Merkledb split node storage into value and intermediate

x/merkledb/cache.go

@@ -15,10 +15,10 @@ type onEvictCache[K comparable, V any] struct {
 	lock       sync.RWMutex
 	maxSize    int
 	fifo       linkedhashmap.LinkedHashmap[K, V]
-	onEviction func(V) error
+	onEviction func(K, V) error
 }
 
-func newOnEvictCache[K comparable, V any](maxSize int, onEviction func(V) error) onEvictCache[K, V] {
+func newOnEvictCache[K comparable, V any](maxSize int, onEviction func(K, V) error) onEvictCache[K, V] {
 	return onEvictCache[K, V]{
 		maxSize:    maxSize,
 		fifo:       linkedhashmap.New[K, V](),
@@ -55,7 +55,7 @@ func (c *onEvictCache[K, V]) Put(key K, value V) error {
 	if c.fifo.Len() > c.maxSize {
 		oldestKey, oldestVal, _ := c.fifo.Oldest()
 		c.fifo.Delete(oldestKey)
-		return c.onEviction(oldestVal)
+		return c.onEviction(oldestKey, oldestVal)
 	}
 	return nil
 }
@@ -75,12 +75,12 @@ func (c *onEvictCache[K, V]) Flush() error {
 	// modifies [c.fifo], which violates the iterator's invariant.
 	var errs wrappers.Errs
 	for {
-		_, node, exists := c.removeOldest()
+		key, value, exists := c.removeOldest()
 		if !exists {
 			// The cache is empty.
 			return errs.Err
 		}
 
-		errs.Add(c.onEviction(node))
+		errs.Add(c.onEviction(key, value))
 	}
 }

x/merkledb/cache_test.go

@@ -16,7 +16,7 @@ func TestNewOnEvictCache(t *testing.T) {
 	require := require.New(t)
 
 	called := false
-	onEviction := func(int) error {
+	onEviction := func(int, int) error {
 		called = true
 		return nil
 	}
@@ -28,7 +28,7 @@ func TestNewOnEvictCache(t *testing.T) {
 	require.Zero(cache.fifo.Len())
 	// Can't test function equality directly so do this
 	// to make sure it was assigned correctly
-	require.NoError(cache.onEviction(0))
+	require.NoError(cache.onEviction(0, 0))
 	require.True(called)
 }
 
@@ -39,7 +39,7 @@ func TestOnEvictCacheNoOnEvictionError(t *testing.T) {
 	require := require.New(t)
 
 	evicted := []int{}
-	onEviction := func(n int) error {
+	onEviction := func(key int, n int) error {
 		evicted = append(evicted, n)
 		return nil
 	}
@@ -156,7 +156,7 @@ func TestOnEvictCacheOnEvictionError(t *testing.T) {
 	var (
 		require    = require.New(t)
 		evicted    = []int{}
-		onEviction = func(n int) error {
+		onEviction = func(key, n int) error {
 			// Evicting even keys errors
 			evicted = append(evicted, n)
 			if n%2 == 0 {

x/merkledb/codec.go

@@ -106,6 +106,7 @@ func (c *codecImpl) encodeDBNode(n *dbNode) []byte {
 			path := entry.compressedPath.Serialize()
 			c.encodeSerializedPath(buf, path)
 			_, _ = buf.Write(entry.id[:])
+			c.encodeBool(buf, entry.hasValue)
 		}
 	}
 	return buf.Bytes()
@@ -179,9 +180,14 @@ func (c *codecImpl) decodeDBNode(b []byte, n *dbNode) error {
 		if err != nil {
 			return err
 		}
+		hasValue, err := c.decodeBool(src)
+		if err != nil {
+			return err
+		}
 		n.children[byte(index)] = child{
 			compressedPath: compressedPath.deserialize(),
 			id:             childID,
+			hasValue:       hasValue,
 		}
 	}
 	if src.Len() != 0 {