[Nguyen Minh Hoang]_Create db_to_gorm.go_Week 2 #27
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NemCaBong
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| } | ||
| func generateSessionID() string { | ||
| // tạo ra 1 session ID ngẫu nhiên | ||
| return fmt.Sprintf("%d", time.Now().UnixNano()) |
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generate session id like this is not random, and may cause collision a lot, can use a hash function from user_name + timestamp, or uuid
| // HSet được sử dụng để lưu trữ một cặp khóa-giá trị trong một hash (bảng băm) của Redis | ||
| // khóa là sessionID còn "username"->field, username->value | ||
| // err := redisClient.HSet(redisClient.Context(), sessionID, "username", username, "password", password).Err() | ||
| err := redisClient.Set(redisClient.Context(), sessionID, username, 0).Err() |
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should set an expire time for this session data
| // lưu | ||
| c.JSON(http.StatusOK, gin.H{ | ||
| "message": "Login successful", | ||
| "session_id": sessionID, |
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session id is usually stored on header with field Set-Cookie but not body. Can use c.SetCookie function which provided by gin
| } | ||
| func pingHandler(c *gin.Context) { | ||
| // the sessionID will be saved as session_id | ||
| sessionID := c.Query("session_id") |
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same here, session id should be get from header
| // Check if the session ID is valid | ||
| // look up in the redis cached | ||
| // Result() sẽ trả về giá trị value với key cung cấp và err | ||
| userName, err := redisClient.Get(redisClient.Context(), sessionID).Result() |
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should generate a new context for every request something like context.WithTimeout(context.Background(), time.MilliSecond*50)
| } | ||
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| // đặt khóa để chỉ 1 người /ping được 1 lúc mà thôi | ||
| mutex.Lock() |
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what happen if we have more than 2 instances, then there're 2 people can ping at a same time if you use this mutext. What we suppose to do here is a distributed lock implemented by redis
| // giảm số redis query | ||
| // lru.Cache.Get() sẽ lấy khóa callCountKey có dạng call_count:<userName | ||
| // rồi trả về value của key đó nếu không trả về nil | ||
| callCount, _ := lruCache.Get(callCountKey) |
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same here, we suppose to do here is using redis to store call count, because if you use this lruCache, it will only store in local memory, if we have more than 2 instances, the total count is wrong
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