如何利用Redis锁解决高并发问题详解

CREATE TABLE `storage` (
 `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
 `number` int(11) DEFAULT NULL,
 PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=latin1

CREATE TABLE `order` (
 `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
 `number` int(11) DEFAULT NULL,
 PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=latin1

$pdo = new PDO('mysql:host=127.0.0.1;dbname=test', 'root', 'root');
$sql="select `number` from storage where id=1 limit 1";
$res = $pdo->query($sql)->fetch();
$number = $res['number'];
if($number>0)
{
 $sql ="insert into `order` VALUES (null,$number)";

 $order_id = $pdo->query($sql);
 if($order_id)
 {

 $sql="update storage set `number`=`number`-1 WHERE id=1";
 $pdo->query($sql);
 }
}

mysql> select * from storage;
+----+--------+
| id | number |
+----+--------+
| 1 | 0 |
+----+--------+
1 row in set (0.00 sec)

mysql> select * from `order`;
+----+--------+
| id | number |
+----+--------+
| 1 | 10 |
| 2 | 10 |
| 3 | 9 |
| 4 | 7 |
| 5 | 6 |
| 6 | 5 |
| 7 | 5 |
| 8 | 5 |
| 9 | 4 |
| 10 | 1 |
+----+--------+
10 rows in set (0.00 sec)

<"select `number` from storage where id=1 limit 1";
 $res = $pdo->query($sql)->fetch();
 $number = $res['number'];
 if($number>0)
 {
 $sql ="insert into `order` VALUES (null,$number)";

 $order_id = $pdo->query($sql);
 if($order_id)
 {

  $sql="update storage set `number`=`number`-1 WHERE id=1";
  $pdo->query($sql);
 }
 }
 //解锁
 $lockObj->del('storage');

}
else
{
 //加锁不成功执行其他操作。
}

mysql> select * from `order`;
+----+--------+
| id | number |
+----+--------+
| 1 | 10 |
| 2 | 9 |
| 3 | 8 |
| 4 | 7 |
| 5 | 6 |
| 6 | 5 |
| 7 | 4 |
| 8 | 3 |
| 9 | 2 |
| 10 | 1 |
+----+--------+
10 rows in set (0.00 sec)