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Fix cycle dispute-coordinator <-> dispute-distribution (#6489)

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* First iteration of message sender.

* dyn Fn variant (no cloning)

* Full implementation + Clone, without allocs on `Send`

* Further clarifications/cleanup.

* MessageSender -> NestingSender

* Doc update/clarification.

* dispute-coordinator: Send disputes on startup.

+ Some fixes, cleanup.

* Fix whitespace.

* Dispute distribution fixes, cleanup.

* Cargo.lock

* Fix spaces.

* More format fixes.

What is cargo fmt doing actually?

* More fmt fixes.

* Fix nesting sender.

* Fixes.

* Whitespace

* Enable logging.

* Guide update.

* Fmt fixes, typos.

* Remove unused function.

* Simplifications, doc fixes.

* Update roadmap/implementers-guide/src/node/disputes/dispute-coordinator.md

Co-authored-by: Marcin S. <marcin@bytedude.com>

* Fmt + doc example fix.

Co-authored-by: eskimor <eskimor@no-such-url.com>
Co-authored-by: Marcin S. <marcin@bytedude.com>
This commit is contained in:
eskimor
2023-01-10 12:04:05 +01:00
committed by GitHub
parent 44fd95661c
commit cc650fe53d
16 changed files with 778 additions and 642 deletions
Download Patch File Download Diff File Expand all files Collapse all files
polkadot/Cargo.lock
Generated
+2
View File
@@ -6737,6 +6737,7 @@ dependencies = [
"sp-core",
"sp-keyring",
"sp-keystore",
"sp-tracing",
"thiserror",
"tracing-gum",
]
@@ -7005,6 +7006,7 @@ dependencies = [
"env_logger 0.9.0",
"fatality",
"futures",
"futures-channel",
"itertools",
"kvdb",
"kvdb-memorydb",
polkadot/node/core/dispute-coordinator/Cargo.toml
+1
View File
@@ -31,6 +31,7 @@ assert_matches = "1.4.0"
test-helpers = { package = "polkadot-primitives-test-helpers", path = "../../../primitives/test-helpers" }
futures-timer = "3.0.2"
sp-application-crypto = { git = "https://github.com/paritytech/substrate", branch = "master" }
sp-tracing = { git = "https://github.com/paritytech/substrate", branch = "master" }
[features]
# If not enabled, the dispute coordinator will do nothing.
polkadot/node/core/dispute-coordinator/src/import.rs
+61 -43
View File
@@ -87,60 +87,69 @@ impl<'a> CandidateEnvironment<'a> {
/// Whether or not we already issued some statement about a candidate.
pub enum OwnVoteState {
/// We already voted/issued a statement for the candidate.
Voted,
/// We already voted/issued a statement for the candidate and it was an approval vote.
/// Our votes, if any.
Voted(Vec<(ValidatorIndex, (DisputeStatement, ValidatorSignature))>),
/// We are not a parachain validator in the session.
///
/// Needs special treatment as we have to make sure to propagate it to peers, to guarantee the
/// dispute can conclude.
VotedApproval(Vec<(ValidatorIndex, ValidatorSignature)>),
/// We not yet voted for the dispute.
NoVote,
/// Hence we cannot vote.
CannotVote,
}
impl OwnVoteState {
fn new<'a>(votes: &CandidateVotes, env: &CandidateEnvironment<'a>) -> Self {
let mut our_valid_votes = env
.controlled_indices()
let controlled_indices = env.controlled_indices();
if controlled_indices.is_empty() {
return Self::CannotVote
}
let our_valid_votes = controlled_indices
.iter()
.filter_map(|i| votes.valid.raw().get_key_value(i))
.peekable();
let mut our_invalid_votes =
env.controlled_indices.iter().filter_map(|i| votes.invalid.get_key_value(i));
let has_valid_votes = our_valid_votes.peek().is_some();
let has_invalid_votes = our_invalid_votes.next().is_some();
let our_approval_votes: Vec<_> = our_valid_votes
.filter_map(|(index, (k, sig))| {
if let ValidDisputeStatementKind::ApprovalChecking = k {
Some((*index, sig.clone()))
} else {
None
}
})
.collect();
.map(|(index, (kind, sig))| (*index, (DisputeStatement::Valid(*kind), sig.clone())));
let our_invalid_votes = controlled_indices
.iter()
.filter_map(|i| votes.invalid.get_key_value(i))
.map(|(index, (kind, sig))| (*index, (DisputeStatement::Invalid(*kind), sig.clone())));
if !our_approval_votes.is_empty() {
return Self::VotedApproval(our_approval_votes)
}
if has_valid_votes || has_invalid_votes {
return Self::Voted
}
Self::NoVote
Self::Voted(our_valid_votes.chain(our_invalid_votes).collect())
}
/// Whether or not we issued a statement for the candidate already.
fn voted(&self) -> bool {
/// Is a vote from us missing but we are a validator able to vote?
fn vote_missing(&self) -> bool {
match self {
Self::Voted | Self::VotedApproval(_) => true,
Self::NoVote => false,
Self::Voted(votes) if votes.is_empty() => true,
Self::Voted(_) | Self::CannotVote => false,
}
}
/// Get own approval votes, if any.
fn approval_votes(&self) -> Option<&Vec<(ValidatorIndex, ValidatorSignature)>> {
///
/// Empty iterator means, no approval votes. `None` means, there will never be any (we cannot
/// vote).
fn approval_votes(
&self,
) -> Option<impl Iterator<Item = (ValidatorIndex, &ValidatorSignature)>> {
match self {
Self::VotedApproval(votes) => Some(&votes),
_ => None,
Self::Voted(votes) => Some(votes.iter().filter_map(|(index, (kind, sig))| {
if let DisputeStatement::Valid(ValidDisputeStatementKind::ApprovalChecking) = kind {
Some((*index, sig))
} else {
None
}
})),
Self::CannotVote => None,
}
}
/// Get our votes if there are any.
///
/// Empty iterator means, no votes. `None` means, there will never be any (we cannot
/// vote).
fn votes(&self) -> Option<&Vec<(ValidatorIndex, (DisputeStatement, ValidatorSignature))>> {
match self {
Self::Voted(votes) => Some(&votes),
Self::CannotVote => None,
}
}
}
@@ -170,7 +179,7 @@ impl CandidateVoteState<CandidateVotes> {
valid: ValidCandidateVotes::new(),
invalid: BTreeMap::new(),
};
Self { votes, own_vote: OwnVoteState::NoVote, dispute_status: None }
Self { votes, own_vote: OwnVoteState::CannotVote, dispute_status: None }
}
/// Create a new `CandidateVoteState` from already existing votes.
@@ -327,16 +336,25 @@ impl<V> CandidateVoteState<V> {
self.dispute_status.map_or(false, |s| s.is_confirmed_concluded())
}
/// This machine already cast some vote in that dispute/for that candidate.
pub fn has_own_vote(&self) -> bool {
self.own_vote.voted()
/// Are we a validator in the session, but have not yet voted?
pub fn own_vote_missing(&self) -> bool {
self.own_vote.vote_missing()
}
/// Own approval votes if any:
pub fn own_approval_votes(&self) -> Option<&Vec<(ValidatorIndex, ValidatorSignature)>> {
pub fn own_approval_votes(
&self,
) -> Option<impl Iterator<Item = (ValidatorIndex, &ValidatorSignature)>> {
self.own_vote.approval_votes()
}
/// Get own votes if there are any.
pub fn own_votes(
&self,
) -> Option<&Vec<(ValidatorIndex, (DisputeStatement, ValidatorSignature))>> {
self.own_vote.votes()
}
/// Whether or not there is a dispute and it has already enough valid votes to conclude.
pub fn has_concluded_for(&self) -> bool {
self.dispute_status.map_or(false, |s| s.has_concluded_for())
polkadot/node/core/dispute-coordinator/src/initialized.rs
+32 -104
View File
@@ -26,8 +26,7 @@ use futures::{
use sc_keystore::LocalKeystore;
use polkadot_node_primitives::{
disputes::ValidCandidateVotes, CandidateVotes, DisputeMessage, DisputeMessageCheckError,
DisputeStatus, SignedDisputeStatement, Timestamp,
disputes::ValidCandidateVotes, CandidateVotes, DisputeStatus, SignedDisputeStatement, Timestamp,
};
use polkadot_node_subsystem::{
messages::{
@@ -48,6 +47,7 @@ use polkadot_primitives::v2::{
use crate::{
error::{log_error, Error, FatalError, FatalResult, JfyiError, JfyiResult, Result},
import::{CandidateEnvironment, CandidateVoteState},
is_potential_spam,
metrics::Metrics,
status::{get_active_with_status, Clock},
DisputeCoordinatorSubsystem, LOG_TARGET,
@@ -55,7 +55,7 @@ use crate::{
use super::{
backend::Backend,
db,
db, make_dispute_message,
participation::{
self, Participation, ParticipationPriority, ParticipationRequest, ParticipationStatement,
WorkerMessageReceiver,
@@ -396,19 +396,19 @@ impl Initialized {
CompactStatement::Valid(_) =>
ValidDisputeStatementKind::BackingValid(relay_parent),
};
debug_assert!(
SignedDisputeStatement::new_checked(
debug_assert!(
SignedDisputeStatement::new_checked(
DisputeStatement::Valid(valid_statement_kind),
candidate_hash,
session,
validator_public.clone(),
validator_signature.clone(),
).is_ok(),
"Scraped backing votes had invalid signature! candidate: {:?}, session: {:?}, validator_public: {:?}",
candidate_hash,
session,
validator_public,
);
).is_ok(),
"Scraped backing votes had invalid signature! candidate: {:?}, session: {:?}, validator_public: {:?}",
candidate_hash,
session,
validator_public,
);
let signed_dispute_statement =
SignedDisputeStatement::new_unchecked_from_trusted_source(
DisputeStatement::Valid(valid_statement_kind),
@@ -492,20 +492,20 @@ impl Initialized {
})
.cloned()?;
debug_assert!(
SignedDisputeStatement::new_checked(
debug_assert!(
SignedDisputeStatement::new_checked(
