mirror of https://github.com/ethereum/go-ethereum
Merge pull request #2081 from zsfelfoldi/light-chain
core: create a header chain structure shared by full and light clientspull/2322/head
Jeffrey Wilcke
9 years ago
commit
8b58cd0190
@ -0,0 +1,432 @@ |
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// Copyright 2015 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package core |
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import ( |
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crand "crypto/rand" |
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"math" |
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"math/big" |
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mrand "math/rand" |
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"runtime" |
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"sync" |
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"sync/atomic" |
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"time" |
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"github.com/ethereum/go-ethereum/common" |
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"github.com/ethereum/go-ethereum/core/types" |
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"github.com/ethereum/go-ethereum/ethdb" |
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"github.com/ethereum/go-ethereum/logger" |
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"github.com/ethereum/go-ethereum/logger/glog" |
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"github.com/ethereum/go-ethereum/pow" |
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"github.com/hashicorp/golang-lru" |
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) |
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// HeaderChain implements the basic block header chain logic that is shared by
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// core.BlockChain and light.LightChain. It is not usable in itself, only as
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// a part of either structure.
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// It is not thread safe either, the encapsulating chain structures should do
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// the necessary mutex locking/unlocking.
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type HeaderChain struct { |
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chainDb ethdb.Database |
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genesisHeader *types.Header |
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currentHeader *types.Header // Current head of the header chain (may be above the block chain!)
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headerCache *lru.Cache // Cache for the most recent block headers
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tdCache *lru.Cache // Cache for the most recent block total difficulties
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procInterrupt func() bool |
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rand *mrand.Rand |
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getValidator getHeaderValidatorFn |
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} |
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// getHeaderValidatorFn returns a HeaderValidator interface
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type getHeaderValidatorFn func() HeaderValidator |
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// NewHeaderChain creates a new HeaderChain structure.
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// getValidator should return the parent's validator
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// procInterrupt points to the parent's interrupt semaphore
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// wg points to the parent's shutdown wait group
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func NewHeaderChain(chainDb ethdb.Database, getValidator getHeaderValidatorFn, procInterrupt func() bool) (*HeaderChain, error) { |
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headerCache, _ := lru.New(headerCacheLimit) |
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tdCache, _ := lru.New(tdCacheLimit) |
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// Seed a fast but crypto originating random generator
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seed, err := crand.Int(crand.Reader, big.NewInt(math.MaxInt64)) |
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if err != nil { |
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return nil, err |
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} |
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hc := &HeaderChain{ |
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chainDb: chainDb, |
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headerCache: headerCache, |
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tdCache: tdCache, |
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procInterrupt: procInterrupt, |
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rand: mrand.New(mrand.NewSource(seed.Int64())), |
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getValidator: getValidator, |
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} |
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hc.genesisHeader = hc.GetHeaderByNumber(0) |
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if hc.genesisHeader == nil { |
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genesisBlock, err := WriteDefaultGenesisBlock(chainDb) |
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if err != nil { |
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return nil, err |
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} |
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glog.V(logger.Info).Infoln("WARNING: Wrote default ethereum genesis block") |
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hc.genesisHeader = genesisBlock.Header() |
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} |
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hc.currentHeader = hc.genesisHeader |
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if head := GetHeadBlockHash(chainDb); head != (common.Hash{}) { |
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if chead := hc.GetHeader(head); chead != nil { |
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hc.currentHeader = chead |
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} |
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} |
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return hc, nil |
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} |
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// WriteHeader writes a header into the local chain, given that its parent is
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// already known. If the total difficulty of the newly inserted header becomes
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// greater than the current known TD, the canonical chain is re-routed.
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//
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// Note: This method is not concurrent-safe with inserting blocks simultaneously
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// into the chain, as side effects caused by reorganisations cannot be emulated
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// without the real blocks. Hence, writing headers directly should only be done
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// in two scenarios: pure-header mode of operation (light clients), or properly
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// separated header/block phases (non-archive clients).
