[NOD-1005] Use sm.isSynced to check whether should request blocks from invs (#721)

* [NOD-1005] Moved isSyncedForMining to netsync manager, and renamed to isSynced + removed isCurrent

* [NOD-1005] Use sm.isSynced to check whether should request blocks from invs

* [NOD-1005] Use private version of isSynced to avoid infinite loop

* [NOD-1005] Fix a few typos

netsync/manager.go

@@ -103,10 +103,10 @@ type processBlockMsg struct {
 	reply chan processBlockResponse
 }
 
-// isCurrentMsg is a message type to be sent across the message channel for
+// isSyncedMsg is a message type to be sent across the message channel for
 // requesting whether or not the sync manager believes it is synced with the
 // currently connected peers.
-type isCurrentMsg struct {
+type isSyncedMsg struct {
 	reply chan bool
 }
 
@@ -839,7 +839,7 @@ func (sm *SyncManager) sendInvsFromRequestQueue(peer *peerpkg.Peer, state *peerS
 	if err != nil {
 		return err
 	}
-	if sm.current() {
+	if sm.syncPeer == nil || sm.isSynced() {
 		err := sm.addInvsToGetDataMessageFromQueue(gdmsg, state, wire.InvTypeBlock, wire.MaxInvPerGetDataMsg)
 		if err != nil {
 			return err
@@ -968,8 +968,8 @@ out:
 					err:      err,
 				}
 
-			case isCurrentMsg:
-				msg.reply <- sm.current()
+			case isSyncedMsg:
+				msg.reply <- sm.isSynced()
 
 			case pauseMsg:
 				// Wait until the sender unpauses the manager.
@@ -1151,14 +1151,32 @@ func (sm *SyncManager) ProcessBlock(block *util.Block, flags blockdag.BehaviorFl
 	return response.isOrphan, response.err
 }
 
-// IsCurrent returns whether or not the sync manager believes it is synced with
+// IsSynced returns whether or not the sync manager believes it is synced with
 // the connected peers.
-func (sm *SyncManager) IsCurrent() bool {
+func (sm *SyncManager) IsSynced() bool {
 	reply := make(chan bool)
-	sm.msgChan <- isCurrentMsg{reply: reply}
+	sm.msgChan <- isSyncedMsg{reply: reply}
 	return <-reply
 }
 
+// isSynced checks if the node is synced enough based upon its worldview.
+// This is used to determine if the node can support mining and requesting newly-mined blocks.
+// To do that, first it checks if the selected tip timestamp is not older than maxTipAge. If that's the case, it means
+// the node is synced since blocks' timestamps are not allowed to deviate too much into the future.
+// If that's not the case it checks the rate it added new blocks to the DAG recently. If it's faster than
+// blockRate * maxSyncRateDeviation it means the node is not synced, since when the node is synced it shouldn't add
+// blocks to the DAG faster than the block rate.
+func (sm *SyncManager) isSynced() bool {
+	const maxTipAge = 5 * time.Minute
+	isCloseToCurrentTime := sm.dag.Now().Sub(sm.dag.SelectedTipHeader().Timestamp) <= maxTipAge
+	if isCloseToCurrentTime {
+		return true
+	}
+
+	const maxSyncRateDeviation = 1.05
+	return sm.dag.IsSyncRateBelowThreshold(maxSyncRateDeviation)
+}
+
 // Pause pauses the sync manager until the returned channel is closed.
 //
 // Note that while paused, all peer and block processing is halted. The

server/rpc/handle_get_block_template.go

@@ -4,6 +4,12 @@ import (
 	"bytes"
 	"encoding/hex"
 	"fmt"
+	"math/rand"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
 	"github.com/kaspanet/kaspad/blockdag"
 	"github.com/kaspanet/kaspad/config"
 	"github.com/kaspanet/kaspad/mining"
@@ -14,11 +20,6 @@ import (
 	"github.com/kaspanet/kaspad/util/random"
 	"github.com/kaspanet/kaspad/wire"
 	"github.com/pkg/errors"
-	"math/rand"
-	"strconv"
-	"strings"
-	"sync"
-	"time"
 )
 
 const (
@@ -119,24 +120,6 @@ func handleGetBlockTemplate(s *Server, cmd interface{}, closeChan <-chan struct{
 	}
 }
 
-// isSyncedForMining checks if the node is synced enough for mining blocks
-// on top of its world view.
-// To do that, first it checks if the selected tip timestamp is not older than maxTipAge. If that's the case, it means
-// the node is synced since blocks' timestamps are not allowed to deviate too much into the future.
-// If that's not the case it checks the rate it added new blocks to the DAG recently. If it's faster than
-// blockRate * maxSyncRateDeviation it means the node is not synced, since when the node is synced it shouldn't add
-// blocks to the DAG faster than the block rate.
-func isSyncedForMining(s *Server) bool {
-	const maxTipAge = 5 * time.Minute
-	isCloseToCurrentTime := s.cfg.DAG.Now().Sub(s.cfg.DAG.SelectedTipHeader().Timestamp) <= maxTipAge
-	if isCloseToCurrentTime {
-		return true
-	}
-
-	const maxSyncRateDeviation = 1.05
-	return s.cfg.DAG.IsSyncRateBelowThreshold(maxSyncRateDeviation)
-}
-
 // handleGetBlockTemplateRequest is a helper for handleGetBlockTemplate which
 // deals with generating and returning block templates to the caller. It
 // handles both long poll requests as specified by BIP 0022 as well as regular
@@ -652,7 +635,7 @@ func (state *gbtWorkState) updateBlockTemplate(s *Server, useCoinbaseValue bool)
 		// This is not a straight-up error because the choice of whether
 		// to mine or not is the responsibility of the miner rather
 		// than the node's.
-		isSynced := isSyncedForMining(s)
+		isSynced := s.cfg.SyncMgr.IsSynced()
 
 		// Update work state to ensure another block template isn't
 		// generated until needed.

server/rpc/rpcadapters.go

@@ -234,13 +234,13 @@ type rpcSyncMgr struct {
 // Ensure rpcSyncMgr implements the rpcserverSyncManager interface.
 var _ rpcserverSyncManager = (*rpcSyncMgr)(nil)
 
-// IsCurrent returns whether or not the sync manager believes the DAG is
+// IsSynced returns whether or not the sync manager believes the DAG is
 // current as compared to the rest of the network.
 //
 // This function is safe for concurrent access and is part of the
 // rpcserverSyncManager interface implementation.
-func (b *rpcSyncMgr) IsCurrent() bool {
-	return b.syncMgr.IsCurrent()
+func (b *rpcSyncMgr) IsSynced() bool {
+	return b.syncMgr.IsSynced()
 }
 
 // SubmitBlock submits the provided block to the network after processing it

server/rpc/rpcserver.go

@@ -723,9 +723,9 @@ type rpcserverConnManager interface {
 // The interface contract requires that all of these methods are safe for
 // concurrent access.
 type rpcserverSyncManager interface {
-	// IsCurrent returns whether or not the sync manager believes the DAG
+	// IsSynced returns whether or not the sync manager believes the DAG
 	// is current as compared to the rest of the network.
-	IsCurrent() bool
+	IsSynced() bool
 
 	// SubmitBlock submits the provided block to the network after
 	// processing it locally.