consensus/clique, light: light client snapshots on Rinkeby

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
+		// 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
 			}
-			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
-			}
-			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.