4.3. Zend_Cache前端

4.3.1. Zend_Cache_Core

4.3.1.1. 简介

Zend_Cache_Core是一个特别的前端,因为他是模块的核心. 它是一个一般化(generic)的缓存前端,并且由其他类扩展.

[注意] 注意

所有的前端继承自Zend_Cache_Core因此它的方法和选项(描述如下)应该在其他的前端中可用,所以这里没有进行文档化.

4.3.1.2. 可用选项

这些选项被传递给如前面例子中演示的工厂方法.

表 4.1. 核心前端选项

选项 数据类型 默认值 描述
caching boolean true 打开 / 关闭缓存 (对被缓存脚本的调试非常有用)
lifetime int 3600 缓存生命期(秒), 如果设置为 null, 缓存永远有效.
logging boolean false 如果设置为true,日志纪录(通过使用Zend_Log)被激活(但是系统将变慢)
write_control boolean true Enable / disable write control (the cache is read just after writing to detect corrupt entries), enabling write_control will lightly slow the cache writing but not the cache reading (it can detect some corrupt cache files but it's not a perfect control)
automatic_serialization boolean false 打开 / 关闭自动序列化, 可以直接用于保存非字符串数据(但是很慢)
automatic_cleaning_factor int 10 关闭 / 调整自动清理过程 (垃圾收集器): 0 表示不自动清理缓存,1 表示自动清理缓存,并且如果x > 1 表示x写操作后自动随机清理1次.

4.3.1.3. 例子

An example is given in the manual at the very beginning.

如果你只向缓存中存储字符串(由于"automatic_serialization"选项,可能会存储一些布尔值),你可以使用更加简介的构造:


<?php
// we assume you already have $cache

$id 'myBigLoop'// cache id of "what we want to cache"

if (!($data $cache->load($id))) {
    
// cache miss

    
$data '';
    for (
$i 0$i 10000$i++) {
        
$data $data $i;
    }

    
$cache->save($data);

}

// [...] do something with $data (echo it, pass it on etc.)

如果你缓存多个块或则数据实例,意思是一样的:


<?php
// make sure you use unique identifiers:
$id1 'foo';
$id2 'bar';

// block 1
if (!($data $cache->load($id1))) {
    
// cache missed

    
$data '';
    for (
$i=0;$i<10000;$i++) {
        
$data $data $i;
    }

    
$cache->save($data);

}
echo(
$data);

// this isn't affected by caching
echo('NEVER CACHED! ');

// block 2
if (!($data $cache->load($id2))) {
    
// cache missed

    
$data '';
    for (
$i=0;$i<10000;$i++) {
        
$data $data '!';
    }

    
$cache->save($data);

}
echo(
$data);

4.3.2. Zend_Cache_Frontend_Output

4.3.2.1. 简介

Zend_Cache_Frontend_Output 是一个输出捕捉前端.它在PHP中使用输出缓冲捕获start()end() 方法间的一切输出.

4.3.2.2. 可用的选项

该前端除了Zend_Cache_Core那些选项外没有任何特定的选项.

4.3.2.3. 例子

An example is given in the manual at the very beginning. Here it is with minor changes:


<?php
// if it is a cache miss, output buffering is triggered
if (!($cache->start('mypage'))) {

    
// output everything as usual
    
echo 'Hello world! ';
    echo 
'This is cached ('.time().') ';

    
$cache->end(); // output buffering ends

}

echo 
'This is never cached ('.time().').';

Using this form it is fairly easy to set up output caching in your already working project with little or no code refactoring.

4.3.3. Zend_Cache_Frontend_Function

4.3.3.1. Introduction

Zend_Cache_Frontend_Function caches the results of function calls. It has a single main method named call() which takes a function name and parameters for the call in an array.

4.3.3.2. A可用的选项

表 4.2. 函数前端选项

选项 数据类型 默认值 描述
cacheByDefault boolean true 如果为true,默认情况下,函数调用将被缓存.
cachedFunctions array   函数名称总是被缓存
nonCachedFunctions array   决不缓存函数名称

4.3.3.3. 例子

在PHP中使用 call() 函数于使用 call_user_func_array()相同:


<?php
$cache
->call('veryExpensiveFunc'$params);

# $params is an array
# for example to call (with caching) veryExpensiveFunc(1, 'foo', 'bar'), you will use
# $cache->call('veryExpensiveFunc', array(1, 'foo', 'bar'))

Zend_Cache_Frontend_Function is smart enough to cache both the return value of the function and its internal output.

[注意] 注意

You can pass any builtin or user defined function with the exception of array(), echo(), empty(), eval(), exit(), isset(), list(), print() and unset().

4.3.4. Zend_Cache_Frontend_Class

4.3.4.1. Introduction

Zend_Cache_Frontend_Class is different from Zend_Cache_Frontend_Function because it allows caching of object and static method calls.

4.3.4.2. Available options

表 4.3. Class frontend options

Option Data Type Default Value Description
cachedEntity (required) mixed   if set to a class name, we will cache an abstract class and will use only static calls; if set to an object, we will cache this object methods
cacheByDefault boolean true if true, calls will be cached by default
cachedMethods array   method names which will always be cached
nonCachedMethods array   method names which must never be cached

4.3.4.3. Examples

For example, to cache static calls :


<?php
class test {

    
# Static method
    
public static function foobar($param1$param2) {
        echo 
"foobar_output($param1, $param2)";
        return 
"foobar_return($param1, $param2)";
    }

}

// [...]
$frontendOptions = array(
    
'cachedEntity' => 'test' // The name of the class
);
// [...]

