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node: fix grandpa voting rule (#3190)

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* node: fix grandpa voting rule

* node: cleanup find_target
This commit is contained in:
André Silva
2021-06-07 20:45:27 +01:00
committed by GitHub
parent a87df9d854
commit 6f29754cce
1 changed files with 41 additions and 53 deletions
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polkadot/node/service/src/grandpa_support.rs
+41 -53
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@@ -112,31 +112,6 @@ impl<B> grandpa::VotingRule<PolkadotBlock, B> for ApprovalCheckingVotingRule
best_target: &PolkadotHeader,
current_target: &PolkadotHeader,
) -> grandpa::VotingRuleResult<PolkadotBlock> {
// walk backwards until we find the target block
let find_target = move |target_number: BlockNumber, current_header: &PolkadotHeader| {
let mut target_hash = current_header.hash();
let mut target_header = current_header.clone();
loop {
if *target_header.number() < target_number {
unreachable!(
"we are traversing backwards from a known block; \
blocks are stored contiguously; \
qed"
);
}
if *target_header.number() == target_number {
return Some((target_hash, target_number));
}
target_hash = *target_header.parent_hash();
target_header = backend.header(BlockId::Hash(target_hash)).ok()?.expect(
"Header known to exist due to the existence of one of its descendents; qed",
);
}
};
// Query approval checking and issue metrics.
let mut overseer = self.overseer.clone();
let checking_lag = self.checking_lag.clone();
@@ -176,8 +151,12 @@ impl<B> grandpa::VotingRule<PolkadotBlock, B> for ApprovalCheckingVotingRule
let diff = best_number.saturating_sub(base_number);
if diff >= MAX_APPROVAL_CHECKING_FINALITY_LAG {
// Catch up to the best, with some extra lag.
find_target(best_number - MAX_APPROVAL_CHECKING_FINALITY_LAG, &best_header)
.filter(|vote| vote.1 <= current_number)
let target_number = best_number - MAX_APPROVAL_CHECKING_FINALITY_LAG;
if target_number >= current_number {
Some((current_hash, current_number))
} else {
walk_backwards_to_target_block(&*backend, target_number, &best_header).ok()
}
} else {
Some((base_hash, base_number))
}
@@ -214,6 +193,40 @@ impl<B> grandpa::VotingRule<PolkadotBlock, B> for ApprovalCheckingVotingRule
}
}
/// Returns the block hash of the block at the given `target_number` by walking
/// backwards from the given `current_header`.
fn walk_backwards_to_target_block<Block, B>(
backend: &B,
target_number: NumberFor<Block>,
current_header: &Block::Header,
) -> Result<(Block::Hash, NumberFor<Block>), sp_blockchain::Error>
where
Block: BlockT,
B: sp_blockchain::HeaderBackend<Block>,
{
let mut target_hash = current_header.hash();
let mut target_header = current_header.clone();
loop {
if *target_header.number() < target_number {
unreachable!(
"we are traversing backwards from a known block; \
blocks are stored contiguously; \
qed"
);
}
if *target_header.number() == target_number {
return Ok((target_hash, target_number));
}
target_hash = *target_header.parent_hash();
target_header = backend
.header(BlockId::Hash(target_hash))?
.expect("Header known to exist due to the existence of one of its descendents; qed");
}
}
/// A custom GRANDPA voting rule that "pauses" voting (i.e. keeps voting for the
/// same last finalized block) after a given block at height `N` has been
/// finalized and for a delay of `M` blocks, i.e. until the best block reaches
@@ -234,31 +247,6 @@ where
current_target: &Block::Header,
) -> grandpa::VotingRuleResult<Block> {
let aux = || {
// walk backwards until we find the target block
let find_target = |target_number: NumberFor<Block>, current_header: &Block::Header| {
let mut target_hash = current_header.hash();
let mut target_header = current_header.clone();
loop {
if *target_header.number() < target_number {
unreachable!(
"we are traversing backwards from a known block; \
blocks are stored contiguously; \
qed"
);
}
if *target_header.number() == target_number {
return Some((target_hash, target_number));
}
target_hash = *target_header.parent_hash();
target_header = backend.header(BlockId::Hash(target_hash)).ok()?.expect(
"Header known to exist due to the existence of one of its descendents; qed",
);
}
};
// only restrict votes targeting a block higher than the block
// we've set for the pause
if *current_target.number() > self.0 {
@@ -276,7 +264,7 @@ where
// otherwise find the target header at the pause block
// to vote on
return find_target(self.0, current_target);
return walk_backwards_to_target_block(&*backend, self.0, current_target).ok();
}
None