core, light: add NoLock func to avoid double lock

core/blockchain.go

@@ -329,18 +329,14 @@ func (bc *BlockChain) loadLastState() error {
 	if head == (common.Hash{}) {
 		// Corrupt or empty database, init from scratch
 		log.Warn("Empty database, resetting chain")
-		bc.chainmu.Unlock()
-		defer bc.chainmu.Lock()
-		return bc.Reset()
+		return bc.resetWithGenesisBlockNoLock(bc.genesisBlock)
 	}
 	// Make sure the entire head block is available
 	currentBlock := bc.GetBlockByHash(head)
 	if currentBlock == nil {
 		// Corrupt or empty database, init from scratch
 		log.Warn("Head block missing, resetting chain", "hash", head)
-		bc.chainmu.Unlock()
-		defer bc.chainmu.Lock()
-		return bc.Reset()
+		return bc.resetWithGenesisBlockNoLock(bc.genesisBlock)
 	}
 	// Make sure the state associated with the block is available
 	if _, err := state.New(currentBlock.Root(), bc.stateCache); err != nil {
@@ -388,6 +384,85 @@ func (bc *BlockChain) loadLastState() error {
 	return nil
 }
 
+// setHeadNoLock rewinds the local chain to a new head. The callers should hold bc.chainmu.
+func (bc *BlockChain) setHeadNoLock(head uint64) error {
+	log.Warn("Rewinding blockchain", "target", head)
+
+	updateFn := func(db ethdb.KeyValueWriter, header *types.Header) {
+		// Rewind the block chain, ensuring we don't end up with a stateless head block
+		if currentBlock := bc.CurrentBlock(); currentBlock != nil && header.Number.Uint64() < currentBlock.NumberU64() {
+			newHeadBlock := bc.GetBlock(header.Hash(), header.Number.Uint64())
+			if newHeadBlock == nil {
+				newHeadBlock = bc.genesisBlock
+			} else {
+				if _, err := state.New(newHeadBlock.Root(), bc.stateCache); err != nil {
+					// Rewound state missing, rolled back to before pivot, reset to genesis
+					newHeadBlock = bc.genesisBlock
+				}
+			}
+			rawdb.WriteHeadBlockHash(db, newHeadBlock.Hash())
+
+			// Degrade the chain markers if they are explicitly reverted.
+			// In theory we should update all in-memory markers in the
+			// last step, however the direction of SetHead is from high
+			// to low, so it's safe the update in-memory markers directly.
+			bc.currentBlock.Store(newHeadBlock)
+			headBlockGauge.Update(int64(newHeadBlock.NumberU64()))
+		}
+
+		// Rewind the fast block in a simpleton way to the target head
+		if currentFastBlock := bc.CurrentFastBlock(); currentFastBlock != nil && header.Number.Uint64() < currentFastBlock.NumberU64() {
+			newHeadFastBlock := bc.GetBlock(header.Hash(), header.Number.Uint64())
+			// If either blocks reached nil, reset to the genesis state
+			if newHeadFastBlock == nil {
+				newHeadFastBlock = bc.genesisBlock
+			}
+			rawdb.WriteHeadFastBlockHash(db, newHeadFastBlock.Hash())
+
+			// Degrade the chain markers if they are explicitly reverted.
+			// In theory we should update all in-memory markers in the
+			// last step, however the direction of SetHead is from high
+			// to low, so it's safe the update in-memory markers directly.
+			bc.currentFastBlock.Store(newHeadFastBlock)
+			headFastBlockGauge.Update(int64(newHeadFastBlock.NumberU64()))
+		}
+	}
+
+	// Rewind the header chain, deleting all block bodies until then
+	delFn := func(db ethdb.KeyValueWriter, hash common.Hash, num uint64) {
+		// Ignore the error here since light client won't hit this path
+		frozen, _ := bc.db.Ancients()
+		if num+1 <= frozen {
+			// Truncate all relative data(header, total difficulty, body, receipt
+			// and canonical hash) from ancient store.
+			if err := bc.db.TruncateAncients(num + 1); err != nil {
+				log.Crit("Failed to truncate ancient data", "number", num, "err", err)
+			}
+
+			// Remove the hash <-> number mapping from the active store.
+			rawdb.DeleteHeaderNumber(db, hash)
+		} else {
+			// Remove relative body and receipts from the active store.
+			// The header, total difficulty and canonical hash will be
+			// removed in the hc.SetHead function.
+			rawdb.DeleteBody(db, hash, num)
+			rawdb.DeleteReceipts(db, hash, num)
+		}
+		// Todo(rjl493456442) txlookup, bloombits, etc
+	}
+	bc.hc.SetHead(head, updateFn, delFn)
+
+	// Clear out any stale content from the caches
+	bc.bodyCache.Purge()
+	bc.bodyRLPCache.Purge()
+	bc.receiptsCache.Purge()
+	bc.blockCache.Purge()
+	bc.txLookupCache.Purge()
+	bc.futureBlocks.Purge()
+
+	return bc.loadLastState()
+}
+
 // SetHead rewinds the local chain to a new head. In the case of headers, everything
 // above the new head will be deleted and the new one set. In the case of blocks
 // though, the head may be further rewound if block bodies are missing (non-archive
@@ -541,6 +616,34 @@ func (bc *BlockChain) Reset() error {
 	return bc.ResetWithGenesisBlock(bc.genesisBlock)
 }
 
