| 1 | package hostclaim |
| 2 | |
| 3 | import ( |
| 4 | "errors" |
| 5 | "fmt" |
| 6 | ) |
| 7 | |
| 8 | var ( |
| 9 | ErrStaleOp = errors.New("hostclaim: the claim is under a different operation") |
| 10 | ErrWrongState = errors.New("hostclaim: transition not legal from the claim's state") |
| 11 | ErrPendingChore = errors.New("hostclaim: an obligation is pending in a location this operation writes") |
| 12 | // ErrRelocationFinishing is the completion barrier's refusal: the |
| 13 | // serving op journals a completed relocation that its box has not yet |
| 14 | // discharged. It is always returned wrapped with ErrPendingChore, so a |
| 15 | // caller that only knows ErrPendingChore refuses it the same way; the |
| 16 | // move door tells the two apart for its sentence. |
| 17 | ErrRelocationFinishing = errors.New("hostclaim: a completed relocation is not yet discharged") |
| 18 | ) |
| 19 | |
| 20 | func RequireOp(id string) func(*Claim) error { |
| 21 | return func(c *Claim) error { |
| 22 | if id == "" || c.Op.ID != id { |
| 23 | return fmt.Errorf("%w: have %q, want %q", ErrStaleOp, c.Op.ID, id) |
| 24 | } |
| 25 | return nil |
| 26 | } |
| 27 | } |
| 28 | |
| 29 | // StartGuard is §4: one operation at a time, started from serving, and |
| 30 | // CC11: never over a chore in a region or box the operation will write. |
| 31 | // Region HA N13 (ruling 77): nor while a completed relocation's box has |
| 32 | // not discharged its participation (completionBarrier). fencedCompletion |
| 33 | // is completionBarrier's fencedSource (ruling 86): a box whose termination |
| 34 | // fence the caller has verified (VerifyFence, under a FenceAuthority) for |
| 35 | // this start, as a failover's start passes its source. "" when there is |
| 36 | // no verified fence: never a box the caller has not verified, and never |
| 37 | // one inferred from a missing fence. |
| 38 | func StartGuard(c *Claim, regions, boxes []string, fencedCompletion string) error { |
| 39 | if c.Holder == nil || c.Op.Kind != KindServing { |
| 40 | return fmt.Errorf("%w: kind %q", ErrWrongState, c.Op.Kind) |
| 41 | } |
| 42 | if err := completionBarrier(c, fencedCompletion); err != nil { |
| 43 | return err |
| 44 | } |
| 45 | inR, inB := set(regions), set(boxes) |
| 46 | for _, o := range c.Obligations { |
| 47 | if (o.Region != "" && inR[o.Region]) || (o.Box != "" && inB[o.Box]) { |
| 48 | return fmt.Errorf("%w: %s %s%s", ErrPendingChore, o.Kind, o.Region, o.Box) |
| 49 | } |
| 50 | } |
| 51 | return nil |
| 52 | } |
| 53 | |
| 54 | func set(xs []string) map[string]bool { |
| 55 | m := make(map[string]bool, len(xs)) |
| 56 | for _, x := range xs { |
| 57 | m[x] = true |
| 58 | } |
| 59 | return m |
| 60 | } |
| 61 | |
amadan