From 3e17fcfb3d1f76498a3d2507d72aa4a2c47ee4ed Mon Sep 17 00:00:00 2001
From: Robert Habermeier <rphmeier@gmail.com>
Date: Fri, 17 Jan 2020 10:28:19 +0100
Subject: [PATCH] Validation service refactoring (#773)
* add some more docs about statement import
* instantiate environment async
* move attestation service into subfolder
* refactor validation service architecture somewhat
* remove dependence on validation service in proposer
* fix a bunch of warnings
* improve docs
* introduce a builder for the validation service
* extract block production to its own file
* integrate new API into service
* address review grumbles
---
polkadot/service/src/lib.rs | 23 +-
polkadot/statement-table/src/generic.rs | 3 +
.../validation/src/attestation_service.rs | 154 -----
polkadot/validation/src/block_production.rs | 354 ++++++++++
polkadot/validation/src/error.rs | 2 +
polkadot/validation/src/evaluation.rs | 3 +-
polkadot/validation/src/lib.rs | 639 +-----------------
polkadot/validation/src/shared_table/mod.rs | 9 +-
.../validation/src/validation_service/mod.rs | 463 +++++++++++++
9 files changed, 860 insertions(+), 790 deletions(-)
delete mode 100644 polkadot/validation/src/attestation_service.rs
create mode 100644 polkadot/validation/src/block_production.rs
create mode 100644 polkadot/validation/src/validation_service/mod.rs
diff --git a/polkadot/service/src/lib.rs b/polkadot/service/src/lib.rs
index f3872c6663b..40c052ef827 100644
--- a/polkadot/service/src/lib.rs
+++ b/polkadot/service/src/lib.rs
@@ -404,21 +404,28 @@ pub fn new_full<Runtime, Dispatch, Extrinsic>(config: Configuration)
service.client(),
WrappedExecutor(service.spawn_task_handle()),
);
+
+ let (validation_service_handle, validation_service) = consensus::ServiceBuilder {
+ client: client.clone(),
+ network: validation_network.clone(),
+ collators: validation_network,
+ task_executor: Arc::new(WrappedExecutor(service.spawn_task_handle())),
+ availability_store: availability_store.clone(),
+ select_chain: select_chain.clone(),
+ keystore: service.keystore(),
+ max_block_data_size,
+ }.build();
+
+ service.spawn_essential_task(Box::pin(validation_service));
+
let proposer = consensus::ProposerFactory::new(
client.clone(),
- select_chain.clone(),
- validation_network.clone(),
- validation_network,
service.transaction_pool(),
- Arc::new(WrappedExecutor(service.spawn_task_handle())),
- service.keystore(),
- availability_store.clone(),
+ validation_service_handle,
slot_duration,
- max_block_data_size,
backend,
);
- let client = service.client();
let select_chain = service.select_chain().ok_or(ServiceError::SelectChainRequired)?;
let can_author_with =
consensus_common::CanAuthorWithNativeVersion::new(client.executor().clone());
diff --git a/polkadot/statement-table/src/generic.rs b/polkadot/statement-table/src/generic.rs
index f429e59960e..83cae9daf26 100644
--- a/polkadot/statement-table/src/generic.rs
+++ b/polkadot/statement-table/src/generic.rs
@@ -354,6 +354,9 @@ impl<C: Context> Table<C> {
/// Import a signed statement. Signatures should be checked for validity, and the
/// sender should be checked to actually be an authority.
///
+ /// Validity and invalidity statements are only valid if the corresponding
+ /// candidate has already been imported.
+ ///
/// If this returns `None`, the statement was either duplicate or invalid.
pub fn import_statement(
&mut self,
diff --git a/polkadot/validation/src/attestation_service.rs b/polkadot/validation/src/attestation_service.rs
deleted file mode 100644
index a5087f1cd40..00000000000
--- a/polkadot/validation/src/attestation_service.rs
+++ /dev/null
@@ -1,154 +0,0 @@
-// Copyright 2017-2020 Parity Technologies (UK) Ltd.
-// This file is part of Polkadot.
-
-// Polkadot is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-
-// Polkadot is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-// GNU General Public License for more details.
-
-// You should have received a copy of the GNU General Public License
-// along with Polkadot. If not, see <http://www.gnu.org/licenses/>.
-
-//! Attestation service.
-
-/// Attestation service. A long running service that creates and manages parachain attestation
-/// instances.
-///
-/// This uses a handle to an underlying thread pool to dispatch heavy work
-/// such as candidate verification while performing event-driven work
-/// on a local event loop.
-
-use std::{thread, time::Duration, sync::Arc};
-
-use sc_client_api::{BlockchainEvents, BlockBody};
-use sp_blockchain::HeaderBackend;
-use block_builder::BlockBuilderApi;
-use consensus::SelectChain;
-use futures::prelude::*;
-use futures::{future::{ready, select}, task::{Spawn, SpawnExt}};
-use polkadot_primitives::Block;
-use polkadot_primitives::parachain::ParachainHost;
-use babe_primitives::BabeApi;
-use keystore::KeyStorePtr;
-use sp_api::{ApiExt, ProvideRuntimeApi};
-use runtime_primitives::traits::HasherFor;
-
-use tokio::{runtime::Runtime as LocalRuntime};
-use log::{warn, error};
-
-use super::{Network, Collators};
-
-type TaskExecutor = Arc<dyn Spawn + Send + Sync>;
-
-/// Parachain candidate attestation service handle.
-pub(crate) struct ServiceHandle {
- thread: Option<thread::JoinHandle<()>>,
- exit_signal: Option<::exit_future::Signal>,
-}
-
-/// Create and start a new instance of the attestation service.
-pub(crate) fn start<C, N, P, SC>(
- client: Arc<P>,
- select_chain: SC,
- parachain_validation: Arc<crate::ParachainValidation<C, N, P>>,
- thread_pool: TaskExecutor,
- keystore: KeyStorePtr,
- max_block_data_size: Option<u64>,
-) -> ServiceHandle
- where
- C: Collators + Send + Sync + Unpin + 'static,
- C::Collation: Send + Unpin + 'static,
- P: BlockchainEvents<Block> + BlockBody<Block>,
- P: ProvideRuntimeApi<Block> + HeaderBackend<Block> + Send + Sync + 'static,
- P::Api: ParachainHost<Block> +
- BlockBuilderApi<Block> +
- BabeApi<Block> +
- ApiExt<Block, Error = sp_blockchain::Error>,
- N: Network + Send + Sync + 'static,
- N::TableRouter: Send + 'static,
- N::BuildTableRouter: Send + Unpin + 'static,
- SC: SelectChain<Block> + 'static,
- // Rust bug: https://github.com/rust-lang/rust/issues/24159
- sp_api::StateBackendFor<P, Block>: sp_api::StateBackend<HasherFor<Block>>,
-{
- const TIMER_INTERVAL: Duration = Duration::from_secs(30);
-
- let (signal, exit) = ::exit_future::signal();
- let thread = thread::spawn(move || {
- let mut runtime = LocalRuntime::new().expect("Could not create local runtime");
- let notifications = {
- let client = client.clone();
- let validation = parachain_validation.clone();
-
- let keystore = keystore.clone();
-
- let notifications = client.import_notification_stream()
- .for_each(move |notification| {
- let parent_hash = notification.hash;
- if notification.is_new_best {
- let res = validation.get_or_instantiate(
- parent_hash,
- &keystore,
- max_block_data_size,
- );
-
- if let Err(e) = res {
- warn!(
- "Unable to start parachain validation on top of {:?}: {}",
- parent_hash, e
- );
- }
- }
- ready(())
- });
-
- select(notifications, exit.clone())
- };
-
- let prune_old_sessions = {
- let select_chain = select_chain.clone();
- let interval = crate::interval(TIMER_INTERVAL)
- .for_each(move |_| match select_chain.leaves() {
- Ok(leaves) => {
- parachain_validation.retain(|h| leaves.contains(h));
- ready(())
- }
- Err(e) => {
- warn!("Error fetching leaves from client: {:?}", e);
- ready(())
- }
- });
-
- select(interval, exit.clone()).map(|_| ())
- };
-
- runtime.spawn(notifications);
- if let Err(_) = thread_pool.spawn(prune_old_sessions) {
- error!("Failed to spawn old sessions pruning task");
- }
-
- runtime.block_on(exit);
- });
-
- ServiceHandle {
- thread: Some(thread),
- exit_signal: Some(signal),
- }
-}
-
-impl Drop for ServiceHandle {
- fn drop(&mut self) {
- if let Some(signal) = self.exit_signal.take() {
- let _ = signal.fire();
- }
-
- if let Some(thread) = self.thread.take() {
- thread.join().expect("The service thread has panicked");
- }
- }
-}
diff --git a/polkadot/validation/src/block_production.rs b/polkadot/validation/src/block_production.rs
new file mode 100644
index 00000000000..6d4e7363899
--- /dev/null
+++ b/polkadot/validation/src/block_production.rs
@@ -0,0 +1,354 @@
+// Copyright 2020 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot. If not, see <http://www.gnu.org/licenses/>.
