| // Copyright 2022 The LUCI Authors. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| package listener |
| |
| import ( |
| "context" |
| "fmt" |
| "sync" |
| "time" |
| |
| "cloud.google.com/go/pubsub" |
| |
| "go.chromium.org/luci/common/clock" |
| "go.chromium.org/luci/common/data/stringset" |
| "go.chromium.org/luci/common/errors" |
| "go.chromium.org/luci/common/logging" |
| "go.chromium.org/luci/config" |
| |
| "go.chromium.org/luci/cv/internal/changelist" |
| "go.chromium.org/luci/cv/internal/configs/srvcfg" |
| listenerpb "go.chromium.org/luci/cv/settings/listener" |
| ) |
| |
| const ( |
| // reloadInterval defines how often Listener evaluates the latest copy of |
| // the subscription settings and adjusts subscribers as necessary. |
| reloadInterval = time.Minute |
| ) |
| |
| // This interface encapsulate the communication with changelist.Updater. |
| type scheduler interface { |
| Schedule(context.Context, *changelist.UpdateCLTask) error |
| } |
| |
| // Listener fetches and process messages from the subscriptions configured |
| // in the settings. |
| type Listener struct { |
| mu sync.Mutex |
| sbers map[string]*subscriber |
| sch scheduler |
| psClient *pubsub.Client |
| prjFinder *projectFinder |
| } |
| |
| // NewListener constructs a Listener. |
| func NewListener(psClient *pubsub.Client, sch scheduler) *Listener { |
| return &Listener{ |
| sbers: make(map[string]*subscriber), |
| sch: sch, |
| psClient: psClient, |
| prjFinder: &projectFinder{}, |
| } |
| } |
| |
| // Run continuously evaluates the listener settings and manages workers |
| // for each of the subscriptions configured. |
| func (l *Listener) Run(ctx context.Context) { |
| var prevHash string |
| |
| for { |
| meta := &config.Meta{} |
| lcfg, err := srvcfg.GetListenerConfig(ctx, meta) |
| switch { |
| case err != nil: |
| logging.Errorf(ctx, "GetListenerConfig: %s", err) |
| case meta.ContentHash != prevHash: |
| // new config? |
| logging.Infof(ctx, "Listener.Run: new settings.cfg found: %s", meta.ContentHash) |
| if err := l.reload(ctx, lcfg); err != nil { |
| logging.Errorf(ctx, "Listener.reload: %s", err.Error()) |
| } |
| } |
| |
| select { |
| case <-ctx.Done(): |
| logging.Infof(ctx, "Listener.Run: the context is done; exiting") |
| return |
| case <-clock.After(ctx, reloadInterval): |
| } |
| } |
| } |
| |
| func (l *Listener) reload(ctx context.Context, s *listenerpb.Settings) error { |
| if err := l.prjFinder.reload(s); err != nil { |
| return errors.Annotate(err, "projectFinder.reload").Err() |
| } |
| if err := l.reloadSubscribers(ctx, s.GetGerritSubscriptions()); err != nil { |
| return errors.Annotate(err, "reloadSubscribers").Err() |
| } |
| return nil |
| } |
| |
| // reloadSubscribers reloads the subscribers as configured in the settings. |
| // |
| // It will |
| // - start a subscriber for new subscription settings. |
| // - stop the subscriber for removed subscription settings. |
| // - restart the subscriber if it is found dead. |
| func (l *Listener) reloadSubscribers(ctx context.Context, settings []*listenerpb.Settings_GerritSubscription) error { |
| var wg sync.WaitGroup |
| activeHosts := stringset.New(len(settings)) |
| startErrs := errors.NewLazyMultiError(len(settings)) |
| l.mu.Lock() |
| defer l.mu.Unlock() |
| |
| for i, setting := range settings { |
| i, setting := i, setting |
| host := setting.GetHost() |
| if !activeHosts.Add(host) { |
| panic(fmt.Errorf("duplicate host %q; there must be a bug in the cfg validation", host)) |
| } |
| |
| switch sber, ok := l.sbers[host]; { |
| case ctx.Err() != nil: |
| return ctx.Err() |
| |
| case !ok: |
| sber = newGerritSubscriber(l.psClient, l.sch, l.prjFinder, setting) |
| logging.Infof(ctx, "listener.reload: new host %q found; starting a subscriber", host) |
| if err := sber.start(ctx); err != nil { |
| startErrs.Assign(i, err) |
| } |
| l.sbers[host] = sber |
| |
| // If the setting changed, stop the existing subscriber and |
| // start a new one. |
| case !sameGerritSubscriberSettings(ctx, sber, setting): |
| logging.Infof(ctx, "listener.reload: subscriber setting changed for host %q", host) |
| wg.Add(1) |
| newSber := newGerritSubscriber(l.psClient, l.sch, l.prjFinder, setting) |
| l.sbers[host] = newSber |
| |
| go func() { |
| defer wg.Done() |
| sber.stop(ctx) |
| if err := newSber.start(ctx); err != nil { |
| startErrs.Assign(i, err) |
| } |
| }() |
| |
| // did the subscriber stop or fail to start? |
| case sber.isStopped(): |
| logging.Warningf(ctx, "listener.reload: subscriber for host %q was found dead; restarting", host) |
| if err := sber.start(ctx); err != nil { |
| startErrs.Assign(i, err) |
| } |
| } |
| } |
| |
| // stop the Gerrit subscribers for the removed Gerrit hosts. |
| for host, sber := range l.sbers { |
| if !activeHosts.Has(host) { |
| logging.Infof(ctx, "listener.reload: host %q was removed from the settings", host) |
| delete(l.sbers, host) |
| |
| sber := sber |
| wg.Add(1) |
| go func() { |
| defer wg.Done() |
| sber.stop(ctx) |
| }() |
| } |
| } |
| wg.Wait() |
| return startErrs.Get() |
| } |
| |
| // getSubscriber returns the subscriber for a given host. |
| // |
| // Returns nil if there isn't any. |
| func (l *Listener) getSubscriber(host string) *subscriber { |
| l.mu.Lock() |
| defer l.mu.Unlock() |
| return l.sbers[host] |
| } |