Module subtree 

SubtreePrefetch sync types (CIP Appendix B - Protocol Selection Matrix).

Types for subtree prefetch-based synchronization, optimized for deep trees with clustered changes.

When to Use

• max_depth > 3 (deep trees)
• divergence < 20%
• Changes are clustered in subtrees

Trade-offs

Aspect	HashComparison	SubtreePrefetch
Round trips	O(depth)	O(1) per subtree
Data transfer	Minimal	May over-fetch
Best for	Scattered changes	Clustered changes

Validation

All types have is_valid() methods that should be called after deserializing from untrusted sources to prevent resource exhaustion attacks.

Structs

SubtreeData

Data for a single subtree.

SubtreePrefetchRequest

Request for subtree prefetch-based sync.

SubtreePrefetchResponse

Response containing prefetched subtrees.

Constants

DEEP_TREE_THRESHOLD

Minimum tree depth to consider SubtreePrefetch over HashComparison.

DEFAULT_SUBTREE_MAX_DEPTH

Default maximum depth for subtree prefetch.

MAX_CLUSTERED_SUBTREES

Maximum number of differing subtrees for changes to be “clustered”.

MAX_DIVERGENCE_RATIO

Maximum divergence ratio for SubtreePrefetch to be efficient.

MAX_ENTITIES_PER_SUBTREE

Maximum number of entities per subtree.

MAX_SUBTREES_PER_REQUEST

Maximum number of subtree roots in a single request.

MAX_SUBTREE_DEPTH

Maximum allowed depth for subtree traversal requests.

MAX_TOTAL_ENTITIES

Maximum total entities across all subtrees in a response.

Functions

should_use_subtree_prefetch

Compare HashComparison vs SubtreePrefetch for a given scenario.