应用场景

• 高并发，秒杀场景

步骤

1. set key = 0
2. watch key
3. 开启事务 multi
4. set key + 1
5. 事务操作

代码实现

$redis = new Redis("127.0.0.1", 6739);
$key = "incr_key";
$redis->set($key, 0);

$redis->watch($key);
$value = (int) $redis->get($key);
if ($value < 100) {
  $redis->multi();
  $redis->incr($key);
  $res = $redis->exec();
  if ($res) {
    echo "success";
  } else {
    echo "error";
  }
}