I have sript php with three function like this:
public function a($html,$text)
{
//blaa
return array();
}
public function b($html,$text){
//blaa
return array();
}
public function c($html,$text){
//blaa
return array();
}
require_once 'simple_html_dom.php';
$a=array();
$html=new simple_html_dom();
$a=$this->a($html,$text);
$b=$this->b($html,$text);
$c=$this->c($html,$text);
$html->clear();
unset($html);
$a=array_merge($a, $c);
$a=array_merge($a, $b);
a($html,$text) takes 5 seconds before giving a result
b($html,$text) takes 10 seconds before giving a result
c($html,$text) takes 12 seconds before giving a result
Thus the system takes 27 seconds before geving me a result, but I want take my result in 12 seconds. I can't use threads because my hosting does not support threads. How can I solve this problem?
PHP does not support this out of the box. If you really want to do this, you have two basic options (yep, it's going to be dirty). If you want a serious solution depending on your actual use-case, there is another option to consider.
Option 1: Use some AJAX-trickery
Create a page with a button that triggers three AJAX-calls to the different functions that you want to call.
Option 2: Run a command
If you're on UNIX, you can trigger a command from the PHP script to run a PHP script (php xyz.php) and that actually runs it on a different thread.
Serious option: use queues
Seriously: use a queue system like rabbitMQ or BeanstalkD to do these kind of things. Laravel supports it out of the box.
If the wait time is caused by blocking IO (waiting for server response) then curl_multi might help.
From the code you posted, though, it doesn't look like is your problem.
It looks more like simple html dom is taking a long time to parse your html. That's not too surprising because it's not a very good library. If this is the case you should consider switching to DomXPath.
You might wanna look into jQuery deferred objects.... $.when should handle this kinda of situation.
Related
Context :
I'm making a PHP websocket server (here) running as a DAEMON in which there is obviously a main loop listening for sockets connections and incoming data so i can't just create an other loop with a sleep(x_number_of_seconds); in it because it'll freeze my whole server.
I can't execute an external script with a CRON job or fork a new process too (i guess) because I have to be in the scope of my server class to send data to connected client sockets.
Does anyone knows a magic trick to achieve this in PHP ? :/
Some crazy ideas :
Keeping track of the last loop execution time with microtime(true), and compare it with the current time on each loop, if it's about my desired X seconds interval, execute the method... which would result in a very drunk and inconsistent interval loop.
Run a JavaScript setInterval() in a browser that will communicate with my server trough a websocket and tell it to execute my method... i said they where crazy ideas !
Additional infos about what i'm trying to achieve :
I'm making a little online game (RPG like) in which I would like to add some NPCs that updates their behaviours every X seconds.
Is there an other ways of achieving this ? Am I missing something ? Should I rewrite my server in Node.js ??
Thanks a lot for the help !
A perfect alternative doesn't seams to exists so I'll use my crazy solution #1 :
$this->last_tick_time = microtime(true);
$this->tick_interval = 1;
$this->tick_counter = 0;
while(true)
{
//loop code here...
$t= microtime(true) - $this->last_tick_time;
if($t>= $this->tick_interval)
{
$this->on_server_tick(++$this->tick_counter);
$this->last_tick_time = microtime(true) - ($t- $this->tick_interval);
}
}
Basically, if the time elapsed since the last server tick is greater or equal to my desired tick interval, execute on_server_tick() method. And most importantly : we subtract the time overflow to make the next tick happen faster if this one happened too late. This way we fill the gaps and at the end, if the socket_select timeout is set to 1 second, we will never have a gap greater than 1.99999999+ second.
I also keep track of the tick counter, this way I can use modulo (%) to execute code on multiple intervals like this :
protected function on_server_tick($counter)
{
if($counter%5 == 0)
{
// 5 seconds interval
}
if($counter%10 == 0)
{
// 10 seconds interval
}
}
which covers all my needs ! :D
Don't worry PHP, I won't replace you with Node.js, you still my friend.
It looks to me like the websocket-framework you are using is too primitive to allow your server to do other useful things while waiting for connections from clients. The only call to PHP's socket_select() function is hard-coded to a one second timeout, and it does nothing when the time runs out. It really ought to allow a callback or an outside loop.
Look at the http://php.net/manual/en/function.socket-select.php manual page. The last parameter is a timeout time. socket_select() waits for incoming data on a socket or until the timeout time is up, which sounds like what you want to do, but the library has no provision for it. Then look at how the library uses it in core/classes/SocketServer.php.
I'm assuming you call run() and then it just never returns to your calling code until it gets a message on the socket, which prevents you from doing anything.
I have to call a php function wich takes one second to response, in a "for" loop :
for ($i=0; $i<count($wsdlTab); $i++)
{
$serverLoadTab[$i] = $this->getServerLoad($wsdlTab[$i]);
}
My problem is that I would like to call my getServerLoad($wsdlTab[$i]) function simultaneous for each row of my $wsdlTab[$i], to not have to wait one second on each loop.
That is the reason why I need to call that function in a thread.
I have seen various ways to "emulate" threads, but I have not found any way with my limitations :
I have to get the return value of my getServerLoad($wsdlTab[$i]), and put in in an array
The Apache server is on Windows
Thanks in advance for your responses.
You should check out Gearman for parallel processing: http://gearman.org/
PHP doesn't really have asynchronous or threading built-in, as you've discovered.
