feat: support peek multi value for query args (#684)

Co-authored-by: kinggo <[email protected]>

pkg/protocol/args.go

@@ -379,6 +379,17 @@ func (a *Args) PeekExists(key string) (string, bool) {
 	return peekArgStrExists(a.args, key)
 }
 
+// PeekAll returns all the arg values for the given key.
+func (a *Args) PeekAll(key string) [][]byte {
+	var values [][]byte
+	a.VisitAll(func(k, v []byte) {
+		if bytesconv.B2s(k) == key {
+			values = append(values, v)
+		}
+	})
+	return values
+}
+
 func visitArgs(args []argsKV, f func(k, v []byte)) {
 	for i, n := 0, len(args); i < n; i++ {
 		kv := &args[i]

pkg/protocol/args_test.go

@@ -129,3 +129,26 @@ func TestArgsVisitAll(t *testing.T) {
 	})
 	assert.DeepEqual(t, []string{"cloudwego", "hertz", "hello", "world"}, s)
 }
+
+func TestArgsPeekMulti(t *testing.T) {
+	var a Args
+	a.Add("cloudwego", "hertz")
+	a.Add("cloudwego", "kitex")
+	a.Add("cloudwego", "")
+	a.Add("hello", "world")
+
+	vv := a.PeekAll("cloudwego")
+	expectedVV := [][]byte{
+		[]byte("hertz"),
+		[]byte("kitex"),
+		[]byte(nil),
+	}
+	assert.DeepEqual(t, expectedVV, vv)
+
+	vv = a.PeekAll("aaaa")
+	assert.DeepEqual(t, 0, len(vv))
+
+	vv = a.PeekAll("hello")
+	expectedVV = [][]byte{[]byte("world")}
+	assert.DeepEqual(t, expectedVV, vv)
+}