Golang Event.Kv方法代碼示例

// 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)
//.........這裏部分代碼省略.........

// 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)
		}
//.........這裏部分代碼省略.........