[audit][quality] HttpTransact.cc is a 9,430-line monolith with a 499-line core function

Severity: medium · Category: quality
Location: src/proxy/http/HttpTransact.cc:4495

What's wrong

HttpTransact.cc is the largest file in the tree (9,430 lines). handle_cache_operation_on_forward_server_response() alone is 499 lines of nested switch/if logic mutating State in place; client_result_stat() is 318 lines, HandleCacheOpenReadHit() 232, what_is_document_freshness() 206. The function-header comment blocks are empty ('Description:\n// Details :' with nothing filled in), so the only documentation of this cache-correctness-critical logic is the code itself. This concentration makes cache-behavior changes high-risk and reviews ineffective.

Evidence

// Name       : handle_cache_operation_on_forward_server_response
// Description:
//
// Details    :
//
void
HttpTransact::handle_cache_operation_on_forward_server_response(State *s)

Suggested fix

Incrementally extract per-status-code handlers (304, 5xx, 2xx) from handle_cache_operation_on_forward_server_response into named helpers with unit tests, and split HttpTransact.cc along its existing sections (cache decision, freshness, stats, response building) into separate translation units.

Filed from an automated multi-lens codebase audit. Full report: CODEBASE_AUDIT.md / audit-report.html on branch claude/codebase-audit-review-9nw7vz.

Start with src/proxy/http/HttpTransact.cc:4495 and read handle_cache_operation_on_forward_server_response(), then review the related cache decision, freshness, stats, and response-building sections. The suggested scope is to extract 304, 5xx, and 2xx handlers with unit tests and split the existing sections into translation units; done means those changes are covered by tests without changing cache behavior.