bmgr: Remove block manager chain state.

This removes the block manager chain state in favor of using the
blockchain.BlockChain instance now that it is safe for concurrency.

blockmanager.go

@@ -135,31 +135,6 @@ type headerNode struct {
 	hash   *chainhash.Hash
 }
 
-// chainState tracks the state of the best chain as blocks are inserted.  This
-// is done because btcchain is currently not safe for concurrent access and the
-// block manager is typically quite busy processing block and inventory.
-// Therefore, requesting this information from chain through the block manager
-// would not be anywhere near as efficient as simply updating it as each block
-// is inserted and protecting it with a mutex.
-type chainState struct {
-	sync.Mutex
-	newestHash        *chainhash.Hash
-	newestHeight      int32
-	pastMedianTime    time.Time
-	pastMedianTimeErr error
-}
-
-// Best returns the block hash and height known for the tip of the best known
-// chain.
-//
-// This function is safe for concurrent access.
-func (c *chainState) Best() (*chainhash.Hash, int32) {
-	c.Lock()
-	defer c.Unlock()
-
-	return c.newestHash, c.newestHeight
-}
-
 // blockManager provides a concurrency safe block manager for handling all
 // incoming blocks.
 type blockManager struct {
@@ -176,7 +151,6 @@ type blockManager struct {
 	processingReqs    bool
 	syncPeer          *serverPeer
 	msgChan           chan interface{}
-	chainState        chainState
 	wg                sync.WaitGroup
 	quit              chan struct{}
 
@@ -203,20 +177,6 @@ func (b *blockManager) resetHeaderState(newestHash *chainhash.Hash, newestHeight
 	}
 }
 
-// updateChainState updates the chain state associated with the block manager.
-// This allows fast access to chain information since btcchain is currently not
-// safe for concurrent access and the block manager is typically quite busy
-// processing block and inventory.
-func (b *blockManager) updateChainState(newestHash *chainhash.Hash, newestHeight int32) {
-	b.chainState.Lock()
-	defer b.chainState.Unlock()
-
-	b.chainState.newestHash = newestHash
-	b.chainState.newestHeight = newestHeight
-	b.chainState.pastMedianTime = b.chain.BestSnapshot().MedianTime
-	b.chainState.pastMedianTimeErr = nil
-}
-
 // findNextHeaderCheckpoint returns the next checkpoint after the passed height.
 // It returns nil when there is not one either because the height is already
 // later than the final checkpoint or some other reason such as disabled
@@ -635,14 +595,9 @@ func (b *blockManager) handleBlockMsg(bmsg *blockMsg) {
 		// update the chain state.
 		b.progressLogger.LogBlockHeight(bmsg.block)
 
-		// Query the chain for the latest best block since the block
-		// that was processed could be on a side chain or have caused
-		// a reorg.
-		best := b.chain.BestSnapshot()
-		b.updateChainState(best.Hash, best.Height)
-
 		// Update this peer's latest block height, for future
 		// potential sync node candidacy.
+		best := b.chain.BestSnapshot()
 		heightUpdate = best.Height
 		blkHashUpdate = best.Hash
 
@@ -1126,12 +1081,6 @@ out:
 					}
 				}
 
-				// Query the chain for the latest best block
-				// since the block that was processed could be
-				// on a side chain or have caused a reorg.
-				best := b.chain.BestSnapshot()
-				b.updateChainState(best.Hash, best.Height)
-
 				// Allow any clients performing long polling via the
 				// getblocktemplate RPC to be notified when the new block causes
 				// their old block template to become stale.
@@ -1419,10 +1368,6 @@ func newBlockManager(s *server, indexManager blockchain.IndexManager) (*blockMan
 		bmgrLog.Info("Checkpoints are disabled")
 	}
 
-	// Initialize the chain state now that the initial block node index has
-	// been generated.
-	bm.updateChainState(best.Hash, best.Height)
-
 	return &bm, nil
 }
 

cpuminer.go

@@ -125,7 +125,7 @@ func (m *CPUMiner) submitBlock(block *btcutil.Block) bool {
 	// detected and all work on the stale block is halted to start work on
 	// a new block, but the check only happens periodically, so it is
 	// possible a block was found and submitted in between.
-	latestHash, _ := m.server.blockManager.chainState.Best()
+	latestHash := m.server.blockManager.chain.BestSnapshot().Hash
 	msgBlock := block.MsgBlock()
 	if !msgBlock.Header.PrevBlock.IsEqual(latestHash) {
 		minrLog.Debugf("Block submitted via CPU miner with previous "+
@@ -213,8 +213,8 @@ func (m *CPUMiner) solveBlock(msgBlock *wire.MsgBlock, blockHeight int32,
 
