| 1 | package skillwatch |
| 2 | |
| 3 | import ( |
| 4 | "errors" |
| 5 | "io" |
| 6 | ) |
| 7 | |
| 8 | // errHelperStopped reports a helper backend that cannot serve registrations: |
| 9 | // process dead and out of restart budget, or never started. |
| 10 | var errHelperStopped = errors.New("watch helper stopped") |
| 11 | |
| 12 | // helperProcess is the minimal process handle the helper client needs; it |
| 13 | // exists so tests can inject a re-exec without depending on os/exec here. |
| 14 | type helperProcess interface { |
| 15 | Stdin() io.Writer |
| 16 | Stdout() io.Reader |
| 17 | Wait() error |
| 18 | Kill() error |
| 19 | } |
| 20 | |
| 21 | // backend abstracts the physical watch mechanism. register may block (the |
| 22 | // helper path waits for the pipe round trip), so the service always calls it |
| 23 | // from its own goroutine; cancel is fire-and-forget and close is terminal. |
| 24 | type backend interface { |
| 25 | register(id, rootGen uint64, root string, dirs []string) error |
| 26 | cancel(id uint64) |
| 27 | close() error |
| 28 | physicalWatches() uint64 |
| 29 | } |
| 30 | |
| 31 | // errScanOnly reports a service that was asked for no physical watches. |
| 32 | var errScanOnly = errors.New("scan-only service has no physical watches") |
| 33 | |
| 34 | // scanOnlyBackend refuses every registration, which is how the service already |
| 35 | // handles a backend it cannot use: the root degrades to backoff scanning and |
| 36 | // the store keeps working from its scans. Options.ScanOnly selects it so a |
| 37 | // caller can hold a real, closable service without a helper process. |
| 38 | type scanOnlyBackend struct{} |
| 39 | |
| 40 | func (scanOnlyBackend) register(uint64, uint64, string, []string) error { return errScanOnly } |
| 41 | func (scanOnlyBackend) cancel(uint64) {} |
| 42 | func (scanOnlyBackend) close() error { return nil } |
| 43 | func (scanOnlyBackend) physicalWatches() uint64 { return 0 } |
| 44 |