普遍缓存技术
数据缓存:这里所说的数据缓存是指数据库查询缓存,每次访问页面的时候,都会先检测相应的缓存数据是否存在,如果不存在,就连接数据库,得到数据, 并把查询结果序列化后保存到文件中,以后同样的查询结果就直接从缓存表或文件中获得。
用的最广的例子看Discuz的搜索功能,把结果ID缓存到一个表中,下次搜索相同关键字时先搜索缓存表。
举个常用的方法,多表关联的时候,把附表中的内容生成数组保存到主表的一个字段中,需要的时候数组分解一下,这样的好处是只读一个表,坏处就是两个 数据同步会多不少步骤,数据库永远是瓶颈,用硬盘换速度,是这个的关键点。
页面缓存:
每次访问页面的时候,都会先检测相应的缓存页面文件是否存在,如果不存在,就连接数据库,得到数据,显示页面并同时生成缓存页面文件,这样下次访问 的时候页面文件就发挥作用了。(模板引擎和网上常见的一些缓存类通常有此功能)
时间触发缓存:
检查文件是否存在并且时间戳小于设置的过期时间,如果文件修改的时间戳比当前时间戳减去过期时间戳大,那么就用缓存,否则更新缓存。
内容触发缓存:
当插入数据或更新数据时,强制更新缓存。
静态缓存:
这里所说的静态缓存是指静态化,直接生成HTML或xml等文本文件,有更新的时候重生成一次,适合于不太变化的页面,这就不说了。
以上内容是代码级的解决方案,我直接CP别的框架,也懒得改,内容都差不多,很容易就做到,而且会几种方式一起用,但下面的内容是服务器端的缓存方 案,非代码级的,要有多方的合作才能做到
内存缓存:
Memcached是高性能的,分布式的内存对象缓存系统,用于在动态应用中减少数据库负载,提升访问速度。
这里说下Memcached的例子:
- $memcache = new Memcache;
- $memcache->connect(‘localhost’, 11211) or die (“Could not connect”);
- $version = $memcache->getVersion();
- echo “Server’s version: “.$version.”n”;
- $tmp_object = new stdClass;
- $tmp_object->str_attr = ‘test’;
- $tmp_object->int_attr = 123;
- $memcache->set(‘key’, $tmp_object, false, 10) or die (“Failed to save data at the server”);
- echo “Store data in the cache (data will expire in 10 seconds)n”;
- $get_result = $memcache->get(‘key’);
- echo “Data from the cache:n”;
- var_dump($get_result);
- ?>
读库的例子:
- $sql = ‘SELECT * FROM users’;
- $key = md5($sql); //memcached 对象标识符
- if ( !($datas = $mc->get($key)) ) {
- // 在 memcached 中未获取到缓存数据,则使用数据库查询获取记录集。
- echo “n”.str_pad(‘Read datas from MySQL.’, 60, ‘_’).”n”;
- $conn = mysql_connect(‘localhost’, ‘test’, ‘test’);
- mysql_select_db(‘test’);
- $result = mysql_query($sql);
- while ($row = mysql_fetch_object($result))
- $datas[] = $row;
- // 将数据库中获取到的结果集数据保存到 memcached 中,以供下次访问时使用。
- $mc->add($key, $datas);
- } else {
- echo “n”.str_pad(‘Read datas from memcached.’, 60, ‘_’).”n”;
- }
- var_dump($datas);
- ?>
PHP的缓冲器:
有eaccelerator, apc, PHPa,xcache,这个这个就不说了吧,搜索一堆一堆的,自己看啦,知道有这玩意就OK
MYSQL缓存:
这也算非代码级的,经典的数据库就是用的这种方式,看下面的运行时间,0.09xxx之类的
我贴段根据蓝色那家伙修改后部分my.ini 吧,2G的MYISAM表可以在0.05S左右,据说他前后改了有快一年
- [client]
- ……
- default-character-set=gbk
- default-storage-engine=MYISAM
- max_connections=600
- max_connect_errors=500
- back_log=200
- interactive_timeout=7200
- query_cache_size=64M
- ……
- table_cache=512
- ……
- myisam_max_sort_file_size=100G
- myisam_max_extra_sort_file_size=100G
- myisam_sort_buffer_size=128M
- key_buffer_size=1024M
- read_buffer_size=512M
- ……
- thread_concurrency=8
基于反向代理的Web缓存:
如Nginx,SQUID,mod_PRoxy(apache2以上又分为mod_proxy和mod_cache)
NGINX的例子
- #user nobody;
- worker_processes 4;
- error_log logs/error.log crit;
- pid logs/nginx.pid;
- worker_rlimit_nofile 10240;
- events {
- use epoll;
- worker_connections 51200;
- }
- http {
- include mime.types;
- default_type application/octet-stream;
- sendfile on;
- keepalive_timeout 65;
- tcp_nodelay on;
- # server pool
- upstream bspfrontsvr {
- server 10.10.10.224:80 weight=1;
- server 10.10.10.221:80 weight=1;
- }
- upstream bspimgsvr {
- server 10.10.10.201:80 weight=1;
- }
- upstream bspstylesvr {
- server 10.10.10.202:80 weight=1;
- }
- upstream bsphelpsvr {
- server 10.10.10.204:80 weight=1;
- }
- upstream bspwsisvr {
- server 10.10.10.203:80 weight=1;
- }
- upstream bspadminsvr {
- server 10.10.10.222:80 weight=1;
- }
- upstream bspbuyersvr {
- server 10.10.10.223:80 weight=1;
- }
- upstream bspsellersvr {
- server 10.10.10.225:80 weight=1;
- }
- upstream bsploginsvr {
- server 10.10.10.220:443 weight=1;
- }
- upstream bspregistersvr {
- server 10.10.10.220:80 weight=1;
- }
- log_format test_com ‘$remote_addr – $remote_user [$time_local] “$request” ‘
- ‘$status $body_bytes_sent “$http_referer” “$http_user_agent” ‘;
- #——————————————————————–
- #img.test.com
- server {
- listen 10.10.10.230:80;
- server_name img.test.com;
- location / {
