hrtime

(PHP 7 >= 7.3.0, PHP 8)

hrtime — Get the system's high resolution time

Descrizione

hrtime(bool $as_number = false): array|int|float|false

Returns the system's high resolution time, counted from an arbitrary point in time. The delivered timestamp is monotonic and can not be adjusted.

Elenco dei parametri

as_number: Whether the high resolution time should be returned as array or number.

Valori restituiti

Returns an array of integers in the form [seconds, nanoseconds], if the parameter as_number is false. Otherwise the nanoseconds are returned as int (64bit platforms) or float (32bit platforms). Returns false on failure.

Esempi

Example #1 hrtime() usage

<?php
echo hrtime(true), PHP_EOL;
print_r(hrtime());
?>

Il precedente esempio visualizzerà qualcosa simile a:

10444739687370679
Array
(
    [0] => 10444739
    [1] => 687464812
)

Vedere anche:

The High resolution timing extension
microtime() - Restituisce l'attuale UNIX timestamp con i microsecondi

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User Contributed Notes 1 note

down

SenseiSimple ¶

6 years ago


This function is particularly necessary on VMs running on KVM, XEN (openstack, AWS EC2, etc) when timing execution times. 

On these platforms which lack vDSO the common method of using time() or microtime() can dramatically increase CPU/execution time due to the context switching from userland to kernel when running the `gettimeofday()` system call.

The common pattern is:
<?php
$time = -microtime(true);
sleep(5);
$end = sprintf('%f', $time += microtime(true));
?>

Substituted as:
<?php
$start=hrtime(true); 
sleep(5); 
$end=hrtime(true);
$eta=$end-$start;

echo $eta/1e+6; //nanoseconds to milliseconds
//5000.362419

//OR simply

$eta=-hrtime(true);
sleep(5);
$eta+=hrtime(true);

echo $eta/1e+6; //nanoseconds to milliseconds
//5000.088229
?>

There is also the new StopWatch class http://php.net/manual/en/class.hrtime-stopwatch.php

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