dispute_statement.clone(),
candidate_hash,
session,
validator_public.clone(),
validator_signature.clone(),
).is_ok(),
"Scraped dispute votes had invalid signature! candidate: {:?}, session: {:?}, dispute_statement: {:?}, validator_public: {:?}",
candidate_hash,
session,
).is_ok(),
"Scraped dispute votes had invalid signature! candidate: {:?}, session: {:?}, dispute_statement: {:?}, validator_public: {:?}",
candidate_hash,
session,
dispute_statement,
validator_public,
);
validator_public,
);
Some((
SignedDisputeStatement::new_unchecked_from_trusted_source(
@@ -845,18 +845,16 @@ impl Initialized {
let is_included = self.scraper.is_candidate_included(&candidate_hash);
let is_backed = self.scraper.is_candidate_backed(&candidate_hash);
let has_own_vote = new_state.has_own_vote();
let own_vote_missing = new_state.own_vote_missing();
let is_disputed = new_state.is_disputed();
let has_controlled_indices = !env.controlled_indices().is_empty();
let is_confirmed = new_state.is_confirmed();
let potential_spam =
!is_included && !is_backed && !new_state.is_confirmed() && !new_state.has_own_vote();
// We participate only in disputes which are included, backed or confirmed
let allow_participation = is_included || is_backed || is_confirmed;
let potential_spam = is_potential_spam(&self.scraper, &new_state, &candidate_hash);
// We participate only in disputes which are not potential spam.
let allow_participation = !potential_spam;
gum::trace!(
target: LOG_TARGET,
has_own_vote = ?new_state.has_own_vote(),
?own_vote_missing,
?potential_spam,
?is_included,
?candidate_hash,
@@ -903,7 +901,7 @@ impl Initialized {
// - `is_included` lands in prioritised queue
// - `is_confirmed` | `is_backed` lands in best effort queue
// We don't participate in disputes on finalized candidates.
if !has_own_vote && is_disputed && has_controlled_indices && allow_participation {
if own_vote_missing && is_disputed && allow_participation {
let priority = ParticipationPriority::with_priority_if(is_included);
gum::trace!(
target: LOG_TARGET,
@@ -930,9 +928,8 @@ impl Initialized {
target: LOG_TARGET,
?candidate_hash,
?is_confirmed,
?has_own_vote,
?own_vote_missing,
?is_disputed,
?has_controlled_indices,
?allow_participation,
?is_included,
?is_backed,
@@ -946,10 +943,9 @@ impl Initialized {
// Also send any already existing approval vote on new disputes:
if import_result.is_freshly_disputed() {
let no_votes = Vec::new();
let our_approval_votes = new_state.own_approval_votes().unwrap_or(&no_votes);
let our_approval_votes = new_state.own_approval_votes().into_iter().flatten();
for (validator_index, sig) in our_approval_votes {
let pub_key = match env.validators().get(*validator_index) {
let pub_key = match env.validators().get(validator_index) {
None => {
gum::error!(
target: LOG_TARGET,
@@ -979,7 +975,7 @@ impl Initialized {
env.session_info(),
&new_state.votes(),
statement,
*validator_index,
validator_index,
) {
Err(err) => {
gum::error!(
@@ -1150,9 +1146,9 @@ impl Initialized {
Ok(None) => {},
Err(e) => {
gum::error!(
target: LOG_TARGET,
err = ?e,
"Encountered keystore error while signing dispute statement",
target: LOG_TARGET,
err = ?e,
"Encountered keystore error while signing dispute statement",
);
},
}
@@ -1251,74 +1247,6 @@ impl MaybeCandidateReceipt {
}
}
#[derive(Debug, thiserror::Error)]
enum DisputeMessageCreationError {
#[error("There was no opposite vote available")]
NoOppositeVote,
#[error("Found vote had an invalid validator index that could not be found")]
InvalidValidatorIndex,
#[error("Statement found in votes had invalid signature.")]
InvalidStoredStatement,
#[error(transparent)]
InvalidStatementCombination(DisputeMessageCheckError),
}
fn make_dispute_message(
info: &SessionInfo,
votes: &CandidateVotes,
our_vote: SignedDisputeStatement,
our_index: ValidatorIndex,
) -> std::result::Result<DisputeMessage, DisputeMessageCreationError> {
let validators = &info.validators;
let (valid_statement, valid_index, invalid_statement, invalid_index) =
if let DisputeStatement::Valid(_) = our_vote.statement() {
let (validator_index, (statement_kind, validator_signature)) =
votes.invalid.iter().next().ok_or(DisputeMessageCreationError::NoOppositeVote)?;
let other_vote = SignedDisputeStatement::new_checked(
DisputeStatement::Invalid(*statement_kind),
*our_vote.candidate_hash(),
our_vote.session_index(),
validators
.get(*validator_index)
.ok_or(DisputeMessageCreationError::InvalidValidatorIndex)?
.clone(),
validator_signature.clone(),
)
.map_err(|()| DisputeMessageCreationError::InvalidStoredStatement)?;
(our_vote, our_index, other_vote, *validator_index)
} else {
let (validator_index, (statement_kind, validator_signature)) = votes
.valid
.raw()
.iter()
.next()
.ok_or(DisputeMessageCreationError::NoOppositeVote)?;
let other_vote = SignedDisputeStatement::new_checked(
DisputeStatement::Valid(*statement_kind),
*our_vote.candidate_hash(),
our_vote.session_index(),
validators
.get(*validator_index)
.ok_or(DisputeMessageCreationError::InvalidValidatorIndex)?
.clone(),
validator_signature.clone(),
)
.map_err(|()| DisputeMessageCreationError::InvalidStoredStatement)?;
(other_vote, *validator_index, our_vote, our_index)
};
DisputeMessage::from_signed_statements(
valid_statement,
valid_index,
invalid_statement,
invalid_index,
votes.candidate_receipt.clone(),
info,
)
.map_err(DisputeMessageCreationError::InvalidStatementCombination)
}
/// Determine the best block and its block number.
/// Assumes `block_descriptions` are sorted from the one
/// with the lowest `BlockNumber` to the highest.
polkadot/node/core/dispute-coordinator/src/lib.rs
+211 -56
View File
@@ -28,17 +28,21 @@ use std::sync::Arc;
use futures::FutureExt;
use gum::CandidateHash;
use sc_keystore::LocalKeystore;
use polkadot_node_primitives::CandidateVotes;
use polkadot_node_primitives::{
CandidateVotes, DisputeMessage, DisputeMessageCheckError, SignedDisputeStatement,
};
use polkadot_node_subsystem::{
overseer, ActivatedLeaf, FromOrchestra, OverseerSignal, SpawnedSubsystem, SubsystemError,
messages::DisputeDistributionMessage, overseer, ActivatedLeaf, FromOrchestra, OverseerSignal,
SpawnedSubsystem, SubsystemError,
};
use polkadot_node_subsystem_util::{
database::Database,
rolling_session_window::{DatabaseParams, RollingSessionWindow},
};
use polkadot_primitives::v2::{ScrapedOnChainVotes, ValidatorIndex, ValidatorPair};
use polkadot_primitives::v2::{DisputeStatement, ScrapedOnChainVotes, SessionInfo, ValidatorIndex};
use crate::{
error::{FatalResult, JfyiError, Result},
@@ -50,6 +54,7 @@ use db::v1::DbBackend;
use fatality::Split;
use self::{
import::{CandidateEnvironment, CandidateVoteState},
participation::{ParticipationPriority, ParticipationRequest},
spam_slots::{SpamSlots, UnconfirmedDisputes},
};
@@ -274,10 +279,13 @@ impl DisputeCoordinatorSubsystem {
// Prune obsolete disputes:
db::v1::note_earliest_session(overlay_db, rolling_session_window.earliest_session())?;
let now = clock.now();
let active_disputes = match overlay_db.load_recent_disputes() {
Ok(Some(disputes)) =>
get_active_with_status(disputes.into_iter(), clock.now()).collect(),
Ok(None) => Vec::new(),
Ok(disputes) => disputes
.map(|disputes| get_active_with_status(disputes.into_iter(), now))
.into_iter()
.flatten(),
Err(e) => {
gum::error!(target: LOG_TARGET, "Failed initial load of recent disputes: {:?}", e);
return Err(e.into())
@@ -285,9 +293,23 @@ impl DisputeCoordinatorSubsystem {
};
let mut participation_requests = Vec::new();
let mut unconfirmed_disputes: UnconfirmedDisputes = UnconfirmedDisputes::new();
let mut spam_disputes: UnconfirmedDisputes = UnconfirmedDisputes::new();
let (scraper, votes) = ChainScraper::new(ctx.sender(), initial_head).await?;
for ((session, ref candidate_hash), status) in active_disputes {
for ((session, ref candidate_hash), _) in active_disputes {
let env =
match CandidateEnvironment::new(&self.keystore, &rolling_session_window, session) {
None => {
gum::warn!(
target: LOG_TARGET,
session,
"We are lacking a `SessionInfo` for handling db votes on startup."
);
continue
},
Some(env) => env,
};
let votes: CandidateVotes =
match overlay_db.load_candidate_votes(session, candidate_hash) {
Ok(Some(votes)) => votes.into(),
@@ -301,60 +323,52 @@ impl DisputeCoordinatorSubsystem {
continue
},
};
let vote_state = CandidateVoteState::new(votes, &env, now);
let validators = match rolling_session_window.session_info(session) {
None => {
gum::warn!(
let potential_spam = is_potential_spam(&scraper, &vote_state, candidate_hash);
let is_included =
scraper.is_candidate_included(&vote_state.votes().candidate_receipt.hash());
if potential_spam {
gum::trace!(
target: LOG_TARGET,
?session,
?candidate_hash,
"Found potential spam dispute on startup"
);
spam_disputes
.insert((session, *candidate_hash), vote_state.votes().voted_indices());
