Module leopard 

Leopard Indexing for optimized reachability queries

Implements the Leopard indexing strategy from Google Zanzibar to achieve O(1) authorization checks for pre-computed relationship paths.

How it works

Instead of traversing the relationship graph at query time, Leopard pre-computes and materializes transitive closures for frequently accessed relationships.

Example: If owner inherits viewer, and alice is an owner of doc1, the index stores both:

• (alice, owner, doc1) - direct relationship
• (alice, viewer, doc1) - computed/inherited relationship

Performance

• Reads: O(1) lookup in materialized index
• Writes: O(n) where n is the depth of inheritance chain
• Space: O(tuples × avg_inheritance_depth)

Structs

LeopardConfig

Configuration for Leopard indexing

LeopardIndex

Leopard reachability index

LeopardStats

Statistics for Leopard index

ReachabilityEntry

A materialized reachability entry