PHP mysqli: poll() function

mysqli_poll function / mysqli::poll

The mysqli_poll function / mysqli::poll — Poll connections


Object oriented style

public static int mysqli::poll ( array &$read , array &$error , array &$reject , int $sec [, int $usec ] )

Procedural style

int mysqli_poll ( array &$read , array &$error , array &$reject , int $sec [, int $usec ] )


Name Description
read List of connections to check for outstanding results that can be read.
error List of connections on which an error occured, for example, query failure or lost connection.
reject List of connections rejected because no asynchronous query has been run on for which the function could poll results.
sec Maximum number of seconds to wait, must be non-negative.
usec Maximum number of seconds to wait, must be non-negative.

Usage: Procedural style



Name Description Required/Optional
connection Specifies the MySQL connection to use Required

Return value:

Returns number of ready connections upon success, FALSE otherwise.

Version: PHP 5, PHP 7


$link1 = mysqli_connect();
$link1->query("SELECT 'test'", MYSQLI_ASYNC);
$all_links = array($link1);
$processed = 0;
do {
    $links = $errors = $reject = array();
    foreach ($all_links as $link) {
        $links[] = $errors[] = $reject[] = $link;
    if (!mysqli_poll($links, $errors, $reject, 1)) {
    foreach ($links as $link) {
        if ($result = $link->reap_async_query()) {
            if (is_object($result))
        } else die(sprintf("MySQLi Error: %s", mysqli_error($link)));
} while ($processed < count($all_links));

See also

PHP Function Reference

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PHP: Tips of the Day

Di?erence between __CLASS__, get_class() and get_called_class()

__CLASS__ magic constant returns the same result as get_class() function called without parameters and they both return the name of the class where it was defined (i.e. where you wrote the function call/constant name ).

In contrast, get_class($this) and get_called_class() functions call, will both return the name of the actual class which was instantiated:


class Definition_Class {
 public function say(){
 echo '__CLASS__ value: ' . __CLASS__ . "\n";
 echo 'get_called_class() value: ' . get_called_class() . "\n";
 echo 'get_class($this) value: ' . get_class($this) . "\n";
 echo 'get_class() value: ' . get_class() . "\n";
class Actual_Class extends Definition_Class {}
$c = new Actual_Class();


__CLASS__ value: Definition_Class
get_called_class() value: Actual_Class
get_class($this) value: Actual_Class
get_class() value: Definition_Class


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