multi: automate block template regeneration.

blockchain/process.go

@@ -91,6 +91,12 @@ func (b *BlockChain) processOrphans(hash *chainhash.Hash, flags BehaviorFlags) e
 	return nil
 }
 
+// WaitForChain blocks if the chain is processing a block or handling a reorg.
+func (b *BlockChain) WaitForChain() {
+	b.chainLock.RLock()
+	b.chainLock.RUnlock()
+}
+
 // ProcessBlock is the main workhorse for handling insertion of new blocks into
 // the block chain.  It includes functionality such as rejecting duplicate
 // blocks, ensuring blocks follow all rules, orphan handling, and insertion into

blockmanager.go

@@ -67,6 +67,15 @@ const (
 	// otherwise arise from sending old orphan blocks and forcing nodes to
 	// do expensive lottery data calculations for them.
 	maxReorgDepthNotify = 6
+
+	// templateRegenSeconds is the required number of seconds elapsed,
+	// with incoming non vote transactions, before template
+	// regeneration is required.
+	templateRegenSeconds = 30
+
+	// maxTemplateRegenSeconds is the maximum number of seconds elapsed
+	// without incoming transactions before template regeneration is required.
+	maxTemplateRegenSeconds = 60
 )
 
 // zeroHash is the zero value hash (all zeros).  It is defined as a convenience.
@@ -235,60 +244,20 @@ type processTransactionMsg struct {
 	reply         chan processTransactionResponse
 }
 
+// regenMsg handles a request for block template regeneration.
+type regenMsg struct{}
+
+// nonVoteMsg handles a request signalling the receipt of a non vote
+// transaction.
+type nonVoteMsg struct{}
+
 // isCurrentMsg is a message type to be sent across the message channel for
 // requesting whether or not the block manager believes it is synced with
 // the currently connected peers.
 type isCurrentMsg struct {
 	reply chan bool
 }
 
-// getCurrentTemplateMsg handles a request for the current mining block template.
-type getCurrentTemplateMsg struct {
-	reply chan getCurrentTemplateResponse
-}
-
-// getCurrentTemplateResponse is a response sent to the reply channel of a
-// getCurrentTemplateMsg.
-type getCurrentTemplateResponse struct {
-	Template *BlockTemplate
-}
-
-// setCurrentTemplateMsg handles a request to change the current mining block
-// template.
-type setCurrentTemplateMsg struct {
-	Template *BlockTemplate
-	reply    chan setCurrentTemplateResponse
-}
-
-// setCurrentTemplateResponse is a response sent to the reply channel of a
-// setCurrentTemplateMsg.
-type setCurrentTemplateResponse struct {
-}
-
-// getParentTemplateMsg handles a request for the current parent mining block
-// template.
-type getParentTemplateMsg struct {
-	reply chan getParentTemplateResponse
-}
-
-// getParentTemplateResponse is a response sent to the reply channel of a
-// getParentTemplateMsg.
-type getParentTemplateResponse struct {
-	Template *BlockTemplate
-}
-
-// setParentTemplateMsg handles a request to change the parent mining block
-// template.
-type setParentTemplateMsg struct {
-	Template *BlockTemplate
-	reply    chan setParentTemplateResponse
-}
-
-// setParentTemplateResponse is a response sent to the reply channel of a
-// setParentTemplateMsg.
-type setParentTemplateResponse struct {
-}
-
 // headerNode is used as a node in a list of headers that are linked together
 // between checkpoints.
 type headerNode struct {
@@ -407,6 +376,18 @@ type blockManager struct {
 	lotteryDataBroadcast      map[chainhash.Hash]struct{}
 	lotteryDataBroadcastMutex sync.RWMutex
 
+	// the following fields handle block template regeneration and updating
+	// registered clients.
+	mining                     bool
+	lastRegen                  time.Time
+	nonVoteTxCountLastInterval uint64
+	nonVoteTxCount             uint64
+	registeredClients          map[chan *BlockTemplate]struct{}
+	regenMtx                   sync.Mutex
+	templateMtx                sync.RWMutex
+	nonVoteTxCountMtx          sync.RWMutex
+	registerMtx                sync.RWMutex
+
 	cachedCurrentTemplate *BlockTemplate
 	cachedParentTemplate  *BlockTemplate
 	AggressiveMining      bool
@@ -764,12 +745,33 @@ func (b *blockManager) current() bool {
 	return true
 }
 