+
+//! The block production pipeline of Polkadot.
+//!
+//! The `ProposerFactory` exported by this module will be wrapped by some
+//! consensus engine, and triggered when it is time to create a block.
+
+use std::{
+ pin::Pin,
+ sync::Arc,
+ time::{self, Duration, Instant},
+};
+
+use sp_blockchain::HeaderBackend;
+use block_builder::BlockBuilderApi;
+use codec::Encode;
+use consensus::{Proposal, RecordProof};
+use polkadot_primitives::{Hash, Block, BlockId, BlockNumber, Header};
+use polkadot_primitives::parachain::{
+ ParachainHost, AttestedCandidate, NEW_HEADS_IDENTIFIER,
+};
+use runtime_primitives::traits::{DigestFor, HasherFor};
+use futures_timer::Delay;
+use txpool_api::{TransactionPool, InPoolTransaction};
+
+use futures::prelude::*;
+use inherents::InherentData;
+use sp_timestamp::TimestampInherentData;
+use log::{info, debug, trace};
+use sp_api::{ApiExt, ProvideRuntimeApi};
+
+use crate::validation_service::ServiceHandle;
+use crate::dynamic_inclusion::DynamicInclusion;
+use crate::Error;
+
+// Polkadot proposer factory.
+pub struct ProposerFactory<Client, TxPool, Backend> {
+ client: Arc<Client>,
+ transaction_pool: Arc<TxPool>,
+ service_handle: ServiceHandle,
+ babe_slot_duration: u64,
+ backend: Arc<Backend>,
+}
+
+impl<Client, TxPool, Backend> ProposerFactory<Client, TxPool, Backend> {
+ /// Create a new proposer factory.
+ pub fn new(
+ client: Arc<Client>,
+ transaction_pool: Arc<TxPool>,
+ service_handle: ServiceHandle,
+ babe_slot_duration: u64,
+ backend: Arc<Backend>,
+ ) -> Self {
+ ProposerFactory {
+ client,
+ transaction_pool,
+ service_handle: service_handle,
+ babe_slot_duration,
+ backend,
+ }
+ }
+}
+
+impl<Client, TxPool, Backend> consensus::Environment<Block>
+ for ProposerFactory<Client, TxPool, Backend>
+where
+ TxPool: TransactionPool<Block=Block> + 'static,
+ Client: ProvideRuntimeApi<Block> + HeaderBackend<Block> + Send + Sync + 'static,
+ Client::Api: ParachainHost<Block> + BlockBuilderApi<Block>
+ + ApiExt<Block, Error = sp_blockchain::Error>,
+ Backend: sc_client_api::Backend<
+ Block,
+ State = sp_api::StateBackendFor<Client, Block>
+ > + 'static,
+ // Rust bug: https://github.com/rust-lang/rust/issues/24159
+ sp_api::StateBackendFor<Client, Block>: sp_api::StateBackend<HasherFor<Block>> + Send,
+{
+ type CreateProposer = Pin<Box<
+ dyn Future<Output = Result<Self::Proposer, Self::Error>> + Send + 'static
+ >>;
+ type Proposer = Proposer<Client, TxPool, Backend>;
+ type Error = Error;
+
+ fn init(
+ &mut self,
+ parent_header: &Header,
+ ) -> Self::CreateProposer {
+ let parent_hash = parent_header.hash();
+ let parent_number = parent_header.number;
+ let parent_id = BlockId::hash(parent_hash);
+
+ let client = self.client.clone();
+ let transaction_pool = self.transaction_pool.clone();
+ let backend = self.backend.clone();
+ let slot_duration = self.babe_slot_duration.clone();
+
+ let maybe_proposer = self.service_handle
+ .clone()
+ .get_validation_instance(parent_hash)
+ .and_then(move |tracker| future::ready(Ok(Proposer {
+ client,
+ tracker,
+ parent_hash,
+ parent_id,
+ parent_number,
+ transaction_pool,
+ slot_duration,
+ backend,
+ })));
+
+ Box::pin(maybe_proposer)
+ }
+}
+
+/// The Polkadot proposer logic.
+pub struct Proposer<Client, TxPool, Backend> {
+ client: Arc<Client>,
+ parent_hash: Hash,
+ parent_id: BlockId,
+ parent_number: BlockNumber,
+ tracker: Arc<crate::validation_service::ValidationInstanceHandle>,
+ transaction_pool: Arc<TxPool>,
+ slot_duration: u64,
+ backend: Arc<Backend>,
+}
+
+impl<Client, TxPool, Backend> consensus::Proposer<Block> for Proposer<Client, TxPool, Backend> where
+ TxPool: TransactionPool<Block=Block> + 'static,
+ Client: ProvideRuntimeApi<Block> + HeaderBackend<Block> + Send + Sync + 'static,
+ Client::Api: ParachainHost<Block> + BlockBuilderApi<Block> + ApiExt<Block, Error = sp_blockchain::Error>,
+ Backend: sc_client_api::Backend<Block, State = sp_api::StateBackendFor<Client, Block>> + 'static,
+ // Rust bug: https://github.com/rust-lang/rust/issues/24159
+ sp_api::StateBackendFor<Client, Block>: sp_api::StateBackend<HasherFor<Block>> + Send,
+{
+ type Error = Error;
+ type Transaction = sp_api::TransactionFor<Client, Block>;
+ type Proposal = Pin<
+ Box<
+ dyn Future<Output = Result<Proposal<Block, sp_api::TransactionFor<Client, Block>>, Error>>
+ + Send
+ >
+ >;
+
+ fn propose(&mut self,
+ inherent_data: InherentData,
+ inherent_digests: DigestFor<Block>,
+ max_duration: Duration,
+ record_proof: RecordProof,
+ ) -> Self::Proposal {
+ const SLOT_DURATION_DENOMINATOR: u64 = 3; // wait up to 1/3 of the slot for candidates.
+
+ let initial_included = self.tracker.table().includable_count();
+ let now = Instant::now();
+
+ let dynamic_inclusion = DynamicInclusion::new(
+ self.tracker.table().num_parachains(),
+ self.tracker.started(),
+ Duration::from_millis(self.slot_duration / SLOT_DURATION_DENOMINATOR),
+ );
+
+ let parent_hash = self.parent_hash.clone();
+ let parent_number = self.parent_number.clone();
+ let parent_id = self.parent_id.clone();
+ let client = self.client.clone();
+ let transaction_pool = self.transaction_pool.clone();
+ let table = self.tracker.table().clone();
+ let backend = self.backend.clone();
+
+ async move {
+ let enough_candidates = dynamic_inclusion.acceptable_in(
+ now,
+ initial_included,
+ ).unwrap_or_else(|| Duration::from_millis(1));
+
+ let believed_timestamp = match inherent_data.timestamp_inherent_data() {
+ Ok(timestamp) => timestamp,
+ Err(e) => return Err(Error::InherentError(e)),
+ };
+
+ let deadline_diff = max_duration - max_duration / 3;
+ let deadline = match Instant::now().checked_add(deadline_diff) {
+ None => return Err(Error::DeadlineComputeFailure(deadline_diff)),
+ Some(d) => d,
+ };
+
+ let data = CreateProposalData {
+ parent_hash,
+ parent_number,
+ parent_id,
+ client,
+ transaction_pool,
+ table,
+ believed_minimum_timestamp: believed_timestamp,
+ inherent_data: Some(inherent_data),
+ inherent_digests,
+ // leave some time for the proposal finalisation
+ deadline,
+ record_proof,
+ backend,
+ };
+
+ // set up delay until next allowed timestamp.
