Remove four private single-impl interfaces (usbEventListener,
darwinUSBHostDeviceWatch, darwinServerDataDevice, darwinEndpointStateMachine)
and both function-table DI seams (usbipOps, darwinServerOps); production calls
the underlying functions directly. Inline ~25 single-call helpers and fuse
subordinate routines into their sole caller. Collapse single-field helper
structs into their underlying types. Fold server_linux.go/server_darwin.go
into host_linux.go/host_darwin.go.
Delete change-detector tests per .claude/rules/code-test.md: parse round-trip,
mirror, input-validation, and builder-property suites that never exercised
real syscalls, network, or cgo. Six test files removed; linux_test.go slimmed
to three real-system tests; darwin_integration_test.go retains the six
real-cgo tests. Surviving suite: 16 tests that all exercise real OS APIs or
spawn the official Linux usbip server.
Net: -5100 LoC (~37% of the package).
The ExportHost.Reconcile changed bool is computed by both Linux and
Darwin implementations but discarded at the only call site
(reconcileAndBroadcast); the ledger already detects change in
BroadcastIfChanged. linuxImportHost.trackPort had a dead add=true
branch — all callers passed false. darwinExport.Snapshot was setting
StatusReason to the same string as State (tautological). LeaseCheck
for stale captures returned the State name as the reason.
Also trim narrative comments in export_ledger.go that referenced
refactor history or the deleted lease.go file, inline the trivial
checkAvailableUnderLock helper at its only caller, and replace
cloneIsoPackets with slices.Clone.
ServerService used to own three mutexes coordinating six pieces of
mutable state (exports, busy, controlState, controlSeq, controlSubs,
LeaseManager). The lock-ordering rule that fixed the import/attach
race in 0c892411a lived only as a comment. Two-mutex (fast/slow)
ledger absorbs all of it; the two mutexes are never held
simultaneously, so the ordering rule becomes a property of the type
instead of a discipline callers must observe. TryReserveForImport
closes the window where two concurrent OpReqImports could both pass
the busy check before either marked busy.
Collapse ServerService and ClientService to one definition each by
hiding Linux vs Darwin behind ExportHost, ImportHost, and Export
seams. Along the way, extract three state machines that previously
lived as scattered fields on the service structs:
- LeaseManager owns its own mutex and closes the
availability-vs-insert TOCTOU by checking export busy inside Issue
under the same lock as the insert.
- DataSession gives the three per-import data-plane implementations
(Linux kernel handoff, Darwin server data session, Darwin virtual
controller) a uniform Done/Err/Close interface.
- clientAssignment encapsulates the matched/import-all target state
and exposes ApplyMatched/ApplyAll diffs to ClientService, which
keeps worker goroutine lifecycle.
Service busy tracking moves off the per-platform serverExport struct
onto ServerService.busy, since it follows the lease/import lifecycle
rather than physical claim/release. linux_test.go is migrated to
construct ServerService and ClientService through the new host
interfaces.
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