fix: prune uses the latest block height as the target by default (bnb…

…-chain#46)

core/state/pruner/pruner.go

@@ -274,24 +274,17 @@ func (p *Pruner) Prune(root common.Hash) error {
  if stateBloomRoot != (common.Hash{}) {
  return RecoverPruning(p.config.Datadir, p.db, p.config.Cachedir, p.triesInMemory)
  }
- // If the target state root is not specified, use the HEAD-(n-1) as the
+ // If the target state root is not specified, use the HEAD as the
  // target. The reason for picking it is:
- // - in most of the normal cases, the related state is available
- // - the probability of this layer being reorg is very low
+ // - At opBNB, the possibility of reorg is very small, we don't need to roll back the block height,
+ // we just need to wait for the block height to be finalized during pruning.
+ // - Rolling back the block height currently causes the node to get stuck after startup.
+ // Instead of fixing the complex logic that causes the node to get stuck,
+ // we choose a more gentle way to solve the problem.
  var layers []snapshot.Snapshot
  if root == (common.Hash{}) {
- // Retrieve all snapshot layers from the current HEAD.
- // In theory there are n difflayers + 1 disk layer present,
- // so n diff layers are expected to be returned.
- layers = p.snaptree.Snapshots(p.chainHeader.Root, int(p.triesInMemory), true)
- if len(layers) != int(p.triesInMemory) {
- // Reject if the accumulated diff layers are less than n. It
- // means in most of normal cases, there is no associated state
- // with bottom-most diff layer.
- return fmt.Errorf("snapshot not old enough yet: need %d more blocks", int(p.triesInMemory)-len(layers))
- }
- // Use the bottom-most diff layer as the target
- root = layers[len(layers)-1].Root()
+ // Use the latest block header root as the target
+ root = p.chainHeader.Root
  }
  // Ensure the root is really present. The weak assumption
  // is the presence of root can indicate the presence of the
@@ -327,7 +320,7 @@ func (p *Pruner) Prune(root common.Hash) error {
  if len(layers) > 0 {
  log.Info("Selecting bottom-most difflayer as the pruning target", "root", root, "height", p.chainHeader.Number.Uint64()-(p.triesInMemory-1))
  } else {
- log.Info("Selecting user-specified state as the pruning target", "root", root)
+ log.Info("Selecting user-specified state as the pruning target", "root", root, "height", p.chainHeader.Number.Uint64())
  }
  }
  // Before start the pruning, delete the clean trie cache first.