+ let current_timestamp = current_timestamp();
+ if current_timestamp < believed_timestamp {
+ Delay::new(Duration::from_millis(current_timestamp - believed_timestamp))
+ .await;
+ }
+
+ Delay::new(enough_candidates).await;
+
+ tokio_executor::blocking::run(move || {
+ let proposed_candidates = data.table.proposed_set();
+ data.propose_with(proposed_candidates)
+ })
+ .await
+ }.boxed()
+ }
+}
+
+fn current_timestamp() -> u64 {
+ time::SystemTime::now().duration_since(time::UNIX_EPOCH)
+ .expect("now always later than unix epoch; qed")
+ .as_millis() as u64
+}
+
+/// Inner data of the create proposal.
+struct CreateProposalData<Client, TxPool, Backend> {
+ parent_hash: Hash,
+ parent_number: BlockNumber,
+ parent_id: BlockId,
+ client: Arc<Client>,
+ transaction_pool: Arc<TxPool>,
+ table: Arc<crate::SharedTable>,
+ believed_minimum_timestamp: u64,
+ inherent_data: Option<InherentData>,
+ inherent_digests: DigestFor<Block>,
+ deadline: Instant,
+ record_proof: RecordProof,
+ backend: Arc<Backend>,
+}
+
+impl<Client, TxPool, Backend> CreateProposalData<Client, TxPool, Backend> where
+ TxPool: TransactionPool<Block=Block>,
+ Client: ProvideRuntimeApi<Block> + HeaderBackend<Block> + Send + Sync,
+ Client::Api: ParachainHost<Block> + BlockBuilderApi<Block> + ApiExt<Block, Error = sp_blockchain::Error>,
+ Backend: sc_client_api::Backend<Block, State = sp_api::StateBackendFor<Client, Block>> + 'static,
+ // Rust bug: https://github.com/rust-lang/rust/issues/24159
+ sp_api::StateBackendFor<Client, Block>: sp_api::StateBackend<HasherFor<Block>> + Send,
+{
+ fn propose_with(
+ mut self,
+ candidates: Vec<AttestedCandidate>,
+ ) -> Result<Proposal<Block, sp_api::TransactionFor<Client, Block>>, Error> {
+ use runtime_primitives::traits::{Hash as HashT, BlakeTwo256};
+
+ const MAX_TRANSACTIONS: usize = 40;
+
+ let mut inherent_data = self.inherent_data
+ .take()
+ .expect("CreateProposal is not polled after finishing; qed");
+ inherent_data.put_data(NEW_HEADS_IDENTIFIER, &candidates)
+ .map_err(Error::InherentError)?;
+
+ let runtime_api = self.client.runtime_api();
+
+ let mut block_builder = block_builder::BlockBuilder::new(
+ &*self.client,
+ self.client.expect_block_hash_from_id(&self.parent_id)?,
+ self.client.expect_block_number_from_id(&self.parent_id)?,
+ self.record_proof,
+ self.inherent_digests.clone(),
+ &*self.backend,
+ )?;
+
+ {
+ let inherents = runtime_api.inherent_extrinsics(&self.parent_id, inherent_data)?;
+ for inherent in inherents {
+ block_builder.push(inherent)?;
+ }
+
+ let mut unqueue_invalid = Vec::new();
+ let mut pending_size = 0;
+
+ let ready_iter = self.transaction_pool.ready();
+ for ready in ready_iter.take(MAX_TRANSACTIONS) {
+ let encoded_size = ready.data().encode().len();
+ if pending_size + encoded_size >= crate::evaluation::MAX_TRANSACTIONS_SIZE {
+ break;
+ }
+ if Instant::now() > self.deadline {
+ debug!("Consensus deadline reached when pushing block transactions, proceeding with proposing.");
+ break;
+ }
+
+ match block_builder.push(ready.data().clone()) {
+ Ok(()) => {
+ debug!("[{:?}] Pushed to the block.", ready.hash());
+ pending_size += encoded_size;
+ }
+ Err(sp_blockchain::Error::ApplyExtrinsicFailed(sp_blockchain::ApplyExtrinsicFailed::Validity(e)))
+ if e.exhausted_resources() =>
+ {
+ debug!("Block is full, proceed with proposing.");
+ break;
+ }
+ Err(e) => {
+ trace!(target: "transaction-pool", "Invalid transaction: {}", e);
+ unqueue_invalid.push(ready.hash().clone());
+ }
+ }
+ }
+
+ self.transaction_pool.remove_invalid(&unqueue_invalid);
+ }
+
+ let (new_block, storage_changes, proof) = block_builder.build()?.into_inner();
+
+ info!("Prepared block for proposing at {} [hash: {:?}; parent_hash: {}; extrinsics: [{}]]",
+ new_block.header.number,
+ Hash::from(new_block.header.hash()),
+ new_block.header.parent_hash,
+ new_block.extrinsics.iter()
+ .map(|xt| format!("{}", BlakeTwo256::hash_of(xt)))
+ .collect::<Vec<_>>()
+ .join(", ")
+ );
+
+ // TODO: full re-evaluation (https://github.com/paritytech/polkadot/issues/216)
+ let active_parachains = runtime_api.active_parachains(&self.parent_id)?;
+ assert!(crate::evaluation::evaluate_initial(
+ &new_block,
+ self.believed_minimum_timestamp,
+ &self.parent_hash,
+ self.parent_number,
+ &active_parachains[..],
+ ).is_ok());
+
+ Ok(Proposal { block: new_block, storage_changes, proof })
+ }
+}
diff --git a/polkadot/validation/src/error.rs b/polkadot/validation/src/error.rs
index 1890863a077..9ba4922eeb7 100644
--- a/polkadot/validation/src/error.rs
+++ b/polkadot/validation/src/error.rs
@@ -46,6 +46,8 @@ pub enum Error {
Timer(std::io::Error),
#[display(fmt = "Failed to compute deadline of now + {:?}", _0)]
DeadlineComputeFailure(std::time::Duration),
+ #[display(fmt = "Validation service is down.")]
+ ValidationServiceDown,
Join(tokio::task::JoinError)
}
diff --git a/polkadot/validation/src/evaluation.rs b/polkadot/validation/src/evaluation.rs
index 18e0d9829af..76e7e9f8fb5 100644
--- a/polkadot/validation/src/evaluation.rs
+++ b/polkadot/validation/src/evaluation.rs
@@ -16,7 +16,8 @@
//! Polkadot block evaluation and evaluation errors.
-use super::MAX_TRANSACTIONS_SIZE;
+// block size limit.
