[#59] Add node states

cmd/generator/main.go

@@ -134,8 +134,10 @@ func newGenerator(nodeType string) *generator {
 func (g *generator) printImports() {
 	g.p("import (")
 	g.in()
+	g.p("\"sync/atomic\"")
 	g.p("\"unsafe\"")
 	if g.features[expiration] {
+		g.p("")
 		g.p("\"github.com/maypok86/otter/internal/unixtime\"")
 	}
 	g.out()
@@ -178,6 +180,7 @@ func (g *generator) printStruct() {
 		g.p("cost       uint32")
 	}
 
+	g.p("state      uint32")
 	g.p("frequency  uint8")
 	g.p("queueType  uint8")
 	g.out()
@@ -199,6 +202,7 @@ func (g *generator) printConstructors() {
 	if g.features[cost] {
 		g.p("cost:       cost,")
 	}
+	g.p("state:      aliveState,")
 	g.out()
 	g.p("}")
 	g.out()
@@ -365,6 +369,14 @@ func (g *generator) printFunctions() {
 	g.p("}")
 
 	const otherFunctions = `
+func (n *%s[K, V]) IsAlive() bool {
+	return atomic.LoadUint32(&n.state) == aliveState
+}
+
+func (n *%s[K, V]) Die() {
+	atomic.StoreUint32(&n.state, deadState)
+}
+
 func (n *%s[K, V]) Frequency() uint8 {
 	return n.frequency
 }
@@ -460,6 +472,11 @@ const (
 	maxFrequency uint8 = 3
 )
 
+const (
+	aliveState uint32 = iota
+	deadState
+)
+
 // Node is a cache entry.
 type Node[K comparable, V any] interface {
 	// Key returns the key.
@@ -490,6 +507,10 @@ type Node[K comparable, V any] interface {
 	Expiration() uint32
 	// Cost returns the cost of the node.
 	Cost() uint32
+	// IsAlive returns true if the entry is available in the hash-table.
+	IsAlive() bool
+	// Die sets the node to the dead state.
+	Die()
 	// Frequency returns the frequency of the node.
 	Frequency() uint8
 	// IncrementFrequency increments the frequency of the node.
@@ -522,11 +543,11 @@ func Equals[K comparable, V any](a, b Node[K, V]) bool {
 
 type Config struct {
 	WithExpiration bool
-	WithCost bool
+	WithCost       bool
 }
 
 type Manager[K comparable, V any] struct {
-	create func(key K, value V, expiration, cost uint32) Node[K, V]
+	create      func(key K, value V, expiration, cost uint32) Node[K, V]
 	fromPointer func(ptr unsafe.Pointer) Node[K, V]
 }
 

internal/core/cache.go

@@ -159,7 +159,7 @@ func (c *Cache[K, V]) Has(key K) bool {
 // Get returns the value associated with the key in this cache.
 func (c *Cache[K, V]) Get(key K) (V, bool) {
 	got, ok := c.hashmap.Get(key)
-	if !ok {
+	if !ok || !got.IsAlive() {
 		c.stats.IncMisses()
 		return zeroValue[V](), false
 	}
@@ -249,6 +249,7 @@ func (c *Cache[K, V]) set(key K, value V, expiration uint32, onlyIfAbsent bool)
 	evicted := c.hashmap.Set(n)
 	if evicted != nil {
 		// update
+		evicted.Die()
 		c.writeBuffer.Insert(task.NewUpdateTask(n, evicted))
 	} else {
 		// insert
@@ -260,23 +261,24 @@ func (c *Cache[K, V]) set(key K, value V, expiration uint32, onlyIfAbsent bool)
 