# The cached call
$res $cache->foobar('1''2');

To cache classic method calls :


<?php
class test {

    private 
$_string 'hello !';

    public function 
foobar2($param1$param2) {
        echo(
$this->_string);
        echo 
"foobar2_output($param1, $param2)";
        return 
"foobar2_return($param1, $param2)";
    }

}

// [...]
$frontendOptions = array(
    
'cachedEntity' => new test() // An instance of the class
);
// [...]

# The cached call
$res $cache->foobar2('1''2');

4.3.5. Zend_Cache_Frontend_File

4.3.5.1. Introduction

Zend_Cache_Frontend_File is a frontend driven by the modification time of a "master file". It's really interesting for examples in configuration or templates issues.

For instance, you have an XML configuration file which is parsed by a function which returns a "config object" (like with Zend_Config). With Zend_Cache_Frontend_File, you can store the "config object" into cache (to avoid the parsing of the XML config file at each time) but with a sort of strong dependency on the "master file". So, if the XML config file is modified, the cache is immediatly invalidated.

4.3.5.2. Available options

表 4.4. File frontend options

Option Data Type Default Value Description
master_file (mandatory) string the complete path and name of the master file

4.3.5.3. Examples

Use of this frontend is the same than of Zend_Cache_Core. There is no need of a specific example - the only thing to do is to define the master_file when using the factory.

4.3.6. Zend_Cache_Frontend_Page

4.3.6.1. Introduction

Zend_Cache_Frontend_Page is like Zend_Cache_Frontend_Output but designed for a complete page. It's impossible to use Zend_Cache_Frontend_Page for caching only a single block.

On the other hand, the "cache id" is calculated automatically with $_SERVER['REQUEST_URI'] and (depending on options) $_GET, $_POST, $_SESSION, $_COOKIE, $_FILES. More over, you have only one method to call (start()) because the end() call is fully automatic when the page is ended.

For the moment, it's not implemented but we plan to add a HTTP conditional system to save bandwith (the system will send a HTTP 304 Not Modified if the cache is hit and if the browser has already the good version).

4.3.6.2. Available options (for this frontend in Zend_Cache factory)

表 4.5. Page frontend options

Option Data Type Default Value Description
http_conditional boolean false use the http_conditional system (not implemented for the moment)
debug_header boolean false if true, a debug text is added before each cached pages
default_options array array(...see below...) an associative array of default options :
  • (boolean, true by default) cache : cache is on if true

  • (boolean, false by default) cache_with_get_variables : if true, cache is still on even if there are some variables in $_GET array

  • (boolean, false by default) cache_with_post_variables : if true, cache is still on even if there are some variables in $_POST array

  • (boolean, false by default) cache_with_session_variables : if true, cache is still on even if there are some variables in $_SESSION array

  • (boolean, false by default) cache_with_files_variables : if true, cache is still on even if there are some variables in $_FILES array

  • (boolean, false by default) cache_with_cookie_variables : if true, cache is still on even if there are some variables in $_COOKIE array

  • (boolean, true by default) make_id_with_get_variables : if true, the cache id will be dependent of the content of the $_GET array

  • (boolean, true by default) make_id_with_post_variables : if true, the cache id will be dependent of the content of the $_POST array

  • (boolean, true by default) make_id_with_session_variables : if true, the cache id will be dependent of the content of the $_SESSION array

  • (boolean, true by default) make_id_with_files_variables : if true, the cache id will be dependent of the content of the $_FILES array

  • (boolean, true by default) make_id_with_cookie_variables : if true, the cache id will be dependent of the content of the $_COOKIE array

regexps array array() an associative array to set options only for some REQUEST_URI, keys are (PCRE) regexps, values are associative arrays with specific options to set if the regexp matchs on $_SERVER['REQUEST_URI'] (see default_options for the list of available options) ; if several regexps match the $_SERVER['REQUEST_URI'], only the last one will be used

4.3.6.3. Examples

Use of Zend_Cache_Frontend_Page is really trivial :


<?php
// [...] // require, configuration and factory

$cache->start();
// if the cache is hit, the result is sent to the browser and the script stop here

// rest of the page ...

a more complex example which shows a way to get a centralized cache management in a bootstrap file (for using with Zend_Controller for example)


<?php

// [...] you should avoid to put too much lines before the cache section
// [...] for example, for optimal performances, "require_once" or "Zend_Loader::loadClass" should be
// [...] after the cache section

require_once 'Zend/Cache.php';

$frontendOptions = array(
   
'lifetime' => 7200,
   
'debug_header' => true// for debugging
   
'regexps' => array(
       
'^/$' => array('cache' => true),         // cache the whole IndexController
       
'^/index/' => array('cache' => true),    // cache the whole IndexController
       
'^/article/' => array('cache' => false), // we don't cache the ArticleController...
       
'^/article/view/' => array(              // ...but we cache the "view" action of
           
'cache' => true,                     // this ArticleController
           
'cache_with_post_variables' => true,    // and we cache even there are some variables in $_POST
           
'make_id_with_post_variables' => true,   // (but the cache will be dependent of the $_POST array)
       
)
   )
);
$backendOptions = array(
    
'cache_dir' => '/tmp/'
);

// getting a Zend_Cache_Frontend_Page object
$cache Zend_Cache::factory('Page''File'$frontendOptions$backendOptions);

$cache->start();
// if the cache is hit, the result is sent to the browser and the script stop here

// [...] the end of the bootstrap file (these lines won't be executed if the cache is hit)