core, dex, internal: block proposer syncing (first iteration) (#96)

* dex, internal: block proposer syncing (first iteration)

* core: find block from db if not in memory

This fix handles stopping proposing and then restarting

* core: no need to reorg when reset

Dexon will not fork. This commit also fix when a block confirm but
its parent is not in db yet, during restarting proposing.

* dex: always accept NewBlockMsg, NewBlockHashesMsg

We need to accept NewBlockMsg, NewBlockHashesMsg to sync current block with
other peers in block proposer mode when syncing lattice data. It's a waste
when the node is synced and start proposing.

Todo: control msg processing on/off more granular, accept NewBlockMsg,
NewBlockHashesMsg when syncing, but stop when synced.

1 files changed, 2 insertions, 4 deletions

diff --git a/core/blockchain.go b/core/blockchain.go
index 1b3b22e5e..0e87360c3 100644
--- a/core/blockchain.go
+++ b/core/blockchain.go
@@ -1796,8 +1796,6 @@ func (bc *BlockChain) processPendingBlock(
 		return nil, nil, nil, fmt.Errorf("validate witness data error: %v", err)
 	}
 
-	currentBlock := bc.CurrentBlock()
-
 	var (
 		receipts types.Receipts
 		usedGas  = new(uint64)
@@ -1810,8 +1808,8 @@ func (bc *BlockChain) processPendingBlock(
 	var err error
 	parent, exist := bc.pendingBlocks[block.NumberU64()-1]
 	if !exist {
-		parentBlock = currentBlock
-		if parentBlock.NumberU64() != block.NumberU64()-1 {
+		parentBlock = bc.GetBlockByNumber(block.NumberU64() - 1)
+		if parentBlock == nil {
 			return nil, nil, nil, fmt.Errorf("parent block %d not exist", block.NumberU64()-1)
 		}
 	} else {