splistore cold object reification redux

blockstore/context.go

@@ -0,0 +1,21 @@
+package blockstore
+
+import (
+	"context"
+)
+
+type hotViewKey struct{}
+
+var hotView = hotViewKey{}
+
+// WithHotView constructs a new context with an option that provides a hint to the blockstore
+// (e.g. the splitstore) that the object (and its ipld references) should be kept hot.
+func WithHotView(ctx context.Context) context.Context {
+	return context.WithValue(ctx, hotView, struct{}{})
+}
+
+// GetHotView returns true if the hot view option is set in the context
+func GetHotView(ctx context.Context) bool {
+	v := ctx.Value(hotView)
+	return v != nil
+}

blockstore/splitstore/splitstore.go

@@ -161,6 +161,12 @@ type SplitStore struct {
 	txnSyncCond     sync.Cond
 	txnSync         bool
 
+	// background cold object reification
+	reifyMx         sync.Mutex
+	reifyCond       sync.Cond
+	reifyPend       map[cid.Cid]struct{}
+	reifyInProgress map[cid.Cid]struct{}
+
 	// registered protectors
 	protectors []func(func(cid.Cid) error) error
 }
@@ -202,6 +208,10 @@ func Open(path string, ds dstore.Datastore, hot, cold bstore.Blockstore, cfg *Co
 	ss.txnSyncCond.L = &ss.txnSyncMx
 	ss.ctx, ss.cancel = context.WithCancel(context.Background())
 
+	ss.reifyCond.L = &ss.reifyMx
+	ss.reifyPend = make(map[cid.Cid]struct{})
+	ss.reifyInProgress = make(map[cid.Cid]struct{})
+
 	if enableDebugLog {
 		ss.debug, err = openDebugLog(path)
 		if err != nil {
@@ -264,7 +274,13 @@ func (s *SplitStore) Has(ctx context.Context, cid cid.Cid) (bool, error) {
 		return true, nil
 	}
 
-	return s.cold.Has(ctx, cid)
+	has, err = s.cold.Has(ctx, cid)
+	if has && bstore.GetHotView(ctx) {
+		s.reifyColdObject(cid)
+	}
+
+	return has, err
+
 }
 
 func (s *SplitStore) Get(ctx context.Context, cid cid.Cid) (blocks.Block, error) {
@@ -308,8 +324,11 @@ func (s *SplitStore) Get(ctx context.Context, cid cid.Cid) (blocks.Block, error)
 
 		blk, err = s.cold.Get(ctx, cid)
 		if err == nil {
-			stats.Record(s.ctx, metrics.SplitstoreMiss.M(1))
+			if bstore.GetHotView(ctx) {
+				s.reifyColdObject(cid)
+			}
 
+			stats.Record(s.ctx, metrics.SplitstoreMiss.M(1))
 		}
 		return blk, err
 
@@ -359,6 +378,10 @@ func (s *SplitStore) GetSize(ctx context.Context, cid cid.Cid) (int, error) {
 
 		size, err = s.cold.GetSize(ctx, cid)
 		if err == nil {
+			if bstore.GetHotView(ctx) {
+				s.reifyColdObject(cid)
+			}
+
 			stats.Record(s.ctx, metrics.SplitstoreMiss.M(1))
 		}
 		return size, err
@@ -536,6 +559,10 @@ func (s *SplitStore) View(ctx context.Context, cid cid.Cid, cb func([]byte) erro
 
 		err = s.cold.View(ctx, cid, cb)
 		if err == nil {
+			if bstore.GetHotView(ctx) {
+				s.reifyColdObject(cid)
+			}
+
 			stats.Record(s.ctx, metrics.SplitstoreMiss.M(1))
 		}
 		return err
@@ -645,6 +672,9 @@ func (s *SplitStore) Start(chain ChainAccessor, us stmgr.UpgradeSchedule) error
 		}
 	}
 
+	// spawn the reifier
+	go s.reifyOrchestrator()
+
 	// watch the chain
 	chain.SubscribeHeadChanges(s.HeadChange)
 
