whisper: message filtering optimized

whisper/whisperv6/filter.go

@@ -35,6 +35,7 @@ type Filter struct {
 	PoW        float64           // Proof of work as described in the Whisper spec
 	AllowP2P   bool              // Indicates whether this filter is interested in direct peer-to-peer messages
 	SymKeyHash common.Hash       // The Keccak256Hash of the symmetric key, needed for optimization
+	id         string            // unique identifier
 
 	Messages map[common.Hash]*ReceivedMessage
 	mutex    sync.RWMutex
@@ -43,6 +44,9 @@ type Filter struct {
 // Filters represents a collection of filters
 type Filters struct {
 	watchers         map[string]*Filter
+	topicMatcher     map[TopicType]map[*Filter]struct{}
+	allTopicsMatcher map[*Filter]struct{}
+
 	whisper *Whisper
 	mutex   sync.RWMutex
 }
@@ -51,6 +55,8 @@ type Filters struct {
 func NewFilters(w *Whisper) *Filters {
 	return &Filters{
 		watchers:         make(map[string]*Filter),
+		topicMatcher:     make(map[TopicType]map[*Filter]struct{}),
+		allTopicsMatcher: make(map[*Filter]struct{}),
 		whisper:          w,
 	}
 }
@@ -81,7 +87,9 @@ func (fs *Filters) Install(watcher *Filter) (string, error) {
 		watcher.SymKeyHash = crypto.Keccak256Hash(watcher.KeySym)
 	}
 
+	watcher.id = id
 	fs.watchers[id] = watcher
+	fs.addTopicMatcher(watcher)
 	return id, err
 }
 
@@ -91,12 +99,49 @@ func (fs *Filters) Uninstall(id string) bool {
 	fs.mutex.Lock()
 	defer fs.mutex.Unlock()
 	if fs.watchers[id] != nil {
+		fs.removeFromTopicMatchers(fs.watchers[id])
 		delete(fs.watchers, id)
 		return true
 	}
 	return false
 }
 
+// addTopicMatcher adds a filter to the topic matchers
+func (fs *Filters) addTopicMatcher(watcher *Filter) {
+	if len(watcher.Topics) == 0 {
+		fs.allTopicsMatcher[watcher] = struct{}{}
+	} else {
+		for _, t := range watcher.Topics {
+			topic := BytesToTopic(t)
+			if fs.topicMatcher[topic] == nil {
+				fs.topicMatcher[topic] = make(map[*Filter]struct{})
+			}
+			fs.topicMatcher[topic][watcher] = struct{}{}
+		}
+	}
+}
+
+// removeFromTopicMatchers removes a filter from the topic matchers
+func (fs *Filters) removeFromTopicMatchers(watcher *Filter) {
+	delete(fs.allTopicsMatcher, watcher)
+	for _, topic := range watcher.Topics {
+		delete(fs.topicMatcher[BytesToTopic(topic)], watcher)
+	}
+}
+
+// getWatchersByTopic returns a slice containing the filters that
+// match a specific topic
+func (fs *Filters) getWatchersByTopic(topic TopicType) []*Filter {
+	res := make([]*Filter, 0, len(fs.allTopicsMatcher))
+	for watcher, _ := range fs.allTopicsMatcher {
+		res = append(res, watcher)
+	}
+	for watcher, _ := range fs.topicMatcher[topic] {
+		res = append(res, watcher)
+	}
+	return res
+}
+
 // Get returns a filter from the collection with a specific ID
 func (fs *Filters) Get(id string) *Filter {
 	fs.mutex.RLock()
@@ -112,11 +157,10 @@ func (fs *Filters) NotifyWatchers(env *Envelope, p2pMessage bool) {
 	fs.mutex.RLock()
 	defer fs.mutex.RUnlock()
 
-	i := -1 // only used for logging info
-	for _, watcher := range fs.watchers {
-		i++
+	candidates := fs.getWatchersByTopic(env.Topic)
+	for _, watcher := range candidates {
 		if p2pMessage && !watcher.AllowP2P {
-			log.Trace(fmt.Sprintf("msg [%x], filter [%d]: p2p messages are not allowed", env.Hash(), i))
+			log.Trace(fmt.Sprintf("msg [%x], filter [%s]: p2p messages are not allowed", env.Hash(), watcher.id))
 			continue
 		}
 
@@ -128,10 +172,10 @@ func (fs *Filters) NotifyWatchers(env *Envelope, p2pMessage bool) {
 			if match {
 				msg = env.Open(watcher)
 				if msg == nil {
-					log.Trace("processing message: failed to open", "message", env.Hash().Hex(), "filter", i)
+					log.Trace("processing message: failed to open", "message", env.Hash().Hex(), "filter", watcher.id)
 				}
 			} else {
-				log.Trace("processing message: does not match", "message", env.Hash().Hex(), "filter", i)
+				log.Trace("processing message: does not match", "message", env.Hash().Hex(), "filter", watcher.id)
 			}
 		}