I have a block of code and want to run it after certain time intervals, say after every 3 seconds. If I get required result it should die otherwise another request will be sent after 3 seconds. Any idea to do it with php.
Thanks in advance for any help
You can sleep in a loop:
while (true) {
$result = doSomething;
if (resultIsGood) {
break;
}
sleep(3);
}
If you don't want to keep the browser waiting, you can look up ignore_user_abort() solutions on Google.
If what you want to execute MySQL queries (and nothing else), maybe using the MySQL event scheduler could fit your need:
http://dev.mysql.md/doc/refman/5.5/en/events-overview.html
Related
I have built a query ($query_q = "SELECT * FROM `table`;") and am trying to execute it within a function.
public function read_from_table() {
$query_q = "SELECT * FROM `table`";
$query_a = mysql_query($query_q);
while (mysql_fetch_array($query_a)) {
echo "Did it!";
//OR AS TRIED ANOTHER WAY
return "Did it!";
}
}
And called as such:
echo $classInstance->read_from_table();
//OR AS TRIED ANOTHER WAY
$classInstance->read_from_table();
Both the ways that the function and the class have been made have been tried in every conceivable way, and yet I still get no result.
I was getting the error that says the xecution time has exceeded the limit of 30 seconds, so I added the ini_set('max_execution_time', 0); (knowing this removes time limit altogether) to see if the query would execute at all, it has been running now for 30 minutes without a sign of life. Why is the query not executing?
Additional comments:
I am aware that I am using the depreciated mysql_* functions, this is at client request and will be updated after the site has been made live and is complete to a point where I am ready to change it all to mysqli->* functions.
The table that I am calling (it's name has been stripped and replaced with `table`) has only 9 rows in it, so this should not affect the execution time greatly (or will it?).
I have had to strip all sensitive information from the function to satisfy the client and my employer. Please keep in mind that I cannot disclose and information that the client and my employer do not wish to disclose.
The issue was that the internet and server had gone down.
This has since been sorted and is operational.
Thank you for help and support in this.
DigitalMediaMan
try
error_reporting(E_ALL);
if all ok, try run this query from console, look, how many times query will be performed
before this, kill old process in database(show processlist and kill pid)
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 am running a script which constantly works over my Database. How ever It is necessary to restart the script once an hour. Obviously I can't do that automatically. I don't want to use daemon, its too complex for me right now. Easier solution is to use cron job but biggest drawback is, it won't stop the last script. Script runs in infinite while(true) loop
However is that possible if I make function in a script, lets say
function exitScript()
{
exit;
}
And then on Cron job if i do something like
php /home/Path/public_html/webservice/myScript.php exitScript and then
php /home/Path/public_html/webservice/myScript.php
What will be the format and How can I run both one by one using cron job or make another PHP who does so?
I need advice.
Here is a little trick easy to made which you can use..
1st set you cron jobs to run on each hour.
* */1 ..... cronjob.php
2nd At start of your script define 1 constant with time:
define('SCRIPT_START_TIME', time());
3rd At your exit script set up a condition check to exit if 59 minutes are passed from this constant to current time.. :)
function exitScript()
{
if((time() - SCRIPT_START_TIME) > 59*60){
exit();
}
}
4th at each while LOOP start the exit script .
In PHP, I want to put a number of second delay on each iteration of the loop.
for ($i=0; $i <= 10; $i++) {
$file_exists=file_exists($location.$filename);
if($file_exists) {
break;
}
//sleep for 3 seconds
}
How can I do this?
Use PHP sleep() function. http://php.net/manual/en/function.sleep.php
This stops execution of next loop for the given number of seconds. So something like this
for ($i=0; $i <= 10; $i++) {
$file_exists=file_exists($location.$filename);
if($file_exists) {
break;
}
sleep(3); // this should halt for 3 seconds for every loop
}
I see what you are doing... your delaying a script to constantly check for a file on the filesystem (one that is being uploaded or being written by another script I assume). This is a BAD way to do it.
Your script will run slowly. Choking the server if several users are running that script.
Your server may timeout for some users.
HDD access is a costly resource.
There are better ways to do this.
You could use Ajax. And use a timeout to call your PHP script every few seconds. This will avoid the slow script loading. And also you can keep doing it constantly (the current for loop will only run for 33 seconds and then stop).
You can use a database. In some cases database access is faster than HDD access. Especially with views and caching. The script creating the file/uploading the file can set a flag in a table (i.e. file_exists) and then you can have a script that checks that field in your database.
You can use sleep(3) which sleeps the thread for 3 seconds.
Correction sleep method in php are in seconds.
Hare are two ways to sleep php script for some period of time. When you have your code and want to pause script working for some time use these functions.
In these examples the first part of code will be done on script run and the second part of code will be done but with time delay.
Using sleep() function you can define sleep time in seconds.
Example:
echo "Message 1";
// The first part of code.
$timeInSeconds = 3;
sleep($timeInSeconds);
// The second part of code.
echo "Message 2";
This way it is possible to sleep php script for 3 seconds. Using this function you can sleep script for whole number (integer) of seconds.
Using usleep() function you can define sleep time in microseconds. This sleep time is convenient for intervals that require more precise time than one second.
Example:
echo "Message 1";
// The first part of code.
$timeInMicroSeconds = 2487147;
usleep($timeInMicroSeconds);
// The second part of code.
echo "Message 2";
You can use this function if you want to sleep php for smaller time values than second (float). In this example I have put script to sleep for 2.487147 seconds.
Have you considered using a PHP Daemon script using supervisorD. I use it in multiple tasks that are required to be running all the time.
The catch is making sure that each time you are running your script you check for memory resources. If its too high, stop the process and then let it restart itself up again.
I have successfully used this process to be always checking database records for tasks to process.
It might be overkill but worth considering.
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.