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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,158 @@ | ||
| package pubsub | ||
|
|
||
| import ( | ||
| "context" | ||
| "fmt" | ||
| "time" | ||
|
|
||
| "github.com/TBD54566975/ftl/backend/controller/dal" | ||
| "github.com/TBD54566975/ftl/internal/log" | ||
| "github.com/TBD54566975/ftl/internal/model" | ||
| "github.com/TBD54566975/ftl/internal/slices" | ||
| "github.com/alecthomas/atomic" | ||
| "github.com/serialx/hashring" | ||
| ) | ||
|
|
||
| const ( | ||
| controllersPerSubscription = 2 | ||
| ) | ||
|
|
||
| type Manager struct { | ||
| key model.ControllerKey | ||
|
|
||
| // TODO: swap out DAL for a smaller interface once we know what funcs we want | ||
| dal *dal.DAL | ||
| hashRingState atomic.Value[*hashRingState] | ||
| } | ||
|
|
||
| type hashRingState struct { | ||
| hashRing *hashring.HashRing | ||
| controllers []dal.Controller | ||
| idx int | ||
| } | ||
|
|
||
| func New(ctx context.Context, key model.ControllerKey, dal *dal.DAL) *Manager { | ||
| m := &Manager{ | ||
| key: key, | ||
| dal: dal, | ||
| } | ||
|
|
||
| go m.watchForUpdates(ctx) | ||
| return m | ||
| } | ||
|
|
||
| func (m *Manager) HandleTopicNotification() { | ||
|
|
||
| } | ||
|
|
||
| func (m *Manager) HandleEventNotification() { | ||
|
|
||
| } | ||
|
|
||
| // UpdatedControllerList synchronises the hash ring with the active controllers. | ||
| func (m *Manager) UpdatedControllerList(ctx context.Context, controllers []dal.Controller) { | ||
| logger := log.FromContext(ctx).Scope("cron") | ||
| controllerIdx := -1 | ||
| for idx, controller := range controllers { | ||
| if controller.Key.String() == m.key.String() { | ||
| controllerIdx = idx | ||
| break | ||
| } | ||
| } | ||
| if controllerIdx == -1 { | ||
| logger.Tracef("controller %q not found in list of controllers", m.key) | ||
| } | ||
|
|
||
| oldState := m.hashRingState.Load() | ||
| if oldState != nil && len(oldState.controllers) == len(controllers) { | ||
| hasChanged := false | ||
| for idx, new := range controllers { | ||
| old := oldState.controllers[idx] | ||
| if new.Key.String() != old.Key.String() { | ||
| hasChanged = true | ||
| break | ||
| } | ||
| } | ||
| if !hasChanged { | ||
| return | ||
| } | ||
| } | ||
|
|
||
| hashRing := hashring.New(slices.Map(controllers, func(c dal.Controller) string { return c.Key.String() })) | ||
| m.hashRingState.Store(&hashRingState{ | ||
| hashRing: hashRing, | ||
| controllers: controllers, | ||
| idx: controllerIdx, | ||
| }) | ||
| } | ||
|
|
||
| // isResponsibleForSubscription indicates whether a this service should be responsible for attempting jobs, | ||
| // or if enough other controllers will handle it. This allows us to spread the job load across controllers. | ||
| func (m *Manager) isResponsibleForSubscription(subscription model.Subscription) bool { | ||
| hashringState := m.hashRingState.Load() | ||
| if hashringState == nil { | ||
| return true | ||
| } | ||
|
|
||
| initialKey, ok := hashringState.hashRing.GetNode(subscription.Key.String()) | ||
| if !ok { | ||
| return true | ||
| } | ||
|
|
||
| initialIdx := -1 | ||
| for idx, controller := range hashringState.controllers { | ||
| if controller.Key.String() == initialKey { | ||
| initialIdx = idx | ||
| break | ||
| } | ||
| } | ||
| if initialIdx == -1 { | ||
| return true | ||
| } | ||
|
|
||
| if initialIdx+controllersPerSubscription > len(hashringState.controllers) { | ||
| // wraps around | ||
| return hashringState.idx >= initialIdx || hashringState.idx < (initialIdx+controllersPerSubscription)-len(hashringState.controllers) | ||
| } | ||
| return hashringState.idx >= initialIdx && hashringState.idx < initialIdx+controllersPerSubscription | ||
| } | ||
|
|
||
| func (m *Manager) watchForUpdates(ctx context.Context) { | ||
| logger := log.FromContext(ctx).Scope("pubsub") | ||
|
|
||
| // TODO: handle events here. Currently a demo implementation | ||
| for { | ||
| select { | ||
| case <-ctx.Done(): | ||
| return | ||
| case <-time.After(time.Second * 3): | ||
| if err := m.progressSubscriptions(ctx); err != nil { | ||
| logger.Errorf(err, "failed to progress subscriptions") | ||
| continue | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
|
||
| func (m *Manager) progressSubscriptions(ctx context.Context) (err error) { | ||
| subscriptions, err := m.dal.GetSubscriptionsNeedingUpdate(ctx) | ||
| if err != nil { | ||
| return fmt.Errorf("failed to get subscriptions needing update: %w", err) | ||
| } | ||
| for _, subscription := range subscriptions { | ||
| if !m.isResponsibleForSubscription(subscription) { | ||
| continue | ||
| } | ||
| logger := log.FromContext(ctx) | ||
|
|
||
| err := m.dal.ProgressSubscription(ctx, subscription) | ||
| if err != nil { | ||
| logger.Errorf(err, "failed to progress subscription") | ||
| } | ||
| } | ||
| return nil | ||
| } | ||
|
|
||
| func (m *Manager) OnCallCompletion(ctx context.Context, tx *dal.Tx, origin dal.AsyncOriginPubSub, failed bool) error { | ||
| return m.dal.CompleteEventForSubscription(ctx, origin.Subscription.Module, origin.Subscription.Name) | ||
| } |
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