} else {
// Participate if need be:
if vote_state.own_vote_missing() {
gum::trace!(
target: LOG_TARGET,
session,
"Missing info for session which has an active dispute",
?session,
?candidate_hash,
"Found valid dispute, with no vote from us on startup - participating."
);
continue
},
Some(info) => info.validators.clone(),
};
let voted_indices = votes.voted_indices();
// Determine if there are any missing local statements for this dispute. Validators are
// filtered if:
// 1) their statement already exists, or
// 2) the validator key is not in the local keystore (i.e. the validator is remote).
// The remaining set only contains local validators that are also missing statements.
let missing_local_statement = validators
.iter()
.enumerate()
.map(|(index, validator)| (ValidatorIndex(index as _), validator))
.any(|(index, validator)| {
!voted_indices.contains(&index) &&
self.keystore
.key_pair::<ValidatorPair>(validator)
.ok()
.map_or(false, |v| v.is_some())
});
let is_included = scraper.is_candidate_included(&votes.candidate_receipt.hash());
if !status.is_confirmed_concluded() && !is_included {
unconfirmed_disputes.insert((session, *candidate_hash), voted_indices);
}
// Participate for all non-concluded disputes which do not have a
// recorded local statement.
if missing_local_statement {
participation_requests.push((
ParticipationPriority::with_priority_if(is_included),
ParticipationRequest::new(votes.candidate_receipt.clone(), session),
));
participation_requests.push((
ParticipationPriority::with_priority_if(is_included),
ParticipationRequest::new(
vote_state.votes().candidate_receipt.clone(),
session,
),
));
}
// Else make sure our own vote is distributed:
else {
gum::trace!(
target: LOG_TARGET,
?session,
?candidate_hash,
"Found valid dispute, with vote from us on startup - send vote."
);
send_dispute_messages(ctx, &env, &vote_state).await;
}
}
}
Ok((
participation_requests,
votes,
SpamSlots::recover_from_state(unconfirmed_disputes),
scraper,
))
Ok((participation_requests, votes, SpamSlots::recover_from_state(spam_disputes), scraper))
}
}
@@ -407,3 +421,144 @@ async fn wait_for_first_leaf<Context>(ctx: &mut Context) -> Result<Option<Activa
}
}
}
/// Check wheter a dispute for the given candidate could be spam.
///
/// That is the candidate could be made up.
pub fn is_potential_spam<V>(
scraper: &ChainScraper,
vote_state: &CandidateVoteState<V>,
candidate_hash: &CandidateHash,
) -> bool {
let is_disputed = vote_state.is_disputed();
let is_included = scraper.is_candidate_included(candidate_hash);
let is_backed = scraper.is_candidate_backed(candidate_hash);
let is_confirmed = vote_state.is_confirmed();
is_disputed && !is_included && !is_backed && !is_confirmed
}
/// Tell dispute-distribution to send all our votes.
///
/// Should be called on startup for all active disputes where there are votes from us already.
#[overseer::contextbounds(DisputeCoordinator, prefix = self::overseer)]
async fn send_dispute_messages<Context>(
ctx: &mut Context,
env: &CandidateEnvironment<'_>,
vote_state: &CandidateVoteState<CandidateVotes>,
) {
for own_vote in vote_state.own_votes().into_iter().flatten() {
let (validator_index, (kind, sig)) = own_vote;
let public_key = if let Some(key) = env.session_info().validators.get(*validator_index) {
key.clone()
} else {
gum::error!(
target: LOG_TARGET,
?validator_index,
session_index = ?env.session_index(),
"Could not find our own key in `SessionInfo`"
);
continue
};
let our_vote_signed = SignedDisputeStatement::new_checked(
kind.clone(),
vote_state.votes().candidate_receipt.hash(),
env.session_index(),
public_key,
sig.clone(),
);
let our_vote_signed = match our_vote_signed {
Ok(signed) => signed,
Err(()) => {
gum::error!(
target: LOG_TARGET,
"Checking our own signature failed - db corruption?"
);
continue
},
};
let dispute_message = match make_dispute_message(
env.session_info(),
vote_state.votes(),
our_vote_signed,
*validator_index,
) {
Err(err) => {
gum::debug!(target: LOG_TARGET, ?err, "Creating dispute message failed.");
continue
},
Ok(dispute_message) => dispute_message,
};
ctx.send_message(DisputeDistributionMessage::SendDispute(dispute_message)).await;
}
}
#[derive(Debug, thiserror::Error)]
pub enum DisputeMessageCreationError {
#[error("There was no opposite vote available")]
NoOppositeVote,
#[error("Found vote had an invalid validator index that could not be found")]
InvalidValidatorIndex,
#[error("Statement found in votes had invalid signature.")]
InvalidStoredStatement,
#[error(transparent)]
InvalidStatementCombination(DisputeMessageCheckError),
}
/// Create a `DisputeMessage` to be sent to `DisputeDistribution`.
pub fn make_dispute_message(
info: &SessionInfo,
votes: &CandidateVotes,
our_vote: SignedDisputeStatement,
our_index: ValidatorIndex,
) -> std::result::Result<DisputeMessage, DisputeMessageCreationError> {
let validators = &info.validators;
let (valid_statement, valid_index, invalid_statement, invalid_index) =
if let DisputeStatement::Valid(_) = our_vote.statement() {
let (validator_index, (statement_kind, validator_signature)) =
votes.invalid.iter().next().ok_or(DisputeMessageCreationError::NoOppositeVote)?;
let other_vote = SignedDisputeStatement::new_checked(
DisputeStatement::Invalid(*statement_kind),
*our_vote.candidate_hash(),
our_vote.session_index(),
validators
.get(*validator_index)
.ok_or(DisputeMessageCreationError::InvalidValidatorIndex)?
.clone(),
validator_signature.clone(),
)
.map_err(|()| DisputeMessageCreationError::InvalidStoredStatement)?;
(our_vote, our_index, other_vote, *validator_index)
} else {
let (validator_index, (statement_kind, validator_signature)) = votes
.valid
.raw()
.iter()
.next()
.ok_or(DisputeMessageCreationError::NoOppositeVote)?;
let other_vote = SignedDisputeStatement::new_checked(
DisputeStatement::Valid(*statement_kind),
*our_vote.candidate_hash(),
our_vote.session_index(),
validators
.get(*validator_index)
.ok_or(DisputeMessageCreationError::InvalidValidatorIndex)?
.clone(),
validator_signature.clone(),
)
.map_err(|()| DisputeMessageCreationError::InvalidStoredStatement)?;
(other_vote, *validator_index, our_vote, our_index)
};
DisputeMessage::from_signed_statements(
valid_statement,
valid_index,
invalid_statement,
invalid_index,
votes.candidate_receipt.clone(),
info,
)
.map_err(DisputeMessageCreationError::InvalidStatementCombination)
}
polkadot/node/core/dispute-coordinator/src/tests.rs
+56 -112
View File
@@ -32,7 +32,7 @@ use futures::{
use polkadot_node_subsystem_util::database::Database;
use polkadot_node_primitives::{
DisputeStatus, SignedDisputeStatement, SignedFullStatement, Statement,
DisputeMessage, DisputeStatus, SignedDisputeStatement, SignedFullStatement, Statement,
};
use polkadot_node_subsystem::{
messages::{
@@ -291,6 +291,7 @@ impl TestState {
.await;
}
/// Returns any sent `DisputeMessage`s.
async fn handle_sync_queries(
&mut self,
virtual_overseer: &mut VirtualOverseer,
@@ -298,7 +299,7 @@ impl TestState {
block_number: BlockNumber,
session: SessionIndex,
candidate_events: Vec<CandidateEvent>,
) {
) -> Vec<DisputeMessage> {
// Order of messages is not fixed (different on initializing):
#[derive(Debug)]
struct FinishedSteps {
@@ -316,6 +317,7 @@ impl TestState {
}
let mut finished_steps = FinishedSteps::new();
let mut sent_disputes = Vec::new();
while !finished_steps.is_done() {
let recv = overseer_recv(virtual_overseer).await;
@@ -400,6 +402,9 @@ impl TestState {
let block_num = self.headers.get(&hash).map(|header| header.number);
tx.send(Ok(block_num)).unwrap();
},
AllMessages::DisputeDistribution(DisputeDistributionMessage::SendDispute(msg)) => {
sent_disputes.push(msg);
},
AllMessages::RuntimeApi(RuntimeApiMessage::Request(
_new_leaf,
RuntimeApiRequest::CandidateEvents(tx),
@@ -439,14 +444,25 @@ impl TestState {
},
}
}
return sent_disputes
}
async fn handle_resume_sync(
&mut self,
virtual_overseer: &mut VirtualOverseer,
session: SessionIndex,
) {
) -> Vec<DisputeMessage> {
self.handle_resume_sync_with_events(virtual_overseer, session, Vec::new()).await
}
async fn handle_resume_sync_with_events(
&mut self,
virtual_overseer: &mut VirtualOverseer,
session: SessionIndex,
mut initial_events: Vec<CandidateEvent>,
) -> Vec<DisputeMessage> {
let leaves: Vec<Hash> = self.headers.keys().cloned().collect();
let mut messages = Vec::new();
for (n, leaf) in leaves.iter().enumerate() {
gum::debug!(
block_number= ?n,
@@ -463,15 +479,14 @@ impl TestState {
)))
.await;
self.handle_sync_queries(
virtual_overseer,
*leaf,
n as BlockNumber,
session,
Vec::new(),
)
.await;
let events = if n == 1 { std::mem::take(&mut initial_events) } else { Vec::new() };
let mut new_messages = self
.handle_sync_queries(virtual_overseer, *leaf, n as BlockNumber, session, events)
.await;
messages.append(&mut new_messages);
}
messages
}
fn session_info(&self) -> SessionInfo {
