Is it possible to set a delay between 2 portion of code in PHP? I want something like this-
<?php
function firstFunc(){
echo "anything";
}
function secondFunc(){
echo "something";
}
// call first fumction
firstFunc();
// I want the script to wait for 2 seconds here, then call second function
secondFunc();
Is it possible?
If you want to delay the execution of something, you can use the sleep($seconds) function. Here's what the documentation says
Delays the program execution for the given number of seconds.
It returns zero on success and false on error.
So you can do something like:
<?php
function firstFunc(){
echo "anything";
}
function secondFunc(){
echo "something";
}
// call first function
firstFunc();
sleep(2); //Delays execution for 2 seconds.
secondFunc();
?>
Keep in mind though, PHP is a server side language. The only thing the client will receive from a PHP script(if the client has to receive anything at all) is HTML(or CSS, JS and so on). So when you run this code, the page will show nothing for 2 seconds and then output anything and something together because the delay is happening at a server level, and not on client machine. If you want a kind a delay where something is visible on the screen and then after 2 seconds anything appears, you want to use JavaScript.
Hope this helps :)
You should use function sleep(int seconds)
I wanted to execute a bunch of code for 5 seconds and if it has not finished executing within the specificed time frame I need to execute another piece of code..
Whether it's possible?
Ex..
There are two functions A and B
If A takes more than 30 seconds to execute the control should pass on to B
During function A you could periodically check how long the script has been executing, and if it goes over x seconds, run B:
function checkTime($start) {
$current = time();
$secondsToExecute = 5;
if (($start+$secondsToExecute) <= $current) {
func_b();
}
}
function func_a($start) {
// do some code
checkTime($start);
// do some code
checkTime($start);
// do some code
}
function func_b() {
// do something else
exit();
}
func_a(time());
http://php.net/manual/en/features.connection-handling.php
Set a time limit and a shutdown function, which checks if the status is 2 (timeout) and does your stuff if so.
One thing to note is that the time limit set this way only counts actual php processing time. Time spent with php waiting for another process or a database or http connection, etc, will not count and your time limit will not be considered reached.
If you need to count actual time that passed, even if it was not php processing time, you're going to have to go with the above suggested answer. Manually inserting that time check in places where it makes sense is the best, i.e. inside loops that you know may run too long, maybe even not on every iteration but on every N iterations, etc. Alternatively a more general approach is to use register_tick_function(), but that might lead to a noticeable performance hit with a low tick count, and you must take care to unregister it or use appropriate flags so you don't end up infinitely starting more and more calls to your timeout handling code once the timeout has happened.
Other approaches are also possible, you can register a handler for some signal using pcntl_signal() and have it sent to your process when the time limit is reached by an outside program ('man timeout' if you are on a linux box) or by a fork()-ed instance of your own php script, etc.
Is it possible to start a block of code (maybe just call a function) and if it doesn't execute within a certain time skip it.
//give this function 10 seconds to execute
$value = mega_function();// could take anything from 1-1000 seconds
//if 10 seconds have passed and the value is still not set, abort it and set $value = false;
No. You would have to either
Call the function inside an external file using curl or file_get_contents() - you can set a timeout there
Keep track of the time inside mega_function() and return() if necessary.
What does mega_function() do?
Try looking into threads, but it might be awkward to do something like this in PHP:)
Look at http://php.net/manual/en/function.pcntl-fork.php and all pnctl related functions for creating childs, sending signals between them, waiting for child to finish or killing threads.
I have php scripts that call perl scripts to do various things and sometimes I get it where it just goes on and on without getting a response back, this is based on the variable that is being passed to the perl script and I am doing a lot of different ones in succession so I can't get really debug it directly since I don't have a response from perl...
I would really like to just be able to set a php function or block of code to timeout after a certain number of seconds.. I have been searching on this but haven't found anything yet on how to do this,
I was thinking something like this could work but I don't think it would dynamically update the $time variable, but maybe there is a way to get this to work? Any advice is appreciated
$time = time();
$timeout = $time + 5; //just as an example
do {
// do stuff
} while ($time < $timeout)
Your best bet would be to use proc_open, sleep for your timeout amount and then call proc_terminate if the process still hasn't completed.
See http://us3.php.net/manual/en/book.exec.php for details on the proc_* family.
Well, I'm not so sure this question would have an answer based on how I asked it, so what I am going to do is do the perl call where php doesn't wait for a response and have perl write the output to a text file, then have php read this after specified number of seconds, I think this is the simplest way to do this, its just for a small app i am running on a local server
The question sort of says it all - is there a function which does the same as the JavaScript function setTimeout() for PHP? I've searched php.net, and I can't seem to find any...
There is no way to delay execution of part of the code of in the current script. It wouldn't make much sense, either, as the processing of a PHP script takes place entirely on server side and you would just delay the overall execution of the script. There is sleep() but that will simply halt the process for a certain time.
