add some comments

filter/access_key.go

@@ -14,6 +14,8 @@ type AccessKeyPair struct {
 	Options      string `yaml:"options"   json:"options,omitempty" property:"options"`
 }
 
+// This SPI Extension support us to store our AccessKeyPair or load AccessKeyPair from other
+// storage, such as filesystem.
 type AccessKeyStorage interface {
 	GetAccessKeyPair(protocol.Invocation, *common.URL) *AccessKeyPair
 }

filter/authenticator.go

@@ -6,6 +6,10 @@ import (
 )
 
 type Authenticator interface {
+
+	// give a sign to request
 	Sign(protocol.Invocation, *common.URL) error
+
+	// verify the signature of the request is valid or not
 	Authenticate(protocol.Invocation, *common.URL) error
 }

filter/filter_impl/auth/accesskey_storage.go

@@ -8,9 +8,11 @@ import (
 	"github.com/apache/dubbo-go/protocol"
 )
 
+// The default implementation of AccesskeyStorage
 type DefaultAccesskeyStorage struct {
 }
 
+// get AccessKeyPair from url by the key "accessKeyId" and "secretAccessKey"
 func (storage *DefaultAccesskeyStorage) GetAccessKeyPair(invocation protocol.Invocation, url *common.URL) *filter.AccessKeyPair {
 	return &filter.AccessKeyPair{
 		AccessKey: url.GetParam(constant.ACCESS_KEY_ID_KEY, ""),

filter/filter_impl/auth/consumer_sign.go

@@ -12,6 +12,7 @@ import (
 	"github.com/apache/dubbo-go/protocol"
 )
 
+// This filter is working for signing the request on consumer side
 type ConsumerSignFilter struct {
 }
 

filter/filter_impl/auth/default_authenticator.go

@@ -20,6 +20,7 @@ func init() {
 	extension.SetAuthenticator(constant.DEFAULT_AUTHENTICATOR, GetDefaultAuthenticator)
 }
 
+// The default implemetation of Authenticator
 type DefaultAuthenticator struct {
 }
 

filter/filter_impl/auth/provider_auth.go

@@ -9,6 +9,7 @@ import (
 	"github.com/apache/dubbo-go/protocol"
 )
 
+// This filter is used to verify the correctness of the signature on provider side
 type ProviderAuthFilter struct {
 }
 

filter/filter_impl/auth/sign_util.go

@@ -9,6 +9,7 @@ import (
 	"strings"
 )
 
+// get a signature string with given information, such as metadata or parameters
 func Sign(metadata, key string) string {
 	return doSign([]byte(metadata), key)
 }