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core, eth/downloader: fix genesis state missing due to state sync (et…
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…hereum#28124)

* core: fix chain repair corner case in path-based scheme

* eth/downloader: disable trie database whenever state sync is launched
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rjl493456442 authored and devopsbo3 committed Nov 10, 2023
1 parent 6ddfb76 commit 5a51327
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Showing 2 changed files with 63 additions and 43 deletions.
97 changes: 55 additions & 42 deletions core/blockchain.go
Original file line number Diff line number Diff line change
Expand Up @@ -340,28 +340,38 @@ func NewBlockChain(db ethdb.Database, cacheConfig *CacheConfig, genesis *Genesis
// Make sure the state associated with the block is available
head := bc.CurrentBlock()
if !bc.HasState(head.Root) {
// Head state is missing, before the state recovery, find out the
// disk layer point of snapshot(if it's enabled). Make sure the
// rewound point is lower than disk layer.
var diskRoot common.Hash
if bc.cacheConfig.SnapshotLimit > 0 {
diskRoot = rawdb.ReadSnapshotRoot(bc.db)
}
if diskRoot != (common.Hash{}) {
log.Warn("Head state missing, repairing", "number", head.Number, "hash", head.Hash(), "snaproot", diskRoot)

snapDisk, err := bc.setHeadBeyondRoot(head.Number.Uint64(), 0, diskRoot, true)
if err != nil {
return nil, err
}
// Chain rewound, persist old snapshot number to indicate recovery procedure
if snapDisk != 0 {
rawdb.WriteSnapshotRecoveryNumber(bc.db, snapDisk)
}
if head.Number.Uint64() == 0 {
// The genesis state is missing, which is only possible in the path-based
// scheme. This situation occurs when the state syncer overwrites it.
//
// The solution is to reset the state to the genesis state. Although it may not
// match the sync target, the state healer will later address and correct any
// inconsistencies.
bc.resetState()
} else {
log.Warn("Head state missing, repairing", "number", head.Number, "hash", head.Hash())
if _, err := bc.setHeadBeyondRoot(head.Number.Uint64(), 0, common.Hash{}, true); err != nil {
return nil, err
// Head state is missing, before the state recovery, find out the
// disk layer point of snapshot(if it's enabled). Make sure the
// rewound point is lower than disk layer.
var diskRoot common.Hash
if bc.cacheConfig.SnapshotLimit > 0 {
diskRoot = rawdb.ReadSnapshotRoot(bc.db)
}
if diskRoot != (common.Hash{}) {
log.Warn("Head state missing, repairing", "number", head.Number, "hash", head.Hash(), "snaproot", diskRoot)

snapDisk, err := bc.setHeadBeyondRoot(head.Number.Uint64(), 0, diskRoot, true)
if err != nil {
return nil, err
}
// Chain rewound, persist old snapshot number to indicate recovery procedure
if snapDisk != 0 {
rawdb.WriteSnapshotRecoveryNumber(bc.db, snapDisk)
}
} else {
log.Warn("Head state missing, repairing", "number", head.Number, "hash", head.Hash())
if _, err := bc.setHeadBeyondRoot(head.Number.Uint64(), 0, common.Hash{}, true); err != nil {
return nil, err
}
}
}
}
Expand Down Expand Up @@ -620,6 +630,28 @@ func (bc *BlockChain) SetSafe(header *types.Header) {
}
}

// resetState resets the persistent state to genesis state if it's not present.
func (bc *BlockChain) resetState() {
// Short circuit if the genesis state is already present.
root := bc.genesisBlock.Root()
if bc.HasState(root) {
return
}
// Reset the state database to empty for committing genesis state.
// Note, it should only happen in path-based scheme and Reset function
// is also only call-able in this mode.
if bc.triedb.Scheme() == rawdb.PathScheme {
if err := bc.triedb.Reset(types.EmptyRootHash); err != nil {
log.Crit("Failed to clean state", "err", err) // Shouldn't happen
}
}
// Write genesis state into database.
if err := CommitGenesisState(bc.db, bc.triedb, bc.genesisBlock.Hash()); err != nil {
log.Crit("Failed to commit genesis state", "err", err)
}
log.Info("Reset state to genesis", "root", root)
}

// setHeadBeyondRoot rewinds the local chain to a new head with the extra condition
// that the rewind must pass the specified state root. This method is meant to be
// used when rewinding with snapshots enabled to ensure that we go back further than
Expand All @@ -646,25 +678,6 @@ func (bc *BlockChain) setHeadBeyondRoot(head uint64, time uint64, root common.Ha
pivot := rawdb.ReadLastPivotNumber(bc.db)
frozen, _ := bc.db.Ancients()

// resetState resets the persistent state to genesis if it's not available.
resetState := func() {
// Short circuit if the genesis state is already present.
if bc.HasState(bc.genesisBlock.Root()) {
return
}
// Reset the state database to empty for committing genesis state.
// Note, it should only happen in path-based scheme and Reset function
// is also only call-able in this mode.
if bc.triedb.Scheme() == rawdb.PathScheme {
if err := bc.triedb.Reset(types.EmptyRootHash); err != nil {
log.Crit("Failed to clean state", "err", err) // Shouldn't happen
}
}
// Write genesis state into database.
if err := CommitGenesisState(bc.db, bc.triedb, bc.genesisBlock.Hash()); err != nil {
log.Crit("Failed to commit genesis state", "err", err)
}
}
updateFn := func(db ethdb.KeyValueWriter, header *types.Header) (*types.Header, bool) {
// Rewind the blockchain, ensuring we don't end up with a stateless head
// block. Note, depth equality is permitted to allow using SetHead as a
Expand All @@ -674,7 +687,7 @@ func (bc *BlockChain) setHeadBeyondRoot(head uint64, time uint64, root common.Ha
if newHeadBlock == nil {
log.Error("Gap in the chain, rewinding to genesis", "number", header.Number, "hash", header.Hash())
newHeadBlock = bc.genesisBlock
resetState()
bc.resetState()
} else {
// Block exists, keep rewinding until we find one with state,
// keeping rewinding until we exceed the optional threshold
Expand Down Expand Up @@ -703,7 +716,7 @@ func (bc *BlockChain) setHeadBeyondRoot(head uint64, time uint64, root common.Ha
}
if beyondRoot || newHeadBlock.NumberU64() == 0 {
if newHeadBlock.NumberU64() == 0 {
resetState()
bc.resetState()
} else if !bc.HasState(newHeadBlock.Root()) {
// Rewind to a block with recoverable state. If the state is
// missing, run the state recovery here.
Expand Down
9 changes: 8 additions & 1 deletion eth/downloader/downloader.go
Original file line number Diff line number Diff line change
Expand Up @@ -398,7 +398,14 @@ func (d *Downloader) synchronise(id string, hash common.Hash, td, ttd *big.Int,
log.Info("Block synchronisation started")
}
if mode == SnapSync {
// Snap sync uses the snapshot namespace to store potentially flakey data until
// Snap sync will directly modify the persistent state, making the entire
// trie database unusable until the state is fully synced. To prevent any
// subsequent state reads, explicitly disable the trie database and state
// syncer is responsible to address and correct any state missing.
if d.blockchain.TrieDB().Scheme() == rawdb.PathScheme {
d.blockchain.TrieDB().Reset(types.EmptyRootHash)
}
// Snap sync uses the snapshot namespace to store potentially flaky data until
// sync completely heals and finishes. Pause snapshot maintenance in the mean-
// time to prevent access.
if snapshots := d.blockchain.Snapshots(); snapshots != nil { // Only nil in tests
Expand Down

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