Heim >Datenbank >MySQL-Tutorial >实现一个简单的服务端推送方案-实例篇Polling(服务端阻塞读,SLEE_MySQL
实现一个简单的服务端推送方案-实例篇Polling(服务端阻塞读,SLEE_MySQL
- WBOYOriginal
- 2016-06-01 13:26:591055Durchsuche
bitsCN.com
前面讲过一篇《实现一个简单的服务端推送方案-实例篇Polling(服务端阻塞读)》，那篇文章服务端利用Gearman队列来实现阻塞读，这篇服务器端用原生MySQL的Sleep函数来实现阻塞读，这篇文章也是另一篇文章《使用MySQL构建一个队列表》的实例实现。
客户端代码，JS库为prototype.js：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=gb2312" /><title>无标题文档</title><script language="JavaScript" type="text/javascript" src="./prototype.js"></script></head><body><script language="JavaScript"> var Class = { create: function() { return function() { this.initialize.apply(this, arguments); } } } var Comet = Class.create(); Comet.prototype = { maxvid: 0, url: './backend.php', noerror: true, initialize: function(){ }, connect: function(){ this.ajax = new Ajax.Request(this.url, { method: 'get', parameters: { 'maxvid': this.maxvid }, onSuccess: function(transport){ var response = transport.responseText.evalJSON(); this.comet.maxvid = response['vid']; this.comet.handleResponse(response); this.comet.noerror = true; }, onComplete: function(transport){ if (!this.comet.noerror) setTimeout(function(){ comet.connect() }, 5000); else this.comet.connect(); this.comet.noerror = false; } }); this.ajax.comet = this; }, handleResponse: function(response){ $('content').innerHTML += '<p>' + response['msg'] + '</p>'; } } var comet = new Comet(); comet.connect();</script><p id="content"></p></body></html>服务器端代码，backend.php，在这里当读不到新数据时，就调用"带注释的Sleep函数"来阻塞，阻塞直到超时或线程被KILL
<?phpheader("Cache-Control: no-cache, must-revalidate");header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");flush();//控制浏览器前端不要缓存结果，每次都要重新查询$maxvid = $_GET["maxvid"];//$maxvid = -1;error_log(date("[Y-m-d H:i:s]")." > "."maxvid: ".$maxvid."/n", 3 , "/usr/local/apache2219/logs/php_log");$dblnk = mysql_connect('localhost:3306', 'root', 'cpyf');mysql_select_db('test', $dblnk);if ( $maxvid <= 0 ) { $result = mysql_query("select max(vid) from vdooropen"); $result = mysql_fetch_row($result); $maxvid = $result[0]; error_log(date("[Y-m-d H:i:s]")." > "."maxvid: ".$maxvid."/n", 3 , "/usr/local/apache2219/logs/php_log");}while (1){ $result = mysql_query("select * from vdooropen where vid > $maxvid order by vid limit 1"); $num = mysql_num_rows($result); if ( $num > 0 ) break; mysql_query("/*!999999 wait queue msg */ SELECT SLEEP(300)"); if ( mysql_errno() != 0 ) { mysql_close($dblnk); //必须先关闭 $dblnk = mysql_connect('localhost:3306', 'root', 'cpyf'); mysql_select_db('test', $dblnk); }}$result = mysql_fetch_row($result);// 返回 JSON 数组$response = array();$response['vid'] = $result[0];$response['msg'] = $result[0].",".$result[1].",".$result[2].",".$result[3].",".$result[4];$responseText = json_encode($response);error_log(date("[Y-m-d H:i:s]")." < ".$responseText."/n", 3 , "/usr/local/apache2219/logs/php_log");echo $responseText;flush();?>当新增加数据后，通过show processlist找到带注释的Sleep线程，并KILL掉，阻塞就会退出。增加数据代码如下：
<?php$dblnk = mysql_connect('localhost:3306', 'root', 'cpyf');mysql_select_db('test', $dblnk);mysql_query('insert into vdooropen values(0, 2001, "0863030900020185","20130510-115152","D")');mysql_query('insert into vdooropen values(0, 2001, "0863030900020185","20130510-115152","D")');mysql_query('insert into vdooropen values(0, 2001, "0863030900020185","20130510-115152","D")');mysql_query('insert into vdooropen values(0, 2001, "0863030900020185","20130510-115152","D")');mysql_query('insert into vdooropen values(0, 2001, "0863030900020185","20130510-115152","D")');$result = mysql_query("SHOW PROCESSLIST");$num = mysql_num_rows($result);for ($i = 0; $i < $num; $i++) { $row = mysql_fetch_row($result); if ( strstr($row[7], "wait queue msg") != NULL ) { echo "KILL ".$row[0] . "/n"; mysql_query("KILL ".$row[0]); }}?>Stellungnahme：
Der Inhalt dieses Artikels wird freiwillig von Internetnutzern beigesteuert und das Urheberrecht liegt beim ursprünglichen Autor. Diese Website übernimmt keine entsprechende rechtliche Verantwortung. Wenn Sie Inhalte finden, bei denen der Verdacht eines Plagiats oder einer Rechtsverletzung besteht, wenden Sie sich bitte an admin@php.cn
Vorheriger Artikel：MySQL数据库的备份与还原_MySQLNächster Artikel：Linux下安装MySQL步骤_MySQL