Support chat validation

chat/sign/cache.go

@@ -0,0 +1,42 @@
+package sign
+
+import (
+	"errors"
+)
+
+type SignatureCache struct {
+	signatures   [128]*Signature
+	signIndexes  map[Signature]int
+	cachedBuffer []*Signature
+}
+
+func NewSignatureCache() SignatureCache {
+	return SignatureCache{
+		signIndexes: make(map[Signature]int),
+	}
+}
+
+func (s *SignatureCache) PopOrInsert(self *Signature, lastSeen []*Signature) {
+	var tmp *Signature
+	s.cachedBuffer = s.cachedBuffer[:0] // clear buffer
+	if self != nil {
+		s.cachedBuffer = append(s.cachedBuffer, self)
+	}
+	for _, v := range lastSeen {
+		s.cachedBuffer = append(s.cachedBuffer, v)
+	}
+	for i := 0; i < len(s.cachedBuffer) && i < len(s.signatures); i++ {
+		v := s.cachedBuffer[i]
+		if i, ok := s.signIndexes[*v]; ok {
+			s.signatures[i] = nil
+		}
+		tmp, s.signatures[i] = s.signatures[i], v
+		s.signIndexes[*v] = i
+		if tmp != nil {
+			s.cachedBuffer = append(s.cachedBuffer, tmp)
+			delete(s.signIndexes, *tmp)
+		}
+	}
+}
+
+var UncachedSignature = errors.New("uncached signature")