What I might do in a case like this is separate the script I need to execute in a parallel, putting it into its own, small and self-contained PHP file. Then I'd execute that in a separate thread, storing the result somewhere I could monitor in the original thread. Once all the scripts have returned and filled the results, or with some given timeout, I would then continue with processing.
So, for instance,
prepareResults(); // something like clearing a db row or zeroing out a file or whatever
for ($i=0; $i<count($wsdlTab); $i++) {
exec('./doServerLoad.php ' . $wsdlTab[$i] . ' &');
}
while (!waitingForResults()) { // checking the results table/row/file
}
$serverLoadTab = parseTheResults();
May be request WSDLs in multi threads/forks using pcntl_fork() or curl_multi, and save them to the local drive. Then just parse them:
$soapClient = new SoapClient('WSDLSTemp/wsdl1.wsdl');
// .. do whatever you want...
Consider the following scenario:
http://www.restserver.com/example.php returns some content that I want to work with in my web-application.
I don't want to load it using ajax (SEO issues etc.)
My page takes 100ms to generate, the REST resource also takes 100ms to be loaded.
We assume that the 100ms generation time of my website occour before I begin working with the REST resource. What comes after that can be neglected.
Example Code:
Index.php of my website
<?
do_some_heavy_mysql_stuff(); // takes 100 ms
get_rest_resource(); // takes 100 ms
render_html_with_data_from_mysql_and_rest(); // takes neglectable amount of time
?>
Website will take ~200ms to generate.
I want to turn this into:
<?
Restclient::initiate_rest_loading(); // takes 0ms
do_some_heavy_mysql_stuff(); // takes 100 ms
Restclient::get_rest_resource(); // takes 0 ms because 100 ms have already passed since initiation
render_html_with_data_from_mysql_and_rest(); // takes neglectable amount of time
?>
Website will take ~100ms to generate.
To accomplis this I thought about using something like this:
(I am pretty sure this code will not work because this question is all about asking how to accomplish this, and whether its possible. I just thought some naive code could demonstrate it best)
class Restclient {
public static $buffer;
public static function initiate_rest_loading() {
// open resource
$handle = fopen ("http://www.restserver.com/example.php", "r");
// set to non blocking so fgets will return immediately
stream_set_blocking($handle,0);
// initate loading, but return immediately to continue website generation
fgets($handle, 40960);
}
public static function get_rest_resource() {
// set stream to blocking again because now we really want the data
stream_set_blocking($handle,1);
// get the data and save it so templates can work with it
self::$buffer = fgets($handle, 40960); templates
}
}
So final question:
Is this possible and how?
What do I have to keep an eye on (internal buffer overflows, stream lengths etc.)
Are there better methods?
Does this well work with http resources?
Any input is appriciated!
I hope I explained it understandable. If anything is unclear, please leave a comment, so I can rephrase it!
As "any input is appreciated", here is mine:
What you want is called asynchronous (you want to something while something else is being done "in the background").
To solve your problem, I thought on this:
Separate do_some_heavy_mysql_stuff and get_rest_resource in two different PHP scripts.
Use cURL "multi" ability to do simultaneous requests. Please, check:
curl_multi_init and related PHP functions
Simultaneous HTTP requests in PHP with cURL
This way, you can perform both scripts at the same time. Using cURL multi features, you can call http://example.com/do_some_heavy_mysql_stuff.php and http://example.com/get_rest_resource.php at the same time, and then play with the results as soon as they're available.
These are my first thoughts, and Iim sharing them with you. Maybe there are different and more interesting approaches... Good luck!
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
How could I make sure that the startProcess(); function is being called, but without halting the execution for myFunction(). I'll guess that there's a way to call a function and prevent it from returning it's value to thereby accomplishing this?
Pseudo-code:
function myFunction() {
startProcess();
return $something;
}
function startProcess() {
sleep(5);
// Do stuff that user doesn't should have to wait for.
}
You can't do it. There are some a few functions in PHP that allow async I/O, but nothing like the concurrency you require.
The reason for existing no language support is that PHP is designed to execute short-lived scripts, while the concurrency is managed by the HTTP daemon.
See also:
cur_mult_init
pcntl_fork (unix only)
http://wezfurlong.org/blog/2005/may/guru-multiplexing
To make a small addition to Artefecto's answer, there are some people who've attempted to recreate a sort of threads situation. You can find some information on it using google, but I doubt it'll be helpful as it's just too experimental and probably pretty unreliable.
Found one link that might be helpful for you.
http://w-shadow.com/blog/2008/05/24/improved-thread-simulation-class-for-php/
As far as I can tell from your question and tags, you want to do some background processing, meaning, essentially, multiple threads.
Unfortunately, PHP doesn't do this. There are some IO functions that are asynchronous, but in general you cannot do concurrent processing in PHP.
What is it you want startProcess() to do? There are many ways to keep the user from having to wait.
Emails are a good example: the thread that runs mail() spins until the message is accepted or rejected; you don't want a user to have to wait for that. So you queue up the task, and then process your queue on cron.
function myFunction() {
addToQueue();
return $something;
}
function addToQueue() {
// add stuff to the queue of tasks
}
function runQueue() {
// process the queue of tasks; called by cron.
}
Have you looked at Gearman for farming out this kind of background task?
I'm going to take a shot in the dark here, but does this function look like it could be a solution for your overall goal ?
http://php.net/manual/en/function.register-shutdown-function.php