Skip fast path for mblock if its rblock confirmation is too old (#655)

* Skip fast path for mblock if its rblock confirmation is too old

Author: ping-ke

cluster/sync/minor_task.go

@@ -6,6 +6,7 @@ import (
 	"github.com/QuarkChain/goquarkchain/account"
 	"github.com/QuarkChain/goquarkchain/cluster/rpc"
 	qcom "github.com/QuarkChain/goquarkchain/common"
+	"github.com/QuarkChain/goquarkchain/core"
 	"github.com/QuarkChain/goquarkchain/core/types"
 	"github.com/QuarkChain/goquarkchain/p2p"
 	"github.com/ethereum/go-ethereum/common"
@@ -105,6 +106,26 @@ func NewMinorChainTask(
 			if mTask.header.NumberU64() <= b.CurrentHeader().NumberU64() || b.HasBlock(mTask.header.Hash()) {
 				return true
 			}
+
+			bc, ok := b.(*core.MinorBlockChain)
+			if !ok {
+				return false
+			}
+			// Do not download if the prev root block is not synced
+			rootBlockHeader := bc.GetRootBlockByHash(mTask.header.PrevRootBlockHash)
+			if rootBlockHeader == nil {
+				return true
+			}
+
+			// Do not download if the new header's confirmed root is lower then current root tip last header's confirmed root
+			// This means the minor block's root is a fork, which will be handled by master sync
+			if bc.GetMinorTip() == nil {
+				return false
+			}
+			confirmedRootHeader := bc.GetRootBlockByHash(bc.GetMinorTip().PrevRootBlockHash())
+			if confirmedRootHeader != nil && confirmedRootHeader.NumberU64() > rootBlockHeader.NumberU64() {
+				return true
+			}
 			return false
 		},
 	}

cluster/sync/minor_task_test.go

@@ -100,19 +100,19 @@ func newMinorBlockChain(sz int) (blockchain, ethdb.Database) {
 		blocks = append(blocks, mb)
 	}
 
-	blockchain, err := core.NewMinorBlockChain(db, nil, params.TestChainConfig, clusterConfig, engine, vm.Config{}, nil, fullShardID)
+	mbc, err := core.NewMinorBlockChain(db, nil, params.TestChainConfig, clusterConfig, engine, vm.Config{}, nil, fullShardID)
 	if err != nil {
 		panic(fmt.Sprintf("failed to create minor blockchain: %v", err))
 	}
-	_, err = blockchain.InitGenesisState(rootBlock)
+	_, err = mbc.InitGenesisState(rootBlock)
 	if err != nil {
 		panic(fmt.Sprintf("failed to init minor blockchain: %v", err))
 	}
-	if _, err := blockchain.InsertChain(blocks, false); err != nil {
+	if _, err := mbc.InsertChain(blocks, false); err != nil {
 		panic(fmt.Sprintf("failed to insert minor blocks: %v", err))
 	}
 
-	return &mockblockchain{mbc: blockchain}, db
+	return &mockblockchain{mbc: mbc}, db
 }
 
 func TestMinorChainTask(t *testing.T) {