchains that operate completely independently of Polkadot.
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