php如何应对秒杀抢购高并发思路

<?php
//优化方案1：将库存字段number字段设为unsigned，当库存为0时，因为字段不能为负数，将会返回false
include(‘./mysql.php‘);
$username = ‘wang‘.rand(0,1000);
//生成唯一订单
function build_order_no(){
  return date(‘ymd‘).substr(implode(NULL, array_map(‘ord‘, str_split(substr(uniqid(), 7, 13), 1))), 0, 8);
}
//记录日志
function insertLog($event,$type=0,$username){
    global $conn;
    $sql="insert into ih_log(event,type,usernma)
    values(‘$event‘,‘$type‘,‘$username‘)";
    return mysqli_query($conn,$sql);
}
function insertOrder($order_sn,$user_id,$goods_id,$sku_id,$price,$username,$number)
{
      global $conn;
      $sql="insert into ih_order(order_sn,user_id,goods_id,sku_id,price,username,number)
      values(‘$order_sn‘,‘$user_id‘,‘$goods_id‘,‘$sku_id‘,‘$price‘,‘$username‘,‘$number‘)";
     return  mysqli_query($conn,$sql);
}
//模拟下单操作
//库存是否大于0
$sql="select number from ih_store where goods_id=‘$goods_id‘ and sku_id=‘$sku_id‘ ";
$rs=mysqli_query($conn,$sql);
$row = $rs->fetch_assoc();
  if($row[‘number‘]>0){//高并发下会导致超卖
      if($row[‘number‘]<$number){
        return insertLog(‘库存不够‘,3,$username);
      }
      $order_sn=build_order_no();
      //库存减少
      $sql="update ih_store set number=number-{$number} where sku_id=‘$sku_id‘ and number>0";
      $store_rs=mysqli_query($conn,$sql);
      if($store_rs){
          //生成订单
          insertOrder($order_sn,$user_id,$goods_id,$sku_id,$price,$username,$number);
          insertLog(‘库存减少成功‘,1,$username);
      }else{
          insertLog(‘库存减少失败‘,2,$username);
      }
  }else{
      insertLog(‘库存不够‘,3,$username);
  }


?>

<?php
//优化方案2：使用MySQL的事务，锁住操作的行
include(‘./mysql.php‘);
//生成唯一订单号
function build_order_no(){
  return date(‘ymd‘).substr(implode(NULL, array_map(‘ord‘, str_split(substr(uniqid(), 7, 13), 1))), 0, 8);
}
//记录日志
function insertLog($event,$type=0){
    global $conn;
    $sql="insert into ih_log(event,type)
    values(‘$event‘,‘$type‘)";
    mysqli_query($conn,$sql);
}

//模拟下单操作
//库存是否大于0
mysqli_query($conn,"BEGIN");  //开始事务
$sql="select number from ih_store where goods_id=‘$goods_id‘ and sku_id=‘$sku_id‘ FOR UPDATE";//此时这条记录被锁住,其它事务必须等待此次事务提交后才能执行
$rs=mysqli_query($conn,$sql);
$row=$rs->fetch_assoc();
if($row[‘number‘]>0){
    //生成订单
    $order_sn=build_order_no();
    $sql="insert into ih_order(order_sn,user_id,goods_id,sku_id,price)
    values(‘$order_sn‘,‘$user_id‘,‘$goods_id‘,‘$sku_id‘,‘$price‘)";
    $order_rs=mysqli_query($conn,$sql);
    //库存减少
    $sql="update ih_store set number=number-{$number} where sku_id=‘$sku_id‘";
    $store_rs=mysqli_query($conn,$sql);
    if($store_rs){
      echo ‘库存减少成功‘;
        insertLog(‘库存减少成功‘);
        mysqli_query($conn,"COMMIT");//事务提交即解锁
    }else{
      echo ‘库存减少失败‘;
        insertLog(‘库存减少失败‘);
    }
}else{
  echo ‘库存不够‘;
    insertLog(‘库存不够‘);
    mysqli_query($conn,"ROLLBACK");
}
?>