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func (hc *HeaderChain) WriteHeader(header *types.Header) (status WriteStatus, err error) { |
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// Calculate the total difficulty of the header
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ptd := hc.GetTd(header.ParentHash) |
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if ptd == nil { |
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return NonStatTy, ParentError(header.ParentHash) |
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} |
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localTd := hc.GetTd(hc.currentHeader.Hash()) |
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externTd := new(big.Int).Add(header.Difficulty, ptd) |
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// If the total difficulty is higher than our known, add it to the canonical chain
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// Second clause in the if statement reduces the vulnerability to selfish mining.
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// Please refer to http://www.cs.cornell.edu/~ie53/publications/btcProcFC.pdf
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if externTd.Cmp(localTd) > 0 || (externTd.Cmp(localTd) == 0 && mrand.Float64() < 0.5) { |
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// Delete any canonical number assignments above the new head
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for i := header.Number.Uint64() + 1; GetCanonicalHash(hc.chainDb, i) != (common.Hash{}); i++ { |
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DeleteCanonicalHash(hc.chainDb, i) |
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} |
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// Overwrite any stale canonical number assignments
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head := hc.GetHeader(header.ParentHash) |
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for GetCanonicalHash(hc.chainDb, head.Number.Uint64()) != head.Hash() { |
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WriteCanonicalHash(hc.chainDb, head.Hash(), head.Number.Uint64()) |
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head = hc.GetHeader(head.ParentHash) |
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} |
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// Extend the canonical chain with the new header
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if err := WriteCanonicalHash(hc.chainDb, header.Hash(), header.Number.Uint64()); err != nil { |
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glog.Fatalf("failed to insert header number: %v", err) |
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} |
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if err := WriteHeadHeaderHash(hc.chainDb, header.Hash()); err != nil { |
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glog.Fatalf("failed to insert head header hash: %v", err) |
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} |
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hc.currentHeader = types.CopyHeader(header) |
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status = CanonStatTy |
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} else { |
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status = SideStatTy |
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} |
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// Irrelevant of the canonical status, write the header itself to the database
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if err := WriteTd(hc.chainDb, header.Hash(), externTd); err != nil { |
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glog.Fatalf("failed to write header total difficulty: %v", err) |
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} |
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if err := WriteHeader(hc.chainDb, header); err != nil { |
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glog.Fatalf("failed to write header contents: %v", err) |
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} |
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return |
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} |
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// WhCallback is a callback function for inserting individual headers.
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// A callback is used for two reasons: first, in a LightChain, status should be
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// processed and light chain events sent, while in a BlockChain this is not
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// necessary since chain events are sent after inserting blocks. Second, the
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// header writes should be protected by the parent chain mutex individually.
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type WhCallback func(*types.Header) error |
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// InsertHeaderChain attempts to insert the given header chain in to the local
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// chain, possibly creating a reorg. If an error is returned, it will return the
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// index number of the failing header as well an error describing what went wrong.
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//
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// The verify parameter can be used to fine tune whether nonce verification
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// should be done or not. The reason behind the optional check is because some
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// of the header retrieval mechanisms already need to verfy nonces, as well as
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// because nonces can be verified sparsely, not needing to check each.
