From 4e0796771190b6f8a976d931540d5f21789a882f Mon Sep 17 00:00:00 2001 From: obscuren Date: Wed, 29 Apr 2015 12:43:24 +0200 Subject: [PATCH] core: fixed chain reorg during splits Chain reorgs weren't properly handled when a chain was further ahead. Previously we'd end up with mixed chains in our canonical numbering sequence. Added test for this type of forking. ``` /-o-o-o A o-C-+ \-o-o-o-o B ``` Ends up with with C A1, A2, A3, B4 --- core/chain_manager.go | 58 +++++++++++++++++++++----------------- core/chain_manager_test.go | 52 +++++++++++++++++++++++++++++++++- 2 files changed, 83 insertions(+), 27 deletions(-) diff --git a/core/chain_manager.go b/core/chain_manager.go index 56895b73e..32ad4a2ba 100644 --- a/core/chain_manager.go +++ b/core/chain_manager.go @@ -74,9 +74,8 @@ type ChainManager struct { eventMux *event.TypeMux genesisBlock *types.Block // Last known total difficulty - mu sync.RWMutex - tsmu sync.RWMutex - insertMu sync.Mutex + mu sync.RWMutex + tsmu sync.RWMutex td *big.Int currentBlock *types.Block @@ -321,6 +320,7 @@ func (bc *ChainManager) ResetWithGenesisBlock(gb *types.Block) { bc.insert(bc.genesisBlock) bc.currentBlock = bc.genesisBlock bc.makeCache() + bc.td = gb.Difficulty() } // Export writes the active chain to the given writer. @@ -348,8 +348,6 @@ func (self *ChainManager) Export(w io.Writer) error { func (bc *ChainManager) insert(block *types.Block) { key := append(blockNumPre, block.Number().Bytes()...) bc.blockDb.Put(key, block.Hash().Bytes()) - // Push block to cache - bc.cache.Push(block) bc.blockDb.Put([]byte("LastBlock"), block.Hash().Bytes()) bc.currentBlock = block @@ -360,6 +358,8 @@ func (bc *ChainManager) write(block *types.Block) { enc, _ := rlp.EncodeToBytes((*types.StorageBlock)(block)) key := append(blockHashPre, block.Hash().Bytes()...) bc.blockDb.Put(key, enc) + // Push block to cache + bc.cache.Push(block) } // Accessors @@ -498,9 +498,6 @@ func (self *ChainManager) procFutureBlocks() { } func (self *ChainManager) InsertChain(chain types.Blocks) error { - self.insertMu.Lock() - defer self.insertMu.Unlock() - // A queued approach to delivering events. This is generally faster than direct delivery and requires much less mutex acquiring. var ( queue = make([]interface{}, len(chain)) @@ -557,16 +554,17 @@ func (self *ChainManager) InsertChain(chain types.Blocks) error { // Compare the TD of the last known block in the canonical chain to make sure it's greater. // At this point it's possible that a different chain (fork) becomes the new canonical chain. if block.Td.Cmp(self.td) > 0 { - //if block.Header().Number.Cmp(new(big.Int).Add(cblock.Header().Number, common.Big1)) < 0 { - if block.Number().Cmp(cblock.Number()) <= 0 { + // Check for chain forks. If H(block.num - 1) != block.parent, we're on a fork and need to do some merging + if previous := self.getBlockByNumber(block.NumberU64() - 1); previous.Hash() != block.ParentHash() { chash := cblock.Hash() hash := block.Hash() if glog.V(logger.Info) { glog.Infof("Split detected. New head #%v (%x) TD=%v, was #%v (%x) TD=%v\n", block.Header().Number, hash[:4], block.Td, cblock.Header().Number, chash[:4], self.td) } + // during split we merge two different chains and create the new canonical chain - self.merge(self.getBlockByNumber(block.NumberU64()), block) + self.merge(previous, block) queue[i] = ChainSplitEvent{block, logs} queueEvent.splitCount++ @@ -592,16 +590,19 @@ func (self *ChainManager) InsertChain(chain types.Blocks) error { glog.Infof("inserted block #%d (%d TXs %d UNCs) (%x...)\n", block.Number(), len(block.Transactions()), len(block.Uncles()), block.Hash().Bytes()[0:4]) } } else { + if glog.V(logger.Detail) { + glog.Infof("inserted forked block #%d (%d TXs %d UNCs) (%x...)