# golang Gorm orm & org sqllite # install sqlite3 ``` go get -u github.com/mattn/go-sqlite3 http://tw.gitbook.net/sqlite/sqlite_create_database.html ``` # create sqlite3 database ```sql= CREATE TABLE `userinfo` ( `uid` INTEGER PRIMARY KEY AUTOINCREMENT, `username` VARCHAR(64) NULL, `department` VARCHAR(64) NULL, `created` DATE NULL ); CREATE TABLE `userdetail` ( `uid` INT(10) NULL, `intro` TEXT NULL, `profile` TEXT NULL, PRIMARY KEY (`uid`) ); ``` ![](https://i.imgur.com/XqCUkvO.png) ```go= func main() { http.HandleFunc("/endpoint-2", handler2) } func handler2(w http.ResponseWriter, r *http.Request) { b, err := ioutil.ReadAll(r.Body) if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError) return } fmt.Println("all nowgoroutine :", runtime.NumGoroutine()) go func() { // Block until there are fewer than cap(smallPool) hard-work // goroutines running. smallPool <- struct{}{} defer func() { <-smallPool }() // Let everyone that we are done fmt.Println("working!") time.Sleep(5 * time.Second) fmt.Println("work done") processImage(b) }() // w.WriteHeader(http.StatusAccepted) a += 1 // time.Sleep(2 * time.Second) if runtime.NumGoroutine() < 20 { db, err := sql.Open("sqlite3", "./foo.db") checkErr(err) rows, err := db.Query("SELECT * FROM userinfo") checkErr(err) var output string = "" for rows.Next() { var uid int var username string var department string var created time.Time err = rows.Scan(&uid, &username, &department, &created) checkErr(err) output += strconv.Itoa(uid) + "|" + username + "|" + department + "|" + created.Format("2006-01-02 15:04:05") + "\n" } w.Write([]byte(output)) w.WriteHeader(http.StatusAccepted) db.Close() } else { // w.Write([]byte("pleass wait" + strconv.Itoa(a))) w.WriteHeader(http.StatusNotFound) return // http.ErrUseLastResponse } } ``` # orm https://blog.csdn.net/cnwyt/article/details/118904882 ``` go get -u gorm.io/gorm go get -u gorm.io/driver/sqlite ``` ```go= func main (){ db, err := gorm.Open(sqlite.Open("test.db"), &gorm.Config{}) if err != nil { panic("failed to connect database") } // Migrate the schema db.AutoMigrate(&Product{}) // 插入內容 db.Create(&Product{Title: "新款手機", Code: "D42", Price: 1000}) db.Create(&Product{Title: "新款電腦", Code: "D43", Price: 3500}) // 讀取內容 var product Product db.First(&product, 1) // find product with integer primary key db.First(&product, "code = ?", "D42") // find product with code D42 fmt.Println("%v", product) // 更新操作： 更新單個字段 db.Model(&product).Update("Price", 2000) // 更新操作： 更新多個字段 db.Model(&product).Updates(Product{Price: 2000, Code: "F42"}) // non-zero fields db.Model(&product).Updates(map[string]interface{}{"Price": 2000, "Code": "F42"}) // 刪除操作： db.Delete(&product, 1) } ``` # sql pool & http pool https://codertw.com/%E4%BC%BA%E6%9C%8D%E5%99%A8/154458/ https://gorm.io/docs/connecting_to_the_database.html 實際上在經過查詢可以發現，預設的http 或者 sql 其實底層都是goroutines，則我們也不用像以前的程式去寫 pool 之類的我們只要全局的去宣告就好 global variable ```go= func connDB(lifeTime int, maxCon int, idle int) *gorm.DB { db, err := gorm.Open(sqlite.Open("test.db"), &gorm.Config{}) if err != nil { panic("failed to connect database") } sqlDB, err := db.DB() if err != nil { panic(err) } sqlDB.SetConnMaxLifetime(time.Duration(lifeTime) * time.Second) // 每條連線的存活時間 sqlDB.SetMaxOpenConns(maxCon) // 最大連線數 sqlDB.SetMaxIdleConns(idle) // 最大閒置連線數 return db } func init() { DBConn = connDB(1, 200, 10) // Migrate the schema DBConn.AutoMigrate(&Product{}) // 插入內容 DBConn.Create(&Product{Title: "新款手機", Code: "D42", Price: 1000}) DBConn.Create(&Product{Title: "新款電腦", Code: "D43", Price: 3500}) // 讀取內容 var product Product DBConn.First(&product, 1) // find product with integer primary key DBConn.First(&product, "code = ?", "D42") // find product with code D42 fmt.Println("%v", product) // 更新操作： 更新單個字段 DBConn.Model(&product).Update("Price", 2000) // 更新操作： 更新多個字段 DBConn.Model(&product).Updates(Product{Price: 2000, Code: "F42"}) // non-zero fields DBConn.Model(&product).Updates(map[string]interface{}{"Price": 2000, "Code": "F42"}) // 刪除操作： DBConn.Delete(&product, 1) } func main (){ http.HandleFunc("/endpoint-2", handler2) } func handler2(w http.ResponseWriter, r *http.Request) { b, err := ioutil.ReadAll(r.Body) if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError) return } fmt.Println("all nowgoroutine :", runtime.NumGoroutine()) go func() { // Block until there are fewer than cap(smallPool) hard-work // goroutines running. smallPool <- struct{}{} defer func() { <-smallPool }() // Let everyone that we are done fmt.Println("working!") time.Sleep(5 * time.Second) fmt.Println("work done") processImage(b) }() // w.WriteHeader(http.StatusAccepted) a += 1 // time.Sleep(2 * time.Second) if runtime.NumGoroutine() < 20 { // 讀取內容 var product Product DBConn.First(&product, 1) // find product with integer primary key DBConn.First(&product, "code = ?", "D42") // find product with code D42 fmt.Println("%v", product) // 更新操作： 更新單個字段 DBConn.Model(&product).Update("Price", 2000) b, err := json.Marshal(product) if err != nil { fmt.Println(err) return } w.Write([]byte(string(b))) w.WriteHeader(http.StatusAccepted) // db.Close() } else { // w.Write([]byte("pleass wait" + strconv.Itoa(a))) w.WriteHeader(http.StatusNotFound) return // http.ErrUseLastResponse } } ``` 這樣我們的grom 就可以有pool 了 https://ithelp.ithome.com.tw/articles/10238565 ![](https://i.imgur.com/6uNFCSi.png) # http request 阻塞(? 預設 golang 的 http 都是非阻塞，原因就是chrome or edge 會將當前頁面去做緩存之類的東西，所以假設同一個畫面不同分頁可能會出現順序返回，但是實際上是瀏覽器的關係，每一個request 都是 一個Goroutine則 下面畫面是同時訪問http://localhost:8080/endpoint-2 但是在同一個瀏覽器的畫面，可以看到右邊會有出現阻塞現象 ![](https://i.imgur.com/JeugCZb.png) 下面是一個edge 和 chrome 同時訪問可以看到時間戳相差不遠 ![](https://i.imgur.com/Sf1aXOq.png)
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