Backport of adding custom hash for all structs of compiled discovery chain into release/1.22.x#23418
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panman90 merged 3 commits intoApr 16, 2026
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Backport
This PR is auto-generated from #23393 to be assessed for backporting due to the inclusion of the label backport/1.22.
The below text is copied from the body of the original PR.
Description
This PR removes the use of hashstructure_v2 ([github.com/mitchellh/hashstructure/v2] from compiled discovery chain hashing and replaces it with explicit custom hash implementations.
Instead of relying on generic reflective hashing, compiled discovery chain types now implement targeted appendHash logic that hashes each relevant field directly. This makes the hashing behavior more explicit, deterministic, and easier to reason about for performance-sensitive discovery-chain code.
The change includes custom hashing for [CompiledDiscoveryChain] and related nested types, with deterministic handling for:
Testing & Reproduction steps
Added/updated tests in respective test files to validate behaviour:
Performance validation
Captured pprof before vs after this change with 4000 watches on one service.
Comparison shows reduced time spent in hashing-related work on the compiled chain path, with corresponding CPU improvement in that scenario. Results are shared separately.
Links
PR Checklist
PCI review checklist
I have documented a clear reason for, and description of, the change I am making.
If applicable, I've documented a plan to revert these changes if they require more than reverting the pull request.
If applicable, I've documented the impact of any changes to security controls.
Examples of changes to security controls include using new access control methods, adding or removing logging pipelines, etc.
Overview of commits