mysqli::poll

mysqli_poll

(PHP 5 >= 5.3.0, PHP 7)

mysqli::poll -- mysqli_poll — Poll connections

说明

面向对象风格

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

过程化风格

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

Poll connections. 仅可用于 mysqlnd。 The method can be used as static.

参数

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 microseconds to wait, must be non-negative.

返回值

Returns number of ready connections upon success, FALSE otherwise.

范例

Example #1 A mysqli_poll() example

<?php
$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, $reject, 1)) {
        continue;
    }
    foreach ($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));
?>

以上例程会输出：

Array
(
    [0] => test
)

参见

User Contributed Notes

ekalashnikov at gmail dot com 05-Oct-2017 04:07
Improved version of using polling to check for slow query,
"KILL #ID" does not work if id of the myqsli link is the same as the one that kills it,
so you have to disconnect from mysqli and connect again with new link to
kill the #ID.
<?php
// Slow SQL Query
      $SelectSql = 'SELECT * FROM SLOW_QUERY';
      $link = mysqli_connect('localhost','user','pass','database');
      mysqli_query($SelectSql, MYSQLI_ASYNC);
      $thread_id = mysqli_thread_id($link);
      // Ignore user abort so we can kill the query
      ignore_user_abort(true);
      $MaxTime = 5; // seconds
      $Overtime = false;
      $StartTime = time();
      do
      {
          // Poll MySQL
        $links = $errors = $reject = array($link);
        $poll = mysqli_poll($links, $errors, $reject, 0, 500000);
         // Check if the connection is aborted and the query was killed
        if (connection_aborted()) {
          $link_new = mysqli_connect('localhost','user','pass','database');
          mysqli_kill($link_new, $thread_id);
          $kill = mysqli_kill($link_new, $thread_id);
          if ($kill)
          {
            die();
          }
        }
        $EndTime = time();
        // Check overtime, kill if detected overtime
        if ($EndTime - $StartTime > $MaxTime)
        {
          $link_new = mysqli_connect('localhost','user','pass','database');
          mysqli_kill($link_new, $thread_id);
          $Overtime = true;
          echo 'Error: Query took over '.$Overtime.'.';
        }
      } while (!$poll && $Overtime == false);
?>
ekalashnikov at gmail dot com 04-Oct-2017 06:54
This is how you can test and terminate slow query with polling.

<?php
// Slow SQL Query
      $SelectSql = 'SELECT * FROM SLOW_QUERY';
      $link = mysqli_connect('localhost','user','pass','database');
      mysqli_query($SelectSql, MYSQLI_ASYNC);
      $thread_id = mysqli_thread_id($link);
      // Ignore user abort so we can kill the query
      ignore_user_abort(true);
      $MaxTime = 5; // seconds
      $Overtime = false;
      $StartTime = time();
      do
      {
          // Poll MySQL
        $links = $errors = $reject = array($link);
        $poll = mysqli_poll($links, $errors, $reject, 0, 500000);
         // Check if the connection is aborted and the query was killed
        if (connection_aborted() && mysqli_kill($link, $thread_id)) {
            die();
        }
        $EndTime = time();
        // Check overtime, kill if detected overtime
        if ($EndTime - $StartTime > $MaxTime)
        {
          mysqli_kill($link, $thread_id);
          $Overtime = true;
          echo 'Error: Query took over '.$Overtime.'.';
        }
      } while (!$poll && $Overtime == false);
?>
shestero at meta dot ua 21-Jan-2016 09:24
Sometime it's not clear what does it mean as connection is "ready" . Does it mean the query completed or just some records ready to read?
Is it possible to use asynchronous (unblocking) and unbuffered SELECT-query? I.e. with both MYSQLI_ASYNC|MYSQLI_USE_RESULT

I want some poll-like code inside my loop that has four case-options:
1. Poll wait time-out is over but no records of result set is ready.
2. One or more records are ready to read (but the query still running).
3. Query is successfully over (completed; no more records).
4. Error.

Is it possible?

As I understood the operation of reading a record from unbuffered query is blocking if there are no ready records at the moment, and there is no functions to get out how much records are ready ?
l_sanczyk at hotmail dot com 22-Jul-2014 04:56
You can use the following code to execute, for example, 10 simultaneous queries:

$query = "SELECT `field1`, `field2` FROM `table` WHERE `field1`='something'";

$all_links = array();
for($i=0; $i<10; $i++) {
    $link = mysqli_connect("your.mysql.server.here","your@user","pa$$w0rd",DataBase_Name");
    $link->query($query, MYSQLI_ASYNC);
    $all_links[] = $link;
}

$processed = 0;
do {
    $links = $errors = $reject = array();
    foreach ($all_links as $link) {
        $links[] = $errors[] = $reject[] = $link;
    }
    if (!mysqli_poll($links, $errors, $reject, 1)) {
        continue;
    }
    foreach ($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));

NOTE: If you get a "Warning: mysqli::query() expects parameter 2 to be long, string given" you have a mysqlnd installation or configuration issue.