如何共享http goroutines之间的mysql连接? [英] How to share mysql connection between http goroutines?
问题描述
我是Go noob,并且找不到任何在Go中打开mysql连接然后在http处理程序中共享它的完整示例。这是我的代码到目前为止,我将如何使用我在HomeHandler中的main()中打开的db连接?
package main
$ p / p>
import(
database / sql
fmt
_github.com/go-sql-driver/mysql
github.com/gorilla/mux
log
net / http
$ b func main(){
fmt.Println(启动)
db,err:= sql.Open (mysql,root:@ / mydb?charset = utf8)
if err!= nil {
log.Fatalf(Error opening database:%v,err)
}
db.SetMaxIdleConns(100)
$ b $:= mux.NewRouter()
r.HandleFunc(/,HomeHandler)
http.Handle(/,r)
http.ListenAndServe(:8080,nil)
}
func HomeHandler(w http。 ResponseWriter,r * http.Request){
fmt.Fprintf(w,home)
}
解决方案数据库/ sql包为您自动管理连接池。
sql.Open(..)
返回一个句柄,其中表示连接池,而不是单个连接。如果池中的所有连接都忙,database / sql包会自动打开一个新连接。
这意味着,您只需要共享db-处理并在HTTP处理程序中使用它:
package main
import(
数据库/ sql
fmt
github.com/gorilla/mux
_github.com/go-sql-driver/mysql
log
net / http
)
var db * sql.DB //在main和HTTP处理程序之间共享它的全局变量
func main (){
fmt.Println(启动)
var err错误
db,err = sql.Open(mysql,root @ unix(/ tmp /mysql.sock)/ mydb)//这并不真正打开一个新连接
如果err!= nil {
log.Fatalf(初始化数据库连接时出错:%s,错误。 Error())
}
db.SetMaxIdleConns(100)
err = db.Ping()//如果需要的话,这会打开一个连接。这确保数据库可以访问
,如果err!= nil {
log.Fatalf(打开数据库连接时出错:%s,err.Error())
}
r:= mux.NewRouter()
r.HandleFunc(/,HomeHandler)
http.Handle(/,r)
http。 ListenAndServe(:8080,nil)
}
func HomeHandler(w http.ResponseWriter,r * http.Request){
var msg string
err:扫描(& msg)
if err!= nil {
fmt.Fprintf(w,数据库错误!)
} else {
fmt.Fprintf(w,msg)
}
}
I'm a Go noob and can't find any complete examples of opening a mysql connection in Go and then sharing it among http handlers. Here is my code so far, how would I use the db connection that I opened in main() in my HomeHandler?
package main import ( "database/sql" "fmt" _ "github.com/go-sql-driver/mysql" "github.com/gorilla/mux" "log" "net/http" ) func main() { fmt.Println("starting up") db, err := sql.Open("mysql", "root:@/mydb?charset=utf8") if err != nil { log.Fatalf("Error opening database: %v", err) } db.SetMaxIdleConns(100) r := mux.NewRouter() r.HandleFunc("/", HomeHandler) http.Handle("/", r) http.ListenAndServe(":8080", nil) } func HomeHandler(w http.ResponseWriter, r *http.Request) { fmt.Fprintf(w, "home") }
解决方案The database/sql package manages the connection pooling automatically for you.
sql.Open(..)
returns a handle which represents a connection pool, not a single connection. The database/sql package automatically opens a new connection if all connections in the pool are busy.Applied to your code this means, that you just need to share the db-handle and use it in the HTTP handlers:
package main import ( "database/sql" "fmt" "github.com/gorilla/mux" _ "github.com/go-sql-driver/mysql" "log" "net/http" ) var db *sql.DB // global variable to share it between main and the HTTP handler func main() { fmt.Println("starting up") var err error db, err = sql.Open("mysql", "root@unix(/tmp/mysql.sock)/mydb") // this does not really open a new connection if err != nil { log.Fatalf("Error on initializing database connection: %s", err.Error()) } db.SetMaxIdleConns(100) err = db.Ping() // This DOES open a connection if necessary. This makes sure the database is accessible if err != nil { log.Fatalf("Error on opening database connection: %s", err.Error()) } r := mux.NewRouter() r.HandleFunc("/", HomeHandler) http.Handle("/", r) http.ListenAndServe(":8080", nil) } func HomeHandler(w http.ResponseWriter, r *http.Request) { var msg string err := db.QueryRow("SELECT msg FROM hello WHERE page=?", "home").Scan(&msg) if err != nil { fmt.Fprintf(w, "Database Error!") } else { fmt.Fprintf(w, msg) } }
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