 				// The current block is stale if the best block
 				// has changed.
-				bestHash, _ := m.server.blockManager.chainState.Best()
+				best := m.server.blockManager.chain.BestSnapshot()
-				if !header.PrevBlock.IsEqual(bestHash) {
+				if !header.PrevBlock.IsEqual(best.Hash) {
 					return false
 				}
 
@@ -292,7 +292,7 @@ out:
 		// this would otherwise end up building a new block template on
 		// a block that is in the process of becoming stale.
 		m.submitBlockLock.Lock()
-		_, curHeight := m.server.blockManager.chainState.Best()
+		curHeight := m.server.blockManager.chain.BestSnapshot().Height
 		if curHeight != 0 && !m.server.blockManager.IsCurrent() {
 			m.submitBlockLock.Unlock()
 			time.Sleep(time.Second)
@@ -559,7 +559,7 @@ func (m *CPUMiner) GenerateNBlocks(n uint32) ([]*chainhash.Hash, error) {
 		// be changing and this would otherwise end up building a new block
 		// template on a block that is in the process of becoming stale.
 		m.submitBlockLock.Lock()
-		_, curHeight := m.server.blockManager.chainState.Best()
+		curHeight := m.server.blockManager.chain.BestSnapshot().Height
 
 		// Choose a payment address at random.
 		rand.Seed(time.Now().UnixNano())

mining.go

@@ -280,26 +280,14 @@ func logSkippedDeps(tx *btcutil.Tx, deps map[chainhash.Hash]*txPrioItem) {
 // on the end of the current best chain.  In particular, it is one second after
 // the median timestamp of the last several blocks per the chain consensus
 // rules.
-func minimumMedianTime(chainState *chainState) (time.Time, error) {
+func minimumMedianTime(chainState *blockchain.BestState) time.Time {
-	chainState.Lock()
+	return chainState.MedianTime.Add(time.Second)
-	defer chainState.Unlock()
-	if chainState.pastMedianTimeErr != nil {
-		return time.Time{}, chainState.pastMedianTimeErr
-	}
-
-	return chainState.pastMedianTime.Add(time.Second), nil
 }
 
 // medianAdjustedTime returns the current time adjusted to ensure it is at least
 // one second after the median timestamp of the last several blocks per the
 // chain consensus rules.
-func medianAdjustedTime(chainState *chainState, timeSource blockchain.MedianTimeSource) (time.Time, error) {
+func medianAdjustedTime(chainState *blockchain.BestState, timeSource blockchain.MedianTimeSource) time.Time {
-	chainState.Lock()
-	defer chainState.Unlock()
-	if chainState.pastMedianTimeErr != nil {
-		return time.Time{}, chainState.pastMedianTimeErr
-	}
-
 	// The timestamp for the block must not be before the median timestamp
 	// of the last several blocks.  Thus, choose the maximum between the
 	// current time and one second after the past median time.  The current
@@ -307,12 +295,12 @@ func medianAdjustedTime(chainState *chainState, timeSource blockchain.MedianTime
 	// block timestamp does not supported a precision greater than one
 	// second.
 	newTimestamp := timeSource.AdjustedTime()
-	minTimestamp := chainState.pastMedianTime.Add(time.Second)
+	minTimestamp := minimumMedianTime(chainState)
 	if newTimestamp.Before(minTimestamp) {
 		newTimestamp = minTimestamp
 	}
 
-	return newTimestamp, nil
+	return newTimestamp
 }
 
 // NewBlockTemplate returns a new block template that is ready to be solved
@@ -381,13 +369,11 @@ func NewBlockTemplate(policy *mining.Policy, server *server, payToAddress btcuti
 	var txSource mining.TxSource = server.txMemPool
 	blockManager := server.blockManager
 	timeSource := server.timeSource
-	chainState := &blockManager.chainState
 
 	// Extend the most recently known best block.
-	chainState.Lock()
+	best := blockManager.chain.BestSnapshot()
-	prevHash := chainState.newestHash
+	prevHash := best.Hash
-	nextBlockHeight := chainState.newestHeight + 1
+	nextBlockHeight := best.Height + 1
-	chainState.Unlock()
 
 	// Create a standard coinbase transaction paying to the provided
 	// address.  NOTE: The coinbase value will be updated to include the
@@ -701,10 +687,7 @@ mempoolLoop:
 	// Calculate the required difficulty for the block.  The timestamp
 	// is potentially adjusted to ensure it comes after the median time of
 	// the last several blocks per the chain consensus rules.
-	ts, err := medianAdjustedTime(chainState, timeSource)
+	ts := medianAdjustedTime(best, timeSource)
-	if err != nil {
-		return nil, err
-	}
 	reqDifficulty, err := blockManager.chain.CalcNextRequiredDifficulty(ts)
 	if err != nil {
 		return nil, err
@@ -759,11 +742,8 @@ func UpdateBlockTime(msgBlock *wire.MsgBlock, bManager *blockManager) error {
 	// The new timestamp is potentially adjusted to ensure it comes after
 	// the median time of the last several blocks per the chain consensus
 	// rules.
-	newTimestamp, err := medianAdjustedTime(&bManager.chainState,
+	best := bManager.chain.BestSnapshot()
-		bManager.server.timeSource)
+	newTimestamp := medianAdjustedTime(best, bManager.server.timeSource)
-	if err != nil {
-		return err
-	}
 	msgBlock.Header.Timestamp = newTimestamp
 
