Oliver Tale-Yazdi
eefd5fe449
This MR is the merge of https://github.com/paritytech/substrate/pull/14414 and https://github.com/paritytech/substrate/pull/14275. It implements [RFC#13](https://github.com/polkadot-fellows/RFCs/pull/13), closes https://github.com/paritytech/polkadot-sdk/issues/198. ----- This Merge request introduces three major topicals: 1. Multi-Block-Migrations 1. New pallet `poll` hook for periodic service work 1. Replacement hooks for `on_initialize` and `on_finalize` in cases where `poll` cannot be used and some more general changes to FRAME. The changes for each topical span over multiple crates. They are listed in topical order below. # 1.) Multi-Block-Migrations Multi-Block-Migrations are facilitated by creating `pallet_migrations` and configuring `System::Config::MultiBlockMigrator` to point to it. Executive picks this up and triggers one step of the migrations pallet per block. The chain is in lockdown mode for as long as an MBM is ongoing. Executive does this by polling `MultiBlockMigrator::ongoing` and not allowing any transaction in a block, if true. A MBM is defined through trait `SteppedMigration`. A condensed version looks like this: ```rust /// A migration that can proceed in multiple steps. pub trait SteppedMigration { type Cursor: FullCodec + MaxEncodedLen; type Identifier: FullCodec + MaxEncodedLen; fn id() -> Self::Identifier; fn max_steps() -> Option<u32>; fn step( cursor: Option<Self::Cursor>, meter: &mut WeightMeter, ) -> Result<Option<Self::Cursor>, SteppedMigrationError>; } ``` `pallet_migrations` can be configured with an aggregated tuple of these migrations. It then starts to migrate them one-by-one on the next runtime upgrade. Two things are important here: - 1. Doing another runtime upgrade while MBMs are ongoing is not a good idea and can lead to messed up state. - 2. **Pallet Migrations MUST BE CONFIGURED IN `System::Config`, otherwise it is not used.** The pallet supports an `UpgradeStatusHandler` that can be used to notify external logic of upgrade start/finish (for example to pause XCM dispatch). Error recovery is very limited in the case that a migration errors or times out (exceeds its `max_steps`). Currently the runtime dev can decide in `FailedMigrationHandler::failed` how to handle this. One follow-up would be to pair this with the `SafeMode` pallet and enact safe mode when an upgrade fails, to allow governance to rescue the chain. This is currently not possible, since governance is not `Mandatory`. ## Runtime API - `Core`: `initialize_block` now returns `ExtrinsicInclusionMode` to inform the Block Author whether they can push transactions. ### Integration Add it to your runtime implementation of `Core` and `BlockBuilder`: ```patch diff --git a/runtime/src/lib.rs b/runtime/src/lib.rs @@ impl_runtime_apis! { impl sp_block_builder::Core<Block> for Runtime { - fn initialize_block(header: &<Block as BlockT>::Header) { + fn initialize_block(header: &<Block as BlockT>::Header) -> RuntimeExecutiveMode { Executive::initialize_block(header) } ... } ``` # 2.) `poll` hook A new pallet hook is introduced: `poll`. `Poll` is intended to replace mostly all usage of `on_initialize`. The reason for this is that any code that can be called from `on_initialize` cannot be migrated through an MBM. Currently there is no way to statically check this; the implication is to use `on_initialize` as rarely as possible. Failing to do so can result in broken storage invariants. The implementation of the poll hook depends on the `Runtime API` changes that are explained above. # 3.) Hard-Deadline callbacks Three new callbacks are introduced and configured on `System::Config`: `PreInherents`, `PostInherents` and `PostTransactions`. These hooks are meant as replacement for `on_initialize` and `on_finalize` in cases where the code that runs cannot be moved to `poll`. The reason for this is to make the usage of HD-code (hard deadline) more explicit - again to prevent broken invariants by MBMs. # 4.) FRAME (general changes) ## `frame_system` pallet A new memorize storage item `InherentsApplied` is