feat(cache):增加向redis保存用户会话的函数。

cache/session.go

@@ -0,0 +1,42 @@
+package cache
+
+import (
+	"electricity_bill_calc/global"
+	"electricity_bill_calc/model"
+	"fmt"
+	"time"
+
+	"github.com/go-redis/redis/v8"
+	"github.com/vmihailenco/msgpack/v5"
+)
+
+func CacheSession(session *model.Session) error {
+	key := fmt.Sprintf("session:%s", session.Token)
+	serializedSession, err := msgpack.Marshal(session)
+
+	if err != nil {
+		return err
+	}
+
+	validRemains := time.Until(session.ExpiresAt)
+	cmd := global.RedisConn.SetNX(global.Ctx, key, serializedSession, validRemains)
+	return cmd.Err()
+}
+
+func RetreiveSession(token string) (*model.Session, error) {
+	key := fmt.Sprintf("session:%s", token)
+	result, err := global.RedisConn.Get(global.Ctx, key).Result()
+	if err != nil {
+		if err == redis.Nil {
+			return nil, nil
+		} else {
+			return nil, err
+		}
+	}
+	session := &model.Session{}
+	err = msgpack.Unmarshal([]byte(result), session)
+	if err != nil {
+		return nil, err
+	}
+	return session, nil
+}