+pub(crate) const MAX_TRANSACTIONS_SIZE: usize = 4 * 1024 * 1024;
use codec::Encode;
use polkadot_primitives::{Block, Hash, BlockNumber};
diff --git a/polkadot/validation/src/lib.rs b/polkadot/validation/src/lib.rs
index 860c1a6f365..41f2552aebd 100644
--- a/polkadot/validation/src/lib.rs
+++ b/polkadot/validation/src/lib.rs
@@ -31,50 +31,22 @@
use std::{
collections::{HashMap, HashSet},
- pin::Pin,
sync::Arc,
- time::{self, Duration, Instant},
};
-use babe_primitives::BabeApi;
-use sc_client_api::{Backend, BlockchainEvents, BlockBody};
-use sp_blockchain::HeaderBackend;
-use block_builder::BlockBuilderApi;
use codec::Encode;
-use consensus::{SelectChain, Proposal, RecordProof};
-use availability_store::Store as AvailabilityStore;
-use parking_lot::Mutex;
-use polkadot_primitives::{Hash, Block, BlockId, BlockNumber, Header};
+use polkadot_primitives::Hash;
use polkadot_primitives::parachain::{
Id as ParaId, Chain, DutyRoster, CandidateReceipt,
- ParachainHost, AttestedCandidate, Statement as PrimitiveStatement, Message, OutgoingMessages,
+ Statement as PrimitiveStatement, Message, OutgoingMessages,
Collation, PoVBlock, ErasureChunk, ValidatorSignature, ValidatorIndex,
- ValidatorPair, ValidatorId, NEW_HEADS_IDENTIFIER,
+ ValidatorPair, ValidatorId,
};
use primitives::Pair;
-use runtime_primitives::traits::{DigestFor, HasherFor};
-use futures_timer::Delay;
-use txpool_api::{TransactionPool, InPoolTransaction};
-use attestation_service::ServiceHandle;
use futures::prelude::*;
-use futures::{future::{select, ready}, stream::unfold, task::{Spawn, SpawnExt}};
-use collation::collation_fetch;
-use dynamic_inclusion::DynamicInclusion;
-use inherents::InherentData;
-use sp_timestamp::TimestampInherentData;
-use log::{info, debug, warn, trace, error};
-use keystore::KeyStorePtr;
-use sp_api::{ApiExt, ProvideRuntimeApi};
-
-type TaskExecutor = Arc<dyn Spawn + Send + Sync>;
-
-fn interval(duration: Duration) -> impl Stream<Item=()> + Send + Unpin {
- unfold((), move |_| {
- futures_timer::Delay::new(duration).map(|_| Some(((), ())))
- }).map(drop)
-}
+pub use self::block_production::ProposerFactory;
pub use self::collation::{
validate_collation, validate_incoming, message_queue_root, egress_roots, Collators,
produce_receipt_and_chunks,
@@ -84,20 +56,19 @@ pub use self::shared_table::{
SharedTable, ParachainWork, PrimedParachainWork, Validated, Statement, SignedStatement,
GenericStatement,
};
+pub use self::validation_service::{ServiceHandle, ServiceBuilder};
#[cfg(not(target_os = "unknown"))]
pub use parachain::wasm_executor::{run_worker as run_validation_worker};
-mod attestation_service;
mod dynamic_inclusion;
mod evaluation;
mod error;
mod shared_table;
pub mod collation;
-
-// block size limit.
-const MAX_TRANSACTIONS_SIZE: usize = 4 * 1024 * 1024;
+pub mod validation_service;
+pub mod block_production;
/// Incoming messages; a series of sorted (ParaId, Message) pairs.
pub type Incoming = Vec<(ParaId, Vec<Message>)>;
@@ -148,6 +119,13 @@ pub trait Network {
) -> Self::BuildTableRouter;
}
+/// The local duty of a validator.
+#[derive(Debug)]
+pub struct LocalDuty {
+ validation: Chain,
+ index: ValidatorIndex,
+}
+
/// Information about a specific group.
#[derive(Debug, Clone, Default)]
pub struct GroupInfo {
@@ -246,595 +224,6 @@ pub fn outgoing_queues(outgoing_targeted: &'_ OutgoingMessages)
})
}
-// finds the first key we are capable of signing with out of the given set of validators,
-// if any.
-fn signing_key(validators: &[ValidatorId], keystore: &KeyStorePtr) -> Option<Arc<ValidatorPair>> {
- let keystore = keystore.read();
- validators.iter()
- .find_map(|v| {
- keystore.key_pair::<ValidatorPair>(&v).ok()
- })
- .map(|pair| Arc::new(pair))
-}
-
-/// Constructs parachain-agreement instances.
-struct ParachainValidation<C, N, P> {
- /// The client instance.
- client: Arc<P>,
- /// The backing network handle.
- network: N,
- /// Parachain collators.
- collators: C,
- /// handle to remote task executor
- handle: TaskExecutor,
- /// Store for extrinsic data.
- availability_store: AvailabilityStore,
- /// Live agreements. Maps relay chain parent hashes to attestation
- /// instances.
- live_instances: Mutex<HashMap<Hash, Arc<AttestationTracker>>>,
-}
-
-impl<C, N, P> ParachainValidation<C, N, P> where
- C: Collators + Send + Unpin + 'static + Sync,
- N: Network,
- P: ProvideRuntimeApi<Block> + HeaderBackend<Block> + BlockBody<Block> + Send + Sync + 'static,
- P::Api: ParachainHost<Block> + BlockBuilderApi<Block> + ApiExt<Block, Error = sp_blockchain::Error>,
- C::Collation: Send + Unpin + 'static,
- N::TableRouter: Send + 'static,
- N::BuildTableRouter: Unpin + Send + 'static,
- // Rust bug: https://github.com/rust-lang/rust/issues/24159
- sp_api::StateBackendFor<P, Block>: sp_api::StateBackend<HasherFor<Block>>,
-{
- /// Get an attestation table for given parent hash.
- ///
- /// This starts a parachain agreement process on top of the parent hash if
- /// one has not already started.
- ///
- /// Additionally, this will trigger broadcast of data to the new block's duty
- /// roster.
- fn get_or_instantiate(
- &self,
- parent_hash: Hash,
- keystore: &KeyStorePtr,
- max_block_data_size: Option<u64>,
- )
- -> Result<Arc<AttestationTracker>, Error>
- {
- let mut live_instances = self.live_instances.lock();
- if let Some(tracker) = live_instances.get(&parent_hash) {
- return Ok(tracker.clone());
- }
-
- let id = BlockId::hash(parent_hash);
-
- let validators = self.client.runtime_api().validators(&id)?;
- let sign_with = signing_key(&validators[..], keystore);
-
- let duty_roster = self.client.runtime_api().duty_roster(&id)?;
-
- let (group_info, local_duty) = make_group_info(
- duty_roster,
- &validators,
- sign_with.as_ref().map(|k| k.public()),
- )?;
-
- info!(
- "Starting parachain attestation session on top of parent {:?}. Local parachain duty is {:?}",
- parent_hash,
- local_duty,
- );
-
- let active_parachains = self.client.runtime_api().active_parachains(&id)?;
-
- debug!(target: "validation", "Active parachains: {:?}", active_parachains);
-
- // If we are a validator, we need to store our index in this round in availability store.
- // This will tell which erasure chunk we should store.
- if let Some(ref local_duty) = local_duty {
- if let Err(e) = self.availability_store.add_validator_index_and_n_validators(
- &parent_hash,
- local_duty.index,
- validators.len() as u32,
- ) {
- warn!(
- target: "validation",
- "Failed to add validator index and n_validators to the availability-store: {:?}", e
- )
- }
- }
-
- let table = Arc::new(SharedTable::new(
- validators.clone(),
- group_info,
- sign_with,
- parent_hash,
- self.availability_store.clone(),
- max_block_data_size,
- ));
-
- let (_drop_signal, exit) = exit_future::signal();
-
- let router = self.network.communication_for(
- table.clone(),
- &validators,
- exit.clone(),
- );
-
- if let Some((Chain::Parachain(id), index)) = local_duty.as_ref().map(|d| (d.validation, d.index)) {
- self.launch_work(parent_hash, id, router, max_block_data_size, validators.len(), index, exit);
- }
-
- let tracker = Arc::new(AttestationTracker {
- table,
- started: Instant::now(),
- _drop_signal,
- });
-
- live_instances.insert(parent_hash, tracker.clone());
-
- Ok(tracker)
- }
-
- /// Retain validation sessions matching predicate.
- fn retain<F: FnMut(&Hash) -> bool>(&self, mut pred: F) {
- self.live_instances.lock().retain(|k, _| pred(k))
- }
-
- // launch parachain work asynchronously.
- fn launch_work(
- &self,
- relay_parent: Hash,
- validation_para: ParaId,
- build_router: N::BuildTableRouter,
- max_block_data_size: Option<u64>,
- authorities_num: usize,
- local_id: ValidatorIndex,
- exit: exit_future::Exit,
- ) {
- let (collators, client) = (self.collators.clone(), self.client.clone());
- let availability_store = self.availability_store.clone();
-
- let with_router = move |router: N::TableRouter| {
- // fetch a local collation from connected collators.
- let collation_work = collation_fetch(
- validation_para,
- relay_parent,
- collators,
- client.clone(),
- max_block_data_size,
- );
-
- collation_work.map(move |result| match result {
- Ok((collation, outgoing_targeted, fees_charged)) => {
- match produce_receipt_and_chunks(
- authorities_num,
- &collation.pov,
- &outgoing_targeted,
- fees_charged,
- &collation.info,
- ) {
- Ok((receipt, chunks)) => {
- // Apparently the `async move` block is the only way to convince
- // the compiler that we are not moving values out of borrowed context.
