之前我們曾深入的探讨過PHP緩存技術,其中主要提到了資料緩存。資料緩存主要是指資料庫查詢緩存,每次通路頁面的時候,都會先檢測相應的緩存資料是否存在,如果不存在,就連接配接資料庫,得到資料, 并把查詢結果序列化後儲存到檔案中,以後同樣的查詢結果就直接從緩存表或檔案中獲得。用的最廣的例子看Discuz的搜尋功能,把結果ID緩存到一個表中,下次搜尋相同關鍵字時先搜尋緩存表。
舉個常用的方法,多表關聯的時候,把附表中的内容生成數組儲存到主表的一個字段中,需要的時候數組分解一下,這樣的好處是隻讀一個表,壞處就是兩個 資料同步會多不少步驟,資料庫永遠是瓶頸,用硬碟換速度,是這個的關鍵點。
頁面緩存
每次通路頁面的時候,都會先檢測相應的緩存頁面檔案是否存在,如果不存在,就連接配接資料庫,得到資料,顯示頁面并同時生成緩存頁面檔案,這樣下次通路 的時候頁面檔案就發揮作用了。(模闆引擎和網上常見的一些緩存類通常有此功能)
時間觸發緩存
檢查檔案是否存在并且時間戳小于設定的過期時間,如果檔案修改的時間戳比目前時間戳減去過期時間戳大,那麼就用緩存,否則更新緩存。
内容觸發緩存
當插入資料或更新資料時,強制更新緩存。
靜态緩存
這裡所說的靜态緩存是指靜态化,直接生成HTML或xml等文本檔案,有更新的時候重生成一次,适合于不太變化的頁面,這就不說了。
記憶體緩存
Memcached是高性能的,分布式的記憶體對象緩存系統,用于在動态應用中減少資料庫負載,提升通路速度。
<?php
$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);
?>
讀庫的例子:
$sql = ‘SELECT * FROM users’;
$key = md5($sql); //memcached 對象辨別符
if ( !($datas = $mc->get($key)) ) {
// 在 memcached 中未擷取到緩存資料,則使用資料庫查詢擷取記錄集
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;
// 将資料庫中擷取到的結果集資料儲存到 memcached 中,以供下次通路時使用
$mc->add($key, $datas);
} else {
echo “n”.str_pad(‘Read datas from memcached.’, 60, ‘_’).”n”;
}
var_dump($datas);
PHP的緩沖器
比如eaccelerator,apc,phpa,xcache等等。
MySQL緩存
這也算非代碼級的,經典的資料庫就是用的這種方式,看下面的運作時間,0.09xxx之類的。
[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緩存
如Nginx,SQUID,mod_PRoxy(apache2以上又分為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_name style.test.com;
proxy_pass http://bspstylesvr;
access_log logs/style.log test_com;
#help.test.com
server_name help.test.com;
proxy_pass http://bsphelpsvr;
access_log logs/help.log test_com;
#admin.test.com
server_name admin.test.com;
proxy_pass http://bspadminsvr;
access_log logs/admin.log test_com;
#buyer.test.com
server_name buyer.test.com;
proxy_pass http://bspbuyersvr;
access_log logs/buyer.log test_com;
#seller.test.com
server_name seller.test.com;
proxy_pass http://bspsellersvr;
access_log logs/seller.log test_com;
#wsi.test.com
server_name wsi.test.com;
proxy_pass http://bspwsisvr;
access_log logs/wsi.log test_com;
#www.test.com
server_name www.test.com *.test.com;
location ~ ^/NginxStatus/ {
stub_status on;
access_log off;
proxy_pass http://bspfrontsvr;
access_log logs/www.log test_com;
error_page 500 502 503 504 /50x.html;
location = /50x.html {
root html;
#login.test.com
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;
proxy_pass https://bsploginsvr;
access_log logs/login.log test_com;
#login.test.com for register
proxy_pass http://bspregistersvr;
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:
<VirtualHost *>
ServerName www.zxsv.com
ServerAdmin [email protected]
# 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%