implement custom proposer (#1320)

* network bridge skeleton * move some primitives around and add debug impls * protocol registration glue & abstract network interface * add send_msgs to subsystemctx * select logic * transform different events into actions and handle * implement remaining network bridge state machine * start test skeleton * make network methods asynchronous * extract subsystem out to subsystem crate * port over overseer to subsystem context trait * fix minimal example * fix overseer doc test * update network-bridge crate * write a subsystem test-helpers crate * write a network test helper for network-bridge * set up (broken) view test * Revamp network to be more async-friendly and not require Sync * fix spacing * fix test compilation * insert side-channel for actions * Add some more message types to AllMessages * introduce a test harness * impl ProvideInherent for InclusionInherent * reduce import churn; correct expect message * move inclusion inherent identifier into primitives It's not clear precisely why this is desired, but it's a pattern I've seen in several places, so I'm going this to be on the safe side. Worst case, we can revert this commit pretty easily. * bump kusama spec_version to placate CI * copy sc_basic_authorship::{ProposerFactory, Proposer} We have from the problem description: > This Proposer will require an OverseerHandle to make requests via. That's next on the plate. * use polkadot custom proposer instead of basic-authorship one * add some tests * ensure service compiles and passes tests * fix typo * fix service-new compilation * Subsystem test helpers send messages synchronously * remove smelly action inspector * remove superfluous let binding * fix warnings * add license header * empty commit; maybe github will notice the one with changes * Update node/network/bridge/src/lib.rs Co-authored-by: Peter Goodspeed-Niklaus <coriolinus@users.noreply.github.com> * add sanity check to only include valid inherents * stub: encapsulate block production mechanics instead of copying them The goal is to end up with something like what's in validation::block_production::*, which encapsulates basic block production mechanics. This is a better idea than just straight-up copying those mechanics. * partial implementation of propose fn Doesn't actually compile yet; need to bring in some other commits to ensure ProvisionerMessage is a thing, and also figure out how to get the block hash given the current context. * fix compilation * clear a few more compile errors * finish fn propose * broken: add timeout to proposal * add timeout to proposal * guide: provisioner is responsible for selecting parachain candidates * implement ProvisionerMessage::RequestInherentData & update fn propose * impl CreateProposer::init; clean up * impl std::error::Error for Error * document error-handling rationale * cause polkadot-service-new to compile correctly * Move potentially-blocking call from fn init -> fn propose This means that we can wrap the delayed call into the same timeout check used elsewhere. * document struct Proposer * extract provisioner data fetch This satisfies two requirements: - only applies the timeout to actually fetching the provisioner data, not to constructing the block after - simplifies the problem of injecting default data if we could not get the real provisioner data in time. Co-authored-by: Robert Habermeier <rphmeier@gmail.com> Co-authored-by: Gavin Wood <gavin@parity.io>
2026-06-14 18:01:04 +00:00 · 2020-07-05 19:22:52 +02:00
parent 19ef40a7c9
commit f2104562d8
10 changed files with 352 additions and 7 deletions
@@ -0,0 +1,262 @@
+use futures::prelude::*;
+use futures::select;
+use polkadot_node_subsystem::{messages::{AllMessages, ProvisionerInherentData, ProvisionerMessage}, SubsystemError};
+use polkadot_overseer::OverseerHandler;
+use polkadot_primitives::{
+	inclusion_inherent,
+	parachain::ParachainHost,
+	Block, Hash, Header,
+};
+use sc_block_builder::{BlockBuilderApi, BlockBuilderProvider};
+use sp_api::{ApiExt, ProvideRuntimeApi};
+use sp_blockchain::HeaderBackend;
+use sp_consensus::{Proposal, RecordProof};
