[lbry] claimtrie: created node cache

claimtrie/node/cache.go

@@ -0,0 +1,101 @@
+package node
+
+import (
+	"container/list"
+	"sync"
+
+	"github.com/lbryio/lbcd/claimtrie/change"
+)
+
+type cacheLeaf struct {
+	node    *Node
+	element *list.Element
+	changes []change.Change
+	height  int32
+}
+
+type Cache struct {
+	nodes map[string]*cacheLeaf
+	order *list.List
+	mtx   sync.Mutex
+	limit int
+}
+
+func (nc *Cache) insert(name []byte, n *Node, height int32) {
+	key := string(name)
+
+	nc.mtx.Lock()
+	defer nc.mtx.Unlock()
+
+	existing := nc.nodes[key]
+	if existing != nil {
+		existing.node = n
+		existing.height = height
+		existing.changes = nil
+		nc.order.MoveToFront(existing.element)
+		return
+	}
+
+	for nc.order.Len() >= nc.limit {
+		// TODO: maybe ensure that we don't remove nodes that have a lot of changes?
+		delete(nc.nodes, nc.order.Back().Value.(string))
+		nc.order.Remove(nc.order.Back())
+	}
+
+	element := nc.order.PushFront(key)
+	nc.nodes[key] = &cacheLeaf{node: n, element: element, height: height}
+}
+
+func (nc *Cache) fetch(name []byte, height int32) (*Node, []change.Change, int32) {
+	key := string(name)
+
+	nc.mtx.Lock()
+	defer nc.mtx.Unlock()
+
+	existing := nc.nodes[key]
+	if existing != nil && existing.height <= height {
+		nc.order.MoveToFront(existing.element)
+		return existing.node, existing.changes, existing.height
+	}
+	return nil, nil, -1
+}
+
+func (nc *Cache) addChanges(changes []change.Change, height int32) {
+	nc.mtx.Lock()
+	defer nc.mtx.Unlock()
+
+	for _, c := range changes {
+		key := string(c.Name)
+		existing := nc.nodes[key]
+		if existing != nil && existing.height <= height {
+			existing.changes = append(existing.changes, c)
+		}
+	}
+}
+
+func (nc *Cache) drop(names [][]byte) {
+	nc.mtx.Lock()
+	defer nc.mtx.Unlock()
+
+	for _, name := range names {
+		key := string(name)
+		existing := nc.nodes[key]
+		if existing != nil {
+			// we can't roll it backwards because we don't know its previous height value; just toast it
+			delete(nc.nodes, key)
+			nc.order.Remove(existing.element)
+		}
+	}
+}
+
+func (nc *Cache) clear() {
+	nc.mtx.Lock()
+	defer nc.mtx.Unlock()
+	nc.nodes = map[string]*cacheLeaf{}
+	nc.order = list.New()
+	// we'll let the GC sort out the remains...
+}
+
+func NewCache(limit int) *Cache {
+	return &Cache{limit: limit, nodes: map[string]*cacheLeaf{}, order: list.New()}
+}

claimtrie/node/manager.go

@@ -21,6 +21,7 @@ type Manager interface {
 	IterateNames(predicate func(name []byte) bool)
 	Hash(name []byte) (*chainhash.Hash, int32)
 	Flush() error
+	ClearCache()
 }
 
 type BaseManager struct {
@@ -30,19 +31,28 @@ type BaseManager struct {
 	changes []change.Change
 
 	tempChanges map[string][]change.Change
+
+	cache *Cache
 }
 
 func NewBaseManager(repo Repo) (*BaseManager, error) {
 
 	nm := &BaseManager{
 		repo:  repo,
+		cache: NewCache(10000), // TODO: how many should we cache?
 	}
 
 	return nm, nil
 }
 
+func (nm *BaseManager) ClearCache() {
+	nm.cache.clear()
+}
+
 func (nm *BaseManager) NodeAt(height int32, name []byte) (*Node, error) {
 
+	n, changes, oldHeight := nm.cache.fetch(name, height)
+	if n == nil {
 		changes, err := nm.repo.LoadChanges(name)
 		if err != nil {
 			return nil, errors.Wrap(err, "in load changes")
@@ -52,10 +62,30 @@ func (nm *BaseManager) NodeAt(height int32, name []byte) (*Node, error) {
 			changes = append(changes, nm.tempChanges[string(name)]...)
 		}
 
-	n, err := nm.newNodeFromChanges(changes, height)
+		n, err = nm.newNodeFromChanges(changes, height)
 		if err != nil {
 			return nil, errors.Wrap(err, "in new node")
 		}
+		// TODO: how can we tell what needs to be cached?
+		if nm.tempChanges == nil && height == nm.height && n != nil && (len(changes) > 7 || len(name) < 12) {
+			nm.cache.insert(name, n, height)
+		}
+	} else {
+		if nm.tempChanges != nil { // making an assumption that we only ever have tempChanges for a single block
+			changes = append(changes, nm.tempChanges[string(name)]...)
+		}
+		n = n.Clone()
+		updated, err := nm.updateFromChanges(n, changes, height)
+		if err != nil {
+			return nil, errors.Wrap(err, "in update from changes")
+		}
+		if !updated {
+			n.AdjustTo(oldHeight, height, name)
+		}
+		if nm.tempChanges == nil && height == nm.height { // TODO: how many changes before we update the cache?
+			nm.cache.insert(name, n, height)
+		}
+	}
 
 	return n, nil
 }
@@ -66,17 +96,13 @@ func (nm *BaseManager) node(name []byte) (*Node, error) {
 	return nm.NodeAt(nm.height, name)
 }
 