\n", block.Number(), len(block.Transactions()), len(block.Uncles()), block.Hash().Bytes()[0:4]) + } + queue[i] = ChainSideEvent{block, logs} queueEvent.sideCount++ } + self.futureBlocks.Delete(block.Hash()) } self.mu.Unlock() stats.processed++ - self.futureBlocks.Delete(block.Hash()) - } if (stats.queued > 0 || stats.processed > 0) && bool(glog.V(logger.Info)) { @@ -615,33 +616,38 @@ func (self *ChainManager) InsertChain(chain types.Blocks) error { return nil } -// merge takes two blocks, an old chain and a new chain and will reconstruct the blocks and inserts them +// diff takes two blocks, an old chain and a new chain and will reconstruct the blocks and inserts them // to be part of the new canonical chain. -func (self *ChainManager) merge(oldBlock, newBlock *types.Block) { +func (self *ChainManager) diff(oldBlock, newBlock *types.Block) types.Blocks { glog.V(logger.Debug).Infof("Applying diff to %x & %x\n", oldBlock.Hash().Bytes()[:4], newBlock.Hash().Bytes()[:4]) - var oldChain, newChain types.Blocks - // First find the split (common ancestor) so we can perform an adequate merge + var newChain types.Blocks + // first find common number + for newBlock = newBlock; newBlock.NumberU64() != oldBlock.NumberU64(); newBlock = self.GetBlock(newBlock.ParentHash()) { + newChain = append(newChain, newBlock) + } + + glog.V(logger.Debug).Infoln("Found common number", newBlock.Number()) for { - oldBlock, newBlock = self.GetBlock(oldBlock.ParentHash()), self.GetBlock(newBlock.ParentHash()) if oldBlock.Hash() == newBlock.Hash() { break } - oldChain = append(oldChain, oldBlock) newChain = append(newChain, newBlock) + + oldBlock, newBlock = self.GetBlock(oldBlock.ParentHash()), self.GetBlock(newBlock.ParentHash()) } + return newChain +} + +// merge merges two different chain to the new canonical chain +func (self *ChainManager) merge(oldBlock, newBlock *types.Block) { + newChain := self.diff(oldBlock, newBlock) + // insert blocks for _, block := range newChain { self.insert(block) } - - if glog.V(logger.Detail) { - for i, oldBlock := range oldChain { - glog.Infof("- %.10v = %x\n", oldBlock.Number(), oldBlock.Hash()) - glog.Infof("+ %.10v = %x\n", newChain[i].Number(), newChain[i].Hash()) - } - } } func (self *ChainManager) update() { diff --git a/core/chain_manager_test.go b/core/chain_manager_test.go index c2911150a..a88afd7c8 100644 --- a/core/chain_manager_test.go +++ b/core/chain_manager_test.go @@ -9,6 +9,7 @@ import ( "strconv" "testing" + "github.com/ethereum/go-ethereum/core/state" "github.com/ethereum/go-ethereum/core/types" "github.com/ethereum/go-ethereum/ethdb" "github.com/ethereum/go-ethereum/event" @@ -56,12 +57,14 @@ func testFork(t *testing.T, bman *BlockProcessor, i, N int, f func(td1, td2 *big } // Compare difficulties f(tdpre, td) + + // Loop over parents making sure reconstruction is done properly } func printChain(bc *ChainManager) { for i := bc.CurrentBlock().Number().Uint64(); i > 0; i-- { b := bc.GetBlockByNumber(uint64(i)) - fmt.Printf("\t%x\n", b.Hash()) + fmt.Printf("\t%x %v\n", b.Hash(), b.Difficulty()) } } @@ -344,3 +347,50 @@ func TestGetAncestors(t *testing.T) { ancestors := chainMan.GetAncestors(chain[len(chain)-1], 4) fmt.Println(ancestors) } + +type bproc struct{} + +func (bproc) Process(*types.Block) (state.Logs, error) { return nil, nil } + +func makeChainWithDiff(genesis *types.Block, d []int, seed byte) []*types.Block { + var chain []*types.Block + for i, difficulty := range d { + header := &types.Header{Number: big.NewInt(int64(i + 1)), Difficulty: big.NewInt(int64(difficulty))} + block := types.NewBlockWithHeader(header) + copy(block.HeaderHash[:2], []byte{byte(i + 1), seed}) + if i == 0 { + block.ParentHeaderHash = genesis.Hash() + } else { + copy(block.ParentHeaderHash[:2], []byte{byte(i), seed}) + } + + chain = append(chain, block) + } + return chain +} + +func TestReorg(t *testing.T) { + db, _ := ethdb.NewMemDatabase() + var eventMux event.TypeMux + + genesis := GenesisBlock(db) + bc := &ChainManager{blockDb: db, stateDb: db, genesisBlock: genesis, eventMux: &eventMux} + bc.cache = NewBlockCache(100) + bc.futureBlocks = NewBlockCache(100) + bc.processor = bproc{} + bc.ResetWithGenesisBlock(genesis) + bc.txState = state.ManageState(bc.State()) + + chain1 := makeChainWithDiff(genesis, []int{1, 2, 4}, 10) + chain2 := makeChainWithDiff(genesis, []int{1, 2, 3, 4}, 11) + + bc.InsertChain(chain1) + bc.InsertChain(chain2) + + prev := bc.CurrentBlock() + for block := bc.GetBlockByNumber(bc.CurrentBlock().NumberU64() - 1); block.NumberU64() != 0; prev, block = block, bc.GetBlockByNumber(block.NumberU64()-1) { + if prev.ParentHash() != block.Hash() { + t.Errorf("parent hash mismatch %x - %x", prev.ParentHash(), block.Hash()) + } + } +}