分布式锁：不同实现方式实践测评（上）

package dao
import (
   "database/sql"
   "fmt"
   _ "github.com/go-sql-driver/mysql"
)
type Book struct {
   Id    int64  `json:"id"`
   Name  string `json:"name"`
   Price int32  `json:"price"`
   Store int64  `json:"store"`
}
type BookDao struct {
   db     *sql.DB
   tbName string
}
func NewBookDao() *BookDao {
   mysqlDB, err := sql.Open("mysql", "root:12345@tcp(127.0.0.1:3306)/test?charset=utf8")
   if err != nil {
      fmt.Errorf("Open mysql connection is err  %s", err)
   }
   return &BookDao{db: mysqlDB, tbName: "book"}
}
func (dao *BookDao) GetBookById(id int64) (Book, error) {
   var book Book
   querySql := fmt.Sprintf("SELECT id,name,price,store FROM %s WHERE id=%d", dao.tbName, id)
   rows, err := dao.db.Query(querySql)
   if err != nil {
      fmt.Errorf("GetBookById Query err %s", err)
      return Book{}, err
   }
   if rows.Next() {
      err = rows.Scan(&book.Id, &book.Name, &book.Price, &book.Store)
      if err != nil {
         fmt.Errorf("GetBookById Scan err %s", err)
         return Book{}, err
      }
   }
   return book, nil
}
func (dao *BookDao) UpdateBookStoreById(book Book) error {
   updateSql := fmt.Sprintf("UPDATE %s SET name=?,price=?,store=? WHERE id=?", dao.tbName)
   stmt, err := dao.db.Prepare(updateSql)
   if err != nil {
      fmt.Errorf("UpdateBookStoreById Prepare err %s", err)
      return err
   }
   _, err = stmt.Exec(book.Name, book.Price, book.Store, book.Id)
   return err
}
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package service
import (
   "fmt"
   "lock_demo/dao"
)
var orderCount int32 //记录订单数量
func BuyBook(userName string, buyNum int64) string {
   bookDao := dao.NewBookDao()
   book, err := bookDao.GetBookById(1)
   if err != nil {
      fmt.Errorf("GetBookById err %s", err)
      return userName + "购买失败"
   }
   if book.Store >= buyNum && book.Store > 0 {
      book.Store = book.Store - buyNum
      err := bookDao.UpdateBookStoreById(book)
      if err != nil {
         fmt.Errorf("UpdateBookStoreById err %s", err)
         return userName + "购买失败"
      }
      orderCount += 1
      fmt.Printf("===%s 购买成功!数量:%d,剩余:%d,订单量:%d ===\n", userName, buyNum, book.Store, orderCount)
      return userName + "购买成功"
   }
   fmt.Printf("===%s 购买失败!数量:%d,剩余:%d,数量不足===\n", userName, buyNum, book.Store)
   return userName + "购买失败"
}
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package main
import (
   "fmt"
   "github.com/spf13/cast"
   "lock_demo/service"
   "net/http"
)
func RunServer() {
   http.HandleFunc("/buyBook", func(w http.ResponseWriter, r *http.Request) {
      username := r.URL.Query().Get("name")
      buyNum := r.URL.Query().Get("num")
      resp := service.BuyBook(username, cast.ToInt64(buyNum))
      _, err := w.Write([]byte(resp))
      if err != nil {
         fmt.Errorf("write err %s", err)
      }
   })
   err := http.ListenAndServe(":8081", nil)
   if err != nil {
      fmt.Errorf("Http run err %s ", err)
   }
}
func main() {
   RunServer()
}
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github.com/go-redis/redis/v8 v8.11.4
   github.com/go-redsync/redsync/v4 v4.6.0
   github.com/go-sql-driver/mysql v1.6.0
   github.com/go-zookeeper/zk v1.0.3
   github.com/spf13/cast v1.5.0
   go.etcd.io/etcd/client/v3 v3.5.5
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CREATE TABLE `book`(
   `id` int(11) NOT NULL,
   `name` varchar(255) NOT NULL,
   `price` double NOT NULL,
   `store` int(11) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
insert into book value(1,'Go学习笔记',299,100);
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GET http://localhost:8081/buyBook
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GET http://localhost:8081/buyBook?name=BarryYan&num=1
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