What is it, and what is a tick event in PHP?

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What is it, and what is a tick event in PHP?

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#1 by (4 votes)
#2 by (4 votes)

5

I was looking at some functions in PHP.net, and I came across a function called declare , and in the example, there is something like this:

declare(ticks=1);

Below is another example:

declare(ticks=1);

// A function called on each tick event
function tick_handler() {
    echo "tick_handler() called\n";
}
register_tick_function('tick_handler');

As I understand it, it is a method that is called every time the value of a variable is accessed / changed. Even reading the documentation, I did not understand exactly what this method does. In what situations could it be useful? What is a tick event ?

php

asked by anonymous 02.02.2014 / 00:23

2 answers

4

Functions registered as tick handlers are invoked after Zend Engine executes one or more PHP commands, not just when variables are changed.

This serves to execute tasks in parallel emulating a limited species of multi-tasking.

It is not a very used thing because it can make your scripts very slow, so there are not many useful applications for this function.

02.02.2014 / 01:21

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score 4 · Accepted Answer

In what situations could it be useful?

Adding to the mlemos response, giving more concrete examples ...

Ticks have some utility in debugging. For example, to define a memory usage profile (code optimization or memory leak detection). In an intensive script that sometimes exceeds memory limits, I can use this feature to set X to X to detect how much memory is being used by the process. I also used tests on PHP builds without active debugging, in the final stage of developing C extensions for PHP, to simulate break-points in code.

As this feature allows you to simulate "multi-threading", it can be used to simulate parallel computing. Some uses mentioned may be:

create resource checking routines, such as whether a connection remains active.

Simulate a simple Event Driven Application.

However, since the interpreter stops executing the "normal" code to execute the tick handler, if the code is too long, it can make the application very slow.