How to implement scheduled tasks in PHP_PHP Tutorial

I analyzed in uchome that this is how uchome does it

1. Store all scheduled tasks in the database

2. Every time the user performs an operation or opens a page, a scheduled task is executed in sequence. That is, it is judged in turn, and when the time is up, it is executed in the user process.

Uuchome’s scheduled task code is in ./source/function_cron.php

The above is just an analysis of the approximate results of the scheduled tasks in the uhome code, and I hope that someone has a good method and can share it.

ignore_user_abort()

I have thoroughly studied scheduled tasks some time ago and believe that there are many ideas for scheduled tasks, but the most suitable for the Web is the trigger type, which is similar to DZ and PHPWind. It seems that most web applications also do this. Let’s talk about a few other things for reference

1. In order to provide stable triggering, use crontab+wget or ab to provide scheduled access

　2. nohup + php writing daemon

3. Write an infinite loop directly in PHP and provide triggering. At this time, you need to use cache or database to assist in launching the loop, and you must use sleep or usleep to control the trigger frequency

　4, crontab+php

5. There are differences in web triggering methods. One is timed triggering and the other is periodic triggering. DZ and PHPWind are both timed triggers. The last one I used is periodic triggering

The specific implementation ideas are easy to think about, so I won’t go into details

If you have a host, you must use crontab to execute command line PHP

Nothing can only be written in code

It would be better to use crontab. If you use a loop, it is best to separate the loop from the specific processing program, otherwise the memory will keep increasing.

I accidentally discovered this function -ignore_user_abort in the PHP manual today. This function can help us implement scheduled tasks like cron in Linux. Let's take a look at how to implement it.

First, let’s take a look at the explanation of this function in the PHP manual

Description

int ignore_user_abort ([ bool $setting ] )

Sets whether a client disconnect should cause a script to be aborted.

That is to say, the following program will be executed regardless of whether the client closes the browser.

Let’s take a look at its parameters

Parameters

Setting

　If not set, the function will only return the current setting.

This function accepts a parameter to determine whether to enable the ignore_user_abort function.

Look at the return value:

　Return Values

Returns the previous setting, as a boolean.

It says here that the previous setting is returned, and it is a bool value. After my test, this statement is wrong. The returned value is obviously int type. If you don’t believe it, you can write a php file to test it.

Having said so much, how do you use this function in PHP to implement scheduled tasks? You can also use another function, this function is set_time_limit, through set_time_limit0) you can set the running time of the program to unlimited, PHP default The running time is 30 seconds, and the program can be executed without limit through set_time_limit(0). Just add ignore_user_abort(1) and set_time_limit(0) before the program is executed. How to write the final program? Let me give you an example.

The code is as follows: ​ ​

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