- let av_clone = availability_store.clone();
- let chunks_clone = chunks.clone();
- let receipt_clone = receipt.clone();
-
- let res = async move {
- if let Err(e) = av_clone.clone().add_erasure_chunks(
- relay_parent.clone(),
- receipt_clone,
- chunks_clone,
- ).await {
- warn!(target: "validation", "Failed to add erasure chunks: {}", e);
- }
- }
- .unit_error()
- .boxed()
- .then(move |_| {
- router.local_collation(collation, receipt, outgoing_targeted, (local_id, &chunks));
- ready(())
- });
-
- Ok(Some(res))
- }
- Err(e) => {
- warn!(target: "validation", "Failed to produce a receipt: {:?}", e);
- Ok(None)
- }
- }
- }
- Err(e) => {
- warn!(target: "validation", "Failed to collate candidate: {:?}", e);
- Ok(None)
- }
- })
- };
-
- let router = build_router
- .map_ok(with_router)
- .map_err(|e| {
- warn!(target: "validation" , "Failed to build table router: {:?}", e);
- })
- .and_then(|f| f)
- .and_then(|f| match f {
- Some(f) => f.map(Ok).boxed(),
- None => ready(Ok(())).boxed(),
- }).boxed();
-
- let cancellable_work = select(exit, router).map(drop);
-
- // spawn onto thread pool.
- if self.handle.spawn(cancellable_work).is_err() {
- error!("Failed to spawn cancellable work task");
- }
- }
-}
-
-/// Parachain validation for a single block.
-struct AttestationTracker {
- _drop_signal: exit_future::Signal,
- table: Arc<SharedTable>,
- started: Instant,
-}
-
-/// Polkadot proposer factory.
-pub struct ProposerFactory<C, N, P, SC, TxPool, B> {
- parachain_validation: Arc<ParachainValidation<C, N, P>>,
- transaction_pool: Arc<TxPool>,
- keystore: KeyStorePtr,
- _service_handle: ServiceHandle,
- babe_slot_duration: u64,
- _select_chain: SC,
- max_block_data_size: Option<u64>,
- backend: Arc<B>,
-}
-
-impl<C, N, P, SC, TxPool, B> ProposerFactory<C, N, P, SC, TxPool, B> where
- C: Collators + Send + Sync + Unpin + 'static,
- C::Collation: Send + Unpin + 'static,
- P: BlockchainEvents<Block> + BlockBody<Block>,
- P: ProvideRuntimeApi<Block> + HeaderBackend<Block> + Send + Sync + 'static,
- P::Api: ParachainHost<Block> +
- BlockBuilderApi<Block> +
- BabeApi<Block> +
- ApiExt<Block, Error = sp_blockchain::Error>,
- N: Network + Send + Sync + 'static,
- N::TableRouter: Send + 'static,
- N::BuildTableRouter: Send + Unpin + 'static,
- TxPool: TransactionPool,
- SC: SelectChain<Block> + 'static,
- // Rust bug: https://github.com/rust-lang/rust/issues/24159
- sp_api::StateBackendFor<P, Block>: sp_api::StateBackend<HasherFor<Block>>,
-{
- /// Create a new proposer factory.
- pub fn new(
- client: Arc<P>,
- _select_chain: SC,
- network: N,
- collators: C,
- transaction_pool: Arc<TxPool>,
- thread_pool: TaskExecutor,
- keystore: KeyStorePtr,
- availability_store: AvailabilityStore,
- babe_slot_duration: u64,
- max_block_data_size: Option<u64>,
- backend: Arc<B>,
- ) -> Self {
- let parachain_validation = Arc::new(ParachainValidation {
- client: client.clone(),
- network,
- collators,
- handle: thread_pool.clone(),
- availability_store: availability_store.clone(),
- live_instances: Mutex::new(HashMap::new()),
- });
-
- let service_handle = crate::attestation_service::start(
- client,
- _select_chain.clone(),
- parachain_validation.clone(),
- thread_pool,
- keystore.clone(),
- max_block_data_size,
- );
-
- ProposerFactory {
- parachain_validation,
- transaction_pool,
- keystore,
- _service_handle: service_handle,
- babe_slot_duration,
- _select_chain,
- max_block_data_size,
- backend,
- }
- }
-}
-
-impl<C, N, P, SC, TxPool, B> consensus::Environment<Block> for ProposerFactory<C, N, P, SC, TxPool, B> where
- C: Collators + Send + Unpin + 'static + Sync,
- N: Network,
- TxPool: TransactionPool<Block=Block> + 'static,
- P: ProvideRuntimeApi<Block> + HeaderBackend<Block> + BlockBody<Block> + Send + Sync + 'static,
- P::Api: ParachainHost<Block> +
- BlockBuilderApi<Block> +
- BabeApi<Block> +
- ApiExt<Block, Error = sp_blockchain::Error>,
- C::Collation: Send + Unpin + 'static,
- N::TableRouter: Send + 'static,
- N::BuildTableRouter: Send + Unpin + 'static,
- SC: SelectChain<Block>,
- B: Backend<Block, State = sp_api::StateBackendFor<P, Block>> + 'static,
- // Rust bug: https://github.com/rust-lang/rust/issues/24159
- sp_api::StateBackendFor<P, Block>: sp_api::StateBackend<HasherFor<Block>> + Send,
-{
- type CreateProposer = Pin<Box<
- dyn Future<Output = Result<Self::Proposer, Self::Error>> + Send + Unpin + 'static
- >>;
- type Proposer = Proposer<P, TxPool, B>;
- type Error = Error;
-
- fn init(
- &mut self,
- parent_header: &Header,
- ) -> Self::CreateProposer {
- let parent_hash = parent_header.hash();
- let parent_id = BlockId::hash(parent_hash);
-
- let maybe_proposer = self.parachain_validation.get_or_instantiate(
- parent_hash,
- &self.keystore,
- self.max_block_data_size,
- ).map(|tracker| Proposer {
- client: self.parachain_validation.client.clone(),
- tracker,
- parent_hash,
- parent_id,
- parent_number: parent_header.number,
- transaction_pool: self.transaction_pool.clone(),
- slot_duration: self.babe_slot_duration,
- backend: self.backend.clone(),
- });
-
- Box::pin(future::ready(maybe_proposer))
- }
-}
-
-/// The local duty of a validator.
-#[derive(Debug)]
-pub struct LocalDuty {
- validation: Chain,
- index: ValidatorIndex,
-}
-
-/// The Polkadot proposer logic.
-pub struct Proposer<Client, TxPool, Backend> {
- client: Arc<Client>,
- parent_hash: Hash,
- parent_id: BlockId,
- parent_number: BlockNumber,
- tracker: Arc<AttestationTracker>,
- transaction_pool: Arc<TxPool>,
- slot_duration: u64,
- backend: Arc<Backend>,
-}
-
-impl<Client, TxPool, Backend> consensus::Proposer<Block> for Proposer<Client, TxPool, Backend> where
- TxPool: TransactionPool<Block=Block> + 'static,
- Client: ProvideRuntimeApi<Block> + HeaderBackend<Block> + Send + Sync + 'static,
- Client::Api: ParachainHost<Block> + BlockBuilderApi<Block> + ApiExt<Block, Error = sp_blockchain::Error>,
- Backend: sc_client_api::Backend<Block, State = sp_api::StateBackendFor<Client, Block>> + 'static,
- // Rust bug: https://github.com/rust-lang/rust/issues/24159
- sp_api::StateBackendFor<Client, Block>: sp_api::StateBackend<HasherFor<Block>> + Send,
-{
- type Error = Error;
- type Transaction = sp_api::TransactionFor<Client, Block>;
- type Proposal = Pin<
- Box<
- dyn Future<Output = Result<Proposal<Block, sp_api::TransactionFor<Client, Block>>, Error>>
- + Send
- >
- >;
-
- fn propose(&mut self,
- inherent_data: InherentData,
- inherent_digests: DigestFor<Block>,
- max_duration: Duration,
- record_proof: RecordProof,
- ) -> Self::Proposal {
- const SLOT_DURATION_DENOMINATOR: u64 = 3; // wait up to 1/3 of the slot for candidates.
