Oliver Tale-Yazdi
e1c033ebe1
(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 <>
Cumulus ☁️
This repository contains both the Cumulus SDK and also specific chains implemented on top of this SDK.
If you only want to run a Polkadot Parachain Node, check out our container section.
Cumulus SDK
A set of tools for writing Substrate-based Polkadot parachains. Refer to the included overview for architectural details, and the Connect to a relay chain how-to guide for a guided walk-through of using these tools.
It's easy to write blockchains using Substrate, and the overhead of writing parachains' distribution, p2p, database, and synchronization layers should be just as low. This project aims to make it easy to write parachains for Polkadot by leveraging the power of Substrate.
Cumulus clouds are shaped sort of like dots; together they form a system that is intricate, beautiful and functional.
Consensus
parachain-consensus
is a consensus engine for Substrate that follows a Polkadot relay
chain. This will run a Polkadot node internally,
and dictate to the client and synchronization algorithms which chain to follow,
finalize, and treat as best.
Collator
A Polkadot collator for the parachain is implemented by the
polkadot-parachain binary (previously called polkadot-collator).
You may run polkadot-parachain locally after building it or using one of the container option described
here.
Relay Chain Interaction
To operate a parachain node, a connection to the corresponding relay chain is necessary. This can be achieved in one of three ways:
- Run a full relay chain node within the parachain node (default)
- Connect to an external relay chain node via WebSocket RPC
- Run a light client for the relay chain
In-process Relay Chain Node
If an external relay chain node is not specified (default behavior), then a full relay chain node is spawned within the same process.
This node has all of the typical components of a regular Polkadot node and will have to fully sync with the relay chain to work.
Example command
polkadot-parachain \
--chain parachain-chainspec.json \
--tmp \
-- \
--chain relaychain-chainspec.json
External Relay Chain Node
An external relay chain node is connected via WebsSocket RPC by using the --relay-chain-rpc-urls command line
argument. This option accepts one or more space-separated WebSocket URLs to a full relay chain node. By default, only
the first URL will be used, with the rest as a backup in case the connection to the first node is lost.
Parachain nodes using this feature won't have to fully sync with the relay chain to work, so in general they will use fewer system resources.
Note: At this time, any parachain nodes using this feature will still spawn a significantly cut-down relay chain node in-process. Even though they lack the majority of normal Polkadot subsystems, they will still need to connect directly to the relay chain network.
Example command
polkadot-parachain \
--chain parachain-chainspec.json \
--tmp \
--relay-chain-rpc-urls \
"ws://relaychain-rpc-endpoint:9944" \
"ws://relaychain-rpc-endpoint-backup:9944" \
-- \
--chain relaychain-chainspec.json
Relay Chain Light Client
An internal relay chain light client provides a fast and lightweight approach for connecting to the relay chain network. It provides relay chain notifications and facilitates runtime calls.
To specify which chain the light client should connect to, users need to supply a relay chain chain-spec as part of the relay chain arguments.
Note: At this time, any parachain nodes using this feature will still spawn a significantly cut-down relay chain node in-process. Even though they lack the majority of normal Polkadot subsystems, they will still need to connect directly to the relay chain network.
Example command
polkadot-parachain \
--chain parachain-chainspec.json \
--tmp \
--relay-chain-light-client \
-- \
--chain relaychain-chainspec.json
Installation and Setup
Before building Cumulus SDK based nodes / runtimes prepare your environment by following Substrate installation instructions.
To launch a local network, you can use zombienet for quick setup and experimentation or follow the manual setup.
Zombienet
We use Zombienet to spin up networks for integration tests and local networks. Follow these installation steps to set it up on your machine. A simple network specification with two relay chain nodes and one collator is located at zombienet/examples/small_network.toml.
Which provider should I use?
Zombienet offers multiple providers to run networks. Choose the one that best fits your needs:
- Podman: Choose this if you want to spin up a network quick and easy.
- Native: Choose this if you want to develop and deploy your changes. Requires compilation of the binaries.
- Kubernetes: Choose this for advanced use-cases or running on cloud-infrastructure.
How to run
To run the example network, use the following commands:
# Podman provider
zombienet --provider podman spawn ./zombienet/examples/small_network.toml
# Native provider, assumes polkadot and polkadot-parachains binary in $PATH
zombienet --provider native spawn ./zombienet/examples/small_network.toml
Manual Setup
Launch the Relay Chain
# Clone
git clone https://github.com/paritytech/polkadot-sdk
# Compile Polkadot
cargo build --release --bin polkadot
# Generate a raw chain spec
./target/release/polkadot build-spec --chain rococo-local --disable-default-bootnode --raw > rococo-local-cfde.json
# Alice
./target/release/polkadot --chain rococo-local-cfde.json --alice --tmp
# Bob (In a separate terminal)
./target/release/polkadot --chain rococo-local-cfde.json --bob --tmp --port 30334
Launch the Parachain
# Clone
git clone https://github.com/paritytech/polkadot-sdk
# Compile
cargo build --release --bin polkadot-parachain
# Export genesis state
./target/release/polkadot-parachain export-genesis-state > genesis-state
# Export genesis wasm
./target/release/polkadot-parachain export-genesis-wasm > genesis-wasm
# Collator1
./target/release/polkadot-parachain --collator --alice --force-authoring \
--tmp --port 40335 --rpc-port 9946 -- --chain ../polkadot/rococo-local-cfde.json --port 30335
# Collator2
./target/release/polkadot-parachain --collator --bob --force-authoring \
--tmp --port 40336 --rpc-port 9947 -- --chain ../polkadot/rococo-local-cfde.json --port 30336
# Parachain Full Node 1
./target/release/polkadot-parachain --tmp --port 40337 --rpc-port 9948 -- \
--chain ../polkadot/rococo-local-cfde.json --port 30337
Register the parachain
Asset Hub 🪙
This repository also contains the Asset Hub runtimes. Asset Hub is a system parachain providing an asset store for the Polkadot ecosystem.
Build & Launch a Node
To run an Asset Hub node, you will need to compile the polkadot-parachain binary:
cargo build --release --locked --bin polkadot-parachain
Once the executable is built, launch the parachain node via:
CHAIN=asset-hub-westend # or asset-hub-kusama
./target/release/polkadot-parachain --chain $CHAIN
Refer to the setup instructions to run a local network for development.
Contracts 📝
See the contracts-rococo readme for details.
Bridge-hub 📝
See the bridge-hubs readme for details.
Rococo 👑
Rococo is becoming a Community Parachain Testbed for parachain teams in the Polkadot ecosystem. It supports multiple parachains with the differentiation of long-term connections and recurring short-term connections, to see which parachains are currently connected and how long they will be connected for see here.
Rococo is an elaborate style of design and the name describes the painstaking effort that has gone into this project.
Build & Launch Rococo Collators
Collators are similar to validators in the relay chain. These nodes build the blocks that will eventually be included by the relay chain for a parachain.
To run a Rococo collator you will need to compile the following binary:
cargo build --release --locked --bin polkadot-parachain
Once the executable is built, launch collators for each parachain (repeat once each for chain tick, trick, track):
./target/release/polkadot-parachain --chain $CHAIN --validator
You can also build using a container.
Parachains
The network uses horizontal message passing (HRMP) to enable communication between parachains and the relay chain and, in turn, between parachains. This means that every message is sent to the relay chain, and from the relay chain to its destination parachain.