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fix minor race condition in aura seal generation (#5910)

This commit is contained in:
Robert Habermeier 2017-06-22 20:44:04 +02:00 committed by Gav Wood
parent b6fd18a9ca
commit 796482c129
1 changed files with 8 additions and 2 deletions
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10
ethcore/src/engines/authority_round.rs
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@ -319,14 +319,20 @@ impl Engine for AuthorityRound {
/// This operation is synchronous and may (quite reasonably) not be available, in which `false` will
/// be returned.
fn generate_seal(&self, block: &ExecutedBlock) -> Seal {
// first check to avoid generating signature most of the time
// (but there's still a race to the `compare_and_swap`)
if self.proposed.load(AtomicOrdering::SeqCst) { return Seal::None; }
let header = block.header();
let step = self.step.load();
if self.is_step_proposer(header.parent_hash(), step, header.author()) {
if let Ok(signature) = self.signer.sign(header.bare_hash()) {
trace!(target: "engine", "generate_seal: Issuing a block for step {}.", step);
self.proposed.store(true, AtomicOrdering::SeqCst);
return Seal::Regular(vec![encode(&step).to_vec(), encode(&(&H520::from(signature) as &[u8])).to_vec()]);
// only issue the seal if we were the first to reach the compare_and_swap.
if !self.proposed.compare_and_swap(false, true, AtomicOrdering::SeqCst) {
return Seal::Regular(vec![encode(&step).to_vec(), encode(&(&H520::from(signature) as &[u8])).to_vec()]);
}
} else {
warn!(target: "engine", "generate_seal: FAIL: Accounts secret key unavailable.");
}