PHP mysqli poll() Method

The PHP mysqli::poll() / mysqli_poll() function is used for poll connections. The method can be used as static.

Note: Available only with mysqlnd.

Syntax

//Object-oriented style
public mysqli::poll(read, error, reject, seconds, microseconds)

//Procedural style
mysqli_poll(mysql, read, error, reject, seconds, microseconds)

Parameters

`mysql`	`Required.` For procedural style only: Specify a mysqli object returned by mysqli_connect() or mysqli_init().
`read`	`Required.` Specify list of connections to check for outstanding results that can be read.
`error`	`Required.` Specify list of connections on which an error occurred. For example - query failure or lost connection.
`reject`	`Required.` Specify list of connections rejected because no asynchronous query has been run on for which the function could poll results.
`seconds`	`Required.` Specify maximum number of seconds to wait. It must be non-negative.
`microseconds`	`Optional.` Specify maximum number of microseconds to wait. It must be non-negative.

Return Value

Returns number of ready connections upon success, false otherwise.

Example: mysqli_poll() example

The example below shows the usage of mysqli_poll() function.

<?php
$link1 = mysqli_connect();
$link1->query("SELECT 'demo'", 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, 0, 50000)) {
    continue;
  }

  foreach ($links as $link) {
    if ($result = $link->reap_async_query()) {
      print_r($result->fetch_row());
      if (is_object($result))
        mysqli_free_result($result);
    } else {
      die(sprintf("MySQLi Error: %s", mysqli_error($link)));
    }
    $processed++;
  }
} while ($processed < count($all_links));
?>

The output of the above code will be similar to:

Array
(
    [0] => demo
)

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