refactor

rq/internal/update/serverchange.go

@@ -0,0 +1,106 @@
+package update
+
+import (
+	"crypto/md5"
+	"errors"
+	"fmt"
+	"io"
+	"sort"
+
+	"zero/core/hash"
+	"zero/core/jsonx"
+	"zero/rq/internal"
+)
+
+var ErrInvalidServerChange = errors.New("not a server change message")
+
+type (
+	weightedKey struct {
+		Key    string
+		Weight int
+	}
+
+	Snapshot struct {
+		Keys         []string
+		WeightedKeys []weightedKey
+	}
+
+	ServerChange struct {
+		Previous Snapshot
+		Current  Snapshot
+		Servers  []string
+	}
+)
+
+func (s Snapshot) GetCode() string {
+	keys := append([]string(nil), s.Keys...)
+	sort.Strings(keys)
+	weightedKeys := append([]weightedKey(nil), s.WeightedKeys...)
+	sort.SliceStable(weightedKeys, func(i, j int) bool {
+		return weightedKeys[i].Key < weightedKeys[j].Key
+	})
+
+	digest := md5.New()
+	for _, key := range keys {
+		io.WriteString(digest, fmt.Sprintf("%s\n", key))
+	}
+	for _, wkey := range weightedKeys {
+		io.WriteString(digest, fmt.Sprintf("%s:%d\n", wkey.Key, wkey.Weight))
+	}
+
+	return fmt.Sprintf("%x", digest.Sum(nil))
+}
+
+func (sc ServerChange) CreateCurrentHash() *hash.ConsistentHash {
+	curHash := hash.NewConsistentHash()
+
+	for _, key := range sc.Current.Keys {
+		curHash.Add(key)
+	}
+	for _, wkey := range sc.Current.WeightedKeys {
+		curHash.AddWithWeight(wkey.Key, wkey.Weight)
+	}
+
+	return curHash
+}
+
+func (sc ServerChange) CreatePrevHash() *hash.ConsistentHash {
+	prevHash := hash.NewConsistentHash()
+
+	for _, key := range sc.Previous.Keys {
+		prevHash.Add(key)
+	}
+	for _, wkey := range sc.Previous.WeightedKeys {
+		prevHash.AddWithWeight(wkey.Key, wkey.Weight)
+	}
+
+	return prevHash
+}
+
+func (sc ServerChange) GetCode() string {
+	return sc.Current.GetCode()
+}
+
+func IsServerChange(message string) bool {
+	return len(message) > 0 && message[0] == internal.ServerSensitivePrefix
+}
+
+func (sc ServerChange) Marshal() (string, error) {
+	body, err := jsonx.Marshal(sc)
+	if err != nil {
+		return "", err
+	}
+
+	return string(append([]byte{internal.ServerSensitivePrefix}, body...)), nil
+}
+
+func UnmarshalServerChange(body string) (ServerChange, error) {
+	if len(body) == 0 {
+		return ServerChange{}, ErrInvalidServerChange
+	}
+
+	var change ServerChange
+	err := jsonx.UnmarshalFromString(body[1:], &change)
+
+	return change, err
+}