@@ -2148,6 +2163,7 @@ fn concluded_supermajority_against_non_active_after_time() {
#[test]
fn resume_dispute_without_local_statement() {
sp_tracing::init_for_tests();
let session = 1;
test_harness(|mut test_state, mut virtual_overseer| {
@@ -2188,10 +2204,8 @@ fn resume_dispute_without_local_statement() {
handle_approval_vote_request(&mut virtual_overseer, &candidate_hash, HashMap::new())
.await;
// Missing availability -> No local vote.
// Participation won't happen here because the dispute is neither backed, not confirmed
// nor the candidate is included. Or in other words - we'll refrain from participation.
assert_eq!(confirmation_rx.await, Ok(ImportStatementsResult::ValidImport));
{
@@ -2216,7 +2230,17 @@ fn resume_dispute_without_local_statement() {
// local statement for the active dispute.
.resume(|mut test_state, mut virtual_overseer| {
Box::pin(async move {
test_state.handle_resume_sync(&mut virtual_overseer, session).await;
let candidate_receipt = make_valid_candidate_receipt();
// Candidate is now backed:
let dispute_messages = test_state
.handle_resume_sync_with_events(
&mut virtual_overseer,
session,
vec![make_candidate_backed_event(candidate_receipt.clone())],
)
.await;
assert_eq!(dispute_messages.len(), 0, "We don't expect any messages sent here.");
let candidate_receipt = make_valid_candidate_receipt();
let candidate_hash = candidate_receipt.hash();
@@ -2282,6 +2306,7 @@ fn resume_dispute_without_local_statement() {
#[test]
fn resume_dispute_with_local_statement() {
sp_tracing::init_for_tests();
let session = 1;
test_harness(|mut test_state, mut virtual_overseer| {
@@ -2359,10 +2384,19 @@ fn resume_dispute_with_local_statement() {
})
})
// Alice should not send a DisputeParticiationMessage::Participate on restart since she has a
// local statement for the active dispute.
// local statement for the active dispute, instead she should try to (re-)send her vote.
.resume(|mut test_state, mut virtual_overseer| {
let candidate_receipt = make_valid_candidate_receipt();
Box::pin(async move {
test_state.handle_resume_sync(&mut virtual_overseer, session).await;
let messages = test_state
.handle_resume_sync_with_events(
&mut virtual_overseer,
session,
vec![make_candidate_backed_event(candidate_receipt.clone())],
)
.await;
assert_eq!(messages.len(), 1, "A message should have gone out.");
// Assert that subsystem is not sending Participation messages because we issued a local statement
assert!(virtual_overseer.recv().timeout(TEST_TIMEOUT).await.is_none());
@@ -2390,7 +2424,12 @@ fn resume_dispute_without_local_statement_or_local_key() {
let candidate_hash = candidate_receipt.hash();
test_state
.activate_leaf_at_session(&mut virtual_overseer, session, 1, Vec::new())
.activate_leaf_at_session(
&mut virtual_overseer,
session,
1,
vec![make_candidate_included_event(candidate_receipt.clone())],
)
.await;
let (valid_vote, invalid_vote) = generate_opposing_votes_pair(
@@ -2464,101 +2503,6 @@ fn resume_dispute_without_local_statement_or_local_key() {
});
}
#[test]
fn resume_dispute_with_local_statement_without_local_key() {
let session = 1;
let test_state = TestState::default();
let mut test_state = test_state.resume(|mut test_state, mut virtual_overseer| {
Box::pin(async move {
test_state.handle_resume_sync(&mut virtual_overseer, session).await;
let candidate_receipt = make_valid_candidate_receipt();
let candidate_hash = candidate_receipt.hash();
test_state
.activate_leaf_at_session(&mut virtual_overseer, session, 1, Vec::new())
.await;
let local_valid_vote = test_state
.issue_explicit_statement_with_index(
ValidatorIndex(0),
candidate_hash,
session,
true,
)
.await;
let (valid_vote, invalid_vote) = generate_opposing_votes_pair(
&test_state,
ValidatorIndex(1),
ValidatorIndex(2),
candidate_hash,
session,
VoteType::Explicit,
)
.await;
let (pending_confirmation, confirmation_rx) = oneshot::channel();
virtual_overseer
.send(FromOrchestra::Communication {
msg: DisputeCoordinatorMessage::ImportStatements {
candidate_receipt: candidate_receipt.clone(),
session,
statements: vec![
(local_valid_vote, ValidatorIndex(0)),
(valid_vote, ValidatorIndex(1)),
(invalid_vote, ValidatorIndex(2)),
],
pending_confirmation: Some(pending_confirmation),
},
})
.await;
handle_approval_vote_request(&mut virtual_overseer, &candidate_hash, HashMap::new())
.await;
assert_eq!(confirmation_rx.await, Ok(ImportStatementsResult::ValidImport));
{
let (tx, rx) = oneshot::channel();
virtual_overseer
.send(FromOrchestra::Communication {
msg: DisputeCoordinatorMessage::ActiveDisputes(tx),
})
.await;
assert_eq!(rx.await.unwrap().len(), 1);
}
virtual_overseer.send(FromOrchestra::Signal(OverseerSignal::Conclude)).await;
assert!(virtual_overseer.try_recv().await.is_none());
test_state
})
});
// No keys:
test_state.subsystem_keystore =
make_keystore(vec![Sr25519Keyring::Two.to_seed()].into_iter()).into();
// Two should not send a DisputeParticiationMessage::Participate on restart since we gave
// her a non existing key.
test_state.resume(|mut test_state, mut virtual_overseer| {
Box::pin(async move {
test_state.handle_resume_sync(&mut virtual_overseer, session).await;
// Assert that subsystem is not sending Participation messages because we don't
// have a key.
assert!(virtual_overseer.recv().timeout(TEST_TIMEOUT).await.is_none());
virtual_overseer.send(FromOrchestra::Signal(OverseerSignal::Conclude)).await;
assert!(virtual_overseer.try_recv().await.is_none());
test_state
})
});
}
#[test]
fn issue_valid_local_statement_does_cause_distribution_but_not_duplicate_participation() {
issue_local_statement_does_cause_distribution_but_not_duplicate_participation(true);
polkadot/node/network/dispute-distribution/src/lib.rs
+39 -31
View File
@@ -29,6 +29,7 @@ use std::{num::NonZeroUsize, time::Duration};
use futures::{channel::mpsc, FutureExt, StreamExt, TryFutureExt};
use polkadot_node_network_protocol::authority_discovery::AuthorityDiscovery;
use polkadot_node_subsystem_util::nesting_sender::NestingSender;
use sp_keystore::SyncCryptoStorePtr;
use polkadot_node_network_protocol::request_response::{incoming::IncomingRequestReceiver, v1};
@@ -51,33 +52,33 @@ use polkadot_node_subsystem_util::{runtime, runtime::RuntimeInfo};
/// to this subsystem, unknown dispute. This is to make sure, we get our vote out, even on
/// restarts.
///
/// The actual work of sending and keeping track of transmission attempts to each validator for a
/// particular dispute are done by [`SendTask`]. The purpose of the `DisputeSender` is to keep
/// track of all ongoing disputes and start and clean up `SendTask`s accordingly.
/// The actual work of sending and keeping track of transmission attempts to each validator for a
/// particular dispute are done by [`SendTask`]. The purpose of the `DisputeSender` is to keep
/// track of all ongoing disputes and start and clean up `SendTask`s accordingly.
mod sender;
use self::sender::{DisputeSender, TaskFinish};
use self::sender::{DisputeSender, DisputeSenderMessage};
/// ## The receiver [`DisputesReceiver`]
/// ## The receiver [`DisputesReceiver`]
///
/// The receiving side is implemented as `DisputesReceiver` and is run as a separate long running task within
/// this subsystem ([`DisputesReceiver::run`]).
/// The receiving side is implemented as `DisputesReceiver` and is run as a separate long running task within
/// this subsystem ([`DisputesReceiver::run`]).
///
/// Conceptually all the receiver has to do, is waiting for incoming requests which are passed in
/// via a dedicated channel and forwarding them to the dispute coordinator via
/// `DisputeCoordinatorMessage::ImportStatements`. Being the interface to the network and untrusted
/// nodes, the reality is not that simple of course. Before importing statements the receiver will
/// batch up imports as well as possible for efficient imports while maintaining timely dispute
/// resolution and handling of spamming validators:
/// Conceptually all the receiver has to do, is waiting for incoming requests which are passed in
/// via a dedicated channel and forwarding them to the dispute coordinator via
/// `DisputeCoordinatorMessage::ImportStatements`. Being the interface to the network and untrusted
/// nodes, the reality is not that simple of course. Before importing statements the receiver will
/// batch up imports as well as possible for efficient imports while maintaining timely dispute
/// resolution and handling of spamming validators:
///
/// - Drop all messages from non validator nodes, for this it requires the [`AuthorityDiscovery`]
/// service.
/// - Drop messages from a node, if it sends at a too high rate.
/// - Filter out duplicate messages (over some period of time).
/// - Drop any obviously invalid votes (invalid signatures for example).
/// - Ban peers whose votes were deemed invalid.