added. It is used by executive to track whether inherents have already been applied. Executive and can then execute the MBMs directly between inherents and transactions. The `Config` gets five new items: - `SingleBlockMigrations` this is the new way of configuring migrations that run in a single block. Previously they were defined as last generic argument of `Executive`. This shift is brings all central configuration about migrations closer into view of the developer (migrations that are configured in `Executive` will still work for now but is deprecated). - `MultiBlockMigrator` this can be configured to an engine that drives MBMs. One example would be the `pallet_migrations`. Note that this is only the engine; the exact MBMs are injected into the engine. - `PreInherents` a callback that executes after `on_initialize` but before inherents. - `PostInherents` a callback that executes after all inherents ran (including MBMs and `poll`). - `PostTransactions` in symmetry to `PreInherents`, this one is called before `on_finalize` but after all transactions. A sane default is to set all of these to `()`. Example diff suitable for any chain: ```patch @@ impl frame_system::Config for Test { type MaxConsumers = ConstU32<16>; + type SingleBlockMigrations = (); + type MultiBlockMigrator = (); + type PreInherents = (); + type PostInherents = (); + type PostTransactions = (); } ``` An overview of how the block execution now looks like is here. The same graph is also in the rust doc. <details><summary>Block Execution Flow</summary> <p>  </p> </details> ## Inherent Order Moved to https://github.com/paritytech/polkadot-sdk/pull/2154 --------------- ## TODO - [ ] Check that `try-runtime` still works - [ ] Ensure backwards compatibility with old Runtime APIs - [x] Consume weight correctly - [x] Cleanup --------- Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> Co-authored-by: Liam Aharon <liam.aharon@hotmail.com> Co-authored-by: Juan Girini <juangirini@gmail.com> Co-authored-by: command-bot <> Co-authored-by: Francisco Aguirre <franciscoaguirreperez@gmail.com> Co-authored-by: Gavin Wood <gavin@parity.io> Co-authored-by: Bastian Köcher <git@kchr.de>
Polkadot
Implementation of a https://polkadot.network node in Rust based on the Substrate framework.
The README provides information about installing the polkadot binary and developing on the codebase. For more specific
guides, like how to run a validator node, see the Polkadot Wiki.
Installation
Using a pre-compiled binary
If you just wish to run a Polkadot node without compiling it yourself, you may either:
- run the latest binary from our releases page (make sure to also
download all the
workerbinaries and put them in the same directory aspolkadot), or - install Polkadot from one of our package repositories.
Debian-based (Debian, Ubuntu)
Currently supports Debian 10 (Buster) and Ubuntu 20.04 (Focal), and derivatives. Run the following
commands as the root user.
# Import the security@parity.io GPG key
gpg --recv-keys --keyserver hkps://keys.mailvelope.com 9D4B2B6EB8F97156D19669A9FF0812D491B96798
gpg --export 9D4B2B6EB8F97156D19669A9FF0812D491B96798 > /usr/share/keyrings/parity.gpg
# Add the Parity repository and update the package index
echo 'deb [signed-by=/usr/share/keyrings/parity.gpg] https://releases.parity.io/deb release main' > /etc/apt/sources.list.d/parity.list
apt update
# Install the `parity-keyring` package - This will ensure the GPG key
# used by APT remains up-to-date
apt install parity-keyring
# Install polkadot
apt install polkadot
Installation from the Debian repository will create a systemd service that can be used to run a
Polkadot node. This is disabled by default, and can be started by running systemctl start polkadot
on demand (use systemctl enable polkadot to make it auto-start after reboot). By default, it will
run as the polkadot user. Command-line flags passed to the binary can be customized by editing
/etc/default/polkadot. This file will not be overwritten on updating Polkadot. You may also just
run the node directly from the command-line.
