From 9f036647e4b3e7c3aa8941dc239f85326a5e5ecd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?P=C3=A9ter=20Szil=C3=A1gyi?= <peterke@gmail.com>
Date: Tue, 21 Aug 2018 14:39:28 +0300
Subject: consensus/clique, light: light client snapshots on Rinkeby

---
 light/lightchain.go  | 34 ++++++++++++++++++++++------------
 light/postprocess.go | 25 +++++++++++++------------
 2 files changed, 35 insertions(+), 24 deletions(-)

(limited to 'light')

diff --git a/light/lightchain.go b/light/lightchain.go
index b7e629e88..b5afe1f0e 100644
--- a/light/lightchain.go
+++ b/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
 }
diff --git a/light/postprocess.go b/light/postprocess.go
index 42985aff0..f105d57b5 100644
--- a/light/postprocess.go
+++ b/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 (
-- 
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