radixdb: add RadixDB struct and utility functions

radixdb.go

@@ -1,6 +1,8 @@
 // Package radixdb provides a persistable Radix tree implementation.
 package radixdb
 
+import "sync"
+
 // node represents an in-memory node of a Radix tree. This implementation
 // is designed to be memory-efficient by using a minimal set of fields to
 // represent each node. In a Radix tree, the node's key inherently carries
@@ -10,3 +12,28 @@ type node struct {
 	value    any     // Data associated with this node, if any.
 	children []*node // Pointers to child nodes.
 }
+
+// RadixDB represents an in-memory Radix tree, providing concurrency-safe read
+// and write APIs. It maintains a reference to the root node and tracks various
+// metadata such as the total number of nodes.
+type RadixDB struct {
+	root     *node        // Pointer to the root node.
+	numNodes uint64       // Number of nodes in the tree.
+	mu       sync.RWMutex // RWLock for concurrency management.
+}
+
+// Empty returns true if the tree is empty.
+func (rdb *RadixDB) Empty() bool {
+	rdb.mu.RLock()
+	defer rdb.mu.RUnlock()
+
+	return rdb.root == nil && rdb.numNodes == 0
+}
+
+// Len returns the number of nodes in the tree as uint64.
+func (rdb *RadixDB) Len() uint64 {
+	rdb.mu.RLock()
+	defer rdb.mu.RUnlock()
+
+	return rdb.numNodes
+}