russell@unturf.com
db29a08762
B&W print-friendly diagrams + tinkerpop-0001 + wave-3 proof sections. Squash of 94 local commits onto remote master.
1.1 KiB
1.1 KiB
| id | repo | severity | status | created |
|---|---|---|---|---|
| erlang-0001 | otp | HIGH | PATCHED | 2026-03-23 |
Defect
File: lib/stdlib/src/digraph.erl:578
Pattern: lists:member(V, Xs) in one_path/8 — used by get_path, get_cycle, get_short_path
Complexity: O(V²)
Language: Erlang
Description
one_path/8 in Erlang's stdlib digraph module tracks visited vertices using a plain list Xs and tests membership with lists:member(V, Xs). This function is the underlying implementation for get_path, get_cycle, and get_short_path. For each vertex visited during path search, the full visited list is scanned linearly, resulting in O(V²) total work for paths of length V through the graph.
Fix
Replace: lists:member(V, Xs)
With: sets:is_element(V, XsSet)
Data structure change: Xs: list() → XsSet: sets:set()
Work required
- Patch in
defects/erlang/patch/ - Unit test — asserts exact operation counts before/after (in
defects/erlang/unit/) - Integration test (in
defects/erlang/integration/) - Benchmark — before/after on V=100,200,400,800 (in
defects/erlang/bench/) - White paper section