@@ -676,6 +706,7 @@ func (s *SplitStore) Close() error {
 		}
 	}
 
+	s.reifyCond.Broadcast()
 	s.cancel()
 	return multierr.Combine(s.markSetEnv.Close(), s.debug.Close())
 }

blockstore/splitstore/splitstore_reify.go

@@ -0,0 +1,185 @@
+package splitstore
+
+import (
+	"runtime"
+	"sync/atomic"
+
+	"golang.org/x/xerrors"
+
+	blocks "github.com/ipfs/go-block-format"
+	cid "github.com/ipfs/go-cid"
+)
+
+func (s *SplitStore) reifyColdObject(c cid.Cid) {
+	if isUnitaryObject(c) {
+		return
+	}
+
+	s.reifyMx.Lock()
+	defer s.reifyMx.Unlock()
+
+	_, ok := s.reifyInProgress[c]
+	if ok {
+		return
+	}
+
+	s.reifyPend[c] = struct{}{}
+	s.reifyCond.Broadcast()
+}
+
+func (s *SplitStore) reifyOrchestrator() {
+	workers := runtime.NumCPU() / 4
+	if workers < 2 {
+		workers = 2
+	}
+
+	workch := make(chan cid.Cid, workers)
+	defer close(workch)
+
+	for i := 0; i < workers; i++ {
+		go s.reifyWorker(workch)
+	}
+
+	for {
+		s.reifyMx.Lock()
+		for len(s.reifyPend) == 0 && atomic.LoadInt32(&s.closing) == 0 {
+			s.reifyCond.Wait()
+		}
+
+		if atomic.LoadInt32(&s.closing) != 0 {
+			s.reifyMx.Unlock()
+			return
+		}
+
+		reifyPend := s.reifyPend
+		s.reifyPend = make(map[cid.Cid]struct{})
+		s.reifyMx.Unlock()
+
+		for c := range reifyPend {
+			select {
+			case workch <- c:
+			case <-s.ctx.Done():
+				return
+			}
+		}
+	}
+}
+
+func (s *SplitStore) reifyWorker(workch chan cid.Cid) {
+	for c := range workch {
+		s.doReify(c)
+	}
+}
+
+func (s *SplitStore) doReify(c cid.Cid) {
+	var toreify, totrack, toforget []cid.Cid
+
+	defer func() {
+		s.reifyMx.Lock()
+		defer s.reifyMx.Unlock()
+
+		for _, c := range toreify {
+			delete(s.reifyInProgress, c)
+		}
+		for _, c := range totrack {
+			delete(s.reifyInProgress, c)
+		}
+		for _, c := range toforget {
+			delete(s.reifyInProgress, c)
+		}
+	}()
+
+	s.txnLk.RLock()
+	defer s.txnLk.RUnlock()
+
+	err := s.walkObject(c, newTmpVisitor(),
+		func(c cid.Cid) error {
+			if isUnitaryObject(c) {
+				return errStopWalk
+			}
+
+			s.reifyMx.Lock()
+			_, inProgress := s.reifyInProgress[c]
+			if !inProgress {
+				s.reifyInProgress[c] = struct{}{}
+			}
+			s.reifyMx.Unlock()
+
+			if inProgress {
+				return errStopWalk
+			}
+
+			has, err := s.hot.Has(s.ctx, c)
+			if err != nil {
+				return xerrors.Errorf("error checking hotstore: %w", err)
+			}
+
+			if has {
+				if s.txnMarkSet != nil {
+					hasMark, err := s.txnMarkSet.Has(c)
+					if err != nil {
+						log.Warnf("error checking markset: %s", err)
+					} else if hasMark {
+						toforget = append(toforget, c)
+						return errStopWalk
+					}
+				} else {
+					totrack = append(totrack, c)
+					return errStopWalk
+				}
+			}
+
+			toreify = append(toreify, c)
+			return nil
+		})
+
+	if err != nil {
+		log.Warnf("error walking cold object for reification (cid: %s): %s", c, err)
+		return
+	}
+
+	log.Debugf("reifying %d objects rooted at %s", len(toreify), c)
+
+	batch := make([]blocks.Block, 0, len(toreify))
+	for _, c := range toreify {
+		blk, err := s.cold.Get(s.ctx, c)
+		if err != nil {
+			log.Warnf("error retrieving cold object for reification (cid: %s): %s", c, err)
+			continue
+		}
+
+		if err := s.checkClosing(); err != nil {
+			return
+		}
+
+		batch = append(batch, blk)
+	}
+
+	if len(batch) > 0 {
+		err = s.hot.PutMany(s.ctx, batch)
+		if err != nil {
+			log.Warnf("error reifying cold object (cid: %s): %s", c, err)
+			return
+		}
+	}
+
+	if s.txnMarkSet != nil {
+		if len(toreify) > 0 {
+			if err := s.txnMarkSet.MarkMany(toreify); err != nil {
+				log.Warnf("error marking reified objects: %s", err)
+			}
+		}
+		if len(totrack) > 0 {
+			if err := s.txnMarkSet.MarkMany(totrack); err != nil {
+				log.Warnf("error marking tracked objects: %s", err)
+			}
+		}
+	} else {
+		if len(toreify) > 0 {
+			s.trackTxnRefMany(toreify)
+		}
+		if len(totrack) > 0 {
+			s.trackTxnRefMany(totrack)
+		}
+	}
+}