+// NotifyRegisteredTemplateClients broadcasts the provided block template
+// to all registered clients.
+func (b *blockManager) NotifyRegisteredTemplateClients(t *BlockTemplate) {
+	b.registerMtx.Lock()
+	for c := range b.registeredClients {
+		c <- t
+		// Delete the client after updating it.
+		delete(b.registeredClients, c)
+	}
+	b.registerMtx.Unlock()
+}
+
+// RequestTemplateUpdate registers a client for block template updates.
+func (b *blockManager) RequestTemplateUpdate() chan *BlockTemplate {
+	updateChan := make(chan *BlockTemplate)
+	b.registerMtx.Lock()
+	b.registeredClients[updateChan] = struct{}{}
+	b.registerMtx.Unlock()
+	return updateChan
+}
+
 // checkBlockForHiddenVotes checks to see if a newly added block contains
 // any votes that were previously unknown to our daemon. If it does, it
 // adds these votes to the cached parent block template.
 //
 // This is UNSAFE for concurrent access. It must be called in single threaded
-// access through the block mananger. All template access must also be routed
+// access through the block manager. All template access must also be routed
 // through the block manager.
 func (b *blockManager) checkBlockForHiddenVotes(block *dcrutil.Block) {
 	var votesFromBlock []*dcrutil.Tx
@@ -1592,6 +1594,15 @@ func (b *blockManager) limitMap(m map[chainhash.Hash]struct{}, limit int) {
 // the fetching should proceed.
 func (b *blockManager) blockHandler() {
 	candidatePeers := list.New()
+	b.lastRegen = b.server.txMemPool.LastUpdated()
+	updateNonVoteCounters := func() {
+		b.nonVoteTxCountMtx.Lock()
+		b.nonVoteTxCountLastInterval, b.nonVoteTxCount = b.nonVoteTxCount, 0
+		b.nonVoteTxCountMtx.Unlock()
+	}
+	ticker := time.NewTicker(time.Second)
+	defer ticker.Stop()
+
 out:
 	for {
 		select {
@@ -1805,31 +1816,92 @@ out:
 			case isCurrentMsg:
 				msg.reply <- b.current()
 
-			case getCurrentTemplateMsg:
-				cur := deepCopyBlockTemplate(b.cachedCurrentTemplate)
-				msg.reply <- getCurrentTemplateResponse{
-					Template: cur,
-				}
-
-			case setCurrentTemplateMsg:
-				b.cachedCurrentTemplate = deepCopyBlockTemplate(msg.Template)
-				msg.reply <- setCurrentTemplateResponse{}
-
-			case getParentTemplateMsg:
-				par := deepCopyBlockTemplate(b.cachedParentTemplate)
-				msg.reply <- getParentTemplateResponse{
-					Template: par,
+			case nonVoteMsg:
+				if b.mining {
+					// Increment the non vote transaction counter.
+					b.nonVoteTxCountMtx.Lock()
+					b.nonVoteTxCount++
+					b.nonVoteTxCountMtx.Unlock()
 				}
 
-			case setParentTemplateMsg:
-				b.cachedParentTemplate = deepCopyBlockTemplate(msg.Template)
-				msg.reply <- setParentTemplateResponse{}
+			case regenMsg:
+				b.chain.WaitForChain()
+				go func() {
+					if b.mining {
+						// Pick a mining address at random.
+						rand.Seed(time.Now().UnixNano())
+						payToAddr :=
+							cfg.miningAddrs[rand.Intn(len(cfg.miningAddrs))]
+
+						// Regenerate the block template.
+						b.templateMtx.Lock()
+						template, err :=
+							NewBlockTemplate(b.server.rpcServer.policy, b.server,
+								payToAddr)
+						if err != nil {
+							bmgrLog.Infof(
+								"block template generation failed: %v", err)
+						}
 
+						if template != nil {
+							// Update the current and parent templates and
+							// notify all registered template clients.
+							b.cachedParentTemplate, b.cachedCurrentTemplate =
+								b.cachedCurrentTemplate, template
+
+							b.NotifyRegisteredTemplateClients(b.cachedCurrentTemplate)
+							bmgrLog.Debugf("block template generated "+
+								"(height: %v, hash: %v)",
+								template.Block.Header.Height,
+								template.Block.BlockHash())
+
+							// Update the last regen time.
+							b.regenMtx.Lock()
+							b.lastRegen = time.Now()
+							b.regenMtx.Unlock()
+						}
+						b.templateMtx.Unlock()
+					}
+				}()
 			default:
 				bmgrLog.Warnf("Invalid message type in block "+
 					"handler: %T", msg)
 			}
 