+use sp_inherents::InherentData;
+use sp_runtime::traits::{DigestFor, HashFor};
+use sp_transaction_pool::TransactionPool;
+use std::{fmt, pin::Pin, sync::Arc, time};
+
+/// How long proposal can take before we give up and err out
+const PROPOSE_TIMEOUT: core::time::Duration = core::time::Duration::from_secs(2);
+
+/// Custom Proposer factory for Polkadot
+pub struct ProposerFactory<TxPool, Backend, Client> {
+	inner: sc_basic_authorship::ProposerFactory<TxPool, Backend, Client>,
+	overseer: OverseerHandler,
+}
+
+impl<TxPool, Backend, Client> ProposerFactory<TxPool, Backend, Client> {
+	pub fn new(
+		client: Arc<Client>,
+		transaction_pool: Arc<TxPool>,
+		overseer: OverseerHandler,
+	) -> Self {
+		ProposerFactory {
+			inner: sc_basic_authorship::ProposerFactory::new(
+				client,
+				transaction_pool,
+				None,
+			),
+			overseer,
+		}
+	}
+}
+
+impl<TxPool, Backend, Client> sp_consensus::Environment<Block>
+	for ProposerFactory<TxPool, Backend, Client>
+where
+	TxPool: 'static + TransactionPool<Block = Block>,
+	Client: 'static
+		+ BlockBuilderProvider<Backend, Block, Client>
+		+ ProvideRuntimeApi<Block>
+		+ HeaderBackend<Block>
+		+ Send
+		+ Sync,
+	Client::Api:
+		ParachainHost<Block> + BlockBuilderApi<Block> + ApiExt<Block, Error = sp_blockchain::Error>,
+	Backend:
+		'static + sc_client_api::Backend<Block, State = sp_api::StateBackendFor<Client, Block>>,
+	// Rust bug: https://github.com/rust-lang/rust/issues/24159
+	sp_api::StateBackendFor<Client, Block>: sp_api::StateBackend<HashFor<Block>> + Send,
+{
+	type CreateProposer = Pin<Box<
+		dyn Future<Output = Result<Self::Proposer, Self::Error>> + Send + 'static,
+	>>;
+	type Proposer = Proposer<TxPool, Backend, Client>;
+	type Error = Error;
+
+	fn init(&mut self, parent_header: &Header) -> Self::CreateProposer {
+		// create the inner proposer
+		let proposer = self.inner.init(parent_header).into_inner();
+
+		// data to be moved into the future
+		let overseer = self.overseer.clone();
+		let parent_header_hash = parent_header.hash();
+
+		async move {
+			Ok(Proposer {
+				inner: proposer?,
+				overseer,
+				parent_header_hash,
+			})
+		}.boxed()
+	}
+}
+
+/// Custom Proposer for Polkadot.
+///
+/// This proposer gets the ProvisionerInherentData and injects it into the wrapped
+/// proposer's inherent data, then delegates the actual proposal generation.
+pub struct Proposer<TxPool: TransactionPool<Block = Block>, Backend, Client> {
+	inner: sc_basic_authorship::Proposer<Backend, Block, Client, TxPool>,
+	overseer: OverseerHandler,
+	parent_header_hash: Hash,
+}
+
+// This impl has the same generic bounds as the Proposer impl.
+impl<TxPool, Backend, Client> Proposer<TxPool, Backend, Client>
+where
+	TxPool: 'static + TransactionPool<Block = Block>,
+	Client: 'static
+		+ BlockBuilderProvider<Backend, Block, Client>
+		+ ProvideRuntimeApi<Block>
+		+ HeaderBackend<Block>
+		+ Send
+		+ Sync,
+	Client::Api:
+		ParachainHost<Block> + BlockBuilderApi<Block> + ApiExt<Block, Error = sp_blockchain::Error>,
+	Backend:
+		'static + sc_client_api::Backend<Block, State = sp_api::StateBackendFor<Client, Block>>,
+	// Rust bug: https://github.com/rust-lang/rust/issues/24159
+	sp_api::StateBackendFor<Client, Block>: sp_api::StateBackend<HashFor<Block>> + Send,
+{
+	/// Get provisioner inherent data
+	///
+	/// This function has a constant timeout: `PROPOSE_TIMEOUT`.
+	fn get_provisioner_data(&self) -> impl Future<Output = Result<ProvisionerInherentData, Error>> {
+		// clone this (lightweight) data because we're going to move it into the future
+		let mut overseer = self.overseer.clone();
+		let parent_header_hash = self.parent_header_hash.clone();
+
+		let mut provisioner_inherent_data = async move {
+			let (sender, receiver) = futures::channel::oneshot::channel();
+
+			// strictly speaking, we don't _have_ to .await this send_msg before opening the
+			// receiver; it's possible that the response there would be ready slightly before
+			// this call completes. IMO it's not worth the hassle or overhead of spawning a
+			// distinct task for that kind of miniscule efficiency improvement.
