PHP usleep

usleep() function is an inbuilt function of PHP standard library which is used for making the current script in execution to a halt for some microseconds and milliseconds as per specified requirement. There is no specific return type for the PHP usleep function which makes the time-space complexity of the function constant. PHP usleep function behaves like sleep function only with a mere difference of the fact that in PHP usleep function that parameter needs to be specified in a proper way till It gets passed as a parameter from the function.

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Syntax:

usleep(microseconds)

The syntax flow is in a way where the specified parameter needs to be passed from the function and then the function will be made available according to the requirement.

Passing of the parameter from function is a mandatory approach. There is no return type only makes the function in execution to halt for a certain interval of time as mentioned.

How usleep Function works in PHP?

usleep function() is an inbuilt function in PHP which is used to make the entire process in execution to halt for some microseconds or milliseconds. Let’s see the working flow of usleep function which is as follows :

• usleep function is a function in PHP related to time which is used for bringing the entire process in execution to halt according to the passed parameter to the function which can be either in milliseconds or microseconds depending upon the requirement of the user or implementor.
• This function passes an argument or parameter that is a mandatory element of the entire function without which execution of a function is not possible and useless.
• Time space trade off for using the usleep function is constant as there is no major changes or data structure involving pointer transitions or external manipulation.
• The behavior for usleep function is same as sleep function with a mere fact of difference that the usleep function passes that mandatory parameter through the function that needs to be for small amount or say for fraction of seconds otherwise it might bring the entire system with some unusual behavior which is not required.
• There is no return type for this function.
• There are many types of errors and exceptions which is dealt with at the time of execution of usleep function in PHP.
• The error associated with the usleep function in PHP occurs in a way where the function throws an error in case the number of seconds specified as a parameter is negative.
• There is some major complexity or say performance related issue while using usleep() function in PHP which is mostly related to consumption of CPU cycles and must be used only if it is necessary. This comes out to be a major drawback for the usleep function for reference.
• Thus, the alternative approach to the PHP usleep() function is to use sleep() function which is considered a more preferred approach as it does not consume a greater number of CPU cycles compared to usleep() function.
• There is a version compatibility issue also which needs to be kept in mind the usleep() function in PHP is used for the PHP version of 4+. Also, the changelog for this version describes that the function did not work on the Windows platform until PHP 5.
• There is a probability that on Windows the system might feel some delay as the system might sleep longer than the given or specified time depending on the hardware.
• There are other functions also related to sleep and timing constraints which includes time_nanosleep(), time_sleep_until(), set_time_limit().
• There are very minute differences related to the mentioned function and usleep function but they do possess very minute differences within them which may remove all the queries and doubts for the users related to all the inbuilt functions related to the same standard libraries and also while execution of these kind of function very important point to keep in mind is the requirement.
• Requirement related to the use of PHP usleep should be clear and crisp otherwise the execution of usleep function might land the user with some unwanted errors and exception that will increase the complexity.

Examples of PHP usleep

Following are the examples are given below:

Example #1

This program demonstrates the usleep() function in PHP which is used for representing the delay in execution while informing the end user of the time with the specified parameter to the function with 8 milliseconds delay as shown in the output.

Code:

<!DOCTYPE html>
<html>
<body>
<?php
echo date('hr:in:sec')
. "<br>";
usleep(800000);
echo date('hr:in:sec');
?>
</body>
</html>

Output:

Example #2

This program demonstrates the difference in both the usleep() and sleep() function with the difference in CPU circle consumption. This takes input as for date in sleep() mode for 5 seconds and then start again once the halt completes for 3 seconds and behaves merely different as compared to usleep as shown in the output.

Code:

<?php
echo date('h:i:s')
. "\n";
sleep(5);
echo date('hr:in:sec')
. "\n";
?>

Output:

Example #3

This program demonstrates the difference in usleep with time_nanosecond() function containing difference with seconds and nanoseconds almost like usleep() and sleep() function as shown in the output.

Code:

<!DOCTYPE html>
<html>
<body>
<?php
if (time_nanosleep(3,5000000) === true)
{
echo "nanosleep time for 3 or 5 seconds.";
}
?>
</body>
</html>

Output:

Example #4

This program demonstrates the difference between the PHP usleep() function and time_sleep_until() function which is used for getting the values of time in boolean format as shown in the output.

Code:

<?php
var_dump(time_sleep_until(time()+1));
var_dump(time_sleep_until(microtime(false)+0.8));
?>

Output:

Note: If the time_sleep_until() function compared to sleep function will be used then it will return value as false when given a negative value.

Conclusion

PHP usleep() function in PHP is a function which is used for making the program in execution to halt for analyzing the fault or may be for some requirement changes but is useful for programmers as it can be handled accordingly in PHP and is a great source of manipulation with scripts in PHP.

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