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func (hc *HeaderChain) InsertHeaderChain(chain []*types.Header, checkFreq int, writeHeader WhCallback) (int, error) { |
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// Collect some import statistics to report on
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stats := struct{ processed, ignored int }{} |
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start := time.Now() |
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// Generate the list of headers that should be POW verified
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verify := make([]bool, len(chain)) |
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for i := 0; i < len(verify)/checkFreq; i++ { |
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index := i*checkFreq + hc.rand.Intn(checkFreq) |
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if index >= len(verify) { |
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index = len(verify) - 1 |
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} |
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verify[index] = true |
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} |
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verify[len(verify)-1] = true // Last should always be verified to avoid junk
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// Create the header verification task queue and worker functions
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tasks := make(chan int, len(chain)) |
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for i := 0; i < len(chain); i++ { |
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tasks <- i |
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} |
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close(tasks) |
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errs, failed := make([]error, len(tasks)), int32(0) |
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process := func(worker int) { |
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for index := range tasks { |
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header, hash := chain[index], chain[index].Hash() |
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// Short circuit insertion if shutting down or processing failed
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if hc.procInterrupt() { |
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return |
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} |
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if atomic.LoadInt32(&failed) > 0 { |
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return |
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} |
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// Short circuit if the header is bad or already known
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if BadHashes[hash] { |
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errs[index] = BadHashError(hash) |
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atomic.AddInt32(&failed, 1) |
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return |
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} |
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if hc.HasHeader(hash) { |
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continue |
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} |
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// Verify that the header honors the chain parameters
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checkPow := verify[index] |
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var err error |
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if index == 0 { |
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err = hc.getValidator().ValidateHeader(header, hc.GetHeader(header.ParentHash), checkPow) |
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} else { |
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err = hc.getValidator().ValidateHeader(header, chain[index-1], checkPow) |
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} |
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if err != nil { |
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errs[index] = err |
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atomic.AddInt32(&failed, 1) |
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return |
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} |
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} |
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} |
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// Start as many worker threads as goroutines allowed
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pending := new(sync.WaitGroup) |
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for i := 0; i < runtime.GOMAXPROCS(0); i++ { |
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pending.Add(1) |
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go func(id int) { |
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defer pending.Done() |
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process(id) |
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}(i) |
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} |
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pending.Wait() |
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// If anything failed, report
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if failed > 0 { |
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for i, err := range errs { |
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if err != nil { |
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return i, err |
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} |
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} |
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} |
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// All headers passed verification, import them into the database
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for i, header := range chain { |
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// Short circuit insertion if shutting down
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if hc.procInterrupt() { |
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glog.V(logger.Debug).Infoln("premature abort during header chain processing") |
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break |
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} |
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hash := header.Hash() |
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// If the header's already known, skip it, otherwise store
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if hc.HasHeader(hash) { |
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stats.ignored++ |
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continue |
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} |
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if err := writeHeader(header); err != nil { |
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return i, err |
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} |
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stats.processed++ |
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} |
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// Report some public statistics so the user has a clue what's going on
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first, last := chain[0], chain[len(chain)-1] |
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glog.V(logger.Info).Infof("imported %d header(s) (%d ignored) in %v. #%v [%x… / %x…]", stats.processed, stats.ignored, |
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time.Since(start), last.Number, first.Hash().Bytes()[:4], last.Hash().Bytes()[:4]) |
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return 0, nil |
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} |
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// GetBlockHashesFromHash retrieves a number of block hashes starting at a given
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// hash, fetching towards the genesis block.
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func (hc *HeaderChain) GetBlockHashesFromHash(hash common.Hash, max uint64) []common.Hash { |
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// Get the origin header from which to fetch
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header := hc.GetHeader(hash) |
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if header == nil { |
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return nil |
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} |
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// Iterate the headers until enough is collected or the genesis reached
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chain := make([]common.Hash, 0, max) |
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for i := uint64(0); i < max; i++ { |
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if header = hc.GetHeader(header.ParentHash); header == nil { |
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break |
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} |
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chain = append(chain, header.Hash()) |
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if header.Number.Cmp(common.Big0) == 0 { |
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break |
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} |
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} |
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return chain |
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} |
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// GetTd retrieves a block's total difficulty in the canonical chain from the
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// database by hash, caching it if found.
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func (hc *HeaderChain) GetTd(hash common.Hash) *big.Int { |
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// Short circuit if the td's already in the cache, retrieve otherwise
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if cached, ok := hc.tdCache.Get(hash); ok { |
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return cached.(*big.Int) |
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} |
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td := GetTd(hc.chainDb, hash) |
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if td == nil { |
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return nil |
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} |
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// Cache the found body for next time and return
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hc.tdCache.Add(hash, td) |
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return td |
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} |
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// GetHeader retrieves a block header from the database by hash, caching it if
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// found.
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func (hc *HeaderChain) GetHeader(hash common.Hash) *types.Header { |
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// Short circuit if the header's already in the cache, retrieve otherwise
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if header, ok := hc.headerCache.Get(hash); ok { |
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return header.(*types.Header) |
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} |
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header := GetHeader(hc.chainDb, hash) |
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if header == nil { |
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return nil |
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} |
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// Cache the found header for next time and return
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hc.headerCache.Add(header.Hash(), header) |
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return header |
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} |
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// HasHeader checks if a block header is present in the database or not, caching
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// it if present.
