Optimize authority_checker hot paths for transaction authorization

[heifner]

Summary

• Fast-path for single-key authorities (~37% faster): Bypasses meta_permission_map allocation and rollback overhead for the most common case (single key, no account references)
• Fast-path for threshold-1 multi-key authorities (~46% faster): Handles 1-of-N configurations (e.g. 1-of-3 active) by returning on first matching key without rollback overhead
• Binary search for key matching (up to 55% faster for large key sets): Replaces linear boost::find with std::lower_bound on the already-sorted provided_keys vector
• flat_map permission cache: Switches permission_cache_type from std::map to flat_map for better cache locality with typical small permission sets
• Short-circuit irrelevant-auth check: Skips redundant DB lookups and hierarchy walks in authorization_manager::check_authorization when declared permission name matches the minimum (the common case)
• Auth benchmark suite: New benchmark covering single-key, multi-sig, large key sets, and recursive permission resolution scenarios

Benchmark Results (Release build, 10k runs, minimum ns)

Benchmark	Before	After	Change
auth_single_key	61 ns	39 ns	-36%
auth_single_key_fail	62 ns	35 ns	-44%
auth_multisig_1of3	~79 ns	43 ns	-46%
auth_multisig_2of3	79 ns	83 ns	+5%
auth_multisig_3of5	104 ns	109 ns	+5%
auth_search_in_50_keys	272 ns	164 ns	-40%
auth_10keys_in_50_provided	853 ns	379 ns	-56%
auth_recursive_2_level	128 ns	118 ns	-8%
auth_recursive_3_level	215 ns	214 ns	~0%

Multi-sig 2-of-3/3-of-5 show a small ~5% regression from std::lower_bound's operator< vs boost::find's operator== at small N. The absolute cost increase is ~4-5ns, dwarfed by the gains on the dominant single-key and threshold-1 paths.

[Copilot]

Pull request overview

This PR optimizes hot paths in authority_checker and related authorization checks to reduce transaction authorization overhead, and adds a dedicated authorization benchmark suite to track performance changes.

Changes:

• Add fast paths for common key-only authorities and switch key matching to binary search over sorted provided_keys.
• Replace the permission cache from std::map to flat_map and adjust recursion logic to handle iterator invalidation.
• Add an auth benchmark feature with scenarios covering single-key, multisig, large key sets, and recursive resolution.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
libraries/chain/include/sysio/chain/authority_checker.hpp	Adds fast paths, binary-search key lookup, and changes permission cache to flat_map.
libraries/chain/authorization_manager.cpp	Skips irrelevant-auth hierarchy checks when declared permission already equals the minimum.
benchmark/benchmark.hpp	Declares auth_benchmarking() entry point.
benchmark/benchmark.cpp	Registers auth as a runnable benchmark feature.
benchmark/auth.cpp	Implements new authorization microbenchmarks.

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[Copilot]

assert(cache_itr != cached_permissions.end()) is used in this header without including <cassert>, which can cause compilation failures depending on include order. Also, in Release builds with NDEBUG, the assert is compiled out and cache_itr->second = ... would be undefined behavior if the lookup ever failed; prefer a non-elided check (e.g., SYS_ASSERT/SYS_THROW) or an explicit if (cache_itr == end) ... fallback, and add the proper header if you keep assert.

[heifner]

439211d