-
- let initial_included = self.tracker.table.includable_count();
- let now = Instant::now();
-
- let dynamic_inclusion = DynamicInclusion::new(
- self.tracker.table.num_parachains(),
- self.tracker.started,
- Duration::from_millis(self.slot_duration / SLOT_DURATION_DENOMINATOR),
- );
-
- let parent_hash = self.parent_hash.clone();
- let parent_number = self.parent_number.clone();
- let parent_id = self.parent_id.clone();
- let client = self.client.clone();
- let transaction_pool = self.transaction_pool.clone();
- let table = self.tracker.table.clone();
- let backend = self.backend.clone();
-
- async move {
- let enough_candidates = dynamic_inclusion.acceptable_in(
- now,
- initial_included,
- ).unwrap_or_else(|| Duration::from_millis(1));
-
- let believed_timestamp = match inherent_data.timestamp_inherent_data() {
- Ok(timestamp) => timestamp,
- Err(e) => return Err(Error::InherentError(e)),
- };
-
- let deadline_diff = max_duration - max_duration / 3;
- let deadline = match Instant::now().checked_add(deadline_diff) {
- None => return Err(Error::DeadlineComputeFailure(deadline_diff)),
- Some(d) => d,
- };
-
- let data = CreateProposalData {
- parent_hash,
- parent_number,
- parent_id,
- client,
- transaction_pool,
- table,
- believed_minimum_timestamp: believed_timestamp,
- inherent_data: Some(inherent_data),
- inherent_digests,
- // leave some time for the proposal finalisation
- deadline,
- record_proof,
- backend,
- };
-
- // set up delay until next allowed timestamp.
- let current_timestamp = current_timestamp();
- if current_timestamp < believed_timestamp {
- Delay::new(Duration::from_millis(current_timestamp - believed_timestamp))
- .await;
- }
-
- Delay::new(enough_candidates).await;
-
- tokio_executor::blocking::run(move || {
- let proposed_candidates = data.table.proposed_set();
- data.propose_with(proposed_candidates)
- })
- .await
- }.boxed()
- }
-}
-
-fn current_timestamp() -> u64 {
- time::SystemTime::now().duration_since(time::UNIX_EPOCH)
- .expect("now always later than unix epoch; qed")
- .as_millis() as u64
-}
-
-/// Inner data of the create proposal.
-struct CreateProposalData<Client, TxPool, Backend> {
- parent_hash: Hash,
- parent_number: BlockNumber,
- parent_id: BlockId,
- client: Arc<Client>,
- transaction_pool: Arc<TxPool>,
- table: Arc<SharedTable>,
- believed_minimum_timestamp: u64,
- inherent_data: Option<InherentData>,
- inherent_digests: DigestFor<Block>,
- deadline: Instant,
- record_proof: RecordProof,
- backend: Arc<Backend>,
-}
-
-impl<Client, TxPool, Backend> CreateProposalData<Client, TxPool, Backend> where
- TxPool: TransactionPool<Block=Block>,
- Client: ProvideRuntimeApi<Block> + HeaderBackend<Block> + Send + Sync,
- Client::Api: ParachainHost<Block> + BlockBuilderApi<Block> + ApiExt<Block, Error = sp_blockchain::Error>,
- Backend: sc_client_api::Backend<Block, State = sp_api::StateBackendFor<Client, Block>> + 'static,
- // Rust bug: https://github.com/rust-lang/rust/issues/24159
- sp_api::StateBackendFor<Client, Block>: sp_api::StateBackend<HasherFor<Block>> + Send,
-{
- fn propose_with(
- mut self,
- candidates: Vec<AttestedCandidate>,
- ) -> Result<Proposal<Block, sp_api::TransactionFor<Client, Block>>, Error> {
- use runtime_primitives::traits::{Hash as HashT, BlakeTwo256};
-
- const MAX_TRANSACTIONS: usize = 40;
-
- let mut inherent_data = self.inherent_data
- .take()
- .expect("CreateProposal is not polled after finishing; qed");
- inherent_data.put_data(NEW_HEADS_IDENTIFIER, &candidates)
- .map_err(Error::InherentError)?;
-
- let runtime_api = self.client.runtime_api();
-
- let mut block_builder = block_builder::BlockBuilder::new(
- &*self.client,
- self.client.expect_block_hash_from_id(&self.parent_id)?,
- self.client.expect_block_number_from_id(&self.parent_id)?,
- self.record_proof,
- self.inherent_digests.clone(),
- &*self.backend,
- )?;
-
- {
- let inherents = runtime_api.inherent_extrinsics(&self.parent_id, inherent_data)?;
- for inherent in inherents {
- block_builder.push(inherent)?;
- }
-
- let mut unqueue_invalid = Vec::new();
- let mut pending_size = 0;
-
- let ready_iter = self.transaction_pool.ready();
- for ready in ready_iter.take(MAX_TRANSACTIONS) {
- let encoded_size = ready.data().encode().len();
- if pending_size + encoded_size >= MAX_TRANSACTIONS_SIZE {
- break;
- }
- if Instant::now() > self.deadline {
- debug!("Consensus deadline reached when pushing block transactions, proceeding with proposing.");
- break;
- }
-
- match block_builder.push(ready.data().clone()) {
- Ok(()) => {
- debug!("[{:?}] Pushed to the block.", ready.hash());
- pending_size += encoded_size;
- }
- Err(sp_blockchain::Error::ApplyExtrinsicFailed(sp_blockchain::ApplyExtrinsicFailed::Validity(e)))
- if e.exhausted_resources() =>
- {
- debug!("Block is full, proceed with proposing.");
- break;
- }
- Err(e) => {
- trace!(target: "transaction-pool", "Invalid transaction: {}", e);
- unqueue_invalid.push(ready.hash().clone());
- }
- }
- }
-
- self.transaction_pool.remove_invalid(&unqueue_invalid);
- }
-
- let (new_block, storage_changes, proof) = block_builder.build()?.into_inner();
-
- info!("Prepared block for proposing at {} [hash: {:?}; parent_hash: {}; extrinsics: [{}]]",
- new_block.header.number,
- Hash::from(new_block.header.hash()),
- new_block.header.parent_hash,
- new_block.extrinsics.iter()
- .map(|xt| format!("{}", BlakeTwo256::hash_of(xt)))
- .collect::<Vec<_>>()
- .join(", ")
- );
-
- // TODO: full re-evaluation (https://github.com/paritytech/polkadot/issues/216)
- let active_parachains = runtime_api.active_parachains(&self.parent_id)?;
- assert!(evaluation::evaluate_initial(
- &new_block,
- self.believed_minimum_timestamp,
- &self.parent_hash,
- self.parent_number,
- &active_parachains[..],
- ).is_ok());
-
- Ok(Proposal { block: new_block, storage_changes, proof })
- }
-}
-
#[cfg(test)]
mod tests {
use super::*;
diff --git a/polkadot/validation/src/shared_table/mod.rs b/polkadot/validation/src/shared_table/mod.rs
index ad5eca61b3d..a6c22d62745 100644
--- a/polkadot/validation/src/shared_table/mod.rs
+++ b/polkadot/validation/src/shared_table/mod.rs
@@ -431,7 +431,10 @@ impl SharedTable {
/// Import a single statement with remote source, whose signature has already been checked.
///
- /// The statement producer, if any, will produce only statements concerning the same candidate
+ /// Validity and invalidity statements are only valid if the corresponding
+ /// candidate has already been imported.
+ ///
+ /// The ParachainWork, if any, will produce only statements concerning the same candidate
/// as the one just imported
pub fn import_remote_statement<R: TableRouter>(
&self,
@@ -446,8 +449,10 @@ impl SharedTable {
/// Import many statements at once.
///
/// Provide an iterator yielding remote, pre-checked statements.
+ /// Validity and invalidity statements are only valid if the corresponding
+ /// candidate has already been imported.