-// newNodeFromChanges returns a new Node constructed from the changes.
+func (nm *BaseManager) updateFromChanges(n *Node, changes []change.Change, height int32) (bool, error) {
-// The changes must preserve their order received.
-func (nm *BaseManager) newNodeFromChanges(changes []change.Change, height int32) (*Node, error) {
 
-	if len(changes) == 0 {
-		return nil, nil
-	}
-
-	n := New()
-	previous := changes[0].Height
 	count := len(changes)
+	if count == 0 {
+		return false, nil
+	}
+	previous := changes[0].Height
 
 	for i, chg := range changes {
 		if chg.Height < previous {
@@ -95,15 +121,37 @@ func (nm *BaseManager) newNodeFromChanges(changes []change.Change, height int32)
 		delay := nm.getDelayForName(n, chg)
 		err := n.ApplyChange(chg, delay)
 		if err != nil {
-			return nil, errors.Wrap(err, "in apply change")
+			return false, errors.Wrap(err, "in apply change")
 		}
 	}
 
 	if count <= 0 {
-		return nil, nil
+		// we applied no changes, which means we shouldn't exist if we had all the changes
+		// or might mean nothing significant if we are applying a partial changeset
+		return false, nil
 	}
 	lastChange := changes[count-1]
-	return n.AdjustTo(lastChange.Height, height, lastChange.Name), nil
+	n.AdjustTo(lastChange.Height, height, lastChange.Name)
+	return true, nil
+}
+
+// newNodeFromChanges returns a new Node constructed from the changes.
+// The changes must preserve their order received.
+func (nm *BaseManager) newNodeFromChanges(changes []change.Change, height int32) (*Node, error) {
+
+	if len(changes) == 0 {
+		return nil, nil
+	}
+
+	n := New()
+	updated, err := nm.updateFromChanges(n, changes, height)
+	if err != nil {
+		return nil, errors.Wrap(err, "in update from changes")
+	}
+	if updated {
+		return n, nil
+	}
+	return nil, nil
 }
 
 func (nm *BaseManager) AppendChange(chg change.Change) {
@@ -220,6 +268,7 @@ func (nm *BaseManager) IncrementHeightTo(height int32, temporary bool) ([][]byte
 	}
 
 	if !temporary {
+		nm.cache.addChanges(nm.changes, height)
 		if err := nm.repo.AppendChanges(nm.changes); err != nil { // destroys names
 			return nil, errors.Wrap(err, "in append changes")
 		}
@@ -255,6 +304,8 @@ func (nm *BaseManager) DecrementHeightTo(affectedNames [][]byte, height int32) (
 				return affectedNames, errors.Wrap(err, "in drop changes")
 			}
 		}
+
+		nm.cache.drop(affectedNames)
 	}
 	nm.height = height
 

claimtrie/node/node.go

@@ -110,7 +110,7 @@ func (n *Node) ApplyChange(chg change.Change, delay int32) error {
 }
 
 // AdjustTo activates claims and computes takeovers until it reaches the specified height.
-func (n *Node) AdjustTo(height, maxHeight int32, name []byte) *Node {
+func (n *Node) AdjustTo(height, maxHeight int32, name []byte) {
 	changed := n.handleExpiredAndActivated(height) > 0
 	n.updateTakeoverHeight(height, name, changed)
 	if maxHeight > height {
@@ -120,7 +120,6 @@ func (n *Node) AdjustTo(height, maxHeight int32, name []byte) *Node {
 			height = h
 		}
 	}
-	return n
 }
 
 func (n *Node) updateTakeoverHeight(height int32, name []byte, refindBest bool) {
@@ -340,3 +339,28 @@ func (n *Node) SortClaimsByBid() {
 		return OutPointLess(n.Claims[j].OutPoint, n.Claims[i].OutPoint)
 	})
 }
+
+func (n *Node) Clone() *Node {
+	clone := New()
+	if n.SupportSums != nil {
+		clone.SupportSums = map[string]int64{}
+		for key, value := range n.SupportSums {
+			clone.SupportSums[key] = value
+		}
+	}
+	clone.Supports = make(ClaimList, len(n.Supports))
+	for i, support := range n.Supports {
+		clone.Supports[i] = &Claim{}
+		*clone.Supports[i] = *support
+	}
+	clone.Claims = make(ClaimList, len(n.Claims))
+	for i, claim := range n.Claims {
+		clone.Claims[i] = &Claim{}
+		*clone.Claims[i] = *claim
+	}
+	clone.TakenOverAt = n.TakenOverAt
+	if n.BestClaim != nil {
+		clone.BestClaim = clone.Claims.find(byID(n.BestClaim.ClaimID))
+	}
+	return clone
+}

claimtrie/node/normalizing_manager.go

@@ -34,6 +34,7 @@ func (nm *NormalizingManager) IncrementHeightTo(height int32, temporary bool) ([
 func (nm *NormalizingManager) DecrementHeightTo(affectedNames [][]byte, height int32) ([][]byte, error) {
 	if nm.normalizedAt > height {
 		nm.normalizedAt = -1
+		nm.ClearCache()
 	}
 	return nm.Manager.DecrementHeightTo(affectedNames, height)
 }
@@ -110,5 +111,7 @@ func (nm *NormalizingManager) addNormalizationForkChangesIfNecessary(height int3
 
 		return true
 	}
+
+	nm.Manager.ClearCache()
 	nm.Manager.IterateNames(predicate)
 }