This does not work with mysqlnd and is marked as wontfix: https://bugs.php.net/bug.php?id=52561
(PHP 5, PHP 7, PHP 8)
mysqli::ping -- mysqli_ping — ping 一个连接，或者如果连接处于断开状态，重新连接
此函数自 PHP 8.4.0 起弃用。强烈建议不要应用此函数。
面向对象风格
过程化风格
检查到服务器的连接是否还正常。在启用 mysqli.reconnect 选项的前提下，如果连接已经断开，ping 操作会尝试重新建立连接。
注意: mysqlnd 驱动会忽略 php.ini 中的 mysqli.reconnect 选项，所以它不会自动重连。
客户端建立连接之后，长时间处于闲置状态，可以用此函数来检查服务器是否关闭了这个连接，如有必要，将会自动重新建立到服务器的连接。
If mysqli error reporting is enabled (MYSQLI_REPORT_ERROR) and the requested operation fails,
a warning is generated. If, in addition, the mode is set to MYSQLI_REPORT_STRICT,
a mysqli_sql_exception is thrown instead.
| 版本 | 说明 |
|---|---|
| 8.4.0 |
mysqli::ping() 和 mysqli_ping()
都已弃用。自 PHP 8.2.0 起，reconnect 功能已不可用，因此该函数已过时。
|
示例 #1 mysqli::ping() 示例
面向对象风格
<?php
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");
/* 检查连接 */
if ($mysqli->connect_errno) {
printf("Connect failed: %s\n", $mysqli->connect_error);
exit();
}
/* 检查连接是否还活跃 */
if ($mysqli->ping()) {
printf ("Our connection is ok!\n");
} else {
printf ("Error: %s\n", $mysqli->error);
}
/* 关闭连接 */
$mysqli->close();
?>过程化风格
<?php
$link = mysqli_connect("localhost", "my_user", "my_password", "world");
/* 检查连接 */
if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());
exit();
}
/* 检查连接是否还活跃 */
if (mysqli_ping($link)) {
printf ("Our connection is ok!\n");
} else {
printf ("Error: %s\n", mysqli_error($link));
}
/* 关闭连接 */
mysqli_close($link);
?>以上示例会输出：
Our connection is ok!
This does not work with mysqlnd and is marked as wontfix: https://bugs.php.net/bug.php?id=52561As jay at grooveshark dot com very helpfully pointed out, the mysqlnd driver which is becoming pretty standard does not obey reconnect commands. If you have a DB wrapper class (which hopefully you do) you can implement your own version of ping() such as:
<?php
class db extends mysqli
{
private $db_host;
private $db_user;
private $db_pass;
private $db_name;
private $persistent;
public function __construct($db_host, $db_user, $db_pass, $db_name, $persistent = true)
{
$this->db_host = $db_host;
$this->db_user = $db_user;
$this->db_pass = $db_pass;
$this->db_name = $db_name;
$this->persistent = $persistent;
parent::init();
parent::options(MYSQLI_OPT_CONNECT_TIMEOUT, 1);
@parent::real_connect(($this->persistent ? 'p:' : '') . $this->db_host, $this->db_user, $this->db_pass, $this->db_name);
if ($this->connect_errno)
die("All DB servers down!\n");
}
public function ping()
{
@parent::query('SELECT LAST_INSERT_ID()');
if ($this->errno == 2006)
$this->__construct($this->db_host, $this->db_user, $this->db_pass, $this->db_name, $this->persistent);
}
...
}
$db = new db(DB_HOST, DB_USER, DB_PASS, DB_NAME);
// Some code that potentially takes a really long time to execute goes here
// Ping for safety to try to gracefully reconnect
$db->ping();
// Now we should be able to run queries again
$db->query('SELECT LAST_INSERT_ID()');
?>
If you wanted you could even put "$this->ping();" at the top of db::query() to avoid any explicit reconnection calls but I wouldn't recommend it due to the (slight) overhead of running the cheap "SELECT LAST_INSERT_ID()" query every time prior to running your real intended query. There are probably even cheaper queries to run in favor of "SELECT LAST_INSERT_ID()" but it was the first that came to mind and is cheap enough for most purposes since you shouldn't be calling ping() a whole bunch anyway.The behaviour about the option mysqli.reconnect is default set to Off at Debian PHP Packages. So i would recommend to update the first line description about the recommendation at the option mysqli.reconnect. (practice note ;))