+			overseer.send_msg(AllMessages::Provisioner(
+				ProvisionerMessage::RequestInherentData(parent_header_hash, sender),
+			)).await?;
+
+			receiver.await.map_err(Error::ClosedChannelFromProvisioner)
+		}
+		.boxed()
+		.fuse();
+
+		let mut timeout = wasm_timer::Delay::new(PROPOSE_TIMEOUT).fuse();
+
+		async move {
+			select! {
+				pid = provisioner_inherent_data => pid,
+				_ = timeout => Err(Error::Timeout),
+			}
+		}
+	}
+}
+
+impl<TxPool, Backend, Client> sp_consensus::Proposer<Block> for Proposer<TxPool, Backend, Client>
+where
+	TxPool: 'static + TransactionPool<Block = Block>,
+	Client: 'static
+		+ BlockBuilderProvider<Backend, Block, Client>
+		+ ProvideRuntimeApi<Block>
+		+ HeaderBackend<Block>
+		+ Send
+		+ Sync,
+	Client::Api:
+		ParachainHost<Block> + BlockBuilderApi<Block> + ApiExt<Block, Error = sp_blockchain::Error>,
+	Backend:
+		'static + sc_client_api::Backend<Block, State = sp_api::StateBackendFor<Client, Block>>,
+	// Rust bug: https://github.com/rust-lang/rust/issues/24159
+	sp_api::StateBackendFor<Client, Block>: sp_api::StateBackend<HashFor<Block>> + Send,
+{
+	type Transaction = sc_client_api::TransactionFor<Backend, Block>;
+	type Proposal = Pin<Box<
+		dyn Future<Output = Result<Proposal<Block, sp_api::TransactionFor<Client, Block>>, Error>> + Send,
+	>>;
+	type Error = Error;
+
+	fn propose(
+		self,
+		mut inherent_data: InherentData,
+		inherent_digests: DigestFor<Block>,
+		max_duration: time::Duration,
+		record_proof: RecordProof,
+	) -> Self::Proposal {
+		let provisioner_data = self.get_provisioner_data();
+
+		async move {
+			let provisioner_data = match provisioner_data.await {
+				Ok(pd) => pd,
+				Err(err) => {
+					log::warn!("could not get provisioner inherent data; injecting default data: {}", err);
+					Default::default()
+				}
+			};
+
+			inherent_data.put_data(
+				inclusion_inherent::INHERENT_IDENTIFIER,
+				&provisioner_data,
+			)?;
+
+			self.inner
+				.propose(inherent_data, inherent_digests, max_duration, record_proof)
+				.await
+				.map_err(Into::into)
+		}
+		.boxed()
+	}
+}
+
+// It would have been more ergonomic to use thiserror to derive the
+// From implementations, Display, and std::error::Error, but unfortunately
+// two of the wrapped errors (sp_inherents::Error, SubsystemError) also
+// don't impl std::error::Error, which breaks the thiserror derive.
+#[derive(Debug)]
+pub enum Error {
+	Consensus(sp_consensus::Error),
+	Blockchain(sp_blockchain::Error),
+	Inherent(sp_inherents::Error),
+	Timeout,
+	ClosedChannelFromProvisioner(futures::channel::oneshot::Canceled),
+	Subsystem(SubsystemError)
+}
+
+impl From<sp_consensus::Error> for Error {
+	fn from(e: sp_consensus::Error) -> Error {
+		Error::Consensus(e)
+	}
+}
+
+impl From<sp_blockchain::Error> for Error {
+	fn from(e: sp_blockchain::Error) -> Error {
+		Error::Blockchain(e)
+	}
+}
+
+impl From<sp_inherents::Error> for Error {
+	fn from(e: sp_inherents::Error) -> Error {
+		Error::Inherent(e)
+	}
+}
+
+impl From<SubsystemError> for Error {
+	fn from(e: SubsystemError) -> Error {
+		Error::Subsystem(e)
+	}
+}
+
+impl fmt::Display for Error {
+	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+		match self {
+			Self::Consensus(err) => write!(f, "consensus error: {}", err),
+			Self::Blockchain(err) => write!(f, "blockchain error: {}", err),
+			Self::Inherent(err) => write!(f, "inherent error: {:?}", err),
+			Self::Timeout => write!(f, "timeout: provisioner did not return inherent data after {:?}", PROPOSE_TIMEOUT),
+			Self::ClosedChannelFromProvisioner(err) => write!(f, "provisioner closed inherent data channel before sending: {}", err),
+			Self::Subsystem(err) => write!(f, "subsystem error: {:?}", err),
+		}
+	}
+}
+
+impl std::error::Error for Error {
+	fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+		match self {
+			Self::Consensus(err) => Some(err),
+			Self::Blockchain(err) => Some(err),
+			Self::ClosedChannelFromProvisioner(err) => Some(err),
+			_ => None
+		}
+	}
+}