| 1 | package activator |
| 2 | |
| 3 | import ( |
| 4 | "context" |
| 5 | "github.com/carlosframework/platform/internal/controlname" |
| 6 | ) |
| 7 | |
| 8 | // SeedExclusion is a process-local preparation fence. Only its original |
| 9 | // executor may resume it after failed cleanup; it is never a wire identity. |
| 10 | type SeedExclusion struct { |
| 11 | service *Service |
| 12 | host string |
| 13 | } |
| 14 | |
| 15 | func (a *Service) AcquireSeedExclusion(ctx context.Context, host string, prior *SeedExclusion) (*SeedExclusion, error) { |
| 16 | if a == nil || ctx == nil || !controlname.ValidHostShape(host) { |
| 17 | return nil, ErrFenceNotInstalled |
| 18 | } |
| 19 | for { |
| 20 | if err := ctx.Err(); err != nil { |
| 21 | return nil, err |
| 22 | } |
| 23 | a.mu.Lock() |
| 24 | if a.shuttingDown { |
| 25 | a.mu.Unlock() |
| 26 | return nil, ErrFenceNotInstalled |
| 27 | } |
| 28 | if prior != nil { |
| 29 | ok := prior.service == a && prior.host == host && a.seedExclusions[host] == prior && a.fences[host] == ^uint64(0) |
| 30 | a.mu.Unlock() |
| 31 | if !ok { |
| 32 | return nil, ErrFenceHeld |
| 33 | } |
| 34 | return prior, nil |
| 35 | } |
| 36 | if a.fences[host] != 0 { |
| 37 | a.mu.Unlock() |
| 38 | return nil, ErrFenceHeld |
| 39 | } |
| 40 | wait := a.tokenPreparations[host] |
| 41 | if e := a.entries[host]; e != nil { |
| 42 | if e.state == actWaking { |
| 43 | wait = e.ready |
| 44 | } |
| 45 | if e.state == actStopping { |
| 46 | wait = e.stopped |
| 47 | } |
| 48 | } |
| 49 | if wait != nil { |
| 50 | a.mu.Unlock() |
| 51 | select { |
| 52 | case <-ctx.Done(): |
| 53 | return nil, ctx.Err() |
| 54 | case <-wait: |
| 55 | continue |
| 56 | } |
| 57 | } |
| 58 | token := &SeedExclusion{service: a, host: host} |
| 59 | if a.seedExclusions == nil { |
| 60 | a.seedExclusions = map[string]*SeedExclusion{} |
| 61 | } |
| 62 | if a.fences == nil { |
| 63 | a.fences = map[string]uint64{} |
| 64 | } |
| 65 | a.seedExclusions[host] = token |
| 66 | a.fences[host] = ^uint64(0) |
| 67 | a.mu.Unlock() |
| 68 | return token, nil |
| 69 | } |
| 70 | } |
| 71 | func (t *SeedExclusion) Check(host string) error { |
| 72 | if t == nil || t.service == nil || t.host != host { |
| 73 | return ErrFenceHeld |
| 74 | } |
| 75 | a := t.service |
| 76 | a.mu.Lock() |
| 77 | defer a.mu.Unlock() |
| 78 | if a.seedExclusions[host] != t || a.fences[host] != ^uint64(0) { |
| 79 | return ErrFenceHeld |
| 80 | } |
| 81 | return nil |
| 82 | } |
| 83 | func (t *SeedExclusion) Release() error { |
| 84 | if t == nil || t.service == nil { |
| 85 | return ErrFenceHeld |
| 86 | } |
| 87 | a := t.service |
| 88 | a.mu.Lock() |
| 89 | defer a.mu.Unlock() |
| 90 | if a.seedExclusions[t.host] != t || a.fences[t.host] != ^uint64(0) { |
| 91 | return ErrFenceHeld |
| 92 | } |
| 93 | delete(a.seedExclusions, t.host) |
| 94 | delete(a.fences, t.host) |
| 95 | return nil |
| 96 | } |
| 97 | |
amadan