PHP data caching technology 2_PHP tutorial

Using PEAR to buffer PHP programs

Buffering is a hot topic in the PHP world, because the dynamic pages generated by PHP need to be recalculated every time the user requests it. Regardless of whether the result of the request is the same, PHP will compile the script every time. Such overload would certainly be unbearable for a website with high traffic. Fortunately, the results of the Web can be cached without the need to rerun and compile the script. Commercial products like ZendCache or the open source Alternate PHP Cache provide a way to compile PHP scripts into byte code and cache them.
PEAR's buffering package provides a framework for buffering dynamic content, database queries, and PHP function calls.
Just like Perl has CPAN and TeX has CTAN, PHP also has its own central resource library to store classes, libraries and modules. This library is called PEAR (PHP Extension and Add-On Repository).
This article assumes that you have installed the PEAR environment. If not, you can download it from the PHP website. PEAR's buffer package contains an overall buffer class and several specialized subclasses. Buffer classes use container classes to store and manage buffered data.
The following are the containers currently included in the PEAR buffer, and their respective parameters:
file -- the file container stores buffered data in the file system and is the fastest container.
cache_dir -- This is the directory where the container stores files.
filename_prefix -- the prefix of the cache file, for example: "cache_".
shm -- The shm container puts buffered data into shared memory. Benchmark tests show that under the current implementation, this container is slower than the file container.
shm_key -- the key value used by shared memory.
shm_perm -- Permission to use the shared memory data segment.
shm_size -- The size of allocated shared memory.
sem_key -- The key value of the semaphore.
sem_perm -- semaphore permissions.
db -- PEAR's database abstraction layer.
dsn -- DSN of database connection. You can refer to PEAR’s DB documentation.
cache_table -- the name of the table.
phplib -- The phplib container uses a database abstraction layer to store buffers.
db_class
db_file
db_path
local_file
local_path
ext/dbx -- PHP's database abstraction layer extension. If you want to store buffers in the database, you can use this container.
module
host
db
username
password
cache_table
persistent
The performance improvement you get from using PEAR Cache depends on the buffer container you choose, for example, It is meaningless to store the database results in the database buffer again.
PEAR Cache's function buffer module can buffer the results of any function or method, whether it is PHP's built-in function or a user-defined function. It uses a file container by default and puts the buffered data into a directory called function_cache.
The constructor of the Cache_Function class can have three optional parameters:
$container: the name of the buffer container.
$container_options: Array parameters of the buffer container.
$expires: The time (in seconds) when the buffer object expires.
When a normal function call uses the call() method of the Cache_Function class, buffering can be triggered. Calling call() is easy, one parameter is the name of the function, then the parameters of the function, the second parameter is the first one in the function to be called, and so on, let's look at the example:
Example 1 Calling buffering functions and methods

// 调用 PEAR Cache 的函数缓冲。<br><?php <br>require_once 'Cache/Function.php';<br>// 定义一些类和函数。<br>class foo {<br>function bar($test) {<br>echo "foo::bar($test)<br>";<br>}<br>}<br>class bar {<br>function foobar($object) {<br>echo '$'.$object.'->foobar('.$object.')<br>';<br>}<br>}<br>$bar = new bar;<br>function foobar() {<br>echo 'foobar()';<br>}<br>// 取得 Cache_Function 对象<br>$cache = new Cache_Function();<br>// 对 foo 类的静态函数 bar() 作缓冲(foo::bar())。<br>$cache->call('foo::bar', 'test');<br>// $bar->foobar() <br>$cache->call('bar->foobar', 'bar');<br>$cache->call('foobar');<br>?><br>

Below we use Cache_Output to buffer the output:
Example 2 Buffering the output of the script

// 加载 PEAR Cache 的输出缓冲<br><?php <br>require_once 'Cache/Output.php';<br>$cache = new Cache_Output('file', array('cache_dir' => '.') );<br>// 计算要缓冲页面的标记，我们假定页面的缓冲取决于<br>// URL, HTTP GET 和 POST 变量以及 cookies。<br>$cache_id = $cache->generateID(<br>array('url' => $REQUEST_URI, '<br>post' => $HTTP_POST_VARS, 'cookies' => $HTTP_COOKIE_VARS) );<br>// 查询缓冲<br>if ($content = $cache->start($cache_id)) {<br>// 缓冲命中<br>echo $content;<br>die();<br>}<br>// 缓冲丢失<br>// -- 在这里插入内容产生代码 --<br>// 把页面存入缓冲<br>echo $cache->end();<br>?>

Using the Cache_Output class, it is easy to convert a dynamic database-driven website application into a static one, thereby greatly improving the performance of the site. More and more sites are using GZIP to compress HTML content, which reduces the bandwidth consumption of the server and can also benefit a lot for users who use Modem to access the Internet.
Cache_OutputCompression extends the functionality of the Cache_Output class. It buffers GZIP compressed HTML content, thereby saving CPU compression time.

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