Summary of commonly used caching technologies in PHP

1. Data caching

The data cache mentioned here refers to the database query cache. Every time you access a page, it will first detect whether the corresponding cached data exists. If it does not exist, connect to the database, obtain the data, and serialize the query results. Save it to a file, and the same query results will be obtained directly from the cache table or file in the future.

The most widely used example is the search function of Discuz, which caches the result ID into a table and searches the cache table first when searching for the same keyword next time.
As a common method, when multiple tables are associated, generate an array and save the contents in the attached table to a field in the main table. When necessary, decompose the array. The advantage of this is that only one table can be read, but the disadvantage is There will be many more steps to synchronize the two data. The database is always the bottleneck. Trading the hard disk for speed is the key point of this.

2. Page caching

Every time you visit a page, it will first detect whether the corresponding cached page file exists. If it does not exist, connect to the database, get the data, display the page and generate the cached page file at the same time, so that the page file will be the same the next time you visit. It worked. (Template engines and some common cache classes on the Internet usually have this function).

3. Time-triggered cache

Check whether the file exists and the timestamp is less than the set expiration time. If the file modification timestamp is greater than the current timestamp minus the expiration timestamp, then use the cache, otherwise update the cache.

4. Content-triggered caching

Force the cache to be updated when data is inserted or updated.

5. Static cache

The static caching mentioned here refers to static, directly generating text files such as HTML or XML, and regenerating them when there are updates. It is suitable for pages that do not change much, so I won’t talk about it here.
The above content is a code-level solution. I directly CP other frameworks and am too lazy to change. The content is similar, it is easy to do, and can be used in several ways, but the following content is a server-side caching solution. , non-code level, requires the cooperation of multiple parties to achieve it.

6. Memory Caching

Memcached is a high-performance, distributed memory object caching system used to reduce database load and improve access speed in dynamic applications.
Here is an example of Memcached:

Copy code The code is as follows:

$ 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);

Example of reading library:

Copy code The code is as follows:

$sql = 'SELECT * FROM users';
$key = md5($sql); //memcached object identifier
if ( !($datas = $mc->get($key)) ) {
// If cached data is not obtained in memcached, use database query to obtain the record set.
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;
//Save the result set data obtained from the database to memcached for use during the next access.
$mc->add($key, $datas);
} else {
echo "n".str_pad('Read datas from memcached.', 60, '_')."n ";
}
var_dump($datas);

7. PHP buffers and accelerators

There are eaccelerator, apc, phpa, xcache, let’s not talk about these. Search a bunch of them and see for yourself. It’s OK if you know that there is such a thing.

8. MYSQL Cache

This is also considered non-code level. Classic databases use this method. Look at the running time below, 0.09xxx and the like.
I will post the part of my.ini modified according to the blue guy. , the 2G MYISAM table can be around 0.05S. It is said that he has changed it for almost a year.

Copy code The code is as follows:

[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

9. Web cache based on reverse proxy

Such as Nginx, SQUID, mod_proxy (apache2 and above are divided into mod_proxy and mod_cache)
Example of NGINX:

Copy code The code is as follows:

#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;

apache mod_proxy的例子:

复制代码代码如下:

ServerName jb51.net
ServerAdmin admin@zxsv.com
# reverse proxy setting
ProxyPass / http://jb51.net:8080/
ProxyPassReverse / http://jb51.net: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/jb51_net_access_log combined

10. DNS polling

BIND is an open source DNS server software. This is a big deal to mention. Search for it yourself. Everyone knows that this thing exists.

I know that some big websites such as chinacache do this. To put it simply, it is multi-server. The same page or file is cached on different servers and automatically parsed to the relevant server according to the north and south.

Summary of commonly used caching technologies in PHP_PHP tutorial