Building
Since the Polkadot node is based on Substrate, first set up your build environment according to the Substrate installation instructions.
Install via Cargo
Make sure you have the support software installed from the Build from Source section below this section.
If you want to install Polkadot in your PATH, you can do so with:
cargo install --git https://github.com/paritytech/polkadot-sdk --tag <version> polkadot --locked
Build from Source
Build the client by cloning this repository and running the following commands from the root directory of the repo:
git checkout <latest tagged release>
cargo build --release
Note: if you want to move the built polkadot binary somewhere (e.g. into $PATH) you will also
need to move polkadot-execute-worker and polkadot-prepare-worker. You can let cargo do all this
for you by running:
cargo install --path . --locked
Build from Source with Docker
You can also build from source using Parity CI docker image:
git checkout <latest tagged release>
docker run --rm -it -w /shellhere/polkadot \
-v $(pwd):/shellhere/polkadot \
paritytech/ci-linux:production cargo build --release
sudo chown -R $(id -u):$(id -g) target/
If you want to reproduce other steps of CI process you can use the following guide.
Networks
This repo supports runtimes for Polkadot, Kusama, and Westend.
Connect to Polkadot Mainnet
Connect to the global Polkadot Mainnet network by running:
../target/release/polkadot --chain=polkadot
You can see your node on [telemetry] (set a custom name with --name "my custom name").
telemetry: https://telemetry.polkadot.io/#list/Polkadot
Connect to the "Kusama" Canary Network
Connect to the global Kusama canary network by running:
../target/release/polkadot --chain=kusama
You can see your node on [telemetry] (set a custom name with --name "my custom name").
telemetry: https://telemetry.polkadot.io/#list/Kusama
Connect to the Westend Testnet
Connect to the global Westend testnet by running:
../target/release/polkadot --chain=westend
You can see your node on [telemetry] (set a custom name with --name "my custom name").
telemetry: https://telemetry.polkadot.io/#list/Westend
Obtaining DOTs
If you want to do anything on Polkadot, Kusama, or Westend, then you'll need to get an account and some DOT, KSM, or WND tokens, respectively. Follow the instructions on the Wiki to obtain tokens for your testnet of choice.
Hacking on Polkadot
If you'd actually like to hack on Polkadot, you can grab the source code and build it. Ensure you have Rust and the support software installed.
Then, grab the Polkadot source code:
git clone https://github.com/paritytech/polkadot-sdk.git
cd polkadot
Then build the code. You will need to build in release mode (--release) to start a network. Only
use debug mode for development (faster compile times for development and testing).
cargo build
You can run the tests if you like:
cargo test --workspace --profile testnet
# Or run only the tests for specified crated
cargo test -p <crate-name> --profile testnet
You can start a development chain with:
cargo run --bin polkadot -- --dev
Detailed logs may be shown by running the node with the following environment variables set:
RUST_LOG=debug RUST_BACKTRACE=1 cargo run --bin polkadot -- --dev
Development
You can run a simple single-node development "network" on your machine by running:
cargo run --bin polkadot --release -- --dev
You can muck around by heading to https://polkadot.js.org/apps and choose "Local Node" from the Settings menu.
Local Two-node Testnet
If you want to see the multi-node consensus algorithm in action locally, then you can create a local testnet. You'll need two terminals open. In one, run:
polkadot --dev --alice -d /tmp/alice
And in the other, run:
polkadot --dev --bob -d /tmp/bob --bootnodes '/ip4/127.0.0.1/tcp/30333/p2p/ALICE_BOOTNODE_ID_HERE'
Ensure you replace ALICE_BOOTNODE_ID_HERE with the node ID from the output of the first terminal.
Monitoring
Once you set this up you can take a look at the Polkadot Grafana dashboards that we currently maintain.
Using Docker
Shell Completion
Contributing
Contributing Guidelines
Contributor Code of Conduct
License
Polkadot is GPL 3.0 licensed.