+// resetWithGenesisBlockNoLock purges the entire blockchain, restoring it to the
+// specified genesis state. The callers should hold bc.chainmu.
+func (bc *BlockChain) resetWithGenesisBlockNoLock(genesis *types.Block) error {
+	// Dump the entire block chain and purge the caches
+	if err := bc.setHeadNoLock(0); err != nil {
+		return err
+	}
+	
+	// Prepare the genesis block and reinitialise the chain
+	batch := bc.db.NewBatch()
+	rawdb.WriteTd(batch, genesis.Hash(), genesis.NumberU64(), genesis.Difficulty())
+	rawdb.WriteBlock(batch, genesis)
+	if err := batch.Write(); err != nil {
+		log.Crit("Failed to write genesis block", "err", err)
+	}
+	bc.writeHeadBlock(genesis)
+
+	// Last update all in-memory chain markers
+	bc.genesisBlock = genesis
+	bc.currentBlock.Store(bc.genesisBlock)
+	headBlockGauge.Update(int64(bc.genesisBlock.NumberU64()))
+	bc.hc.SetGenesis(bc.genesisBlock.Header())
+	bc.hc.SetCurrentHeader(bc.genesisBlock.Header())
+	bc.currentFastBlock.Store(bc.genesisBlock)
+	headFastBlockGauge.Update(int64(bc.genesisBlock.NumberU64()))
+	return nil
+}
+
 // ResetWithGenesisBlock purges the entire blockchain, restoring it to the
 // specified genesis state.
 func (bc *BlockChain) ResetWithGenesisBlock(genesis *types.Block) error {

light/lightchain.go

@@ -153,9 +153,7 @@ func (lc *LightChain) HeaderChain() *core.HeaderChain {
 func (lc *LightChain) loadLastState() error {
 	if head := rawdb.ReadHeadHeaderHash(lc.chainDb); head == (common.Hash{}) {
 		// Corrupt or empty database, init from scratch
-		lc.chainmu.Unlock()
-		lc.Reset()
-		lc.chainmu.Lock()
+		lc.resetWithGenesisBlockNoLock(lc.genesisBlock)
 	} else {
 		if header := lc.GetHeaderByHash(head); header != nil {
 			lc.hc.SetCurrentHeader(header)
@@ -169,6 +167,12 @@ func (lc *LightChain) loadLastState() error {
 	return nil
 }
 
+// setHeadNoLock rewinds the local chain to a new head. Callers should hold lc.chainmu.
+func (lc *LightChain) setHeadNoLock(head uint64) error {
+	lc.hc.SetHead(head, nil, nil)
+	return lc.loadLastState()
+}
+
 // SetHead rewinds the local chain to a new head. Everything above the new
 // head will be deleted and the new one set.
 func (lc *LightChain) SetHead(head uint64) error {
@@ -189,6 +193,25 @@ func (lc *LightChain) Reset() {
 	lc.ResetWithGenesisBlock(lc.genesisBlock)
 }
 
+// resetWithGenesisBlockNoLock purges the entire blockchain, restoring it to the
+// specified genesis state. Callers should hold lc.chainmu.
+func (lc *LightChain) resetWithGenesisBlockNoLock(genesis *types.Block) {
+	// Dump the entire block chain and purge the caches
+	lc.setHeadNoLock(0)
+
+	// Prepare the genesis block and reinitialise the chain
+	batch := lc.chainDb.NewBatch()
+	rawdb.WriteTd(batch, genesis.Hash(), genesis.NumberU64(), genesis.Difficulty())
+	rawdb.WriteBlock(batch, genesis)
+	rawdb.WriteHeadHeaderHash(batch, genesis.Hash())
+	if err := batch.Write(); err != nil {
+		log.Crit("Failed to reset genesis block", "err", err)
+	}
+	lc.genesisBlock = genesis
+	lc.hc.SetGenesis(lc.genesisBlock.Header())
+	lc.hc.SetCurrentHeader(lc.genesisBlock.Header())
+}
+
 // ResetWithGenesisBlock purges the entire blockchain, restoring it to the
 // specified genesis state.
 func (lc *LightChain) ResetWithGenesisBlock(genesis *types.Block) {