///
- /// The statement producer, if any, will produce only statements concerning the same candidate
+ /// The ParachainWork, if any, will produce only statements concerning the same candidate
/// as the one just imported
pub fn import_remote_statements<R, I, U>(&self, router: &R, iterable: I) -> U
where
diff --git a/polkadot/validation/src/validation_service/mod.rs b/polkadot/validation/src/validation_service/mod.rs
new file mode 100644
index 00000000000..14dd85c72ee
--- /dev/null
+++ b/polkadot/validation/src/validation_service/mod.rs
@@ -0,0 +1,463 @@
+// Copyright 2017-2020 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot. If not, see <http://www.gnu.org/licenses/>.
+
+//! The validation service is a long-running future that creates and manages parachain attestation
+//! instances.
+//!
+//! As soon as we import a new chain head, we start a parachain attestation session on top of it.
+//! The block authorship service may want access to the attestation session, and for that reason
+//! we expose a `ServiceHandle` which can be used to request a copy of it.
+//!
+//! In fact, the import notification and request from the block production pipeline may race to be
+//! the first one to create the instant, but the import notification will usually win.
+//!
+//! These attestation sessions are kept live until they are periodically garbage-collected.
+
+use std::{time::{Duration, Instant}, sync::Arc};
+use std::collections::HashMap;
+
+use sc_client_api::{BlockchainEvents, BlockBody};
+use sp_blockchain::HeaderBackend;
+use block_builder::BlockBuilderApi;
+use consensus::SelectChain;
+use futures::prelude::*;
+use futures::{future::{ready, select}, task::{Spawn, SpawnExt}};
+use polkadot_primitives::{Block, Hash, BlockId};
+use polkadot_primitives::parachain::{
+ Chain, ParachainHost, Id as ParaId, ValidatorIndex, ValidatorId, ValidatorPair,
+};
+use babe_primitives::BabeApi;
+use keystore::KeyStorePtr;
+use sp_api::{ApiExt, ProvideRuntimeApi};
+use runtime_primitives::traits::HasherFor;
+use availability_store::Store as AvailabilityStore;
+
+use log::{warn, error, info, debug};
+
+use super::{Network, Collators, SharedTable, TableRouter};
+use crate::Error;
+
+/// A handle to spawn background tasks onto.
+pub type TaskExecutor = Arc<dyn Spawn + Send + Sync>;
+
+// Remote processes may request for a validation instance to be cloned or instantiated.
+// They send a oneshot channel.
+type ValidationInstanceRequest = (
+ Hash,
+ futures::channel::oneshot::Sender<Result<Arc<ValidationInstanceHandle>, Error>>,
+);
+
+/// A handle to a single instance of parachain validation, which is pinned to
+/// a specific relay-chain block. This is the instance that should be used when
+/// constructing any
+pub(crate) struct ValidationInstanceHandle {
+ _drop_signal: exit_future::Signal,
+ table: Arc<SharedTable>,
+ started: Instant,
+}
+
+impl ValidationInstanceHandle {
+ /// Access the underlying table of attestations on parachain candidates.
+ pub(crate) fn table(&self) -> &Arc<SharedTable> {
+ &self.table
+ }
+
+ /// The moment we started this validation instance.
+ pub(crate) fn started(&self) -> Instant {
+ self.started.clone()
+ }
+}
+
+/// A handle to the service. This can be used to create a block-production environment.
+#[derive(Clone)]
+pub struct ServiceHandle {
+ sender: futures::channel::mpsc::Sender<ValidationInstanceRequest>,
+}
+
+impl ServiceHandle {
+ /// Requests instantiation or cloning of a validation instance from the service.
+ ///
+ /// This can fail if the service task has shut down for some reason.
+ pub(crate) async fn get_validation_instance(self, relay_parent: Hash)
+ -> Result<Arc<ValidationInstanceHandle>, Error>
+ {
+ let mut sender = self.sender;
+ let instance_rx = loop {
+ let (instance_tx, instance_rx) = futures::channel::oneshot::channel();
+ match sender.send((relay_parent, instance_tx)).await {
+ Ok(()) => break instance_rx,
+ Err(e) => if !e.is_full() {
+ // Sink::send should be doing `poll_ready` before start-send,
+ // so this should only happen when there is a race.
+ return Err(Error::ValidationServiceDown)
+ },
+ }
+ };
+
+ instance_rx.map_err(|_| Error::ValidationServiceDown).await.and_then(|x| x)
+ }
+}
+
+fn interval(duration: Duration) -> impl Stream<Item=()> + Send + Unpin {
+ stream::unfold((), move |_| {
+ futures_timer::Delay::new(duration).map(|_| Some(((), ())))
+ }).map(drop)
+}
+
+/// A builder for the validation service.
+pub struct ServiceBuilder<C, N, P, SC> {
+ /// The underlying blockchain client.
+ pub client: Arc<P>,
+ /// A handle to the network object used to communicate.
+ pub network: N,
+ /// A handle to the collator pool we are using.
+ pub collators: C,
+ /// A handle to a background executor.
+ pub task_executor: TaskExecutor,
+ /// A handle to the availability store.
+ pub availability_store: AvailabilityStore,
+ /// A chain selector for determining active leaves in the block-DAG.
+ pub select_chain: SC,
+ /// The keystore which holds the signing keys.
+ pub keystore: KeyStorePtr,
+ /// The maximum block-data size in bytes.
+ pub max_block_data_size: Option<u64>,
+}
+
+impl<C, N, P, SC> ServiceBuilder<C, N, P, SC> where
+ C: Collators + Send + Sync + Unpin + 'static,
+ C::Collation: Send + Unpin + 'static,
+ P: BlockchainEvents<Block> + BlockBody<Block>,
+ P: ProvideRuntimeApi<Block> + HeaderBackend<Block> + Send + Sync + 'static,
+ P::Api: ParachainHost<Block> +
+ BlockBuilderApi<Block> +
+ BabeApi<Block> +
+ ApiExt<Block, Error = sp_blockchain::Error>,
+ N: Network + Send + Sync + 'static,
+ N::TableRouter: Send + 'static,
+ N::BuildTableRouter: Send + Unpin + 'static,
+ SC: SelectChain<Block> + 'static,
+ // Rust bug: https://github.com/rust-lang/rust/issues/24159
+ sp_api::StateBackendFor<P, Block>: sp_api::StateBackend<HasherFor<Block>>,
+{
+ /// Build the service - this consists of a handle to it, as well as a background
+ /// future to be run to completion.
+ pub fn build(self) -> (ServiceHandle, impl Future<Output = ()> + Send + 'static) {
+ const TIMER_INTERVAL: Duration = Duration::from_secs(30);
+ const CHAN_BUFFER: usize = 10;
+
+ enum Message {
+ CollectGarbage,
+ // relay-parent, receiver for instance.
+ RequestInstance(ValidationInstanceRequest),
+ // new chain heads - import notification.
+ NotifyImport(sc_client_api::BlockImportNotification<Block>),
+ }
+
+ let mut parachain_validation = ParachainValidationInstances {
+ client: self.client.clone(),
+ network: self.network,
+ collators: self.collators,
+ handle: self.task_executor,
+ availability_store: self.availability_store,
+ live_instances: HashMap::new(),
+ };
+
+ let client = self.client;
+ let select_chain = self.select_chain;
+ let keystore = self.keystore;
+ let max_block_data_size = self.max_block_data_size;
+
+ let (tx, rx) = futures::channel::mpsc::channel(CHAN_BUFFER);
+ let interval = interval(TIMER_INTERVAL).map(|_| Message::CollectGarbage);
+ let import_notifications = client.import_notification_stream().map(Message::NotifyImport);
+ let instance_requests = rx.map(Message::RequestInstance);
+ let service = ServiceHandle { sender: tx };
+
+ let background_work = async move {
+ let message_stream = futures::stream::select(interval, instance_requests);
+ let mut message_stream = futures::stream::select(import_notifications, message_stream);
+ while let Some(message) = message_stream.next().await {
+ match message {
+ Message::CollectGarbage => {
+ match select_chain.leaves() {
+ Ok(leaves) => {
+ parachain_validation.retain(|h| leaves.contains(h));
+ }
+ Err(e) => {
+ warn!("Error fetching leaves from client: {:?}", e);
+ }
+ }
+ }
+ Message::RequestInstance((relay_parent, sender)) => {
+ // Upstream will handle the failure case.
