Introduction to php page cache ob series functions_PHP tutorial
Introduction to php page cache ob series functions
I have been exposed to the page cache of phpcms in the past few days and have some feelings. I won’t go into details about its benefits. It is generally used in pages with a lot of database queries. It is not suitable for pages that insert, modify, and delete
PHP page caching mainly uses the ob series of functions, such as ob_start(), ob_end_flush(), ob_get_contents()
The following is the encoding part.
1. Initialization function, usually setting the page cache path, cache file naming format, etc., which can be customized according to personal preferences. The identification ID used here is the encrypted $_SERVER[REQUEST_URI] parameter. There is an if judgment at the end of this function: if the cache period has not passed, load the cache file, otherwise load the source file.
Function page_init()
{
$url = $_SERVER['REQUEST_URI'];//Sub-url, this parameter is generally unique
$pageid = md5($url);
$dir = str_replace('/','_',substr($_SERVER['script_NAME'],1,-4));
//Directory naming method, such as exp_index
if(!file_exists($pd = PAGE_PATH.$dir.'/'))@mkdir($pd,0777) or die("$pd directory creation failed");
// Such as cache/page/exp_index/
define('PAGE_FILE',$pd.$pageid.'.html');
// Such as cache/page/exp_index/cc8ef22b405566745ed21305dd248f0e.html
$contents = file_get_contents(PAGE_FILE);//Read out
if($contents && substr($contents, 13, 10) > time() )//corresponds to the custom header added in the page_cache() function
{
echo substr($contents, 27);
exit(0);
}
return true;
}
2. Page caching function, a trick is used here: add a header information - expiration time - to the content of the cache file, so each time you only need to compare the expiration time in the header with the current time ( Perform it in the page_init() function) to determine whether the cache has expired.
Function page_cache($ttl = 0)
{
$ttl = $ttl ? $ttl : PAGE_TTL;//Cache time, default 3600s
$contents = ob_get_contents();//Get content from cache
$contents = " ".$contents;
//Add custom header: expiration time = generation time cache time
file_put_contents(PAGE_FILE, $contents);//Write to cache file
ob_end_flush();//Release cache
}
3. When using functions, please note that these two functions are executed in sequence, and don’t forget ob_start()
page_init();//Page cache initialization
ob_start();//Enable caching
...//Code segment
page_cache(60);//usually the last line
?>

PHP is mainly procedural programming, but also supports object-oriented programming (OOP); Python supports a variety of paradigms, including OOP, functional and procedural programming. PHP is suitable for web development, and Python is suitable for a variety of applications such as data analysis and machine learning.

PHP originated in 1994 and was developed by RasmusLerdorf. It was originally used to track website visitors and gradually evolved into a server-side scripting language and was widely used in web development. Python was developed by Guidovan Rossum in the late 1980s and was first released in 1991. It emphasizes code readability and simplicity, and is suitable for scientific computing, data analysis and other fields.

PHP is suitable for web development and rapid prototyping, and Python is suitable for data science and machine learning. 1.PHP is used for dynamic web development, with simple syntax and suitable for rapid development. 2. Python has concise syntax, is suitable for multiple fields, and has a strong library ecosystem.

PHP remains important in the modernization process because it supports a large number of websites and applications and adapts to development needs through frameworks. 1.PHP7 improves performance and introduces new features. 2. Modern frameworks such as Laravel, Symfony and CodeIgniter simplify development and improve code quality. 3. Performance optimization and best practices further improve application efficiency.

PHPhassignificantlyimpactedwebdevelopmentandextendsbeyondit.1)ItpowersmajorplatformslikeWordPressandexcelsindatabaseinteractions.2)PHP'sadaptabilityallowsittoscaleforlargeapplicationsusingframeworkslikeLaravel.3)Beyondweb,PHPisusedincommand-linescrip

PHP type prompts to improve code quality and readability. 1) Scalar type tips: Since PHP7.0, basic data types are allowed to be specified in function parameters, such as int, float, etc. 2) Return type prompt: Ensure the consistency of the function return value type. 3) Union type prompt: Since PHP8.0, multiple types are allowed to be specified in function parameters or return values. 4) Nullable type prompt: Allows to include null values and handle functions that may return null values.

In PHP, use the clone keyword to create a copy of the object and customize the cloning behavior through the \_\_clone magic method. 1. Use the clone keyword to make a shallow copy, cloning the object's properties but not the object's properties. 2. The \_\_clone method can deeply copy nested objects to avoid shallow copying problems. 3. Pay attention to avoid circular references and performance problems in cloning, and optimize cloning operations to improve efficiency.

PHP is suitable for web development and content management systems, and Python is suitable for data science, machine learning and automation scripts. 1.PHP performs well in building fast and scalable websites and applications and is commonly used in CMS such as WordPress. 2. Python has performed outstandingly in the fields of data science and machine learning, with rich libraries such as NumPy and TensorFlow.


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