consensus: get Validators from genesis instead of triedb in v1 consor…

…tium. In snap sync, we will disable accessing/mark stale to triedb when enabling path scheme for protecting the persistent storing, so the data of validators only used for checking in some first blocks which we can return hardcore list from genesis data for following the flow of snap-sync from go-eth team.

consensus/consortium/v1/consortium.go

@@ -338,9 +338,19 @@ func (c *Consortium) snapshot(chain consensus.ChainHeaderReader, number uint64,
 			if cpHeader != nil {
 				hash := cpHeader.Hash()
 
-				validators, err := c.getValidatorsFromContract(chain, number)
-				if err != nil {
-					return nil, err
+				var validators []common.Address
+				var err error
+				// Snap Sync mode.
+				if c.skipCheckpointHeaderCheck {
+					validators, err = c.getValidatorsFromGenesis()
+					if err != nil {
+						return nil, err
+					}
+				} else {
+					validators, err = c.getValidatorsFromContract(chain, number-1)
+					if err != nil {
+						return nil, err
+					}
 				}
 
 				snap = newSnapshot(c.config, c.signatures, number, hash, validators)
@@ -485,9 +495,17 @@ func (c *Consortium) Prepare(chain consensus.ChainHeaderReader, header *types.He
 	header.Extra = header.Extra[:extraVanity]
 
 	if number%c.config.Epoch == 0 {
-		validators, err := c.getValidatorsFromContract(chain, number)
-		if err != nil {
-			return err
+		var validators []common.Address
+		if c.skipCheckpointHeaderCheck {
+			validators, err = c.getValidatorsFromGenesis()
+			if err != nil {
+				return err
+			}
+		} else {
+			validators, err = c.getValidatorsFromContract(chain, number-1)
+			if err != nil {
+				return err
+			}
 		}
 
 		for _, signer := range validators {
@@ -756,6 +774,35 @@ func (c *Consortium) doCalcDifficulty(signer common.Address, number uint64, vali
 	return new(big.Int).Set(diffNoTurn)
 }
 
+// getValidatorsFromGenesis gets the list of validators from the genesis block support backward compatibility in v1, only used with Snap Sync.
+func (c *Consortium) getValidatorsFromGenesis() ([]common.Address, error) {
+	if c.chainConfig.ConsortiumV2Block == nil {
+		return nil, errors.New("No genesis block supplied")
+	}
+	var validatorSet []string
+	switch {
+	case c.chainConfig.ChainID.Cmp(big.NewInt(2020)) == 0:
+		validatorSet = []string{
+			"0x000000000000000000000000f224beff587362a88d859e899d0d80c080e1e812",
+			"0x00000000000000000000000011360eacdedd59bc433afad4fc8f0417d1fbebab",
+			"0x00000000000000000000000070bb1fb41c8c42f6ddd53a708e2b82209495e455",
+		}
+	case c.chainConfig.ChainID.Cmp(big.NewInt(2021)) == 0:
+		validatorSet = []string{
+			"0x0000000000000000000000004a4bc674a97737376cfe990ae2fe0d2b6e738393",
+			"0x000000000000000000000000b6bc5bc0410773a3f86b1537ce7495c52e38f88b",
+		}
+	default:
+		log.Info("chainID", c.chainConfig.ChainID)
+		return nil, errors.New("No validator set for this chain only support Mainnet & Testnet")
+	}
+	var addresses []common.Address
+	for _, str := range validatorSet {
+		addresses = append(addresses, common.HexToAddress(str))
+	}
+	return addresses, nil
+}
+
 // Read the validator list from contract
 func (c *Consortium) getValidatorsFromContract(chain consensus.ChainHeaderReader, number uint64) ([]common.Address, error) {
 	if chain.Config().IsFenix(big.NewInt(int64(number))) {
@@ -779,7 +826,7 @@ func (c *Consortium) getValidatorsFromLastCheckpoint(chain consensus.ChainHeader
 
 	if lastCheckpoint == 0 {
 		// TODO(andy): Review if we should put validators in genesis block's extra data
-		return c.getValidatorsFromContract(chain, number)
+		return c.getValidatorsFromGenesis()
 	}
 
 	var header *types.Header