/// - Drop all messages from non validator nodes, for this it requires the [`AuthorityDiscovery`]
/// service.
/// - Drop messages from a node, if it sends at a too high rate.
/// - Filter out duplicate messages (over some period of time).
/// - Drop any obviously invalid votes (invalid signatures for example).
/// - Ban peers whose votes were deemed invalid.
///
/// In general dispute-distribution works on limiting the work the dispute-coordinator will have to
/// do, while at the same time making it aware of new disputes as fast as possible.
/// In general dispute-distribution works on limiting the work the dispute-coordinator will have to
/// do, while at the same time making it aware of new disputes as fast as possible.
///
/// For successfully imported votes, we will confirm the receipt of the message back to the sender.
/// This way a received confirmation guarantees, that the vote has been stored to disk by the
@@ -87,7 +88,7 @@ use self::receiver::DisputesReceiver;
/// Error and [`Result`] type for this subsystem.
mod error;
use error::{log_error, FatalError, FatalResult, Result};
use error::{log_error, Error, FatalError, FatalResult, Result};
#[cfg(test)]
mod tests;
@@ -118,10 +119,10 @@ pub struct DisputeDistributionSubsystem<AD> {
runtime: RuntimeInfo,
/// Sender for our dispute requests.
disputes_sender: DisputeSender,
disputes_sender: DisputeSender<DisputeSenderMessage>,
/// Receive messages from `SendTask`.
sender_rx: mpsc::Receiver<TaskFinish>,
/// Receive messages from `DisputeSender` background tasks.
sender_rx: mpsc::Receiver<DisputeSenderMessage>,
/// Receiver for incoming requests.
req_receiver: Option<IncomingRequestReceiver<v1::DisputeRequest>>,
@@ -167,7 +168,7 @@ where
session_cache_lru_size: NonZeroUsize::new(DISPUTE_WINDOW.get() as usize)
.expect("Dispute window can not be 0; qed"),
});
let (tx, sender_rx) = mpsc::channel(1);
let (tx, sender_rx) = NestingSender::new_root(1);
let disputes_sender = DisputeSender::new(tx, metrics.clone());
Self {
runtime,
@@ -216,9 +217,16 @@ where
log_error(result, "on FromOrchestra")?;
},
MuxedMessage::Sender(result) => {
self.disputes_sender
.on_task_message(result.ok_or(FatalError::SenderExhausted)?)
.await;
let result = self
.disputes_sender
.on_message(
&mut ctx,
&mut self.runtime,
result.ok_or(FatalError::SenderExhausted)?,
)
.await
.map_err(Error::Sender);
log_error(result, "on_message")?;
},
}
}
@@ -260,14 +268,14 @@ enum MuxedMessage {
/// Messages from other subsystems.
Subsystem(FatalResult<FromOrchestra<DisputeDistributionMessage>>),
/// Messages from spawned sender background tasks.
Sender(Option<TaskFinish>),
Sender(Option<DisputeSenderMessage>),
}
#[overseer::contextbounds(DisputeDistribution, prefix = self::overseer)]
impl MuxedMessage {
async fn receive<Context>(
ctx: &mut Context,
from_sender: &mut mpsc::Receiver<TaskFinish>,
from_sender: &mut mpsc::Receiver<DisputeSenderMessage>,
) -> Self {
// We are only fusing here to make `select` happy, in reality we will quit if the stream
// ends.
polkadot/node/network/dispute-distribution/src/sender/mod.rs
+133 -211
View File
@@ -21,19 +21,17 @@ use std::{
time::Duration,
};
use futures::{
channel::{mpsc, oneshot},
future::poll_fn,
Future,
};
use futures::{channel::oneshot, future::poll_fn, Future};
use futures_timer::Delay;
use indexmap::{map::Entry, IndexMap};
use polkadot_node_network_protocol::request_response::v1::DisputeRequest;
use polkadot_node_primitives::{CandidateVotes, DisputeMessage, SignedDisputeStatement};
use polkadot_node_subsystem::{messages::DisputeCoordinatorMessage, overseer, ActiveLeavesUpdate};
use polkadot_node_subsystem_util::runtime::RuntimeInfo;
use polkadot_primitives::v2::{CandidateHash, DisputeStatement, Hash, SessionIndex};
use polkadot_node_primitives::{DisputeMessage, DisputeStatus};
use polkadot_node_subsystem::{
messages::DisputeCoordinatorMessage, overseer, ActiveLeavesUpdate, SubsystemSender,
};
use polkadot_node_subsystem_util::{nesting_sender::NestingSender, runtime::RuntimeInfo};
use polkadot_primitives::v2::{CandidateHash, Hash, SessionIndex};
/// For each ongoing dispute we have a `SendTask` which takes care of it.
///
@@ -53,6 +51,15 @@ pub use error::{Error, FatalError, JfyiError, Result};
use self::error::JfyiErrorResult;
use crate::{Metrics, LOG_TARGET, SEND_RATE_LIMIT};
/// Messages as sent by background tasks.
#[derive(Debug)]
pub enum DisputeSenderMessage {
/// A task finished.
TaskFinish(TaskFinish),
/// A request for active disputes to the dispute-coordinator finished.
ActiveDisputesReady(JfyiErrorResult<Vec<(SessionIndex, CandidateHash, DisputeStatus)>>),
}
/// The `DisputeSender` keeps track of all ongoing disputes we need to send statements out.
///
/// For each dispute a `SendTask` is responsible for sending to the concerned validators for that
@@ -60,7 +67,7 @@ use crate::{Metrics, LOG_TARGET, SEND_RATE_LIMIT};
/// sessions/validator sets and cleans them up when they become obsolete.
///
/// The unit of work for the `DisputeSender` is a dispute, represented by `SendTask`s.
pub struct DisputeSender {
pub struct DisputeSender<M> {
/// All heads we currently consider active.
active_heads: Vec<Hash>,
@@ -72,10 +79,13 @@ pub struct DisputeSender {
/// All ongoing dispute sendings this subsystem is aware of.
///
/// Using an `IndexMap` so items can be iterated in the order of insertion.
disputes: IndexMap<CandidateHash, SendTask>,
disputes: IndexMap<CandidateHash, SendTask<M>>,
/// Sender to be cloned for `SendTask`s.
tx: mpsc::Sender<TaskFinish>,
tx: NestingSender<M, DisputeSenderMessage>,
/// `Some` if we are waiting for a response `DisputeCoordinatorMessage::ActiveDisputes`.
waiting_for_active_disputes: Option<WaitForActiveDisputesState>,
/// Future for delaying too frequent creation of dispute sending tasks.
rate_limit: RateLimit,
@@ -84,15 +94,25 @@ pub struct DisputeSender {
metrics: Metrics,
}
/// State we keep while waiting for active disputes.
///
/// When we send `DisputeCoordinatorMessage::ActiveDisputes`, this is the state we keep while
/// waiting for the response.
struct WaitForActiveDisputesState {
/// Have we seen any new sessions since last refresh?
have_new_sessions: bool,
}
#[overseer::contextbounds(DisputeDistribution, prefix = self::overseer)]
impl DisputeSender {
impl<M: 'static + Send + Sync> DisputeSender<M> {
/// Create a new `DisputeSender` which can be used to start dispute sendings.
pub fn new(tx: mpsc::Sender<TaskFinish>, metrics: Metrics) -> Self {
pub fn new(tx: NestingSender<M, DisputeSenderMessage>, metrics: Metrics) -> Self {
Self {
active_heads: Vec::new(),
active_sessions: HashMap::new(),
disputes: IndexMap::new(),
tx,
waiting_for_active_disputes: None,
rate_limit: RateLimit::new(),
metrics,
}
@@ -122,7 +142,7 @@ impl DisputeSender {
ctx,
runtime,
&self.active_sessions,
self.tx.clone(),
NestingSender::new(self.tx.clone(), DisputeSenderMessage::TaskFinish),
req,
&self.metrics,
)
@@ -133,14 +153,47 @@ impl DisputeSender {
Ok(())
}
/// Receive message from a background task.
pub async fn on_message<Context>(
&mut self,
ctx: &mut Context,
runtime: &mut RuntimeInfo,
msg: DisputeSenderMessage,
) -> Result<()> {
match msg {
DisputeSenderMessage::TaskFinish(msg) => {
let TaskFinish { candidate_hash, receiver, result } = msg;
self.metrics.on_sent_request(result.as_metrics_label());
let task = match self.disputes.get_mut(&candidate_hash) {
None => {
// Can happen when a dispute ends, with messages still in queue:
gum::trace!(
target: LOG_TARGET,
?result,
"Received `FromSendingTask::Finished` for non existing dispute."
);
return Ok(())
},
Some(task) => task,
};
task.on_finished_send(&receiver, result);
},
DisputeSenderMessage::ActiveDisputesReady(result) => {
let state = self.waiting_for_active_disputes.take();
let have_new_sessions = state.map(|s| s.have_new_sessions).unwrap_or(false);
let active_disputes = result?;
self.handle_new_active_disputes(ctx, runtime, active_disputes, have_new_sessions)
.await?;
},
}
Ok(())
}
/// Take care of a change in active leaves.
///
/// - Initiate a retry of failed sends which are still active.
/// - Get new authorities to send messages to.
/// - Get rid of obsolete tasks and disputes.
/// - Get dispute sending started in case we missed one for some reason (e.g. on node startup)
///
/// This function ensures the `SEND_RATE_LIMIT`, therefore it might block.
/// Update our knowledge on sessions and initiate fetching for new active disputes.
pub async fn update_leaves<Context>(
&mut self,
ctx: &mut Context,
@@ -154,14 +207,58 @@ impl DisputeSender {
let have_new_sessions = self.refresh_sessions(ctx, runtime).await?;
let active_disputes = get_active_disputes(ctx).await?;
let unknown_disputes = {
let mut disputes = active_disputes.clone();
disputes.retain(|(_, c)| !self.disputes.contains_key(c));
disputes
};