 // Delete removes the association for this key from the cache.
 func (c *Cache[K, V]) Delete(key K) {
-	deleted := c.hashmap.Delete(key)
-	if deleted != nil {
-		c.writeBuffer.Insert(task.NewDeleteTask(deleted))
-	}
+	c.afterDelete(c.hashmap.Delete(key))
 }
 
 func (c *Cache[K, V]) deleteNode(n node.Node[K, V]) {
-	deleted := c.hashmap.DeleteNode(n)
+	c.afterDelete(c.hashmap.DeleteNode(n))
+}
+
+func (c *Cache[K, V]) afterDelete(deleted node.Node[K, V]) {
 	if deleted != nil {
+		deleted.Die()
 		c.writeBuffer.Insert(task.NewDeleteTask(deleted))
 	}
 }
 
 // DeleteByFunc removes the association for this key from the cache when the given function returns true.
 func (c *Cache[K, V]) DeleteByFunc(f func(key K, value V) bool) {
 	c.hashmap.Range(func(n node.Node[K, V]) bool {
-		if n.IsExpired() {
+		if !n.IsAlive() || n.IsExpired() {
 			return true
 		}
 
@@ -305,6 +307,7 @@ func (c *Cache[K, V]) cleanup() {
 
 		for _, n := range e {
 			c.hashmap.DeleteNode(n)
+			n.Die()
 		}
 
 		expired = clearBuffer(expired)
@@ -346,14 +349,19 @@ func (c *Cache[K, V]) process() {
 			c.evictionMutex.Lock()
 
 			for _, t := range buffer {
+				n := t.Node()
 				switch {
 				case t.IsDelete():
-					c.expirePolicy.Delete(t.Node())
+					c.expirePolicy.Delete(n)
 				case t.IsAdd():
-					c.expirePolicy.Add(t.Node())
+					if n.IsAlive() {
+						c.expirePolicy.Add(n)
+					}
 				case t.IsUpdate():
 					c.expirePolicy.Delete(t.OldNode())
-					c.expirePolicy.Add(t.Node())
+					if n.IsAlive() {
+						c.expirePolicy.Add(n)
+					}
 				}
 			}
 
@@ -366,6 +374,7 @@ func (c *Cache[K, V]) process() {
 
 			for _, n := range d {
 				c.hashmap.DeleteNode(n)
+				n.Die()
 			}
 
 			buffer = clearBuffer(buffer)
@@ -379,7 +388,7 @@ func (c *Cache[K, V]) process() {
 // Iteration stops early when the given function returns false.
 func (c *Cache[K, V]) Range(f func(key K, value V) bool) {
 	c.hashmap.Range(func(n node.Node[K, V]) bool {
-		if n.IsExpired() {
+		if !n.IsAlive() || n.IsExpired() {
 			return true
 		}
 

internal/s3fifo/main.go

@@ -44,7 +44,7 @@ func (m *main[K, V]) evict(deleted []node.Node[K, V]) []node.Node[K, V] {
 	for m.cost > 0 {
 		n := m.q.pop()
 
-		if n.IsExpired() || n.Frequency() == 0 {
+		if !n.IsAlive() || n.IsExpired() || n.Frequency() == 0 {
 			n.Unmark()
 			m.cost -= n.Cost()
 			return append(deleted, n)

internal/s3fifo/policy.go

@@ -92,7 +92,7 @@ func (p *Policy[K, V]) Write(
 
 		// already deleted in map
 		if t.IsDelete() {
-			p.delete(t.Node())
+			p.delete(n)
 			continue
 		}
 
@@ -103,7 +103,9 @@ func (p *Policy[K, V]) Write(
 		}
 
 		// add
-		deleted = p.insert(deleted, n)
+		if n.IsAlive() {
+			deleted = p.insert(deleted, n)
+		}
 	}
 	return deleted
 }

internal/s3fifo/small.go

@@ -53,7 +53,7 @@ func (s *small[K, V]) evict(deleted []node.Node[K, V]) []node.Node[K, V] {
 	n := s.q.pop()
 	s.cost -= n.Cost()
 	n.Unmark()
-	if n.IsExpired() {
+	if !n.IsAlive() || n.IsExpired() {
 		return append(deleted, n)
 	}