Detailed explanation of how Smarty template engine caches

This article mainly introduces the Smarty template engine caching mechanism, and analyzes the principles of the Smarty template engine caching mechanism in the form of examples, how to enable and use it, and related precautions. Friends in need can refer to it. I hope to be helpful.

The details are as follows:

First let’s talk about smarty caching and compilation. These are two different concepts. Compilation is enabled by default, while the caching mechanism needs to be turned on manually. Smarty compiled The file is still a PHP file, so it is still compiled when executed. If it involves a database, it still needs to access the database, so the overhead is not small, so smarty caching is needed to solve it!

1. Enable global cache

$smarty->cache_dir = "/caches/"; //缓存目录
$smarty->caching = true; //开启缓存,为flase的时侯缓存无效
$smarty->cache_lifetime = 3600; //缓存时间

2. Use multiple caches for one page

For example: an article template page Multiple article pages will be generated, and of course cached into many pages. It is very simple to implement. Just set the second parameter in the display() method and specify a unique identifier. The following php code:

$smarty->display('index.tpl',$_GET["article_id"]);

As above, cache an article page through the second parameter of the article's id.

3. Reduce the cost of caching

In other words, the cached page does not need to be processed by the database, and can be judged through the is_cached() method!

if(!$smarty->is_cached('index.tpl')){
 //调用数据库
}
$smarty->display('index.tpl');

4. Clear the cache

Generally, the cache is not turned on during the development process, because the output result remains unchanged during the cache time, but it is turned on during the application process Caching can greatly improve web performance. The method to clear the cache is as follows:

clear_all_cache();//清除所有缓存
clear_cache('index.tpl');//清除index.tpl的缓存
clear_cache('index.tpl',cache_id);//清除指定id的缓存

5. Turn off local caching

If part of a page is cached, but another part does not need to be cached, You can do this. For example, to display the user's login name, you need to turn off the cache. Smarty provides the following three solutions:

(1) Use part of the insert template not to be cached

Definition A processing function to be used for an insert tag. The function name format is: insert_xx (array $params, object &$smarty) where xx is the name of insert. That is to say, if the function you define is insert_abc, use the method in the template For {insert name=abc}

parameters are passed in through $params

can also be made into an insert plug-in, the file name is: insert.xx.php, and the function name is: smarty_insert_aa($ params, &$smarty), xx definition is the same as above

(2)$smarty->register_block($params, &$smarty) prevents a certain block of the entire page from being cached

Define a block:

smarty_block_name($params,$content, &$smarty){return $content;} 
//name表示区域名

Register block:

$smarty->register_block(name, smarty_block_name, false);
//第三参数false表示该区域不被缓存

Template writing:

{name}内容 {/name}

Write as block plug-in:

Step 1: Define a plug-in function: block.cacheless.php and place it in smarty’s plugins directory

The content of block.cacheless.php is as follows:

Step 2: Write programs and templates

Sample program: testCacheLess.php

caching=true;
$smarty->cache_lifetime = 6;
$smarty->display(cache.tpl);
?>

Template used: cache.tpl

已经缓存的:{$smarty.now}

{cacheless}
没有缓存的:{$smarty.now}
{/cacheless}

Now run it and find that it is It doesn’t work, both lines of content are cached

Step 3: Rewrite Smarty_Compiler.class.php(Note: This file is very important, please back it up first. Restore when necessary)

Find:

Copy code The code is as follows:

$this->_plugins[block ][$tag_command] = array($plugin_func, null, null, null, true);

Modify to:

if($tag_command == cacheless) $this->_plugins[block][$tag_command] = array($plugin_func, null, null, null, false);
else $this->_plugins[block][$tag_command] = array($plugin_func, null, null, null, true);

You can also directly change the last parameter of the original sentence to false , that is, turn off the default cache.

(3) Use register_function to prevent the plug-in from outputting from the cache

index.tpl:

{current_time}{/p}
index.php:
function smarty_function_current_time($params, &$smarty){
  return date("Y-m-d H:m:s");
}
$smarty=new smarty();
$smarty->caching = true;
$smarty->register_function('current_time','smarty_function_current_time',false);
if(!$smarty->is_cached()){
  .......
}
$smarty->display('index.tpl');

Note:

Define a function, the function name format is ：smarty_type_name($params, &$smarty)
type is function

name is the user-defined label name, here it is {current_time}

two Parameters are required, even if they are not used in the function, they must be written. The functions of the two parameters are the same as above.

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