// Not yet waiting for data, request an update:
match self.waiting_for_active_disputes.take() {
None => {
self.waiting_for_active_disputes =
Some(WaitForActiveDisputesState { have_new_sessions });
let mut sender = ctx.sender().clone();
let mut tx = self.tx.clone();
let active_disputes: HashSet<_> = active_disputes.into_iter().map(|(_, c)| c).collect();
let get_active_disputes_task = async move {
let result = get_active_disputes(&mut sender).await;
let result =
tx.send_message(DisputeSenderMessage::ActiveDisputesReady(result)).await;
if let Err(err) = result {
gum::debug!(
target: LOG_TARGET,
?err,
"Sending `DisputeSenderMessage` from background task failed."
);
}
};
ctx.spawn("get_active_disputes", Box::pin(get_active_disputes_task))
.map_err(FatalError::SpawnTask)?;
},
Some(state) => {
let have_new_sessions = state.have_new_sessions || have_new_sessions;
let new_state = WaitForActiveDisputesState { have_new_sessions };
self.waiting_for_active_disputes = Some(new_state);
gum::debug!(
target: LOG_TARGET,
"Dispute coordinator slow? We are still waiting for data on next active leaves update."
);
},
}
Ok(())
}
/// Handle new active disputes response.
///
/// - Initiate a retry of failed sends which are still active.
/// - Get new authorities to send messages to.
/// - Get rid of obsolete tasks and disputes.
///
/// This function ensures the `SEND_RATE_LIMIT`, therefore it might block.
async fn handle_new_active_disputes<Context>(
&mut self,
ctx: &mut Context,
runtime: &mut RuntimeInfo,
active_disputes: Vec<(SessionIndex, CandidateHash, DisputeStatus)>,
have_new_sessions: bool,
) -> Result<()> {
let active_disputes: HashSet<_> = active_disputes.into_iter().map(|(_, c, _)| c).collect();
// Cleanup obsolete senders (retain keeps order of remaining elements):
self.disputes
@@ -188,165 +285,9 @@ impl DisputeSender {
should_rate_limit = sends_happened && have_new_sessions;
}
}
// This should only be non-empty on startup, but if not - we got you covered.
//
// Initial order will not be maintained in that case, but that should be fine as disputes
// recovered at startup will be relatively "old" anyway and we assume that no more than a
// third of the validators will go offline at any point in time anyway.
for dispute in unknown_disputes {
// Rate limiting handled inside `start_send_for_dispute` (calls `start_sender`).
self.start_send_for_dispute(ctx, runtime, dispute).await?;
}
Ok(())
}
/// Receive message from a sending task.
pub async fn on_task_message(&mut self, msg: TaskFinish) {
let TaskFinish { candidate_hash, receiver, result } = msg;
self.metrics.on_sent_request(result.as_metrics_label());
let task = match self.disputes.get_mut(&candidate_hash) {
None => {
// Can happen when a dispute ends, with messages still in queue:
gum::trace!(
target: LOG_TARGET,
?result,
"Received `FromSendingTask::Finished` for non existing dispute."
);
return
},
Some(task) => task,
};
task.on_finished_send(&receiver, result);
}
/// Call `start_sender` on all passed in disputes.
///
/// Recover necessary votes for building up `DisputeMessage` and start sending for all of them.
async fn start_send_for_dispute<Context>(
&mut self,
ctx: &mut Context,
runtime: &mut RuntimeInfo,
dispute: (SessionIndex, CandidateHash),
) -> Result<()> {
let (session_index, candidate_hash) = dispute;
// A relay chain head is required as context for receiving session info information from runtime and
// storage. We will iterate `active_sessions` to find a suitable head. We assume that there is at
// least one active head which, by `session_index`, is at least as recent as the `dispute` passed in.
// We need to avoid picking an older one from a session that might not yet exist in storage.
// Related to <https://github.com/paritytech/polkadot/issues/4730> .
let ref_head = self
.active_sessions
.iter()
.find_map(|(active_session_index, head_hash)| {
// There might be more than one session index that is at least as recent as the dispute
// so we just pick the first one. Keep in mind we are talking about the session index for the
// child of block identified by `head_hash` and not the session index for the block.
if active_session_index >= &session_index {
Some(head_hash)
} else {
None
}
})
.ok_or(JfyiError::NoActiveHeads)?;
let info = runtime
.get_session_info_by_index(ctx.sender(), *ref_head, session_index)
.await?;
let our_index = match info.validator_info.our_index {
None => {
gum::trace!(
target: LOG_TARGET,
"Not a validator in that session - not starting dispute sending."
);
return Ok(())
},
Some(index) => index,
};
let votes = match get_candidate_votes(ctx, session_index, candidate_hash).await? {
None => {
gum::debug!(
target: LOG_TARGET,
?session_index,
?candidate_hash,
"No votes for active dispute?! - possible, due to race."
);
return Ok(())
},
Some(votes) => votes,
};
let our_valid_vote = votes.valid.raw().get(&our_index);
let our_invalid_vote = votes.invalid.get(&our_index);
let (valid_vote, invalid_vote) = if let Some(our_valid_vote) = our_valid_vote {
// Get some invalid vote as well:
let invalid_vote =
votes.invalid.iter().next().ok_or(JfyiError::MissingVotesFromCoordinator)?;
((&our_index, our_valid_vote), invalid_vote)
} else if let Some(our_invalid_vote) = our_invalid_vote {
// Get some valid vote as well:
let valid_vote =
votes.valid.raw().iter().next().ok_or(JfyiError::MissingVotesFromCoordinator)?;
(valid_vote, (&our_index, our_invalid_vote))
} else {
// There is no vote from us yet - nothing to do.
return Ok(())
};
let (valid_index, (kind, signature)) = valid_vote;
let valid_public = info
.session_info
.validators
.get(*valid_index)
.ok_or(JfyiError::InvalidStatementFromCoordinator)?;
let valid_signed = SignedDisputeStatement::new_checked(
DisputeStatement::Valid(*kind),
candidate_hash,
session_index,
valid_public.clone(),
signature.clone(),
)
.map_err(|()| JfyiError::InvalidStatementFromCoordinator)?;
let (invalid_index, (kind, signature)) = invalid_vote;
let invalid_public = info
.session_info
.validators
.get(*invalid_index)
.ok_or(JfyiError::InvalidValidatorIndexFromCoordinator)?;
let invalid_signed = SignedDisputeStatement::new_checked(
DisputeStatement::Invalid(*kind),
candidate_hash,
session_index,
invalid_public.clone(),
signature.clone(),
)
.map_err(|()| JfyiError::InvalidValidatorIndexFromCoordinator)?;
// Reconstructing the checked signed dispute statements is hardly useful here and wasteful,
// but I don't want to enable a bypass for the below smart constructor and this code path
// is supposed to be only hit on startup basically.
//
// Revisit this decision when the `from_signed_statements` is unneeded for the normal code
// path as well.
let message = DisputeMessage::from_signed_statements(
valid_signed,
*valid_index,
invalid_signed,
*invalid_index,
votes.candidate_receipt,
&info.session_info,
)
.map_err(JfyiError::InvalidDisputeFromCoordinator)?;
// Finally, get the party started:
self.start_sender(ctx, runtime, message).await
}
/// Make active sessions correspond to currently active heads.
///
/// Returns: true if sessions changed.
@@ -431,33 +372,14 @@ async fn get_active_session_indices<Context>(
}
/// Retrieve Set of active disputes from the dispute coordinator.
#[overseer::contextbounds(DisputeDistribution, prefix = self::overseer)]
async fn get_active_disputes<Context>(
ctx: &mut Context,
) -> JfyiErrorResult<Vec<(SessionIndex, CandidateHash)>> {
async fn get_active_disputes<Sender>(
sender: &mut Sender,
) -> JfyiErrorResult<Vec<(SessionIndex, CandidateHash, DisputeStatus)>>
where
Sender: SubsystemSender<DisputeCoordinatorMessage>,
{
let (tx, rx) = oneshot::channel();
// Caller scope is in `update_leaves` and this is bounded by fork count.
ctx.send_unbounded_message(DisputeCoordinatorMessage::ActiveDisputes(tx));
rx.await
.map_err(|_| JfyiError::AskActiveDisputesCanceled)
.map(|disputes| disputes.into_iter().map(|d| (d.0, d.1)).collect())
}
/// Get all locally available dispute votes for a given dispute.
#[overseer::contextbounds(DisputeDistribution, prefix = self::overseer)]
async fn get_candidate_votes<Context>(
ctx: &mut Context,
session_index: SessionIndex,
candidate_hash: CandidateHash,
) -> JfyiErrorResult<Option<CandidateVotes>> {
let (tx, rx) = oneshot::channel();
// Caller scope is in `update_leaves` and this is bounded by fork count.
ctx.send_unbounded_message(DisputeCoordinatorMessage::QueryCandidateVotes(
vec![(session_index, candidate_hash)],
tx,
));
rx.await
.map(|v| v.get(0).map(|inner| inner.to_owned().2))
.map_err(|_| JfyiError::AskCandidateVotesCanceled)
sender.send_message(DisputeCoordinatorMessage::ActiveDisputes(tx)).await;
rx.await.map_err(|_| JfyiError::AskActiveDisputesCanceled)
}
polkadot/node/network/dispute-distribution/src/sender/send_task.rs
+11 -11
View File
@@ -16,7 +16,7 @@
use std::collections::{HashMap, HashSet};