<?php
//优化方案4：使用非阻塞的文件排他锁
include (‘./mysql.php‘);
//生成唯一订单号
function build_order_no(){
  return date(‘ymd‘).substr(implode(NULL, array_map(‘ord‘, str_split(substr(uniqid(), 7, 13), 1))), 0, 8);
}
//记录日志
function insertLog($event,$type=0){
    global $conn;
    $sql="insert into ih_log(event,type)
    values(‘$event‘,‘$type‘)";
    mysqli_query($conn,$sql);
}


$fp = fopen("lock.txt", "w+");
if(!flock($fp,LOCK_EX | LOCK_NB)){
    echo "系统繁忙，请稍后再试";
    return;
}
//下单
$sql="select number from ih_store where goods_id=‘$goods_id‘ and sku_id=‘$sku_id‘";
$rs =  mysqli_query($conn,$sql);
$row = $rs->fetch_assoc();
if($row[‘number‘]>0){//库存是否大于0
    //模拟下单操作
    $order_sn=build_order_no();
    $sql="insert into ih_order(order_sn,user_id,goods_id,sku_id,price)
    values(‘$order_sn‘,‘$user_id‘,‘$goods_id‘,‘$sku_id‘,‘$price‘)";
    $order_rs =  mysqli_query($conn,$sql);
    //库存减少
    $sql="update ih_store set number=number-{$number} where sku_id=‘$sku_id‘";
    $store_rs =  mysqli_query($conn,$sql);
    if($store_rs){
      echo ‘库存减少成功‘;
        insertLog(‘库存减少成功‘);
        flock($fp,LOCK_UN);//释放锁
    }else{
      echo ‘库存减少失败‘;
        insertLog(‘库存减少失败‘);
    }
}else{
  echo ‘库存不够‘;
    insertLog(‘库存不够‘);
}
fclose($fp);


 ?>

<?php

$redis = new redis();
 $result = $redis->connect(‘127.0.0.1‘, 6379);
 echo $mywatchkey = $redis->get("mywatchkey");

/*
  //插入抢购数据
 if($mywatchkey>0)
 {
     $redis->watch("mywatchkey");
  //启动一个新的事务。
    $redis->multi();
   $redis->set("mywatchkey",$mywatchkey-1);
   $result = $redis->exec();
   if($result) {
      $redis->hSet("watchkeylist","user_".mt_rand(1,99999),time());
      $watchkeylist = $redis->hGetAll("watchkeylist");
        echo "抢购成功！<br/>"; 
        $re = $mywatchkey - 1;   
        echo "剩余数量：".$re."<br/>";
        echo "用户列表：<pre>";
        print_r($watchkeylist);
   }else{
      echo "手气不好，再抢购！";exit;
   }  
 }else{
     // $redis->hSet("watchkeylist","user_".mt_rand(1,99999),"12");
     //  $watchkeylist = $redis->hGetAll("watchkeylist");
        echo "fail！<br/>";    
        echo ".no result<br/>";
        echo "用户列表：<pre>";
      //  var_dump($watchkeylist);  
 }*/


$rob_total = 100;   //抢购数量
if($mywatchkey<=$rob_total){
    $redis->watch("mywatchkey");
    $redis->multi(); //在当前连接上启动一个新的事务。
    //插入抢购数据
    $redis->set("mywatchkey",$mywatchkey+1);
    $rob_result = $redis->exec();
    if($rob_result){
         $redis->hSet("watchkeylist","user_".mt_rand(1, 9999),$mywatchkey);
        $mywatchlist = $redis->hGetAll("watchkeylist");
        echo "抢购成功！<br/>";
     
        echo "剩余数量：".($rob_total-$mywatchkey-1)."<br/>";
        echo "用户列表：<pre>";
        var_dump($mywatchlist);
    }else{
          $redis->hSet("watchkeylist","user_".mt_rand(1, 9999),‘meiqiangdao‘);
        echo "手气不好，再抢购！";exit;
    }
}
?>