+		case <-ticker.C:
+			go func() {
+				if b.mining {
+					b.nonVoteTxCountMtx.RLock()
+					hasNewNonVoteTxs := b.nonVoteTxCount > 0
+					b.nonVoteTxCountMtx.RUnlock()
+
+					b.regenMtx.Lock()
+					timeDiff := time.Since(b.lastRegen)
+					regen := b.server.txMemPool.LastUpdated().After(b.lastRegen.
+						Add(templateRegenSeconds * time.Second))
+					b.regenMtx.Unlock()
+
+					// Signal template regeneration if a minute has elapsed
+					// since the last regeneration and there is at least one
+					// registered subscriber for block template updates.
+					if timeDiff.Seconds() > maxTemplateRegenSeconds {
+						b.RegenTemplate()
+						updateNonVoteCounters()
+						return
+					}
+
+					// Signal template regeneration if thirty seconds have
+					// elapsed and at least a new non vote transaction has
+					// been accepted by the mempool nd there is at least one
+					// registered subscriber for block template updates.
+					if regen && hasNewNonVoteTxs {
+						b.RegenTemplate()
+					}
+
+					updateNonVoteCounters()
+				}
+			}()
+
 		case <-b.quit:
 			break out
 		}
@@ -2119,7 +2191,9 @@ func (b *blockManager) handleNotifyMsg(notification *blockchain.Notification) {
 
 		// Drop the associated mining template from the old chain, since it
 		// will be no longer valid.
+		b.templateMtx.Lock()
 		b.cachedCurrentTemplate = nil
+		b.templateMtx.Unlock()
 	}
 }
 
@@ -2413,39 +2487,19 @@ func (b *blockManager) TicketPoolValue() (dcrutil.Amount, error) {
 	return b.chain.TicketPoolValue()
 }
 
-// GetCurrentTemplate gets the current block template for mining.
-func (b *blockManager) GetCurrentTemplate() *BlockTemplate {
-	reply := make(chan getCurrentTemplateResponse)
-	b.msgChan <- getCurrentTemplateMsg{reply: reply}
-	response := <-reply
-	return response.Template
-}
-
-// SetCurrentTemplate sets the current block template for mining.
-func (b *blockManager) SetCurrentTemplate(bt *BlockTemplate) {
-	reply := make(chan setCurrentTemplateResponse)
-	b.msgChan <- setCurrentTemplateMsg{Template: bt, reply: reply}
-	<-reply
-}
-
-// GetParentTemplate gets the current parent block template for mining.
-func (b *blockManager) GetParentTemplate() *BlockTemplate {
-	reply := make(chan getParentTemplateResponse)
-	b.msgChan <- getParentTemplateMsg{reply: reply}
-	response := <-reply
-	return response.Template
+// RegenTemplate regenerates the block template.
+func (b *blockManager) RegenTemplate() {
+	b.msgChan <- regenMsg{}
 }
 
-// SetParentTemplate sets the current parent block template for mining.
-func (b *blockManager) SetParentTemplate(bt *BlockTemplate) {
-	reply := make(chan setParentTemplateResponse)
-	b.msgChan <- setParentTemplateMsg{Template: bt, reply: reply}
-	<-reply
+// ReceiveNonVoteTx signals the receipt of a non vote transaction.
+func (b *blockManager) ReceiveNonVoteTx() {
+	b.msgChan <- nonVoteMsg{}
 }
 
 // newBlockManager returns a new Decred block manager.
 // Use Start to begin processing asynchronous block and inv updates.
-func newBlockManager(s *server, indexManager blockchain.IndexManager, interrupt <-chan struct{}) (*blockManager, error) {
+func newBlockManager(s *server, indexManager blockchain.IndexManager, mining bool, interrupt <-chan struct{}) (*blockManager, error) {
 	bm := blockManager{
 		server:              s,
 		rejectedTxns:        make(map[chainhash.Hash]struct{}),
@@ -2456,6 +2510,12 @@ func newBlockManager(s *server, indexManager blockchain.IndexManager, interrupt
 		progressLogger:      newBlockProgressLogger("Processed", bmgrLog),
 		msgChan:             make(chan interface{}, cfg.MaxPeers*3),
 		headerList:          list.New(),
+		mining:              mining,
+		regenMtx:            sync.Mutex{},
+		templateMtx:         sync.RWMutex{},
+		nonVoteTxCountMtx:   sync.RWMutex{},
+		registerMtx:         sync.RWMutex{},
+		registeredClients:   make(map[chan *BlockTemplate]struct{}),
 		AggressiveMining:    !cfg.NonAggressive,
 		quit:                make(chan struct{}),
 	}