use futures::{channel::mpsc, future::RemoteHandle, Future, FutureExt, SinkExt};
use futures::{future::RemoteHandle, Future, FutureExt};
use polkadot_node_network_protocol::{
request_response::{
@@ -27,7 +27,7 @@ use polkadot_node_network_protocol::{
IfDisconnected,
};
use polkadot_node_subsystem::{messages::NetworkBridgeTxMessage, overseer};
use polkadot_node_subsystem_util::{metrics, runtime::RuntimeInfo};
use polkadot_node_subsystem_util::{metrics, nesting_sender::NestingSender, runtime::RuntimeInfo};
use polkadot_primitives::v2::{
AuthorityDiscoveryId, CandidateHash, Hash, SessionIndex, ValidatorIndex,
};
@@ -44,7 +44,7 @@ use crate::{
/// Keeps track of all the validators that have to be reached for a dispute.
///
/// The unit of work for a `SendTask` is an authority/validator.
pub struct SendTask {
pub struct SendTask<M> {
/// The request we are supposed to get out to all `parachain` validators of the dispute's session
/// and to all current authorities.
request: DisputeRequest,
@@ -58,7 +58,7 @@ pub struct SendTask {
has_failed_sends: bool,
/// Sender to be cloned for tasks.
tx: mpsc::Sender<TaskFinish>,
tx: NestingSender<M, TaskFinish>,
}
/// Status of a particular vote/statement delivery to a particular validator.
@@ -100,7 +100,7 @@ impl TaskResult {
}
#[overseer::contextbounds(DisputeDistribution, prefix = self::overseer)]
impl SendTask {
impl<M: 'static + Send + Sync> SendTask<M> {
/// Initiates sending a dispute message to peers.
///
/// Creation of new `SendTask`s is subject to rate limiting. As each `SendTask` will trigger
@@ -110,7 +110,7 @@ impl SendTask {
ctx: &mut Context,
runtime: &mut RuntimeInfo,
active_sessions: &HashMap<SessionIndex, Hash>,
tx: mpsc::Sender<TaskFinish>,
tx: NestingSender<M, TaskFinish>,
request: DisputeRequest,
metrics: &Metrics,
) -> Result<Self> {
@@ -272,9 +272,9 @@ impl SendTask {
///
/// And spawn tasks for handling the response.
#[overseer::contextbounds(DisputeDistribution, prefix = self::overseer)]
async fn send_requests<Context>(
async fn send_requests<Context, M: 'static + Send + Sync>(
ctx: &mut Context,
tx: mpsc::Sender<TaskFinish>,
tx: NestingSender<M, TaskFinish>,
receivers: Vec<AuthorityDiscoveryId>,
req: DisputeRequest,
metrics: &Metrics,
@@ -307,11 +307,11 @@ async fn send_requests<Context>(
}
/// Future to be spawned in a task for awaiting a response.
async fn wait_response_task(
async fn wait_response_task<M: 'static + Send + Sync>(
pending_response: impl Future<Output = OutgoingResult<DisputeResponse>>,
candidate_hash: CandidateHash,
receiver: AuthorityDiscoveryId,
mut tx: mpsc::Sender<TaskFinish>,
mut tx: NestingSender<M, TaskFinish>,
_timer: Option<metrics::prometheus::prometheus::HistogramTimer>,
) {
let result = pending_response.await;
@@ -320,7 +320,7 @@ async fn wait_response_task(
Ok(DisputeResponse::Confirmed) =>
TaskFinish { candidate_hash, receiver, result: TaskResult::Succeeded },
};
if let Err(err) = tx.feed(msg).await {
if let Err(err) = tx.send_message(msg).await {
gum::debug!(
target: LOG_TARGET,
%err,
polkadot/node/network/dispute-distribution/src/tests/mod.rs
+2 -60
View File
@@ -45,7 +45,7 @@ use polkadot_node_network_protocol::{
request_response::{v1::DisputeResponse, Recipient, Requests},
IfDisconnected,
};
use polkadot_node_primitives::{CandidateVotes, DisputeStatus, UncheckedDisputeMessage};
use polkadot_node_primitives::DisputeStatus;
use polkadot_node_subsystem::{
messages::{
AllMessages, DisputeCoordinatorMessage, DisputeDistributionMessage, ImportStatementsResult,
@@ -479,65 +479,6 @@ fn receive_rate_limit_is_enforced() {
test_harness(test);
}
#[test]
fn disputes_are_recovered_at_startup() {
let test = |mut handle: TestSubsystemContextHandle<DisputeDistributionMessage>, _| async move {
let relay_parent = Hash::random();
let candidate = make_candidate_receipt(relay_parent);
let _ = handle_subsystem_startup(&mut handle, Some(candidate.hash())).await;
let message = make_dispute_message(candidate.clone(), ALICE_INDEX, FERDIE_INDEX).await;
// Requests needed session info:
assert_matches!(
handle.recv().await,
AllMessages::DisputeCoordinator(
DisputeCoordinatorMessage::QueryCandidateVotes(
query,
tx,
)
) => {
let (session_index, candidate_hash) = query.get(0).unwrap().clone();
assert_eq!(session_index, MOCK_SESSION_INDEX);
assert_eq!(candidate_hash, candidate.hash());
let unchecked: UncheckedDisputeMessage = message.into();
tx.send(vec![(session_index, candidate_hash, CandidateVotes {
candidate_receipt: candidate,
valid: [(
unchecked.valid_vote.validator_index,
(unchecked.valid_vote.kind,
unchecked.valid_vote.signature
),
)].into_iter().collect(),
invalid: [(
unchecked.invalid_vote.validator_index,
(
unchecked.invalid_vote.kind,
unchecked.invalid_vote.signature
),
)].into_iter().collect(),
})])
.expect("Receiver should stay alive.");
}
);
let expected_receivers = {
let info = &MOCK_SESSION_INFO;
info.discovery_keys
.clone()
.into_iter()
.filter(|a| a != &Sr25519Keyring::Ferdie.public().into())
.collect()
// All validators are also authorities in the first session, so we are
// done here.
};
check_sent_requests(&mut handle, expected_receivers, true).await;
conclude(&mut handle).await;
};
test_harness(test);
}
#[test]
fn send_dispute_gets_cleaned_up() {
let test = |mut handle: TestSubsystemContextHandle<DisputeDistributionMessage>, _| async move {
@@ -605,6 +546,7 @@ fn send_dispute_gets_cleaned_up() {
#[test]
fn dispute_retries_and_works_across_session_boundaries() {
sp_tracing::try_init_simple();
let test = |mut handle: TestSubsystemContextHandle<DisputeDistributionMessage>, _| async move {
let old_head = handle_subsystem_startup(&mut handle, None).await;
polkadot/node/primitives/src/disputes/message.rs
+1 -1
View File
@@ -28,7 +28,7 @@ use polkadot_primitives::v2::{
CandidateReceipt, DisputeStatement, SessionIndex, SessionInfo, ValidatorIndex,
};
/// A dispute initiating/participating message that is guaranteed to have been built from signed
/// A dispute initiating/participating message that have been built from signed
/// statements.
///
/// And most likely has been constructed correctly. This is used with
polkadot/node/subsystem-util/Cargo.toml
+1
View File
@@ -8,6 +8,7 @@ edition.workspace = true
[dependencies]
async-trait = "0.1.57"
futures = "0.3.21"
futures-channel = "0.3.23"
itertools = "0.10"
parity-scale-codec = { version = "3.1.5", default-features = false, features = ["derive"] }
parking_lot = "0.11.2"
polkadot/node/subsystem-util/src/lib.rs
+6
View File
@@ -72,6 +72,12 @@ pub mod runtime;
/// Database trait for subsystem.
pub mod database;
/// Nested message sending
///
/// Useful for having mostly synchronous code, with submodules spawning short lived asynchronous
/// tasks, sending messages back.
pub mod nesting_sender;
mod determine_new_blocks;
#[cfg(test)]
polkadot/node/subsystem-util/src/nesting_sender.rs
+207
View File
@@ -0,0 +1,207 @@
// Copyright 2022-2023 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/>.
//! ## Background
//!
//! Writing concurrent and even multithreaded by default is inconvenient and slow: No references
//! hence lots of needless cloning and data duplication, locks, mutexes, ... We should reach
//! for concurrency and parallelism when there is an actual need, not just because we can and it is
//! reasonably safe in Rust.
//!
//! I very much agree with many points in this blog post for example:
//!
//! <https://maciej.codes/2022-06-09-local-async.html>
//!
//! Another very good post by Pierre (Tomaka):
//!
//! <https://tomaka.medium.com/a-look-back-at-asynchronous-rust-d54d63934a1c>
//!
//! ## Architecture
//!
//! This module helps with this in part. It does not break the multithreaded by default approach,
//! but it breaks the `spawn everything` approach. So once you `spawn` you will still be
//! multithreaded by default, despite that for most tasks we spawn (which just wait for network or some
//! message to arrive), that is very much pointless and needless overhead. You will just spawn less in
//! the first place.
//!
//! By default your code is single threaded, except when actually needed:
//! - need to wait for long running synchronous IO (a threaded runtime is actually useful here)
//! - need to wait for some async event (message to arrive)
//! - need to do some hefty CPU bound processing (a thread is required here as well)
//!
//! and it is not acceptable to block the main task for waiting for the result, because we actually
//! really have other things to do or at least need to stay responsive just in case.
//!
//! With the types and traits in this module you can achieve exactly that: You write modules which
//! just execute logic and can call into the functions of other modules - yes we are calling normal
//! functions. For the case a module you are calling into requires an occasional background task,
