clique: ensure validator restores state before trying to seal

ethcore/src/engines/clique/mod.rs

@@ -38,7 +38,7 @@ use types::ancestry_action::AncestryAction;
 use engines::{Engine, Seal, EngineError, ConstructedVerifier, Headers, PendingTransitionStore};
 use super::signer::EngineSigner;
 use machine::{Call, AuxiliaryData, EthereumMachine};
-use self::signer_snapshot::{CliqueState, SignerAuthorization, NONCE_AUTH_VOTE, NONCE_DROP_VOTE, NULL_AUTHOR, DIFF_INTURN, DIFF_NOT_INTURN};
+use self::signer_snapshot::{CliqueState, SignerAuthorization, SnapshotState, NONCE_AUTH_VOTE, NONCE_DROP_VOTE, NULL_AUTHOR, DIFF_INTURN, DIFF_NOT_INTURN};
 
 pub const SIGNER_VANITY_LENGTH: u32 = 32;
 // Fixed number of extra-data prefix bytes reserved for signer vanity
@@ -132,6 +132,62 @@ impl Clique {
  Err(e) => { Err(From::from("failed to sign header")) }
  }
  }
+
+ fn state(&self, parent: &Header) -> Option<SnapshotState> {
+ let mut state = self.state.write();
+
+ match state.state(&parent.hash()) {
+ Some(st) => Some(st),
+ None => {
+ let client = self.client.read();
+ if let Some(c) = client.as_ref().and_then(|w|{ w.upgrade()}) {
+ let last_checkpoint_number = (parent.number() / self.epoch_length as u64) * self.epoch_length;
+ let mut chain: &mut Vec<Header> = &mut Vec::new();
+ chain.push(parent.clone());
+
+ // populate chain to last checkpoint
+ let mut last = chain.last().unwrap().clone();
+
+ while last.number() != last_checkpoint_number +1 {
+ if let Some(next) = c.block_header(BlockId::Hash(*last.parent_hash())) {
+ chain.push(next.decode().unwrap().clone());
+ last = chain.last().unwrap().clone();
+ } else {
+ trace!(target: "engine", "no parent state for {}", &parent.hash());
+ return None;
+ }
+ }
+
+ // Get the last checkpoint header
+ if let Some(last_checkpoint_header) = c.block_header(BlockId::Hash(*chain.last().unwrap().parent_hash())) {
+ if let Err(_) = state.apply_checkpoint(&last_checkpoint_header.decode().unwrap()) {
+ trace!(target: "engine", "failed to apply checkpoint");
+ return None;
+ }
+ }
+
+ // Catching up state.
+ chain.reverse();
+
+ trace!(target: "engine",
+ "verify_block_family backfilling state. last_checkpoint: {}, chain: {:?}.",
+ last_checkpoint_number, chain);
+
+ for item in chain {
+ if let Err(_) = state.apply(item) {
+ trace!(target: "engine", "failed to apply item");
+ return None;
+ }
+ }
+
+ return state.state(&parent.hash());
+ } else {
+ trace!(target: "engine", "failed to upgrade client");
+ return None;
+ }
+ }
+ }
+ }
 }
 
 impl Engine<EthereumMachine> for Clique {
@@ -269,6 +325,10 @@ impl Engine<EthereumMachine> for Clique {
  return Seal::None;
  }
 
+ if self.state(&_parent).is_none() {
+ panic!("could not recover voting state when sealing on block {}", _parent.number() + 1 );
+ }
+
  let mut state = self.state.write();
 
  match state.proposer_authorization(&block.header) {
@@ -396,44 +456,12 @@ impl Engine<EthereumMachine> for Clique {
  header.number(), *self.state.read());
  */
 
+ if self.state(&parent).is_none() {
+ return Err(From::from(format!("could not parse parent state for {}", &parent.hash())));
+ }
+
  let mut state = self.state.write();
 
- // see if we have parent state
- if state.state(&parent.hash()).is_none() {
- let client = self.client.read();
- if let Some(c) = client.as_ref().and_then(|w|{ w.upgrade()}) {
- let last_checkpoint_number = (parent.number() / self.epoch_length as u64) * self.epoch_length;
- let mut chain: &mut Vec<Header> = &mut Vec::new();
- chain.push(parent.clone());
-
- // populate chain to last checkpoint
- let mut last = chain.last().unwrap().clone();
-
- while last.number() != last_checkpoint_number +1 {
- if let Some(next) = c.block_header(BlockId::Hash(*last.parent_hash())) {
- chain.push(next.decode().unwrap().clone());
- last = chain.last().unwrap().clone();
- } else {
- return Err(From::from("No parent state exist."));
- }
- }
-
- // Get the last checkpoint header
- if let Some(last_checkpoint_header) = c.block_header(BlockId::Hash(*chain.last().unwrap().parent_hash())) {
- state.apply_checkpoint(&last_checkpoint_header.decode().unwrap())?;
- }
- // Catching up state.
- chain.reverse();
-
- trace!(target: "engine",
- "verify_block_family backfilling state. last_checkpoint: {}, chain: {:?}.",
- last_checkpoint_number, chain);
-
- for item in chain {
- state.apply(item)?;
- }
- }
- }
  if (header.number() % self.epoch_length == 0) {
  // TODO: we may still need to validate checkpoint state
  state.apply_checkpoint(header);