// syncWatchers periodically syncs unsynced watchers by: Iterate all unsynced
// watchers to get the minimum revision within its range, skipping the
// watcher if its current revision is behind the compact revision of the
// store. And use this minimum revision to get all key-value pairs. Then send
// those events to watchers.
func (s *watchableStore) syncWatchers() {
s.store.mu.Lock()
defer s.store.mu.Unlock()
if len(s.unsynced) == 0 {
return
}
// in order to find key-value pairs from unsynced watchers, we need to
// find min revision index, and these revisions can be used to
// query the backend store of key-value pairs
minRev := int64(math.MaxInt64)
curRev := s.store.currentRev.main
compactionRev := s.store.compactMainRev
prefixes := make(map[string]struct{})
for _, set := range s.unsynced {
for w := range set {
k := string(w.key)
if w.cur > curRev {
panic("watcher current revision should not exceed current revision")
}
if w.cur < compactionRev {
select {
case w.ch <- WatchResponse{WatchID: w.id, CompactRevision: compactionRev}:
s.unsynced.delete(w)
default:
// retry next time
}
continue
}
if minRev >= w.cur {
minRev = w.cur
}
if w.prefix {
prefixes[k] = struct{}{}
}
}
}
minBytes, maxBytes := newRevBytes(), newRevBytes()
revToBytes(revision{main: minRev}, minBytes)
revToBytes(revision{main: curRev + 1}, maxBytes)
// UnsafeRange returns keys and values. And in boltdb, keys are revisions.
// values are actual key-value pairs in backend.
tx := s.store.b.BatchTx()
tx.Lock()
ks, vs := tx.UnsafeRange(keyBucketName, minBytes, maxBytes, 0)
evs := []storagepb.Event{}
// get the list of all events from all key-value pairs
for i, v := range vs {
var kv storagepb.KeyValue
if err := kv.Unmarshal(v); err != nil {
log.Panicf("storage: cannot unmarshal event: %v", err)
}
k := string(kv.Key)
if _, ok := s.unsynced.getSetByKey(k); !ok && !matchPrefix(k, prefixes) {
continue
}
var ev storagepb.Event
switch {
case isTombstone(ks[i]):
ev.Type = storagepb.DELETE
default:
ev.Type = storagepb.PUT
}
ev.Kv = &kv
evs = append(evs, ev)
}
tx.Unlock()
for w, es := range newWatcherToEventMap(s.unsynced, evs) {
select {
// s.store.Rev also uses Lock, so just return directly
case w.ch <- WatchResponse{WatchID: w.id, Events: es, Revision: s.store.currentRev.main}:
pendingEventsGauge.Add(float64(len(es)))
default:
// TODO: handle the full unsynced watchers.
// continue to process other watchers for now, the full ones
// will be processed next time and hopefully it will not be full.
continue
}
w.cur = curRev
s.synced.add(w)
s.unsynced.delete(w)
}
slowWatcherGauge.Set(float64(len(s.unsynced)))
}
// syncWatchers periodically syncs unsynced watchers by: Iterate all unsynced
// watchers to get the minimum revision within its range, skipping the
// watcher if its current revision is behind the compact revision of the
// store. And use this minimum revision to get all key-value pairs. Then send
// those events to watchers.
func (s *watchableStore) syncWatchers() {
s.store.mu.Lock()
defer s.store.mu.Unlock()
if len(s.unsynced) == 0 {
return
}
// in order to find key-value pairs from unsynced watchers, we need to
// find min revision index, and these revisions can be used to
// query the backend store of key-value pairs
minRev := int64(math.MaxInt64)
curRev := s.store.currentRev.main
compactionRev := s.store.compactMainRev
// TODO: change unsynced struct type same to this
keyToUnsynced := make(map[string]map[*watcher]struct{})
for w := range s.unsynced {
k := string(w.key)
if w.cur > curRev {
panic("watcher current revision should not exceed current revision")
}
if w.cur < compactionRev {
// TODO: return error compacted to that watcher instead of
// just removing it sliently from unsynced.
delete(s.unsynced, w)
continue
}
if minRev >= w.cur {
minRev = w.cur
}
if _, ok := keyToUnsynced[k]; !ok {
keyToUnsynced[k] = make(map[*watcher]struct{})
}
keyToUnsynced[k][w] = struct{}{}
}
minBytes, maxBytes := newRevBytes(), newRevBytes()
revToBytes(revision{main: minRev}, minBytes)
revToBytes(revision{main: curRev + 1}, maxBytes)
// UnsafeRange returns keys and values. And in boltdb, keys are revisions.
// values are actual key-value pairs in backend.
tx := s.store.b.BatchTx()
tx.Lock()
ks, vs := tx.UnsafeRange(keyBucketName, minBytes, maxBytes, 0)
tx.Unlock()
evs := []storagepb.Event{}
// get the list of all events from all key-value pairs
for i, v := range vs {
var kv storagepb.KeyValue
if err := kv.Unmarshal(v); err != nil {
log.Panicf("storage: cannot unmarshal event: %v", err)
}
k := string(kv.Key)
if _, ok := keyToUnsynced[k]; !ok {
continue
}
var ev storagepb.Event
switch {
case isTombstone(ks[i]):
ev.Type = storagepb.DELETE
default:
ev.Type = storagepb.PUT
}
ev.Kv = &kv
evs = append(evs, ev)
}
for w, es := range newWatcherToEventMap(keyToUnsynced, evs) {
wr := WatchResponse{WatchID: w.id, Events: es}
select {
case w.ch <- wr:
pendingEventsGauge.Add(float64(len(es)))
default:
// TODO: handle the full unsynced watchers.
// continue to process other watchers for now, the full ones
// will be processed next time and hopefully it will not be full.
continue
}
k := string(w.key)
if err := unsafeAddWatcher(&s.synced, k, w); err != nil {
log.Panicf("error unsafeAddWatcher (%v) for key %s", err, k)
}
delete(s.unsynced, w)
}
slowWatcherGauge.Set(float64(len(s.unsynced)))
}