+ let _ = sender.send(parachain_validation.get_or_instantiate(
+ relay_parent,
+ &keystore,
+ max_block_data_size,
+ ));
+ }
+ Message::NotifyImport(notification) => {
+ let relay_parent = notification.hash;
+ if notification.is_new_best {
+ let res = parachain_validation.get_or_instantiate(
+ relay_parent,
+ &keystore,
+ max_block_data_size,
+ );
+
+ if let Err(e) = res {
+ warn!(
+ "Unable to start parachain validation on top of {:?}: {}",
+ relay_parent, e
+ );
+ }
+ }
+ }
+ }
+ }
+ };
+
+ (service, background_work)
+ }
+}
+
+// finds the first key we are capable of signing with out of the given set of validators,
+// if any.
+fn signing_key(validators: &[ValidatorId], keystore: &KeyStorePtr) -> Option<Arc<ValidatorPair>> {
+ let keystore = keystore.read();
+ validators.iter()
+ .find_map(|v| {
+ keystore.key_pair::<ValidatorPair>(&v).ok()
+ })
+ .map(|pair| Arc::new(pair))
+}
+
+/// Constructs parachain-agreement instances.
+pub(crate) struct ParachainValidationInstances<C, N, P> {
+ /// The client instance.
+ client: Arc<P>,
+ /// The backing network handle.
+ network: N,
+ /// Parachain collators.
+ collators: C,
+ /// handle to remote task executor
+ handle: TaskExecutor,
+ /// Store for extrinsic data.
+ availability_store: AvailabilityStore,
+ /// Live agreements. Maps relay chain parent hashes to attestation
+ /// instances.
+ live_instances: HashMap<Hash, Arc<ValidationInstanceHandle>>,
+}
+
+impl<C, N, P> ParachainValidationInstances<C, N, P> where
+ C: Collators + Send + Unpin + 'static,
+ N: Network,
+ P: ProvideRuntimeApi<Block> + HeaderBackend<Block> + BlockBody<Block> + Send + Sync + 'static,
+ P::Api: ParachainHost<Block> + BlockBuilderApi<Block> + ApiExt<Block, Error = sp_blockchain::Error>,
+ C::Collation: Send + Unpin + 'static,
+ N::TableRouter: Send + 'static,
+ N::BuildTableRouter: Unpin + Send + 'static,
+ // Rust bug: https://github.com/rust-lang/rust/issues/24159
+ sp_api::StateBackendFor<P, Block>: sp_api::StateBackend<HasherFor<Block>>,
+{
+ /// Get an attestation table for given parent hash.
+ ///
+ /// This starts a parachain agreement process on top of the parent hash if
+ /// one has not already started.
+ ///
+ /// Additionally, this will trigger broadcast of data to the new block's duty
+ /// roster.
+ fn get_or_instantiate(
+ &mut self,
+ parent_hash: Hash,
+ keystore: &KeyStorePtr,
+ max_block_data_size: Option<u64>,
+ )
+ -> Result<Arc<ValidationInstanceHandle>, Error>
+ {
+ use primitives::Pair;
+
+ if let Some(tracker) = self.live_instances.get(&parent_hash) {
+ return Ok(tracker.clone());
+ }
+
+ let id = BlockId::hash(parent_hash);
+
+ let validators = self.client.runtime_api().validators(&id)?;
+ let sign_with = signing_key(&validators[..], keystore);
+
+ let duty_roster = self.client.runtime_api().duty_roster(&id)?;
+
+ let (group_info, local_duty) = crate::make_group_info(
+ duty_roster,
+ &validators,
+ sign_with.as_ref().map(|k| k.public()),
+ )?;
+
+ info!(
+ "Starting parachain attestation session on top of parent {:?}. Local parachain duty is {:?}",
+ parent_hash,
+ local_duty,
+ );
+
+ let active_parachains = self.client.runtime_api().active_parachains(&id)?;
+
+ debug!(target: "validation", "Active parachains: {:?}", active_parachains);
+
+ // If we are a validator, we need to store our index in this round in availability store.
+ // This will tell which erasure chunk we should store.
+ if let Some(ref local_duty) = local_duty {
+ if let Err(e) = self.availability_store.add_validator_index_and_n_validators(
+ &parent_hash,
+ local_duty.index,
+ validators.len() as u32,
+ ) {
+ warn!(
+ target: "validation",
+ "Failed to add validator index and n_validators to the availability-store: {:?}", e
+ )
+ }
+ }
+
+ let table = Arc::new(SharedTable::new(
+ validators.clone(),
+ group_info,
+ sign_with,
+ parent_hash,
+ self.availability_store.clone(),
+ max_block_data_size,
+ ));
+
+ let (_drop_signal, exit) = exit_future::signal();
+
+ let router = self.network.communication_for(
+ table.clone(),
+ &validators,
+ exit.clone(),
+ );
+
+ if let Some((Chain::Parachain(id), index)) = local_duty.as_ref().map(|d| (d.validation, d.index)) {
+ self.launch_work(parent_hash, id, router, max_block_data_size, validators.len(), index, exit);
+ }
+
+ let tracker = Arc::new(ValidationInstanceHandle {
+ table,
+ started: Instant::now(),
+ _drop_signal,
+ });
+
+ self.live_instances.insert(parent_hash, tracker.clone());
+
+ Ok(tracker)
+ }
+
+ /// Retain validation sessions matching predicate.
+ fn retain<F: FnMut(&Hash) -> bool>(&mut self, mut pred: F) {
+ self.live_instances.retain(|k, _| pred(k))
+ }
+
+ // launch parachain work asynchronously.
+ fn launch_work(
+ &self,
+ relay_parent: Hash,
+ validation_para: ParaId,
+ build_router: N::BuildTableRouter,
+ max_block_data_size: Option<u64>,
+ authorities_num: usize,
+ local_id: ValidatorIndex,
+ exit: exit_future::Exit,
+ ) {
+ let (collators, client) = (self.collators.clone(), self.client.clone());
+ let availability_store = self.availability_store.clone();
+
+ let with_router = move |router: N::TableRouter| {
+ // fetch a local collation from connected collators.
+ let collation_work = crate::collation::collation_fetch(
+ validation_para,
+ relay_parent,
+ collators,
+ client.clone(),
+ max_block_data_size,
+ );
+
+ collation_work.map(move |result| match result {
+ Ok((collation, outgoing_targeted, fees_charged)) => {
+ match crate::collation::produce_receipt_and_chunks(
+ authorities_num,
+ &collation.pov,
+ &outgoing_targeted,
+ fees_charged,
+ &collation.info,
+ ) {
+ Ok((receipt, chunks)) => {
+ // Apparently the `async move` block is the only way to convince
+ // the compiler that we are not moving values out of borrowed context.
+ let av_clone = availability_store.clone();
+ let chunks_clone = chunks.clone();
+ let receipt_clone = receipt.clone();
+
+ let res = async move {
+ if let Err(e) = av_clone.clone().add_erasure_chunks(
+ relay_parent.clone(),
+ receipt_clone,
+ chunks_clone,
+ ).await {
+ warn!(target: "validation", "Failed to add erasure chunks: {}", e);
+ }
+ }
+ .unit_error()
+ .boxed()
+ .then(move |_| {
+ router.local_collation(
+ collation,
+ receipt,
+ outgoing_targeted,
+ (local_id, &chunks),
+ );
+ ready(())
+ });
+
+
+ Some(res)
+ }
+ Err(e) => {
+ warn!(target: "validation", "Failed to produce a receipt: {:?}", e);
+ None
+ }
+ }
+ }
+ Err(e) => {
+ warn!(target: "validation", "Failed to collate candidate: {:?}", e);
+ None
+ }
+ })
+ };
+
+ let router = build_router
+ .map_ok(with_router)
+ .map_err(|e| {
+ warn!(target: "validation" , "Failed to build table router: {:?}", e);
+ });
+
+ let cancellable_work = select(exit, router).map(drop);
+
+ // spawn onto thread pool.
+ if self.handle.spawn(cancellable_work).is_err() {
+ error!("Failed to spawn cancellable work task");
+ }
+ }
+}
--
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