//! you provide it with a `NestingSender<M, ChildModuleMessage>` that it can pass to any spawned tasks.
//!
//! This way you don't have to spawn a task for each module just for it to be able to handle
//! asynchronous events. The module relies on the using/enclosing code/module to forward it any
//! asynchronous messages in a structured way.
//!
//! What makes this architecture nice is the separation of concerns - at the top you only have to
//! provide a sender and dispatch received messages to the root module - it is completely
//! irrelevant how complex that module is, it might consist of child modules also having the need
//! to spawn and receive messages, which in turn do the same, still the root logic stays unchanged.
//! Everything is isolated to the level where it belongs, while we still keep a single task scope
//! in all non blocking/not CPU intensive parts, which allows us to share data via references for
//! example.
//!
//! Because the wrapping is optional and transparent to the lower modules, each module can also be
//! used at the top directly without any wrapping, e.g. for standalone use or for testing purposes.
//!
//! Checkout the documentation of [`NestingSender`][nesting_sender::NestingSender] below for a basic usage example. For a real
//! world usage I would like to point you to the dispute-distribution subsystem which makes use of
//! this architecture.
//!
//! ## Limitations
//!
//! Nothing is ever for free of course: Each level adds an indirect function call to message
//! sending. which should be cheap enough for most applications, but something to keep in mind. In
//! particular we avoided the use of of async traits, which would have required memory allocations
//! on each send. Also cloning of [`NestingSender`][nesting_sender::NestingSender] is more
//! expensive than cloning a plain mpsc::Sender, the overhead should be negligible though.
//!
//! Further limitations: Because everything is routed to the same channel, it is not possible with
//! this approach to put back pressure on only a single source (as all are the same). If a module
//! has a task that requires this, it indeed has to spawn a long running task which can do the
//! back-pressure on that message source or we make it its own subsystem. This is just one of the
//! situations that justifies the complexity of asynchronism.
use std::{convert::identity, sync::Arc};
use futures::{channel::mpsc, SinkExt};
/// A message sender that supports sending nested messages.
///
/// This sender wraps an `mpsc::Sender` and a conversion function for converting given messages of
/// type `Mnested` to the message type actually supported by the mpsc (`M`).
///
/// Example:
///
/// ```rust
/// # use polkadot_node_subsystem_util::nesting_sender::NestingSender;
///
/// enum RootMessage {
/// Child1Message(ChildMessage),
/// Child2Message(OtherChildMessage),
/// SomeOwnMessage,
/// }
///
/// enum ChildMessage {
/// TaskFinished(u32),
/// }
///
/// enum OtherChildMessage {
/// QueryResult(bool),
/// }
///
/// // We would then pass in a `NestingSender` to our child module of the following type:
/// type ChildSender = NestingSender<RootMessage, ChildMessage>;
///
/// // Types in the child module can (and should) be generic over the root type:
/// struct ChildState<M> {
/// tx: NestingSender<M, ChildMessage>,
/// }
///
///
/// // Create the root message sender:
///
/// let (root_sender, receiver) = NestingSender::new_root(1);
/// // Get a sender for the child module based on that root sender:
/// let child_sender = NestingSender::new(root_sender.clone(), RootMessage::Child1Message);
/// // pass `child_sender` to child module ...
/// ```
///
/// `ChildMessage` could itself have a constructor with messages of a child of its own and can use
/// `NestingSender::new` with its own sender and a conversion function to provide a further nested
/// sender, suitable for the child module.
pub struct NestingSender<M, Mnested> {
sender: mpsc::Sender<M>,
conversion: Arc<dyn Fn(Mnested) -> M + 'static + Send + Sync>,
}
impl<M> NestingSender<M, M>
where
M: 'static,
{
/// Create a new "root" sender.
///
/// This is a sender that directly passes messages to the internal mpsc.
///
/// Params: The channel size of the created mpsc.
/// Returns: The newly constructed `NestingSender` and the corresponding mpsc receiver.
pub fn new_root(channel_size: usize) -> (Self, mpsc::Receiver<M>) {
let (sender, receiver) = mpsc::channel(channel_size);
let s = Self { sender, conversion: Arc::new(identity) };
(s, receiver)
}
}
impl<M, Mnested> NestingSender<M, Mnested>
where
M: 'static,
Mnested: 'static,
{
/// Create a new `NestingSender` which wraps a given "parent" sender.
///
/// By passing in a necessary conversion from `Mnested` to `Mparent` (the `Mnested` of the
/// parent sender), we can construct a derived `NestingSender<M, Mnested>` from a
/// `NestingSender<M, Mparent>`.
///
/// Resulting sender does the following conversion:
///
/// ```text
/// Mnested -> Mparent -> M
/// Inputs:
/// F(Mparent) -> M (via parent)
/// F(Mnested) -> Mparent (via child_conversion)
/// Result: F(Mnested) -> M
/// ```
pub fn new<Mparent>(
parent: NestingSender<M, Mparent>,
child_conversion: fn(Mnested) -> Mparent,
) -> Self
where
Mparent: 'static,
{
let NestingSender { sender, conversion } = parent;
Self { sender, conversion: Arc::new(move |x| conversion(child_conversion(x))) }
}
/// Send a message via the underlying mpsc.
///
/// Necessary conversion is accomplished.
pub async fn send_message(&mut self, m: Mnested) -> Result<(), mpsc::SendError> {
// Flushing on an mpsc means to wait for the receiver to pick up the data - we don't want
// to wait for that.
self.sender.feed((self.conversion)(m)).await
}
}
// Helper traits and implementations:
impl<M, M1> Clone for NestingSender<M, M1>
where
M: 'static,
M1: 'static,
{
fn clone(&self) -> Self {
Self { sender: self.sender.clone(), conversion: self.conversion.clone() }
}
}
polkadot/roadmap/implementers-guide/src/node/disputes/dispute-coordinator.md
+13 -8
View File
@@ -400,12 +400,12 @@ and only if all of the following conditions are satisfied:
Whenever any vote on a dispute is imported these conditions are checked. If the
dispute is found not to be potential spam, then spam slots for the disputed candidate hash are cleared. This decrements the spam count for every validator
which had voted invalid.
which had voted invalid.
To keep spam slots from filling up unnecessarily we want to clear spam slots
To keep spam slots from filling up unnecessarily we want to clear spam slots
whenever a candidate is seen to be backed or included. Fortunately this behavior
is acheived by clearing slots on vote import as described above. Because on chain
backing votes are processed when a block backing the disputed candidate is discovered, spam slots are cleared for every backed candidate. Included
backing votes are processed when a block backing the disputed candidate is discovered, spam slots are cleared for every backed candidate. Included
candidates have also been seen as backed on the same fork, so decrementing spam
slots is handled in that case as well.
@@ -681,12 +681,17 @@ struct State {
```
### On startup
When the subsystem is initialised it waits for a new leaf (message `OverseerSignal::ActiveLeaves`).
The leaf is used to initialise a `RollingSessionWindow` instance (contains leaf hash and
`DISPUTE_WINDOW` which is a constant.
Next the active disputes are loaded from the DB. The subsystem checks if there are disputes for
which a local statement is not issued. A list of these is passed to the main loop.
When the subsystem is initialised it waits for a new leaf (message
`OverseerSignal::ActiveLeaves`). The leaf is used to initialise a
`RollingSessionWindow` instance (contains leaf hash and `DISPUTE_WINDOW` which
is a constant).
Next the active disputes are loaded from the DB and initialize spam slots
accordingly, then for each loaded dispute, we either send a
`DisputeDistribution::SendDispute` if there is a local vote from us available or
if there is none and participation is in order, we push the dispute to
participation.
### The main loop
polkadot/roadmap/implementers-guide/src/node/disputes/dispute-distribution.md
+2 -5
View File
@@ -339,11 +339,8 @@ coordinator.
### Node Startup
On startup we need to check with the dispute coordinator for any ongoing
disputes and assume we have not yet sent our statement for those. In case we
find an explicit statement from ourselves via
`DisputeCoordinatorMessage::QueryCandidateVotes` we will pretend to just have
received a `SendDispute` message for that candidate.
Nothing special happens on node startup. We expect the `dispute-coordinator` to
inform us about any ongoing disputes via `SendDispute` messages.
## Backing and Approval Votes