 	// If running on a network that requires recalculating the difficulty,

rpcserver.go

@@ -1363,7 +1363,7 @@ func (state *gbtWorkState) updateBlockTemplate(s *rpcServer, useCoinbaseValue bo
 	// generated.
 	var msgBlock *wire.MsgBlock
 	var targetDifficulty string
-	latestHash, _ := s.server.blockManager.chainState.Best()
+	latestHash := s.server.blockManager.chain.BestSnapshot().Hash
 	template := state.template
 	if template == nil || state.prevHash == nil ||
 		!state.prevHash.IsEqual(latestHash) ||
@@ -1402,12 +1402,8 @@ func (state *gbtWorkState) updateBlockTemplate(s *rpcServer, useCoinbaseValue bo
 		// Find the minimum allowed timestamp for the block based on the
 		// median timestamp of the last several blocks per the chain
 		// consensus rules.
-		chainState := &s.server.blockManager.chainState
+		best := s.server.blockManager.chain.BestSnapshot()
-		minTimestamp, err := minimumMedianTime(chainState)
+		minTimestamp := minimumMedianTime(best)
-		if err != nil {
-			context := "Failed to get minimum median time"
-			return internalRPCError(err.Error(), context)
-		}
 
 		// Update work state to ensure another block template isn't
 		// generated until needed.
@@ -1760,7 +1756,7 @@ func handleGetBlockTemplateRequest(s *rpcServer, request *btcjson.TemplateReques
 	}
 
 	// No point in generating or accepting work before the chain is synced.
-	_, currentHeight := s.server.blockManager.chainState.Best()
+	currentHeight := s.server.blockManager.chain.BestSnapshot().Height
 	if currentHeight != 0 && !s.server.blockManager.IsCurrent() {
 		return nil, &btcjson.RPCError{
 			Code:    btcjson.ErrRPCClientInInitialDownload,
@@ -1923,7 +1919,7 @@ func handleGetBlockTemplateProposal(s *rpcServer, request *btcjson.TemplateReque
 	block := btcutil.NewBlock(&msgBlock)
 
 	// Ensure the block is building from the expected previous block.
-	expectedPrevHash, _ := s.server.blockManager.chainState.Best()
+	expectedPrevHash := s.server.blockManager.chain.BestSnapshot().Hash
 	prevHash := &block.MsgBlock().Header.PrevBlock
 	if expectedPrevHash == nil || !expectedPrevHash.IsEqual(prevHash) {
 		return "bad-prevblk", nil
@@ -2540,7 +2536,8 @@ func handleGetWorkRequest(s *rpcServer) (interface{}, error) {
 	// and it has been at least one minute since the last template was
 	// generated.
 	lastTxUpdate := s.server.txMemPool.LastUpdated()
-	latestHash, latestHeight := s.server.blockManager.chainState.Best()
+	best := s.server.blockManager.chain.BestSnapshot()
+	latestHash, latestHeight := best.Hash, best.Height
 	msgBlock := state.msgBlock
 	if msgBlock == nil || state.prevHash == nil ||
 		!state.prevHash.IsEqual(latestHash) ||
@@ -2769,7 +2766,7 @@ func handleGetWorkSubmission(s *rpcServer, hexData string) (interface{}, error)
 		return false, nil
 	}
 
-	latestHash, _ := s.server.blockManager.chainState.Best()
+	latestHash := s.server.blockManager.chain.BestSnapshot().Hash
 	if !msgBlock.Header.PrevBlock.IsEqual(latestHash) {
 		rpcsLog.Debugf("Block submitted via getwork with previous "+
 			"block %s is stale", msgBlock.Header.PrevBlock)
@@ -2821,7 +2818,7 @@ func handleGetWork(s *rpcServer, cmd interface{}, closeChan <-chan struct{}) (in
 	}
 
 	// No point in generating or accepting work before the chain is synced.
-	_, currentHeight := s.server.blockManager.chainState.Best()
+	currentHeight := s.server.blockManager.chain.BestSnapshot().Height
 	if currentHeight != 0 && !s.server.blockManager.IsCurrent() {
 		return nil, &btcjson.RPCError{
 			Code:    btcjson.ErrRPCClientInInitialDownload,