You can, of course, schedule a PHP script to run at a specific time using cron jobs and the like.
There's the sleep function, which pauses the script for a determined amount of time.
See also usleep, time_nanosleep and time_sleep_until.
PHP isn't event driven, so a setTimeout doesn't make much sense. You can certainly mimic it and in fact, someone has written a Timer class you could use. But I would be careful before you start programming in this way on the server side in PHP.
A few things I'd like to note about timers in PHP:
1) Timers in PHP make sense when used in long-running scripts (daemons and, maybe, in CLI scripts). So if you're not developing that kind of application, then you don't need timers.
2) Timers can be blocking and non-blocking. If you're using sleep(), then it's a blocking timer, because your script just freezes for a specified amount of time.
For many tasks blocking timers are fine. For example, sending statistics every 10 seconds. It's ok to block the script:
while (true) {
sendStat();
sleep(10);
}
3) Non-blocking timers make sense only in event driven apps, like websocket-server. In such applications an event can occur at any time (e.g incoming connection), so you must not block your app with sleep() (obviously).
For this purposes there are event-loop libraries, like reactphp/event-loop, which allows you to handle multiple streams in a non-blocking fashion and also has timer/ interval feature.
4) Non-blocking timeouts in PHP are possible.
It can be implemented by means of stream_select() function with timeout parameter (see how it's implemented in reactphp/event-loop StreamSelectLoop::run()).
5) There are PHP extensions like libevent, libev, event which allow timers implementation (if you want to go hardcore)
Not really, but you could try the tick count function.
http://php.net/manual/en/class.evtimer.php is probably what you are looking for, you can have a function called during set intervals, similar to setInterval in javascript. it is a pecl extension, if you have whm/cpanel you can easily install it through the pecl software/extension installer page.
i hadn't noticed this question is from 2010 and the evtimer class started to be coded in 2012-2013. so as an update to an old question, there is now a class that can do this similar to javascripts settimeout/setinterval.
Warning: You should note that while the sleep command can make a PHP process hang, or "sleep" for a given amount of time, you'd generally implement visual delays within the user interface.
Since PHP is a server side language, merely writing its execution output (generally in the form of HTML) to a web server response: using sleep in this fashion will generally just stall or delay the response.
With that being said, sleep does have practical purposes. Delaying execution can be used to implement back off schemes, such as when retrying a request after a failed connection. Generally speaking, if you need to use a setTimeout in PHP, you're probably doing something wrong.
Solution: If you still want to implement setTimeout in PHP, to answer your question explicitly: Consider that setTimeout possesses two parameters, one which represents the function to run, and the other which represents the amount of time (in milliseconds). The following code would actually meet the requirements in your question:
<?php
// Build the setTimeout function.
// This is the important part.
function setTimeout($fn, $timeout){
// sleep for $timeout milliseconds.
sleep(($timeout/1000));
$fn();
}
// Some example function we want to run.
$someFunctionToExecute = function() {
echo 'The function executed!';
}
// This will run the function after a 3 second sleep.
// We're using the functional property of first-class functions
// to pass the function that we wish to execute.
setTimeout($someFunctionToExecute, 3000);
?>
The output of the above code will be three seconds of delay, followed by the following output:
The function executed!
if you need to make an action after you execute some php code you can do it with an echo
echo "Success.... <script>setTimeout(function(){alert('Hello')}, 3000);</script>";
so after a time in the client(browser) you can do something else, like a redirect to another php script for example or echo an alert
There is a Generator class available in PHP version > 5.5 which provides a function called yield that helps you pause and continue to next function.
generator-example.php
<?php
function myGeneratorFunction()
{
echo "One","\n";
yield;
echo "Two","\n";
yield;
echo "Three","\n";
yield;
}
// get our Generator object (remember, all generator function return
// a generator object, and a generator function is any function that
// uses the yield keyword)
$iterator = myGeneratorFunction();
OUTPUT
One
If you want to execute the code after the first yield you add these line
// get the current value of the iterator
$value = $iterator->current();
// get the next value of the iterator
$value = $iterator->next();
// and the value after that the next value of the iterator
// $value = $iterator->next();
Now you will get output
One
Two
If you minutely see the setTimeout() creates an event loop.
In PHP there are many libraries out there E.g amphp is a popular one that provides event loop to execute code asynchronously.
Javascript snippet
setTimeout(function () {
console.log('After timeout');
}, 1000);
console.log('Before timeout');
Converting above Javascript snippet to PHP using Amphp
Loop::run(function () {
Loop::delay(1000, function () {
echo date('H:i:s') . ' After timeout' . PHP_EOL;
});
echo date('H:i:s') . ' Before timeout' . PHP_EOL;
});
Check this Out!
<?php
set_time_limit(20);
while ($i<=10)
{
echo "i=$i ";
sleep(100);
$i++;
}
?>
Output:
i=0 i=1 i=2 i=3 i=4 i=5 i=6 i=7 i=8 i=9 i=10