improve performance on domain matcher

common/strmatcher/domain_matcher.go

@@ -51,22 +51,38 @@ func (g *DomainMatcherGroup) addMatcher(m domainMatcher, value uint32) {
 }
 
 func (g *DomainMatcherGroup) Match(domain string) uint32 {
+	if len(domain) == 0 {
+		return 0
+	}
+
 	current := g.root
 	if current == nil {
 		return 0
 	}
 
-	parts := breakDomain(domain)
-	for i := len(parts) - 1; i >= 0; i-- {
-		part := parts[i]
-		if current.sub == nil {
+	nextPart := func(idx int) int {
+		for i := idx - 1; i >= 0; i-- {
+			if domain[i] == '.' {
+				return i
+			}
+		}
+		return -1
+	}
+
+	idx := len(domain)
+	for {
+		if idx == -1 || current.sub == nil {
 			break
 		}
+
+		nidx := nextPart(idx)
+		part := domain[nidx+1 : idx]
 		next := current.sub[part]
 		if next == nil {
 			break
 		}
 		current = next
+		idx = nidx
 	}
 	return current.value
 }

common/strmatcher/domain_matcher_test.go

@@ -34,6 +34,22 @@ func TestDomainMatcherGroup(t *testing.T) {
 			Domain: "c.a.b.com",
 			Result: 4,
 		},
+		{
+			Domain: "c.a..b.com",
+			Result: 0,
+		},
+		{
+			Domain: ".com",
+			Result: 0,
+		},
+		{
+			Domain: "com",
+			Result: 0,
+		},
+		{
+			Domain: "",
+			Result: 0,
+		},
 	}
 
 	for _, testCase := range testCases {