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mysqli::poll

mysqli_poll

(PHP 5 >= 5.3.0, PHP 7)

mysqli::poll -- mysqli_poll轮询连接

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 ] )

轮询连接。 仅可用于 mysqlnd。 此方法是 static 的。

参数

read

要检测是否存在可以读取的结果集的连接的数组。

error

发生错误的,例如:SQL 语句执行失败或者已经断开的 连接的数组。

reject

没有可以读取的结果集的连接 的数组。

sec

秒为单位的最大等待时间,不可以为负数。

usec

微秒为单位的最大等待时间,不可以为负数。

返回值

成功执行则返回存在可以读取结果集的连接数量, 否则 FALSE

范例

Example #1 A mysqli_poll() 例程

<?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$errors$reject1)) {
        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

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User Contributed Notes 4 notes

up
4
shestero at meta dot ua
2 years ago
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 ?
up
5
l_sanczyk at hotmail dot com
4 years ago
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.
up
1
ekalashnikov at gmail dot com
1 year ago
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);
?>
up
0
ekalashnikov at gmail dot com
1 year ago
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);
?>
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