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func (hc *HeaderChain) HasHeader(hash common.Hash) bool { |
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return hc.GetHeader(hash) != nil |
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} |
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// GetHeaderByNumber retrieves a block header from the database by number,
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// caching it (associated with its hash) if found.
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func (hc *HeaderChain) GetHeaderByNumber(number uint64) *types.Header { |
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hash := GetCanonicalHash(hc.chainDb, number) |
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if hash == (common.Hash{}) { |
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return nil |
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} |
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return hc.GetHeader(hash) |
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} |
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// CurrentHeader retrieves the current head header of the canonical chain. The
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// header is retrieved from the HeaderChain's internal cache.
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func (hc *HeaderChain) CurrentHeader() *types.Header { |
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return hc.currentHeader |
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} |
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// SetCurrentHeader sets the current head header of the canonical chain.
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func (hc *HeaderChain) SetCurrentHeader(head *types.Header) { |
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if err := WriteHeadHeaderHash(hc.chainDb, head.Hash()); err != nil { |
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glog.Fatalf("failed to insert head header hash: %v", err) |
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} |
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hc.currentHeader = head |
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} |
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// DeleteCallback is a callback function that is called by SetHead before
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// each header is deleted.
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type DeleteCallback func(common.Hash) |
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// SetHead rewinds the local chain to a new head. Everything above the new head
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// will be deleted and the new one set.
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func (hc *HeaderChain) SetHead(head uint64, delFn DeleteCallback) { |
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height := uint64(0) |
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if hc.currentHeader != nil { |
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height = hc.currentHeader.Number.Uint64() |
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} |
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for hc.currentHeader != nil && hc.currentHeader.Number.Uint64() > head { |
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hash := hc.currentHeader.Hash() |
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if delFn != nil { |
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delFn(hash) |
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} |
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DeleteHeader(hc.chainDb, hash) |
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DeleteTd(hc.chainDb, hash) |
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hc.currentHeader = hc.GetHeader(hc.currentHeader.ParentHash) |
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} |
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// Roll back the canonical chain numbering
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for i := height; i > head; i-- { |
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DeleteCanonicalHash(hc.chainDb, i) |
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} |
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// Clear out any stale content from the caches
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hc.headerCache.Purge() |
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hc.tdCache.Purge() |
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if hc.currentHeader == nil { |
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hc.currentHeader = hc.genesisHeader |
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} |
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if err := WriteHeadHeaderHash(hc.chainDb, hc.currentHeader.Hash()); err != nil { |
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glog.Fatalf("failed to reset head header hash: %v", err) |
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} |
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} |
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// SetGenesis sets a new genesis block header for the chain
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func (hc *HeaderChain) SetGenesis(head *types.Header) { |
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hc.genesisHeader = head |
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} |
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// headerValidator is responsible for validating block headers
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//
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// headerValidator implements HeaderValidator.
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type headerValidator struct { |
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hc *HeaderChain // Canonical header chain
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Pow pow.PoW // Proof of work used for validating
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} |
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// NewBlockValidator returns a new block validator which is safe for re-use
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func NewHeaderValidator(chain *HeaderChain, pow pow.PoW) HeaderValidator { |
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return &headerValidator{ |
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Pow: pow, |
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hc: chain, |
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} |
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} |
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// ValidateHeader validates the given header and, depending on the pow arg,
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// checks the proof of work of the given header. Returns an error if the
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// validation failed.
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func (v *headerValidator) ValidateHeader(header, parent *types.Header, checkPow bool) error { |
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// Short circuit if the parent is missing.
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if parent == nil { |
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return ParentError(header.ParentHash) |
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} |
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// Short circuit if the header's already known or its parent missing
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if v.hc.HasHeader(header.Hash()) { |
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return nil |
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} |
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return ValidateHeader(v.Pow, header, parent, checkPow, false) |
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} |
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