- proxy_pass http://bspimgsvr;
- include proxy_setting.conf;
- }
- access_log logs/img.log test_com;
- }
- #style.test.com
- server {
- listen 10.10.10.230:80;
- server_name style.test.com;
- location / {
- proxy_pass http://bspstylesvr;
- include proxy_setting.conf;
- }
- access_log logs/style.log test_com;
- }
- #help.test.com
- server {
- listen 10.10.10.230:80;
- server_name help.test.com;
- location / {
- proxy_pass http://bsphelpsvr;
- include proxy_setting.conf;
- }
- access_log logs/help.log test_com;
- }
- #admin.test.com
- server {
- listen 10.10.10.230:80;
- server_name admin.test.com;
- location / {
- proxy_pass http://bspadminsvr;
- include proxy_setting.conf;
- }
- access_log logs/admin.log test_com;
- }
- #buyer.test.com
- server {
- listen 10.10.10.230:80;
- server_name buyer.test.com;
- location / {
- proxy_pass http://bspbuyersvr;
- include proxy_setting.conf;
- }
- access_log logs/buyer.log test_com;
- }
- #seller.test.com
- server {
- listen 10.10.10.230:80;
- server_name seller.test.com;
- location / {
- proxy_pass http://bspsellersvr;
- include proxy_setting.conf;
- }
- access_log logs/seller.log test_com;
- }
- #wsi.test.com
- server {
- listen 10.10.10.230:80;
- server_name wsi.test.com;
- location / {
- proxy_pass http://bspwsisvr;
- include proxy_setting.conf;
- }
- access_log logs/wsi.log test_com;
- }
- #www.test.com
- server {
- listen 10.10.10.230:80;
- server_name www.test.com *.test.com;
- location ~ ^/NginxStatus/ {
- stub_status on;
- access_log off;
- }
- location / {
- proxy_pass http://bspfrontsvr;
- include proxy_setting.conf;
- }
- access_log logs/www.log test_com;
- error_page 500 502 503 504 /50x.html;
- location = /50x.html {
- root html;
- }
- }
- #login.test.com
- server {
- listen 10.10.10.230:443;
- server_name login.test.com;
- ssl on;
- ssl_certificate cert.pem;
- ssl_certificate_key cert.key;
- ssl_session_timeout 5m;
- ssl_protocols SSLv2 SSLv3 TLSv1;
- ssl_ciphers ALL:!ADH:!EXPORT56:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP;
- ssl_prefer_server_ciphers on;
- location / {
- proxy_pass https://bsploginsvr;
- include proxy_setting.conf;
- }
- access_log logs/login.log test_com;
- }
- #login.test.com for register
- server {
- listen 10.10.10.230:80;
- server_name login.test.com;
- location / {
- proxy_pass http://bspregistersvr;
- include proxy_setting.conf;
- }
- access_log logs/register.log test_com;
- }
- }
- proxy_redirect off;
- proxy_set_header Host $host;
- proxy_set_header X-Real-IP $remote_addr;
- proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
- client_max_body_size 10m;
- client_body_buffer_size 128k;
- proxy_connect_timeout 90;
- proxy_send_timeout 90;
- proxy_read_timeout 90;
- proxy_buffer_size 4k;
- proxy_buffers 4 32k;
- proxy_busy_buffers_size 64k;
- proxy_temp_file_write_size 64k;
- mod_proxy的例子:
- ServerName www.zxsv.com
- ServerAdmin admin@zxsv.com
- # reverse proxy setting
- ProxyPass / http://www.zxsv.com:8080/
- ProxyPassReverse / http://www.zxsv.com:8080/
- # cache dir root
- CacheRoot “/var/www/proxy”
- # max cache storage
- CacheSize 50000000
- # hour: every 4 hour
- CacheGcInterval 4
- # max page expire time: hour
- CacheMaxExpire 240
- # Expire time = (now – last_modified) * CacheLastModifiedFactor
- CacheLastModifiedFactor 0.1
- # defalt expire tag: hour
- CacheDefaultExpire 1
- # force complete after precent of content retrived: 60-90%
- CacheForceCompletion 80
- CustomLog /usr/local/apache/logs/dev_access_log combined
而SQUID的例子我就不说明了,这方面网上有写的太多,大家自己搜索一下
DNS轮询:
BIND是一款开放源码的DNS服务器软件,这个要说起来就大了,自己搜索去,大家知道有这个东西就行了。
我知道的有chinacache 等大站就是这样做的,说简单点就是多服务器啦,把同一个页面或文件缓存到不同的服务器上,按南北自动解析到相关的服务器中。
http://www.cnblogs.com/cnblogs20112011/archive/2011/01/27/1946286.html
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