time_nanosleep
(PHP 5)
time_nanosleep — Delay for a number of seconds and nanoseconds
Описание
Delays program execution for the given number of seconds and nanoseconds .
Список параметров
- seconds
-
Must be a positive integer.
- nanoseconds
-
Must be a positive integer less than 1 billion.
Возвращаемые значения
Возвращает TRUE в случае успешного завершения или FALSE в случае возникновения ошибки.
If the delay was interrupted by a signal, an associative array will be returned with the components:
- seconds - number of seconds remaining in the delay
- nanoseconds - number of nanoseconds remaining in the delay
Примеры
Пример #1 time_nanosleep() example
<?php
// Careful! This won't work as expected if an array is returned
if (time_nanosleep(0, 500000000)) {
echo "Slept for half a second.\n";
}
// This is better:
if (time_nanosleep(0, 500000000) === true) {
echo "Slept for half a second.\n";
}
// And this is the best:
$nano = time_nanosleep(2, 100000);
if ($nano === true) {
echo "Slept for 2 seconds, 100 milliseconds.\n";
} elseif ($nano === false) {
echo "Sleeping failed.\n";
} elseif (is_array($nano)) {
$seconds = $nano['seconds'];
$nanoseconds = $nano['nanoseconds'];
echo "Interrupted by a signal.\n";
echo "Time remaining: $seconds seconds, $nanoseconds nanoseconds.";
}
?>
Примечания
Замечание: Для Windows-платформ эта функция не реализована.
Коментарии
You should take into account, if you use the function replacement down here, the CPU will be in use of 99% for the time of execution...
(A little bit better in this situation is to let the 'full seconds' go by a normal sleep command (makes the thread sleep!, and uses minimum cpu))
<?php
//THIS IS THE FUNCTION WE ARE TALKIN ABOUT
function timeWait($microtime)
{
//optimizations added by me [start]
//sleep the full seconds
sleep(intval($microtime));
//set the microtime to only resleep the last part of the nanos
$microtime = $microtime - intval($microtime);
//optimizations added by me [end]
$timeLimit = $microtime + array_sum(explode(" ",microtime()));
while(array_sum(explode(" ",microtime())) < $timeLimit)
{/*DO NOTHING*/}
return(true);
}
//THIS IS HOW WE CAN USE IT
echo "Process started at " . date("H:i:s") . " and " . current(explode(" ",microtime())) . " nanoseconds.<br>";
timeWait(5.5); //With this call the system will wait 5 seconds and a half. You can use either integer or float.
echo "Process completed at " . date("H:i:s") . " and " . current(explode(" ",microtime())) . " nanoseconds.";
?>
Documentation states that "seconds" must be positive. This is not correct, 0 is possible.
Rather, "seconds" must be non-negative.
Just glancing at this - and the note from over a year ago with a implementation for windows.. with 5.0.0 and higher it would be simplier to just do something like......
<?php
if (!function_exists('time_nanosleep')) {
function time_nanosleep($seconds, $nanoseconds) {
sleep($seconds);
usleep(round($nanoseconds/100));
return true;
}
}
?>
....off the top of my head - obviously simple enough there should be no mistakes.. but those are the ones that always seem to get ya :( .....
A response to the note below:
Your function is also useless, as the WinNT 32 kernel only functions at a minimum of about 10+ ms (1,000 us), rendering usleep() useless, because usleep uses the C function which is provided by the system (in this case, kernel32.dll).
You'll want to use a function that does not rely on the kernel, but rather something made for precise measurement:
<?php
function usleep_win( $micro_seconds )
{
if ( @function_exists( "socket_create" ) && @function_exists( "socket_select" ) )
{
$false = NULL;
$socket = array( socket_create( AF_INET, SOCK_RAW, $false ) );
socket_select( $false, $false, $socket, 0, $micro_seconds );
return true;
}
else
{
return false;
}
}
?>
This function will allow to you sleep for a specified microsecond, although I have measured it to be off by ~5 us.
Again, most of this depends on the hardware in your system. If you _REALLY_ need to be precise to < 10 us, you shouldn't be using WinNT anyways!