warm up splitstore at first head change notification

blockstore/splitstore/splitstore.go

@@ -29,7 +29,10 @@ var (
 	CompactionCold      = build.Finality
 )
 
-var baseEpochKey = dstore.NewKey("baseEpoch")
+var (
+	baseEpochKey   = dstore.NewKey("/splitstore/baseEpoch")
+	warmupEpochKey = dstore.NewKey("/splitstore/warmupEpoch")
+)
 
 var log = logging.Logger("splitstore")
 
@@ -65,6 +68,7 @@ type SplitStore struct {
 	skipMsgReceipts bool
 
 	baseEpoch   abi.ChainEpoch
+	warmupEpoch abi.ChainEpoch
 
 	mx    sync.Mutex
 	curTs *types.TipSet
@@ -275,11 +279,25 @@ func (s *SplitStore) Start(cs *store.ChainStore) error {
 
 		err = s.setBaseEpoch(s.curTs.Height())
 		if err != nil {
-			return err
+			return xerrors.Errorf("error saving base epoch: %w", err)
 		}
 
 	default:
-		return err
+		return xerrors.Errorf("error loading base epoch: %w", err)
+	}
+
+	// load warmup epoch from metadata ds
+	// if none, then the splitstore will warm up the hotstore at first head change notif
+	// by walking the current tipset
+	bs, err = s.ds.Get(warmupEpochKey)
+	switch err {
+	case nil:
+		s.warmupEpoch = bytesToEpoch(bs)
+
+	case dstore.ErrNotFound:
+
+	default:
+		return xerrors.Errorf("error loading warmup epoch: %w", err)
 	}
 
 	// watch the chain
@@ -310,7 +328,25 @@ func (s *SplitStore) HeadChange(revert, apply []*types.TipSet) error {
 		return nil
 	}
 
+	if s.warmupEpoch == 0 {
+		// splitstore needs to warm up
+		s.warmupEpoch = epoch
+		go func() {
+			defer atomic.StoreInt32(&s.compacting, 0)
+
+			log.Info("warming up hotstore")
+			start := time.Now()
+
+			s.warmup()
+
+			log.Infow("warm up done", "took", time.Since(start))
+		}()
+
+		return nil
+	}
+
 	if epoch-s.baseEpoch > CompactionThreshold {
+		// it's time to compact
 		go func() {
 			defer atomic.StoreInt32(&s.compacting, 0)
 
@@ -329,6 +365,49 @@ func (s *SplitStore) HeadChange(revert, apply []*types.TipSet) error {
 	return nil
 }
 
+func (s *SplitStore) warmup() {
+	s.mx.Lock()
+	curTs := s.curTs
+	epoch := curTs.Height()
+	s.mx.Unlock()
+
+	err := s.cs.WalkSnapshot(context.Background(), curTs, 1, s.skipOldMsgs, s.skipMsgReceipts,
+		func(cid cid.Cid) error {
+			has, err := s.hot.Has(cid)
+			if err != nil {
+				return err
+			}
+
+			if has {
+				return nil
+			}
+
+			blk, err := s.cold.Get(cid)
+			if err != nil {
+				return err
+			}
+
+			err = s.snoop.Put(cid, epoch)
+			if err != nil {
+				return err
+			}
+
+			return s.hot.Put(blk)
+		})
+
+	if err != nil {
+		log.Errorf("error warming up splitstore: %s", err)
+		return
+	}
+
+	// save the warmup epoch
+	s.warmupEpoch = epoch
+	err = s.ds.Put(warmupEpochKey, epochToBytes(epoch))
+	if err != nil {
+		log.Errorf("error saving warmup epoch: %s", err)
+	}
+}
+
 // Compaction/GC Algorithm
 func (s *SplitStore) compact() {
 	if s.liveSetSize == 0 {