1.10.2 - #250
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…tion Replace O(n) linear search through NAT table with O(1) reverse lookup map for reply packet NAT translation. Changes: - Add reverseConnKey type for reverse NAT lookups - Add reverseNatTable map to ProxyHandler for O(1) lookups - Populate both forward and reverse maps when creating NAT entries - Replace iteration-based reverse lookup with direct map access Performance: - O(n) → O(1) complexity for reverse NAT lookups - Eliminates lock-held iteration on every reply packet - Removes string comparisons from hot path - Expected 10-50x improvement for reverse NAT lookups This addresses Critical #1 from performance analysis where reply path was walking the entire NAT table to find original mapping.
Replace O(n) map-based subnet rule matching with BART (Binary Aggregated Range Tree) using Supernets() for O(log n) prefix matching. Performance improvements: - 1.3x faster for large rule sets (1000+ rules) - 39x faster for no-match cases (critical for firewall/security) - 1.9x faster for adding rules - Better scaling characteristics Trade-offs: - Small rule sets (10-100): 1.2-1.4x slower for matches (20-30ns overhead) - Large rule sets (1000+): 1.3x faster - No-match: 39x faster (original checks all rules, BART uses O(log n) tree lookup) The no-match performance is particularly important for security/firewall scenarios where many packets are rejected. BART can determine 'no match' in ~7 tree operations vs checking all 100+ rules. Dependencies: - Added: github.com/gaissmai/bart v0.26.0 Files: - netstack2/subnet_lookup.go: New BART-based implementation - netstack2/proxy.go: Removed old map-based implementation, updated to use BART
- Fix prefix canonicalization: use Masked() to handle host bits correctly (e.g., 10.0.0.5/24 and 10.0.0.0/24 are now treated as equal) - Fix empty trie cleanup: use BART's Size() method to check if trie is empty instead of relying on rules slice length, preventing stale entries - Fix go.mod: move BART from indirect to direct dependencies These fixes ensure proper bookkeeping and prevent memory leaks from empty tries hanging around after rule removal.
perf(netstack2): optimize subnet rule matching with BART
…es/newt into LaurenceJJones-optimize-reverse-nat-lookup
miloschwartz
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Mar 4, 2026
mrkhachaturov
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Jun 15, 2026
1.10.2 Former-commit-id: beaf386
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