Merge pull request #17466 from karalabe/rinkeby-light-snapshots

consensus/clique, light: light client snapshots on Rinkeby

Author: karalabe

consensus/clique/clique.go

@@ -387,22 +387,23 @@ func (c *Clique) snapshot(chain consensus.ChainReader, number uint64, hash commo
 				break
 			}
 		}
-		// If we're at block zero, make a snapshot
-		if number == 0 {
-			genesis := chain.GetHeaderByNumber(0)
-			if err := c.VerifyHeader(chain, genesis, false); err != nil {
-				return nil, err
-			}
-			signers := make([]common.Address, (len(genesis.Extra)-extraVanity-extraSeal)/common.AddressLength)
-			for i := 0; i < len(signers); i++ {
-				copy(signers[i][:], genesis.Extra[extraVanity+i*common.AddressLength:])
-			}
-			snap = newSnapshot(c.config, c.signatures, 0, genesis.Hash(), signers)
-			if err := snap.store(c.db); err != nil {
-				return nil, err
+		// If we're at an checkpoint block, make a snapshot if it's known
+		if number%c.config.Epoch == 0 {
+			checkpoint := chain.GetHeaderByNumber(number)
+			if checkpoint != nil {
+				hash := checkpoint.Hash()
+
+				signers := make([]common.Address, (len(checkpoint.Extra)-extraVanity-extraSeal)/common.AddressLength)
+				for i := 0; i < len(signers); i++ {
+					copy(signers[i][:], checkpoint.Extra[extraVanity+i*common.AddressLength:])
+				}
+				snap = newSnapshot(c.config, c.signatures, number, hash, signers)
+				if err := snap.store(c.db); err != nil {
+					return nil, err
+				}
+				log.Info("Stored checkpoint snapshot to disk", "number", number, "hash", hash)
+				break
 			}
-			log.Trace("Stored genesis voting snapshot to disk")
-			break
 		}
 		// No snapshot for this header, gather the header and move backward
 		var header *types.Header

consensus/clique/snapshot_test.go

@@ -84,7 +84,7 @@ func (r *testerChainReader) GetHeaderByNumber(number uint64) *types.Header {
 	if number == 0 {
 		return rawdb.ReadHeader(r.db, rawdb.ReadCanonicalHash(r.db, 0), 0)
 	}
-	panic("not supported")
+	return nil
 }
 
 // Tests that voting is evaluated correctly for various simple and complex scenarios.

light/lightchain.go

@@ -464,22 +464,32 @@ func (self *LightChain) GetHeaderByNumberOdr(ctx context.Context, number uint64)
 func (self *LightChain) Config() *params.ChainConfig { return self.hc.Config() }
 
 func (self *LightChain) SyncCht(ctx context.Context) bool {
+	// If we don't have a CHT indexer, abort
 	if self.odr.ChtIndexer() == nil {
 		return false
 	}
-	headNum := self.CurrentHeader().Number.Uint64()
-	chtCount, _, _ := self.odr.ChtIndexer().Sections()
-	if headNum+1 < chtCount*CHTFrequencyClient {
-		num := chtCount*CHTFrequencyClient - 1
-		header, err := GetHeaderByNumber(ctx, self.odr, num)
-		if header != nil && err == nil {
-			self.mu.Lock()
-			if self.hc.CurrentHeader().Number.Uint64() < header.Number.Uint64() {
-				self.hc.SetCurrentHeader(header)
-			}
-			self.mu.Unlock()
-			return true
+	// Ensure the remote CHT head is ahead of us
+	head := self.CurrentHeader().Number.Uint64()
+	sections, _, _ := self.odr.ChtIndexer().Sections()
+
+	latest := sections*CHTFrequencyClient - 1
+	if clique := self.hc.Config().Clique; clique != nil {
+		latest -= latest % clique.Epoch // epoch snapshot for clique
+	}
+	if head >= latest {
+		return false
+	}
+	// Retrieve the latest useful header and update to it
+	if header, err := GetHeaderByNumber(ctx, self.odr, latest); header != nil && err == nil {
+		self.mu.Lock()
+		defer self.mu.Unlock()
+
+		// Ensure the chain didn't move past the latest block while retrieving it
+		if self.hc.CurrentHeader().Number.Uint64() < header.Number.Uint64() {
+			log.Info("Updated latest header based on CHT", "number", header.Number, "hash", header.Hash())
+			self.hc.SetCurrentHeader(header)
 		}
+		return true
 	}
 	return false
 }

light/postprocess.go

@@ -58,28 +58,29 @@ type TrustedCheckpoint struct {
 	SectionHead, CHTRoot, BloomRoot common.Hash
 }
 
-var (
-	mainnetCheckpoint = TrustedCheckpoint{
+// trustedCheckpoints associates each known checkpoint with the genesis hash of the chain it belongs to
+var trustedCheckpoints = map[common.Hash]TrustedCheckpoint{
+	params.MainnetGenesisHash: {
 		name:        "mainnet",
 		SectionIdx:  187,
 		SectionHead: common.HexToHash("e6baa034efa31562d71ff23676512dec6562c1ad0301e08843b907e81958c696"),
 		CHTRoot:     common.HexToHash("28001955219719cf06de1b08648969139d123a9835fc760547a1e4dabdabc15a"),
 		BloomRoot:   common.HexToHash("395ca2373fc662720ac6b58b3bbe71f68aa0f38b63b2d3553dd32ff3c51eebc4"),
-	}
-
-	ropstenCheckpoint = TrustedCheckpoint{
+	},
+	params.TestnetGenesisHash: {
 		name:        "ropsten",
 		SectionIdx:  117,
 		SectionHead: common.HexToHash("9529b38631ae30783f56cbe4c3b9f07575b770ecba4f6e20a274b1e2f40fede1"),
 		CHTRoot:     common.HexToHash("6f48e9f101f1fac98e7d74fbbcc4fda138358271ffd974d40d2506f0308bb363"),
 		BloomRoot:   common.HexToHash("8242342e66e942c0cd893484e6736b9862ceb88b43ca344bb06a8285ac1b6d64"),
-	}
-)
-
-// trustedCheckpoints associates each known checkpoint with the genesis hash of the chain it belongs to
-var trustedCheckpoints = map[common.Hash]TrustedCheckpoint{
-	params.MainnetGenesisHash: mainnetCheckpoint,
-	params.TestnetGenesisHash: ropstenCheckpoint,
+	},
+	params.RinkebyGenesisHash: {
+		name:        "rinkeby",
+		SectionIdx:  85,
+		SectionHead: common.HexToHash("92cfa67afc4ad8ab0dcbc6fa49efd14b5b19402442e7317e6bc879d85f89d64d"),
+		CHTRoot:     common.HexToHash("2802ec92cd7a54a75bca96afdc666ae7b99e5d96cf8192dcfb09588812f51564"),
+		BloomRoot:   common.HexToHash("ebefeb31a9a42866d8cf2d2477704b4c3d7c20d0e4e9b5aaa77f396e016a1263"),
+	},
 }
 
 var (

params/config.go

@@ -27,6 +27,7 @@ import (
 var (
 	MainnetGenesisHash = common.HexToHash("0xd4e56740f876aef8c010b86a40d5f56745a118d0906a34e69aec8c0db1cb8fa3")
 	TestnetGenesisHash = common.HexToHash("0x41941023680923e0fe4d74a34bdac8141f2540e3ae90623718e47d66d1ca4a2d")
+	RinkebyGenesisHash = common.HexToHash("0x6341fd3daf94b748c72ced5a5b26028f2474f5f00d824504e4fa37a75767e177")
 )
 
 var (